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Sample records for paleoproterozoic snowball earth

  1. Dynamics of a Snowball Earth ocean.

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    Ashkenazy, Yosef; Gildor, Hezi; Losch, Martin; Macdonald, Francis A; Schrag, Daniel P; Tziperman, Eli

    2013-03-07

    Geological evidence suggests that marine ice extended to the Equator at least twice during the Neoproterozoic era (about 750 to 635 million years ago), inspiring the Snowball Earth hypothesis that the Earth was globally ice-covered. In a possible Snowball Earth climate, ocean circulation and mixing processes would have set the melting and freezing rates that determine ice thickness, would have influenced the survival of photosynthetic life, and may provide important constraints for the interpretation of geochemical and sedimentological observations. Here we show that in a Snowball Earth, the ocean would have been well mixed and characterized by a dynamic circulation, with vigorous equatorial meridional overturning circulation, zonal equatorial jets, a well developed eddy field, strong coastal upwelling and convective mixing. This is in contrast to the sluggish ocean often expected in a Snowball Earth scenario owing to the insulation of the ocean from atmospheric forcing by the thick ice cover. As a result of vigorous convective mixing, the ocean temperature, salinity and density were either uniform in the vertical direction or weakly stratified in a few locations. Our results are based on a model that couples ice flow and ocean circulation, and is driven by a weak geothermal heat flux under a global ice cover about a kilometre thick. Compared with the modern ocean, the Snowball Earth ocean had far larger vertical mixing rates, and comparable horizontal mixing by ocean eddies. The strong circulation and coastal upwelling resulted in melting rates near continents as much as ten times larger than previously estimated. Although we cannot resolve the debate over the existence of global ice cover, we discuss the implications for the nutrient supply of photosynthetic activity and for banded iron formations. Our insights and constraints on ocean dynamics may help resolve the Snowball Earth controversy when combined with future geochemical and geological observations.

  2. Snowball Earth: Skating on Thin Ice?

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    Roberson, A. L.; Stout, A. M.; Pollard, D.; Kasting, J. F.

    2011-12-01

    There is evidence of at least two intervals of widespread glaciation during the late Neoproterozoic (600-800 Myr ago), which are commonly referred to as "Snowball Earth" episodes. The global nature of these events is indicated by the fact that glacial deposits are found at low paleolatitudes during this time. Models of a global glacial event have produced a variety of solutions at low latitudes: thick ice, thin ice, slushball, and open ocean . The latter two models are similar, except that the slushball model has its ice-line at higher latitudes. To be viable, a model has to be able to account for the survival of life through the glaciations and also explain the existence of cap carbonates and other glacial debris deposited at low latitudes. The "thick-ice" model is not viable because kilometers of ice prevent the penetration of light necessary for the photosynthetic biota below. The "slushball" model is also not viable as it does not allow the formation of cap carbonates. The "thin-ice" model has been discussed previously and can account for continuation of photosynthetic life and glacial deposits at low paleolatitudes. The recently proposed "open-ocean" or "Jormungand" model also satisfies these requirements. What is it, though, that causes some models to produce thin ice near the equator and others to have open water there? We examine this question using a zonally symmetric energy balance climate model (EBM) with flowing sea glaciers to determine what parameter ranges produce each type of solution.

  3. Investigating the Equatorial Gaps in Snowball Earth Sea Glaciers

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    Spaulding-Astudillo, F.; Ashkenazy, Y.; Tziperman, E.; Abbot, D. S.

    2017-12-01

    The way photosynthetic life survived the Neoproterozoic Snowball Earth events is still a matter of debate that has deep implications for planetary habitability. One option is that gaps in thick, semi-global ice coverage (sea glaciers) could be maintained at the equator by ocean-ice-atmosphere dynamics. We investigate this idea by modifying a global ocean-thick-marine-ice model developed for modeling Neoproterozoic Snowball Events to account for gaps in thick ice and interactions with atmospheric dynamics. Our hypothesis is that in the parameter regime that allows for sea glacier flow, ice flow will make gaps in the thick ice, and therefore an open ocean solution, less likely. This would suggest that oases in thick ice are a more viable survival mechanism for photosynthetic life during a Snowball Earth event.

  4. Snowball Earth: Asynchronous coupling of sea-glacier flow with a global climate model

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    Pollard, D.; Kasting, J. F.; Zugger, M. E.

    2017-05-01

    During Snowball Earth episodes of the Neoproterozoic and Paleoproterozoic, limited amounts of tropical open ocean (Jormungand), or tropical ocean with thin ice cover, would help to explain (1) vigorous glacial activity in low latitudes, (2) survival of photosynthetic life, and (3) deglacial recovery without excessive buildup of atmospheric CO2. Some previous models have suggested that tropical open ocean or thin-ice cover is possible; however, its viability in the presence of kilometer-thick sea glaciers flowing from higher latitudes has not been demonstrated conclusively. Here we describe a new method of asynchronously coupling a zonal sea-glacier model with a 3-D global climate model and apply it to Snowball Earth. Equilibrium curves of ice line versus CO2 are mapped out, as well as their dependence on ocean heat transport efficiency, sea-glacier flow, and other model parameters. No climate states with limited tropical open ocean or thin ice are found in any of our model runs, including those with sea glaciers. If this result is correct, then other refugia such as cryoconite pans would have been required for life to survive. However, the reasons for the differences between our results and others should first be resolved. It is suggested that small-scale convective dynamics, affecting fractional snow cover in low latitudes, may be a critical factor accounting for these differences.

  5. GCM simulations of cold dry Snowball Earth atmospheres

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    Voigt, A.; Held, I.; Marotzke, J.

    2009-12-01

    We use the full-physics atmospheric general circulation model ECHAM5 to investigate cold and virtually dry Snowball Earth atmospheres. These result from specifying sea ice as the surface boundary condition everywhere, corresponding to a frozen aquaplanet, while keeping total solar irradiance at its present-day value of 1365 Wm-2 and setting atmospheric carbon dioxide to 300 ppmv. Here, we present four simulations corresponding to the four possible combinations of enabled or disabled diurnal and seasonal cycles. The aim of this study is twofold. First, we focus on the zonal-mean circulation of Snowball Earth atmospheres, which, due to missing moisture, might constitute an ideal though yet unexplored testbed for theories of atmospheric dynamics. Second, we investigate tropical surface temperatures with an emphasis on the impact of the diurnal and seasonal cycles. This will indicate whether the presence of the diurnal or seasonal cycle would facilitate or anticipate the escape from Snowball Earth conditions when total solar irradiance or atmospheric CO2 levels were increased. The dynamics of the tropical circulation in Snowball Earth atmospheres differs substantially from that in the modern atmosphere. The analysis of the mean zonal momentum budget reveals that the mean flow meridional advection of absolute vorticity is primarily balanced by vertical diffusion of zonal momentum. The contribution of eddies is found to be even smaller than the contribution of mean flow vertical advection of zonal momentum, the latter being usually neglected in theories for the Hadley circulation, at least in its upper tropospheric branch. Suppressing vertical diffusion of horizontal momentum above 850 hPa leads to a stronger Hadley circulation. This behaviour cannot be understood from axisymmetric models of the atmosphere, nor idealized atmospheric general circulation models, which both predict a weakening of the Hadley circulation when the vertical viscosity is decreased globally. We

  6. A carbon isotope challenge to the snowball Earth.

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    Sansjofre, P; Ader, M; Trindade, R I F; Elie, M; Lyons, J; Cartigny, P; Nogueira, A C R

    2011-10-05

    The snowball Earth hypothesis postulates that the planet was entirely covered by ice for millions of years in the Neoproterozoic era, in a self-enhanced glaciation caused by the high albedo of the ice-covered planet. In a hard-snowball picture, the subsequent rapid unfreezing resulted from an ultra-greenhouse event attributed to the buildup of volcanic carbon dioxide (CO(2)) during glaciation. High partial pressures of atmospheric CO(2) (pCO2; from 20,000 to 90,000 p.p.m.v.) in the aftermath of the Marinoan glaciation (∼635 Myr ago) have been inferred from both boron and triple oxygen isotopes. These pCO2 values are 50 to 225 times higher than present-day levels. Here, we re-evaluate these estimates using paired carbon isotopic data for carbonate layers that cap Neoproterozoic glacial deposits and are considered to record post-glacial sea level rise. The new data reported here for Brazilian cap carbonates, together with previous ones for time-equivalent units, provide estimates lower than 3,200 p.p.m.v.--and possibly as low as the current value of ∼400 p.p.m.v. Our new constraint, and our re-interpretation of the boron and triple oxygen isotope data, provide a completely different picture of the late Neoproterozoic environment, with low atmospheric concentrations of carbon dioxide and oxygen that are inconsistent with a hard-snowball Earth.

  7. Factors controlling the initiation of Snowball Earth events

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    Voigt, A.

    2012-12-01

    During the Neoproterozoic glaciations tropical continents were covered by active glaciers that extended down to sea level. To explain these glaciers, the Snowball Earth hypothesis assumes that oceans were completely sea-ice covered during these glaciation, but there is an ongoing debate whether or not some regions of the tropical oceans remained open. In this talk, I will describe past and ongoing climate modelling activities with the comprehensive coupled climate model ECHAM5/MPI-OM that identify and compare factors that control the initiation of Snowball Earth events. I first show that shifting the continents from their present-day location to their Marinoan (635 My BP) low-latitude location increases the planetary albedo, cools the climate, and thereby allows Snowball Earth initiation at higher levels of total solar irradiance and atmospheric CO2. I then present simulations with successively lowered bare sea-ice albedo, disabled sea-ice dynamics, and switched-off ocean heat transport. These simulations show that both lowering the bare sea-ice albedo and disabling sea-ice dynamics increase the critical sea-ice cover in ECHAM5/MPI-OM, but sea-ice dynamics due to strong equatorward sea-ice transport have a much larger influence on the critical CO2. Disabling sea-ice transport allows a state with sea-ice margin at 10 deg latitude by virtue of the Jormungand mechanism. The accumulation of snow on land, in combination with tropical land temperatures below or close to freezing, suggests that tropical land glaciers could easily form in such a state. However, in contrast to aquaplanet simulations without ocean heat transport, there is no sign of a Jormungand hysteresis in the coupled simulations. Ocean heat transport is not responsible for the lack of a Jormungand hysteresis in the coupled simulations. By relating the above findings to previous studies, I will outline promising future avenues of research on the initiation of Snowball Earth events. In particular, an

  8. Relationship between the Neoproterozoic snowball Earth and Cambrian explosion

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    Maruyama, S.; Yoshihara, A.; Isozaki, Y.

    2007-12-01

    Origin of snowball Earth has been debated in terms of greenhouse gas (e.g., Hoffman and Schrag), obliqueness of Earth's rotation axis (Williams, 1975), true polar wander (Evans, 2003), Galactic cosmic ray radiation (Shaviv and Veizer, 2003; Svensmark, 2006), or weakened geomagnetism (Maruyama and Yoshihara, 2003). A major difficulty for the greenhouse gas hypothesis is the on-off switch causing decrease and increase of appropriate amounts of CO2 by plume- and plate tectonics, and also in available amount of CO2 in atmosphere to be consistent with the observations. In contrast, the cosmic ray radiation models due to the star burst peaked at 2.5- 2.1 Ga and 1.4-0.8 Ga can explain on-off switch more easily than the greenhouse gas model. Cosmic ray radiations, however, must be modified by the geomagnetic intensity, fluctuating 150"% to cause the snowball Earth. Time difference between the Neoproterozoic snowball Earth and Cambrian explosion is as large as 250 millions years, and this refuses their direct close-relationship. Role of frequent mass extinctions, i.e., 8 times during 100 m.y. from 585 Ma to 488 Ma, during the Ediacaran and Cambrian, has been proposed (Zhu et al., 2007). This frequency is one order of magnitude higher compared to that in the post-Ordovician time. Yet, the Cambrian explosion cannot be explained by mass extinction which replaced the vacant niches shortly after the mass extinction and never created a new animal with a new body plan. A new model proposed herein is derived from weakened geomagnetism and resultant extensive cosmic radiation to alter gene and genome for a long period over advancement of low magnetic intensity and cosmic radiations (Svensmark, 2006) from 1.2-0.8Ga. As to the new body plans of animals, it took an appreciably long time to prepare all 34 genometypes before the apparent Cambrian explosion. Geochemically extreme conditions and widened shallow marine environment on continental shelf by the return-flow of sweater into

  9. Snowball Earth climate dynamics and Cryogenian geology-geobiology.

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    Hoffman, Paul F; Abbot, Dorian S; Ashkenazy, Yosef; Benn, Douglas I; Brocks, Jochen J; Cohen, Phoebe A; Cox, Grant M; Creveling, Jessica R; Donnadieu, Yannick; Erwin, Douglas H; Fairchild, Ian J; Ferreira, David; Goodman, Jason C; Halverson, Galen P; Jansen, Malte F; Le Hir, Guillaume; Love, Gordon D; Macdonald, Francis A; Maloof, Adam C; Partin, Camille A; Ramstein, Gilles; Rose, Brian E J; Rose, Catherine V; Sadler, Peter M; Tziperman, Eli; Voigt, Aiko; Warren, Stephen G

    2017-11-01

    Geological evidence indicates that grounded ice sheets reached sea level at all latitudes during two long-lived Cryogenian (58 and ≥5 My) glaciations. Combined uranium-lead and rhenium-osmium dating suggests that the older (Sturtian) glacial onset and both terminations were globally synchronous. Geochemical data imply that CO 2 was 10 2 PAL (present atmospheric level) at the younger termination, consistent with a global ice cover. Sturtian glaciation followed breakup of a tropical supercontinent, and its onset coincided with the equatorial emplacement of a large igneous province. Modeling shows that the small thermal inertia of a globally frozen surface reverses the annual mean tropical atmospheric circulation, producing an equatorial desert and net snow and frost accumulation elsewhere. Oceanic ice thickens, forming a sea glacier that flows gravitationally toward the equator, sustained by the hydrologic cycle and by basal freezing and melting. Tropical ice sheets flow faster as CO 2 rises but lose mass and become sensitive to orbital changes. Equatorial dust accumulation engenders supraglacial oligotrophic meltwater ecosystems, favorable for cyanobacteria and certain eukaryotes. Meltwater flushing through cracks enables organic burial and submarine deposition of airborne volcanic ash. The subglacial ocean is turbulent and well mixed, in response to geothermal heating and heat loss through the ice cover, increasing with latitude. Terminal carbonate deposits, unique to Cryogenian glaciations, are products of intense weathering and ocean stratification. Whole-ocean warming and collapsing peripheral bulges allow marine coastal flooding to continue long after ice-sheet disappearance. The evolutionary legacy of Snowball Earth is perceptible in fossils and living organisms.

  10. Snowball Earth termination by destabilization of equatorial permafrost methane clathrate.

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    Kennedy, Martin; Mrofka, David; von der Borch, Chris

    2008-05-29

    The start of the Ediacaran period is defined by one of the most severe climate change events recorded in Earth history--the recovery from the Marinoan 'snowball' ice age, approximately 635 Myr ago (ref. 1). Marinoan glacial-marine deposits occur at equatorial palaeolatitudes, and are sharply overlain by a thin interval of carbonate that preserves marine carbon and sulphur isotopic excursions of about -5 and +15 parts per thousand, respectively; these deposits are thought to record widespread oceanic carbonate precipitation during postglacial sea level rise. This abrupt transition records a climate system in profound disequilibrium and contrasts sharply with the cyclical stratigraphic signal imparted by the balanced feedbacks modulating Phanerozoic deglaciation. Hypotheses accounting for the abruptness of deglaciation include ice albedo feedback, deep-ocean out-gassing during post-glacial oceanic overturn or methane hydrate destabilization. Here we report the broadest range of oxygen isotope values yet measured in marine sediments (-25 per thousand to +12 per thousand) in methane seeps in Marinoan deglacial sediments underlying the cap carbonate. This range of values is likely to be the result of mixing between ice-sheet-derived meteoric waters and clathrate-derived fluids during the flushing and destabilization of a clathrate field by glacial meltwater. The equatorial palaeolatitude implies a highly volatile shelf permafrost pool that is an order of magnitude larger than that of the present day. A pool of this size could have provided a massive biogeochemical feedback capable of triggering deglaciation and accounting for the global postglacial marine carbon and sulphur isotopic excursions, abrupt unidirectional warming, cap carbonate deposition, and a marine oxygen crisis. Our findings suggest that methane released from low-latitude permafrost clathrates therefore acted as a trigger and/or strong positive feedback for deglaciation and warming. Methane hydrate

  11. Rapid sea level rise in the aftermath of a Neoproterozoic snowball Earth.

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    Myrow, P M; Lamb, M P; Ewing, R C

    2018-04-19

    Earth's most severe climate changes occurred during global-scale snowball-Earth glaciations, which profoundly altered Earth's atmosphere, oceans, and biosphere. Extreme rates of glacio-eustatic sea-level rise are a fundamental prediction of the snowball Earth hypothesis, but supporting geologic evidence is lacking. We use paleohydraulic analysis of wave ripples and tidal laminae of the Elatina Formation, Australia - deposited following the Marinoan glaciation ca. 635Ma - to show that water depths of 9-16m remained nearly constant for ~100yrs throughout 27m of sediment accumulation. This accumulation rate was too great to have been accommodated by subsidence, and instead indicates an extraordinarily rapid rate of sea-level rise (0.2-0.27m/yr). Our results substantiate a fundamental prediction of snowball Earth models of rapid deglaciation during the early transition to a super-greenhouse climate. Copyright © 2018, American Association for the Advancement of Science.

  12. Sea-ice dynamics strongly promote Snowball Earth initiation and destabilize tropical sea-ice margins

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    A. Voigt

    2012-12-01

    Full Text Available The Snowball Earth bifurcation, or runaway ice-albedo feedback, is defined for particular boundary conditions by a critical CO2 and a critical sea-ice cover (SI, both of which are essential for evaluating hypotheses related to Neoproterozoic glaciations. Previous work has shown that the Snowball Earth bifurcation, denoted as (CO2, SI*, differs greatly among climate models. Here, we study the effect of bare sea-ice albedo, sea-ice dynamics and ocean heat transport on (CO2, SI* in the atmosphere–ocean general circulation model ECHAM5/MPI-OM with Marinoan (~ 635 Ma continents and solar insolation (94% of modern. In its standard setup, ECHAM5/MPI-OM initiates a~Snowball Earth much more easily than other climate models at (CO2, SI* ≈ (500 ppm, 55%. Replacing the model's standard bare sea-ice albedo of 0.75 by a much lower value of 0.45, we find (CO2, SI* ≈ (204 ppm, 70%. This is consistent with previous work and results from net evaporation and local melting near the sea-ice margin. When we additionally disable sea-ice dynamics, we find that the Snowball Earth bifurcation can be pushed even closer to the equator and occurs at a hundred times lower CO2: (CO2, SI* ≈ (2 ppm, 85%. Therefore, the simulation of sea-ice dynamics in ECHAM5/MPI-OM is a dominant determinant of its high critical CO2 for Snowball initiation relative to other models. Ocean heat transport has no effect on the critical sea-ice cover and only slightly decreases the critical CO2. For disabled sea-ice dynamics, the state with 85% sea-ice cover is stabilized by the Jormungand mechanism and shares characteristics with the Jormungand climate states. However, there is no indication of the Jormungand bifurcation and hysteresis in ECHAM5/MPI-OM. The state with 85% sea-ice cover therefore is a soft Snowball state rather than a true

  13. Radiative effects of ozone on the climate of a Snowball Earth

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    J. Yang

    2012-12-01

    Full Text Available Some geochemical and geological evidence has been interpreted to suggest that the concentration of atmospheric oxygen was only 1–10 % of the present level in the time interval from 750 to 580 million years ago when several nearly global glaciations or Snowball Earth events occurred. This low concentration of oxygen would have been accompanied by a lower ozone concentration than exists at present. Since ozone is a greenhouse gas, this change in ozone concentration would alter surface temperature, and thereby could have an important influence on the climate of the Snowball Earth. Previous works that have focused either on initiation or deglaciation of the proposed Snowball Earth has not taken the radiative effects of ozone changes into account. We address this issue herein by performing a series of simulations using an atmospheric general circulation model with various ozone concentrations.

    Our simulation results demonstrate that, as ozone concentration is uniformly reduced from 100 % to 50 %, surface temperature decreases by approximately 0.8 K at the Equator, with the largest decreases located in the middle latitudes reaching as high as 2.5 K. When ozone concentration is reduced and its vertical and horizontal distribution is simultaneously modulated, surface temperature decreases by 0.4–1.0 K at the Equator and by 4–7 K in polar regions. These results here have uncertainties, depending on model parameterizations of cloud, surface snow albedo, and relevant feedback processes, while they are qualitatively consistent with radiative-convective model results that do not involve such parameterizations and feedbacks. These results suggest that ozone variations could have had a moderate impact on the climate during the Neoproterozoic glaciations.

  14. What Can Earth Paleoclimates Reveal About the Resiliency of Habitable States? An Example from the Neoproterozoic Snowball Earth

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    Sohl, L.

    2014-04-01

    The Neoproterozoic "Snowball Earth" glaciations ( 750-635 Ma) have been a special focus for outer habitable zone investigations, owing in large part to a captivating and controversial hypothesis suggesting that Earth may have only narrowly escaped a runaway icehouse state on multiple occasions (a.k.a. "the hard snowball"; Hoffman and Schrag 2001). A review of climate simulations exploring snowball inception (Godderis et al. 2011) reveals that a broad range of models (EBMs, EMICs and AGCMs) tend to yield hard snowball solutions, whereas models with greater 3-D dynamic response capabilities (AOGCMs) typically do not, unless some of their climate feedback responses (e.g., wind-driven ocean circulation, cloud forcings) are disabled (Poulsen and Jacobs 2004). This finding raises the likelihood that models incorporating dynamic climate feedbacks are essential to understanding how much flexibility there may be in the definition of a planet's habitable zone boundaries for a given point in its history. In the first of a series of new Snowball Earth simulations, we use the NASA/GISS ModelE2 Global Climate Model - a 3-D coupled atmosphere/ocean model with dynamic sea ice response - to explore the impacts of wind-driven ocean circulation, clouds and deep ocean circulation on the sea ice front when solar luminosity and atmospheric carbon dioxide are reduced to Neoproterozoic levels (solar = 94%, CO2 = 40 ppmv). The simulation includes a realistic Neoproterozoic land mass distribution, which is concentrated at mid- to tropical latitudes. After 300 years, the sea ice front is established near 30 degrees latitude, and after 600 years it remains stable. As with earlier coupled model simulations we conclude that runaway glacial states would have been difficult to achieve during the Neoproterozoic, and would be more likely to have occurred during earlier times in Earth history when solar luminosity was less. Inclusion of dynamic climate feedback capabilities in habitable zone

  15. Initiation of a Marinoan Snowball Earth in a state-of-the-art atmosphere-ocean general circulation model

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    A. Voigt

    2011-03-01

    Full Text Available We study the initiation of a Marinoan Snowball Earth (~635 million years before present with the state-of-the-art atmosphere-ocean general circulation model ECHAM5/MPI-OM. This is the most sophisticated model ever applied to Snowball initiation. A comparison with a pre-industrial control climate shows that the change of surface boundary conditions from present-day to Marinoan, including a shift of continents to low latitudes, induces a global-mean cooling of 4.6 K. Two thirds of this cooling can be attributed to increased planetary albedo, the remaining one third to a weaker greenhouse effect. The Marinoan Snowball Earth bifurcation point for pre-industrial atmospheric carbon dioxide is between 95.5 and 96% of the present-day total solar irradiance (TSI, whereas a previous study with the same model found that it was between 91 and 94% for present-day surface boundary conditions. A Snowball Earth for TSI set to its Marinoan value (94% of the present-day TSI is prevented by doubling carbon dioxide with respect to its pre-industrial level. A zero-dimensional energy balance model is used to predict the Snowball Earth bifurcation point from only the equilibrium global-mean ocean potential temperature for present-day TSI. We do not find stable states with sea-ice cover above 55%, and land conditions are such that glaciers could not grow with sea-ice cover of 55%. Therefore, none of our simulations qualifies as a "slushball" solution. While uncertainties in important processes and parameters such as clouds and sea-ice albedo suggest that the Snowball Earth bifurcation point differs between climate models, our results contradict previous findings that Snowball Earth initiation would require much stronger forcings.

  16. ROTATIONAL VARIABILITY OF EARTH'S POLAR REGIONS: IMPLICATIONS FOR DETECTING SNOWBALL PLANETS

    International Nuclear Information System (INIS)

    Cowan, Nicolas B.; Robinson, Tyler; Agol, Eric; Meadows, Victoria S.; Shields, Aomawa L.; Livengood, Timothy A.; Deming, Drake; A'Hearn, Michael F.; Wellnitz, Dennis D.; Charbonneau, David; Lisse, Carey M.; Seager, Sara

    2011-01-01

    We have obtained the first time-resolved, disk-integrated observations of Earth's poles with the Deep Impact spacecraft as part of the EPOXI mission of opportunity. These data mimic what we will see when we point next-generation space telescopes at nearby exoplanets. We use principal component analysis (PCA) and rotational light curve inversion to characterize color inhomogeneities and map their spatial distribution from these unusual vantage points, as a complement to the equatorial views presented by Cowan et al. in 2009. We also perform the same PCA on a suite of simulated rotational multi-band light curves from NASA's Virtual Planetary Laboratory three-dimensional spectral Earth model. This numerical experiment allows us to understand what sorts of surface features PCA can robustly identify. We find that the EPOXI polar observations have similar broadband colors as the equatorial Earth, but with 20%-30% greater apparent albedo. This is because the polar observations are most sensitive to mid-latitudes, which tend to be more cloudy than the equatorial latitudes emphasized by the original EPOXI Earth observations. The cloudiness of the mid-latitudes also manifests itself in the form of increased variability at short wavelengths in the polar observations and as a dominant gray eigencolor in the south polar observation. We construct a simple reflectance model for a snowball Earth. By construction, our model has a higher Bond albedo than the modern Earth; its surface albedo is so high that Rayleigh scattering does not noticeably affect its spectrum. The rotational color variations occur at short wavelengths due to the large contrast between glacier ice and bare land in those wavebands. Thus, we find that both the broadband colors and diurnal color variations of such a planet would be easily distinguishable from the modern-day Earth, regardless of viewing angle.

  17. The initiation of modern soft and hard Snowball Earth climates in CCSM4

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    J. Yang

    2012-05-01

    Full Text Available Geochemical and geological evidence has suggested that several global-scale glaciation events occurred during the Neoproterozoic Era in the interval from 750–580 million years ago. The initiation of these glaciations is thought to have been a consequence of the combined influence of a low level of atmospheric carbon dioxide concentration and an approximately 6% weakening of solar luminosity. The latest version of the Community Climate System Model (CCSM4 is employed herein to explore the detailed combination of forcings required to trigger such extreme glaciation conditions under present-day circumstances of geography and topography. It is found that runaway glaciation occurs in the model under the following conditions: (1 an 8–9% reduction in solar radiation with 286 ppmv CO2 or (2 a 6% reduction in solar radiation with 70–100 ppmv CO2. These thresholds are moderately different from those found to be characteristic of the previously employd CCSM3 model reported recently in Yang et al. (2012a,b, for which the respective critical points corresponded to a 10–10.5% reduction in solar radiation with 286 ppmv CO2 or a 6% reduction in solar radiation with 17.5–20 ppmv CO2. The most important reason for these differences is that the sea ice/snow albedo parameterization employed in CCSM4 is believed to be more realistic than that in CCSM3. Differences in cloud radiative forcings and ocean and atmosphere heat transports also influence the bifurcation points. These results are potentially very important, as they are to serve as control on further calculations which will be devoted to an investigation of the impact of continental configuration.

    We demonstrate that there exist ''soft Snowball'' Earth states, in which the fractional sea ice coverage reaches approximately 60–65%, land masses in low latitudes are covered by perennial snow, and runaway glaciation does not develop. This is

  18. Flexible climate modeling systems: Lessons from Snowball Earth, Titan and Mars

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    Pierrehumbert, R. T.

    2007-12-01

    Climate models are only useful to the extent that real understanding can be extracted from them. Most leading- edge problems in climate change, paleoclimate and planetary climate require a high degree of flexibility in terms of incorporating model physics -- for example in allowing methane or CO2 to be a condensible substance instead of water vapor. This puts a premium on model design that allows easy modification, and on physical parameterizations that are close to fundamentals with as little empirical ad-hoc formulation as possible. I will provide examples from two approaches to this problem we have been using at the University of Chicago. The first is the FOAM general circulation model, which is a clean single-executable Fortran-77/c code supported by auxiliary applications in Python and Java. The second is a new approach based on using Python as a shell for assembling building blocks in compiled-code into full models. Applications to Snowball Earth, Titan and Mars, as well as pedagogical uses, will be discussed. One painful lesson we have learned is that Fortran-95 is a major impediment to portability and cross-language interoperability; in this light the trend toward Fortran-95 in major modelling groups is seen as a significant step backwards. In this talk, I will focus on modeling projects employing a full representation of atmospheric fluid dynamics, rather than "intermediate complexity" models in which the associated transports are parameterized.

  19. Model-dependence of the CO2 threshold for melting the hard Snowball Earth

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    W. R. Peltier

    2011-01-01

    Full Text Available One of the critical issues of the Snowball Earth hypothesis is the CO2 threshold for triggering the deglaciation. Using Community Atmospheric Model version 3.0 (CAM3, we study the problem for the CO2 threshold. Our simulations show large differences from previous results (e.g. Pierrehumbert, 2004, 2005; Le Hir et al., 2007. At 0.2 bars of CO2, the January maximum near-surface temperature is about 268 K, about 13 K higher than that in Pierrehumbert (2004, 2005, but lower than the value of 270 K for 0.1 bar of CO2 in Le Hir et al. (2007. It is found that the difference of simulation results is mainly due to model sensitivity of greenhouse effect and longwave cloud forcing to increasing CO2. At 0.2 bars of CO2, CAM3 yields 117 Wm−2 of clear-sky greenhouse effect and 32 Wm−2 of longwave cloud forcing, versus only about 77 Wm−2 and 10.5 Wm−2 in Pierrehumbert (2004, 2005, respectively. CAM3 has comparable clear-sky greenhouse effect to that in Le Hir et al. (2007, but lower longwave cloud forcing. CAM3 also produces much stronger Hadley cells than that in Pierrehumbert (2005. Effects of pressure broadening and collision-induced absorption are also studied using a radiative-convective model and CAM3. Both effects substantially increase surface temperature and thus lower the CO2 threshold. The radiative-convective model yields a CO2 threshold of about 0.21 bars with surface albedo of 0.663. Without considering the effects of pressure broadening and collision-induced absorption, CAM3 yields an approximate CO2 threshold of about 1.0 bar for surface albedo of about 0.6. However, the threshold is lowered to 0.38 bars as both effects are considered.

  20. Stable "Waterbelt" climates controlled by tropical ocean heat transport: A nonlinear coupled climate mechanism of relevance to Snowball Earth

    Science.gov (United States)

    Rose, Brian E. J.

    2015-02-01

    Ongoing controversy about Neoproterozoic Snowball Earth events motivates a theoretical study of stability and hysteresis properties of very cold climates. A coupled atmosphere-ocean-sea ice general circulation model (GCM) has four stable equilibria ranging from 0% to 100% ice cover, including a "Waterbelt" state with tropical sea ice. All four states are found at present-day insolation and greenhouse gas levels and with two idealized ocean basin configurations. The Waterbelt is stabilized against albedo feedback by intense but narrow wind-driven ocean overturning cells that deliver roughly 100 W m-2 heating to the ice edges. This requires three-way feedback between winds, ocean circulation, and ice extent in which circulation is shifted equatorward, following the baroclinicity at the ice margins. The thermocline is much shallower and outcrops in the tropics. Sea ice is snow-covered everywhere and has a minuscule seasonal cycle. The Waterbelt state spans a 46 W m-2 range in solar constant, has a significant hysteresis, and permits near-freezing equatorial surface temperatures. Additional context is provided by a slab ocean GCM and a diffusive energy balance model, both with prescribed ocean heat transport (OHT). Unlike the fully coupled model, these support no more than one stable ice margin, the position of which is slaved to regions of rapid poleward decrease in OHT convergence. Wide ranges of different climates (including the stable Waterbelt) are found by varying the magnitude and spatial structure of OHT in both models. Some thermodynamic arguments for the sensitivity of climate, and ice extent to OHT are presented.

  1. Oman's low latitude "Snowball Earth" pole revisited: Late Cretaceous remagnetisation of Late Neoproterozoic carbonates in Northern Oman

    Science.gov (United States)

    Rowan, C. J.; Tait, J.

    2010-12-01

    Glaciogenic diamictites and associated ‘cap’ carbonates within the Neoproterozoic Huqf Supergroup of Oman record a period of extreme, possibly global, glaciations between 750-635 Ma (the "Snowball Earth"). We have performed high-resolution paleomagnetic sampling of two sections through ~635 Ma cap carbonates in the Jebel Akhdar region of northern Oman. Stepwise thermal demagnetisation reveals a low temperature component carried by goethite, and a high temperature component carried by haematite, that are both aligned with the modern dipole field direction. Occasional reversed polarity directions antipodal to the present day field indicate pervasive weathering of these outcrops over timescales of at least 1 Ma. Between these two overprints an intermediate component with typical unblocking temperatures of 300-550 C, probably carried by magnetite, can also be isolated in most samples. A robust fold test clearly demonstrates that this component was acquired after Paleozoic folding of the carbonates, and was most likely acquired during exhumation associated with emplacement of the Semail ophiolite during the Late Cretaceous (95-68 Ma). In geographic co-ordinates, the intermediate component has an almost horizontal NNW or SSE direction, similar to directions previously reported from outcrops of the ophiolite close to the Jebel Akhdar region, and from thermally altered basement rocks in the the Saih Hatat window further to the east [Feinberg et al. 1999]. Hints of an older, Permian, remagnetisation of the carbonates, which is also observed in the Saih Hatat basement rocks, have also produced a false polarity stratigraphy in one of the sampled sections. Our results contrast with the previously reported low latitude pole from the Huqf Supergroup [Kilner et al., 2005], which was considered to be amongst the more reliable paleomagnetic data supporting glaciations extending to low latitudes during the late Neoproterozoic. However, this interpretation was made on the basis

  2. Early sponges and toxic protists: possible sources of cryostane, an age diagnostic biomarker antedating Sturtian Snowball Earth.

    Science.gov (United States)

    Brocks, J J; Jarrett, A J M; Sirantoine, E; Kenig, F; Moczydłowska, M; Porter, S; Hope, J

    2016-03-01

    The period 800-717 million years (Ma) ago, in the lead-up to the Sturtian Snowball glaciation, saw an increase in the diversity of eukaryotic microfossils. To afford an independent and complementary view of this evolutionary period, this study presents the distribution of eukaryotic biomarkers from three pre-Sturtian successions across the supercontinent Rodinia: the ca. 780 Ma Kanpa Formation of the Western Australian Officer Basin, the ca. 800-740 Ma Visingsö Group of Sweden, and the 740 Ma Chuar Group in Arizona, USA. The distribution of eukaryotic steranes is remarkably similar in the three successions but distinct from all other known younger and older sterane assemblages. Cholestane was the only conventional structure, while indigenous steranes alkylated in position C-24, such as ergostane, stigmastane, dinosterane and isopropylcholestane, and n-propylcholestane, were not observed. This sterane distribution appears to be age diagnostic for the pre-Sturtian Neoproterozoic. It attests to the distinct evolutionary state of pre-Snowball eukaryotes, pointing to a taxonomic disparity that was still lower than in the Ediacaran (635-541 Ma). All three basins also show the presence of a new C28 sterane that was tentatively identified as 26-methylcholestane, here named cryostane. The only known extant organisms that can methylate sterols in the 26-position are demosponges. This assignment is plausible as molecular clocks place the appearance of the earliest animals into the pre-Sturtian Neoproterozoic. The unusual 26-methylsterol may have protected sponges, but also other eukaryotes, against their own membranolytic toxins. Some protists release lytic toxins to deter predators and kill eukaryotic prey. As conventional membrane sterols can be the site of attack for these toxins, sterols with unusual side-chain modification protect the cell. This interpretation of cryostane supports fossil evidence of predation in the Chuar Group and promotes hypotheses about the

  3. Chronological constraints on the Paleoproterozoic Francevillian Group in Gabon

    Directory of Open Access Journals (Sweden)

    Yusuke Sawaki

    2017-03-01

    Full Text Available The Francevillian Group in Gabonese Republic was recently established as a typical sedimentary sequence for the Paleoproterozoic. However, its age is rather poorly constrained, mainly based on Rb-Sr and Nd-Sm datings. This study reports new zircon data obtained from Chaillu massif and N'goutou complex, which constrain the protolith age of the basement orthogneisses and the igneous age of an intrusive granite, respectively. Most zircons from the orthogneisses are blue and exhibit oscillatory zoning in cathode-luminescence images. Zircons with lower common lead abundances tend to be distributed close to the concordia curve. Two age clusters around 2860 Ma and 2910 Ma are found in zircons plotted on the concordia curve. Based on the Th/U ratios of zircons, these ages correspond to the protolith ages of the orthogneisses, and the zircons are not metamorphic in origin. Syenites and granites were collected from the N'goutou complex that intrudes into the FA and FB units of the Francevillian Group. The granitoids exhibit chemical composition of A-type granite affinity. Half of zircons separated from the granite are non-luminous, and the remaining half exhibit obscure internal textures under cathode-luminescence observation. All zircon grains contain significant amounts of common lead; the lead isotopic variability is probably attributed to the mixing of two components in the zircons. The zircon radiogenic 207Pb/206Pb ratio is 0.13707 ± 0.0010, corresponding to a 207Pb/206Pb age of 2191 ± 13 Ma. This constrains the minimum depositional age of the FA and FB units. Furthermore, the FB unit consists of manganese-rich carbonate rocks and organic carbon-rich black shales with macroscopic fossils. Based on our age constraints, these organisms appeared in the study area just after the last Paleoproterozoic Snowball Earth event, in concert with global scale oxidation event encompassing the Snowball Earth.

  4. No Snowball on Habitable Tidally Locked Planets

    Science.gov (United States)

    Checlair, Jade; Menou, Kristen; Abbot, Dorian S.

    2017-08-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  5. No Snowball on Habitable Tidally Locked Planets

    Energy Technology Data Exchange (ETDEWEB)

    Checlair, Jade; Abbot, Dorian S. [Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Menou, Kristen, E-mail: jadecheclair@uchicago.edu [Centre for Planetary Sciences, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4 (Canada)

    2017-08-20

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO{sub 2} outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  6. No Snowball on Habitable Tidally Locked Planets

    International Nuclear Information System (INIS)

    Checlair, Jade; Abbot, Dorian S.; Menou, Kristen

    2017-01-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO 2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  7. Snowball Throwing in Teaching Grammar

    Directory of Open Access Journals (Sweden)

    Yanuarti Apsari

    2018-05-01

    Full Text Available The aims of this study are to describe the implementation of snowball throwing in teaching grammar and to investigate the benefits of applying snowball throwing. The research was conducted at STKIP Siliwangi Bandung. This study applied qualitative research involving one class consisting of second semester students in English Department who were taking the subject of foundation of English Grammar. The data were obtained from classroom observation and students’ interview. The findings showed that there are seven stages in implementing snowball throwing in teaching grammar. The stages consist of preparing teaching material, forming group, re-explaining the material to the member of the group, formulating question, tossing the ball, answering questions and evaluating teaching and learning process. In addition, the findings also revealed that there are some benefits from applying snowball throwing in teaching grammar such as improving students’ comprehension in learning grammar, creating enjoyable learning atmosphere, increasing students’ vocabulary, developing students’ speaking skill, developing students’ cooperation skill and increasing students’ participation in the class.

  8. Snowballing and flying under the radar

    DEFF Research Database (Denmark)

    Pötz, Katharina Anna; Hjortsø, Carsten Nico Portefée

    2013-01-01

    management and venture development paths. More specifically, flying under radar in terms of operating under lower institutional requirements, and slowly accumulating resources (snowballing) are major leveraging strategies. We integrate our results into a hypothesized framework for resource management in East...

  9. Design-based estimators for snowball sampling

    OpenAIRE

    Shafie, Termeh

    2010-01-01

    Snowball sampling, where existing study subjects recruit further subjects from amongtheir acquaintances, is a popular approach when sampling from hidden populations.Since people with many in-links are more likely to be selected, there will be a selectionbias in the samples obtained. In order to eliminate this bias, the sample data must beweighted. However, the exact selection probabilities are unknown for snowball samplesand need to be approximated in an appropriate way. This paper proposes d...

  10. Petrological and geochemical characteristics of Paleoproterozoic ...

    Indian Academy of Sciences (India)

    Centre of Advanced Study, Department of Geology, Banaras Hindu University, Varanasi 221 005, India ... A number of ENE–WSW trending Paleoproterozoic dykes and plugs of mafic, ultramafic, alkaline and ...... 2005 Integrating ultramafic lamprophyres into the IUGS classification of igneous rocks: Rational and implications;.

  11. Simulating the Snowball Stratosphere and Its Influence On CO2 Inference

    Science.gov (United States)

    Graham, R. J.; Shaw, T.; Abbot, D. S.

    2017-12-01

    According to the snowball Earth hypothesis, a large quantity of CO2 must build up during an event in order to cause eventual deglaciation. One prediction of this model is a depletion in atmospheric oxygen-17 as a result of stratospheric chemical reactions, which has been observed in preserved barite minerals. This represents one of the most dramatic and compelling pieces of evidence in support of the snowball Earth hypothesis. The inference of anomalous atmospheric oxygen-17 based on measurements of barite minerals, however, was made by assuming that the stratosphere-troposphere mass exchange rate and mixing within the stratosphere were the same as the present. In this contribution we test these assumptions with simulations of modern and snowball atmospheric conditions using the global climate model ECHAM5. Our simulations are still running, but we will have results to report by December.

  12. FROM DUST TO PLANETESIMAL: THE SNOWBALL PHASE?

    International Nuclear Information System (INIS)

    Xie Jiwei; Zhou Jilin; Payne, Matthew J.; Ge Jian; Thebault, Philippe

    2010-01-01

    The standard model of planet formation considers an initial phase in which planetesimals form from a dust disk, followed by a phase of mutual planetesimal-planetesimal collisions, leading eventually to the formation of planetary embryos. However, there is a potential transition phase (which we call the 'snowball phase'), between the formation of the first planetesimals and the onset of mutual collisions amongst them, which has often been either ignored or underestimated in previous studies. In this snowball phase, isolated planetesimals move in Keplerian orbits and grow solely via the direct accretion of subcentimeter-sized dust entrained with the gas in the protoplanetary disk. Using a simplified model in which planetesimals are progressively produced from the dust, we consider the expected sizes to which the planetesimals can grow before mutual collisions commence and derive the dependence of this size on a number of critical parameters, including the degree of disk turbulence, the planetesimal size at birth, and the rate of planetesimal creation. For systems in which turbulence is weak and the planetesimals are created at a low rate and with relatively small birth size, we show that the snowball growth phase can be very important, allowing planetesimals to grow by a factor of 10 6 in mass before mutual collisions take over. In such cases, the snowball growth phase can be the dominant mode to transfer mass from the dust to planetesimals. Moreover, such growth can take place within the typical lifetime of a protoplanetary gas disk. A noteworthy result is that, for a wide range of physically reasonable parameters, mutual collisions between planetesimals become significant when they reach sizes ∼100 km, irrespective of their birth size. This could provide an alternative explanation for the turnover point in the size distribution of the present-day asteroid belt. For the specific case of close binaries such as α Centauri, the role of snowball growth could be even

  13. Teknik Sampling Snowball dalam Penelitian Lapangan

    Directory of Open Access Journals (Sweden)

    Nina Nurdiani

    2014-12-01

    Full Text Available Field research can be associated with both qualitative and quantitative research methods, depending on the problems faced and the goals to be achieved. The success of data collection in the field research depends on the determination of the appropriate sampling technique, to obtain accurate data, and reliably. In studies that have problems related to specific issues, requiring a non-probability sampling techniques one of which is the snowball sampling technique. This technique is useful for finding, identifying, selecting and taking samples in a network or chain of relationships. Phased implementation procedures performed through interviews and questionnaires. Snowball sampling technique has strengths and weaknesses in its application. Field research housing sector become the case study to explain this sampling technique.

  14. Teknik Sampling Snowball dalam Penelitian Lapangan

    OpenAIRE

    Nina Nurdiani

    2014-01-01

    Field research can be associated with both qualitative and quantitative research methods, depending on the problems faced and the goals to be achieved. The success of data collection in the field research depends on the determination of the appropriate sampling technique, to obtain accurate data, and reliably. In studies that have problems related to specific issues, requiring a non-probability sampling techniques one of which is the snowball sampling technique. This technique is useful for f...

  15. Geochemistry of the Nsuta Mn deposit in Ghana: Implications for the Paleoproterozoic atmosphere and ocean chemistry

    Science.gov (United States)

    Goto, K. T.; Ito, T.; Suzuki, K.; Kashiwabara, T.; Takaya, Y.; Shimoda, G.; Nozaki, T.; Kiyokawa, S.; Tetteh, G. M.; Nyame, F. K.

    2013-12-01

    Oxygenation of the atmosphere and oceans has influenced the evolution of ocean chemistry and diversification of early life. A number of large manganese (Mn) deposits are distributed in the Paleoproterozoic sedimentary successions that were formed during the great oxidation event (GOE) around 2.4-2.2 Ga (Meynard, 2010). Due to the high redox potential of Mn, occurrences of Mn deposits have been regarded as important evidence for a highly oxidized environment during the Paleoproterozoic (Kirschvink et al., 2000). Furthermore, because Mn oxides strongly adsorb various elements, including bioessential elements such as Mo, formation of large Mn deposits may have affected the seawater chemical composition and ecology during the Paleoproterozoic. However, the genesis of each Mn deposit is poorly constrained, and the relationships among the formation of Mn deposits, the evolution of atmospheric and ocean chemistry, and the diversification of early life are still ambiguous. In this study, we report the Re-Os isotope compositions, rare earth element (REE) compositions, and abundance of manganophile elements in the Mn carbonate ore and host sedimentary rock samples collected from the Nsuta Mn deposit of the Birimian Supergroup, Ghana. The Nsuta deposit is one of the largest Paleoproterozoic Mn deposits, although its genesis remains controversial (Melcher et al., 1995; Mucke et al., 1999). The composite Re-Os isochron age (2149 × 130 Ma) of the Mn carbonate and sedimentary rock samples was consistent with the depositional age of the sedimentary rocks (~2.2 Ga) presumed from the U-Pb zircon age of volcanic rocks (Hirdes and Davis, 1998), suggesting that the timing of Mn ore deposition was almost equivalent to the host rock sedimentation. The PAAS-normalized REE pattern showed a positive Eu anomaly in all samples and a positive Ce anomaly only in the Mn carbonate ore. These REE patterns indicate the possible contribution of Eu-enriched fluids derived from hydrothermal activity

  16. Estimates of atmospheric O2 in the Paleoproterozoic from paleosols

    Science.gov (United States)

    Kanzaki, Yoshiki; Murakami, Takashi

    2016-02-01

    A weathering model was developed to constrain the partial pressure of atmospheric O2 (PO2) in the Paleoproterozoic from the Fe records in paleosols. The model describes the Fe behavior in a weathering profile by dissolution/precipitation of Fe-bearing minerals, oxidation of dissolved Fe(II) to Fe(III) by oxygen and transport of dissolved Fe by water flow, in steady state. The model calculates the ratio of the precipitated Fe(III)-(oxyhydr)oxides from the dissolved Fe(II) to the dissolved Fe(II) during weathering (ϕ), as a function of PO2 . An advanced kinetic expression for Fe(II) oxidation by O2 was introduced into the model from the literature to calculate accurate ϕ-PO2 relationships. The model's validity is supported by the consistency of the calculated ϕ-PO2 relationships with those in the literature. The model can calculate PO2 for a given paleosol, once a ϕ value and values of the other parameters relevant to weathering, namely, pH of porewater, partial pressure of carbon dioxide (PCO2), water flow, temperature and O2 diffusion into soil, are obtained for the paleosol. The above weathering-relevant parameters were scrutinized for individual Paleoproterozoic paleosols. The values of ϕ, temperature, pH and PCO2 were obtained from the literature on the Paleoproterozoic paleosols. The parameter value of water flow was constrained for each paleosol from the mass balance of Si between water and rock phases and the relationships between water saturation ratio and hydraulic conductivity. The parameter value of O2 diffusion into soil was calculated for each paleosol based on the equation for soil O2 concentration with the O2 transport parameters in the literature. Then, we conducted comprehensive PO2 calculations for individual Paleoproterozoic paleosols which reflect all uncertainties in the weathering-relevant parameters. Consequently, robust estimates of PO2 in the Paleoproterozoic were obtained: 10-7.1-10-5.4 atm at ∼2.46 Ga, 10-5.0-10-2.5 atm at ∼2

  17. Radioactive core ions of microclusters, ``snowballs`` in superfluid helium

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, N. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Shimoda, T. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Fujita, Y. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Miyatake, H. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Mizoi, Y. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Kobayashi, H. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Sasaki, M. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Shirakura, T. [Osaka Univ., Toyonaka (Japan). Dept. of Physics; Itahashi, T. [Research Center for Nuclear Physics, Osaka Univ., Ibaraki (Japan); Mitsuoka, S. [Research Center for Nuclear Physics, Osaka Univ., Ibaraki (Japan); Matsukawa, T. [Naruto Univ. of Education, Tokushima (Japan); Ikeda, N. [Kyushu Univ., Fukuoka (Japan). Dept. of Physics; Morinobu, S. [Kyushu Univ., Fukuoka (Japan). Dept. of Physics; Hinde, D.J. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences; Asahi, K. [Tokyo Inst. of Tech. (Japan). Dept. of Physics; Ueno, H. [Tokyo Inst. of Tech. (Japan). Dept. of Physics; Izumi, H. [Tokyo Inst. of Tech. (Japan). Dept. of Physics

    1996-12-01

    Short-lived beta-ray emitters, {sup 12}B, sustaining nuclear spin polarization were introduced into superfluid helium. The nuclear polarization of {sup 12}B was observed via measurement of beta-ray asymmetry. It was found that the nuclear polarization was preserved throughout the lifetime of {sup 12}B (20.3 ms). This suggests that the ``snowball``, an aggregation of helium atoms produced around an alien ion, constitutes a suitable milieu for freezing-out the nuclear spin of the core ion and that most likely the solidification takes place at the interior of the aggregation. (orig.).

  18. Radioactive core ions of microclusters, ''snowballs'' in superfluid helium

    International Nuclear Information System (INIS)

    Takahashi, N.; Mitsuoka, S.; Matsukawa, T.; Ikeda, N.; Morinobu, S.; Hinde, D.J.; Asahi, K.; Ueno, H.; Izumi, H.

    1996-01-01

    Short-lived beta-ray emitters, 12 B, sustaining nuclear spin polarization were introduced into superfluid helium. The nuclear polarization of 12 B was observed via measurement of beta-ray asymmetry. It was found that the nuclear polarization was preserved throughout the lifetime of 12 B (20.3 ms). This suggests that the ''snowball'', an aggregation of helium atoms produced around an alien ion, constitutes a suitable milieu for freezing-out the nuclear spin of the core ion and that most likely the solidification takes place at the interior of the aggregation. (orig.)

  19. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  20. KEEFEKTIFAN PEMBELAJARAN SNOWBALL THROWING BERBANTUAN LEMBAR KEGIATAN SISWA

    Directory of Open Access Journals (Sweden)

    Gallant Alim Purbowo

    2012-06-01

    Full Text Available Abstract Tujuan penelitian ini adalah untuk mengetahui keefektifan pembelajaran Snowball Throwing berbantuan LKS terhadap hasil belajar siswa kelas VIII SMP Negeri 1 Kaliori pada materi lingkaran tahun ajaran 2011/2012. Populasi dalam penelitian ini adalah semua siswa kelas VIII SMP Negeri 1 Kaliori tahun ajaran 2011/2012. Sampel dalam penelitian ini diambil secara cluster random sampling. Data hasil penelitian diperoleh dengan metode tes yang dianalisis dengan menggunakan uji proporsi, uji rata-rata, uji kesamaan dua proporsi, dan uji perbedaan dua rata-rata untuk menguji hipotesis. Hasil penelitian menunjukkan: (1 zhitung =0,5>-(z(0,5-? =-1,64, artinya siswa yang tuntas terhadap hasil belajar pada kelas eksperimen dapat mencapai persentase ketuntasan minimal siswa, (2 thitung=3,9001 >t(1-? =1,69 artinya rata-rata hasil belajar siswa pada kelas eksperimen dapat mencapai KKM, (3 zhitung=2,335>z(0.5-? =1,64, artinya siswa yang tuntas pada kelas eksperimen lebih besar dari kelas kontrol, (4 thitung=2,0194 ? 1,668, artinya rata-rata hasil belajar siswa pada kelas eksperimen lebih dari kelas kontrol. Berdasarkan hasil penelitian tersebut dapat disimpulkan bahwa penerapan Pembelajaran Snowball Throwing berbantuan LKS efektif terhadap hasil belajar siswa kelas VIII SMP Negeri 1 Kaliori pada materi lingkaran. The purpose of this study was to determine the effectiveness of Snowball Throwing learning assisted students worksheets to learning outcomes of VIII grade in SMP Negeri 1 Kaliori in circle material of the school year 2011/2012. The population in this study were all students in VIII grade SMP Negeri 1 Kaliori academic year 2011/2012. The sample in this study were drawn by cluster random sampling. Research data obtained with the test method were analyzed using the proportion test, test averages, test the equality of two proportions, and test the average difference in the two hypotheses. The results showed: (1 zcount = 0.5> - z(0,5-? = -1.64, meaning

  1. Eksperimentasi Model Jigsaw Snowball Drilling dan Peer Tutoring Snowball Drilling pada Materi Pokok Tabung, Kerucut, dan Bola Ditinjau dari Gaya Belajar Siswa

    OpenAIRE

    P, Nelly Indriastuti; Kusmayadi, Tri Atmojo; Usodo, Budi

    2014-01-01

    The aims of this research were to determine: (1) which results better mathematics learning achievement between students who were taught by using jigsaw snowball drilling, peer tutoring snowball drilling, or direct instruction, (2) which has better mathematics learning achievement between students with visual learning styles, auditory, or kinesthetic, (3). at each of the learning model, which one has better mathematics learning achievement between student with visual learning style, auditory, ...

  2. Reconstruction of the Paleoproterozoic deeper ocean environment: Preliminary Report of the Ghana Birimian Greenstone Belt Drilling Project (GHB)

    Science.gov (United States)

    Kiyokawa, S.; Yoshimaru, S.; Miki, T.; Sakai, S.; Ikehara, M.; Yamaguchi, K. E.; Ito, T.; Onoue, T.; Takehara, M.; Tetteh, G. M.; Nyame, F. K.

    2016-12-01

    The Paleoproterozoic Era are one of the most rapid environmental change when the earth surface environment was affected by formation of continents and increasing atmospheric oxygen levels. Major oxidation of Great Oxidation Event (GOE) are reported this ages (eg. Holland, 2006; Condie, 2001; Lyons et al., 2014). The nature of deep sea environments at this time have not been clearly identified and oceanic sediments are mostly involved in subduction. The Paleoproterozoic Birimian Greenstone Belt is an ophiolitic volcaniclastic sequence in Ghana, with depositional age of over 2.3-2.2 Ga (Petersson et al., 2016). Detail research was conducted of the Ashanti (Axim-Konongo) Belt of the Birimian Greenstone Belt along the coast near Cape Three Points area. Very thick volcaniclastic and organic-rich sedimentary rocks, which we now refer to as the Cape Three Points Group, crop out in the lower part of the Birimian Greenstone Belt. Stratigraphically, three unit identified; the lower portion contains thick vesicular volcaniclastic rocks, the middle portion is made up of laminated volcaniclastics and black shale, and the upper portion dominated by fine laminated volcaniclastics with more black shale sequence. Continuous core drilling from Dec 3-12th 2015 of the upper part of the sequence intersected saprolite to a depth of 30m and fresh, well preserved stratigraphy with graded bedding and lamination to a depth of 195m. Half cut cores show well laminated organic rich black shale and relative carbonate rich layers with very fine pyrite grains. SHRIMP age data from a porphyry intrusion into this sequence indicate an age of 2250 Ma. Carbon isotope analysis shows δ13C = -43 to -37‰ for black shale with the very light isotope values for cyanobacterial signature.The fining-upward sequences, well laminated bed and black shales and REE data suggest this sequence situated partly silent stagnant with volcanic activity ocean floor environment around an oceanic island arc condition.

  3. Efektivitas Pembelajaran Matematika melalui Penerapan Model Pembelajaran Kooperatif Tipe Snowball Throwing

    Directory of Open Access Journals (Sweden)

    Andi Mulawakkan Firdaus

    2016-10-01

    Full Text Available [Bahasa]: Penelitian ini merupakan penelitian Eksperimen semu yang bertujuan untuk mendeskripsikan hasil belajar siswa SMP Negeri 13 Makassar yang diajar dengan menggunakan Model Kooperatif Tipe Snowball Throwing dan Metode Ekspositori, serta untuk mengetahui apakah model pembelajaran kooperatif tipe Snowball Throwing efektif digunakan dalam pembelajaran matematika pada siswa kelas VIII SMP Negeri 13 Makassar. Luaran yang akan dihasilkan dari penelitian ini adalah penerapan alternatif pembelajaran yang tidak monoton sehingga dapat meningkatkan hasil belajar matematika siswa dan perangkat pembelajaran (silabus dan RPP yang berorientasi pada pembelajaran koperatif tipe Snowball Throwing. Subjek penelitian dibagi dalam 2 kelompok, yakni kelompok eksperimen yang diajar dengan menggunakan pembelajaran kooperatif tipe Snowball Throwing dan kelompok kontrol yang diajar dengan menggunakan metode ekspositori. Setiap kelompok diajar dengan frekuensi pertemuan yang sama dengan materi yang sama. Hasil penelitian menunjukan bahwa penerapan model pembelajaran kooperatif tipe Snowball Throwing lebih efektif jika dibandingkan dengan penerapan metode ekspositori untuk pokok bahasan sistem persamaan linear dua variabel. [English]: This experiment research aims to describe the learning outcomes of students at SMP Negeri 13 Makassar taught with snowball throwing (cooperative and expository method and to find out whether snowball throwing method is more effective in learning mathematics than the expository method in grade 7. The results of this research are implementing alternative learning method which is not monotonous to improve students' mathematics learning outcomes and producing learning tools that consist of syllabus and lesson plans based on snowball throwing method in cooperative learning. Research subjects are divided into two groups namely the experimental group taught with snowball throwing and the control group taught with the expository method. Each

  4. A geochemical modelling study of the evolution of the chemical composition of seawater linked to a "snowball" glaciation

    Directory of Open Access Journals (Sweden)

    G. Le Hir

    2008-02-01

    Full Text Available The Snowball Earth theory initially proposed by Kirschvink (1992 to explain the Neoproterozoic glacial episodes, suggested that the Earth was fully ice-covered at 720 Ma (Sturtian episode and 640 Ma (Marinoan episode. This succession of extreme climatic crises induced environmental perturbations which are considered as a strong selective pressure on the evolution of life (Hoffman et al., 1998. Using a numerical model of carbon-alkalinity global cycles, we quantify environmental stresses caused by a global glaciation. According to our results, we suggest that during global glaciations, the ocean becomes acidic (pH~6, and undersaturated with respect to carbonate minerals. Moreover the quick transition from ice-house to greenhouse conditions implies an abrupt and large shift of the oceanic surface temperature which causes an extended hypoxia. The intense continental weathering, in the aftermath of the glaciation, deeply affects the seawater composition inducing rapid changes in terms of pH and alkalinity. We also propose a new timing for post glacial perturbations and for the cap carbonates deposition, ~2 Myr instead of 200 kyr as suggested in a previous modelling study. In terms of Precambrian life sustainability, seawater pH modifications appear drastic all along the glaciation, but we suggest that the buffering action of the oceanic crust dissolution avoids a total collapse of biological productivity. But short-lived and large post-glacial perturbations are more critical and may have played the role of an environmental filter proposed in the classic snowball Earth theory. Although the link between environmental changes and life sustainability cannot be modelled accurately, we suggest that only a permissive life (Knoll, 2003 may explain the relative continuity in microfossils diversity observed before, during and after Neoproterozoic glaciation events.

  5. Quantification of atmospheric oxygen levels during the Paleoproterozoic using paleosol compositions and iron oxidation kinetics

    Science.gov (United States)

    Murakami, Takashi; Sreenivas, Bulusu; Sharma, Subrata Das; Sugimori, Hirokazu

    2011-07-01

    The increase in atmospheric oxygen during the Precambrian is a key to understand the co-evolution of life and environment and has remained as a debatable topic. Among various proxies for the estimation of atmospheric oxygen levels, paleosols, ancient weathering profiles, can provide a quantitative pattern of atmospheric oxygen increase during the Precambrian period of Earth history. We have re-evaluated the chemical compositions of paleosols, and presented a new method of applying Fe 2+ oxidation kinetics to the Fe 2+ and Fe 3+ concentrations in paleosols to decipher the quantitative partial pressure of atmospheric oxygen ( P) between 2.5 and 2.0 Ga. We first estimated the compaction factor ( CF, the fraction of original thickness) using the immobile elements such as Ti, Al and Zr on equal volume basis, which was then used to calculate retention fractions ( M R), a mass ratio of paleosol to parent rock, of redox-sensitive elements. The CF and Fe R values were evaluated for factors such as homogeneity of immobile elements, erosion, and formation time of weathering. Fe R increased gradually within the time window of ˜2.5-2.1 Ga and remained close to 1.0 since ˜2.1 Ga onwards. Mn R also increased gradually similar to Fe R but at a slower rate and near complete retention was observed ˜1.85 Ga, suggesting an almost continuous increase in the oxidation of Fe 2+ and Mn 2+ in paleosols ranging in age between ˜2.5 and 1.9 Ga. We have modeled P variations during the Paleoproterozoic by applying Fe 2+ oxidation kinetics to the Fe 2+ and Fe 3+ concentrations in paleosols, which enabled us to derive an Fe 2+ oxidation term referred to as ψ. Possible changes in temperature and P during this time window and their effects on resulting models of P evolution have been also considered. We assumed four cases for the calculations of P variations between 2.5 and 2.0 Ga: no change in either temperature or P, long-term change in only P, long-term changes in both temperature and P

  6. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Google Earth Image and cross-cutting field relationships of distinct Paleoproterozoic mafic dykes from south of Devarakonda area in the Eastern Dharwar Craton has been studied to establish relative emplacement ages. The Devarakonda, covering an area of ∼700 km2, shows spectacular cross-cutting field relationships ...

  7. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 110; Issue 1. Geochemistry of sericite deposits at the base of the Paleoproterozoic Aravalli Supergroup, Rajasthan, India: Evidence for metamorphosed and metasomatised Precambrian Paleosol. B Sreenivas A B Roy R Srinivasan. Volume 110 Issue 1 March 2001 ...

  8. Recruitment of hard-to-reach population subgroups via adaptations of the snowball sampling strategy.

    Science.gov (United States)

    Sadler, Georgia Robins; Lee, Hau-Chen; Lim, Rod Seung-Hwan; Fullerton, Judith

    2010-09-01

    Nurse researchers and educators often engage in outreach to narrowly defined populations. This article offers examples of how variations on the snowball sampling recruitment strategy can be applied in the creation of culturally appropriate, community-based information dissemination efforts related to recruitment to health education programs and research studies. Examples from the primary author's program of research are provided to demonstrate how adaptations of snowball sampling can be used effectively in the recruitment of members of traditionally underserved or vulnerable populations. The adaptation of snowball sampling techniques, as described in this article, helped the authors to gain access to each of the more-vulnerable population groups of interest. The use of culturally sensitive recruitment strategies is both appropriate and effective in enlisting the involvement of members of vulnerable populations. Adaptations of snowball sampling strategies should be considered when recruiting participants for education programs or for research studies when the recruitment of a population-based sample is not essential.

  9. Hydrothermal flake graphite mineralisation in Paleoproterozoic rocks of south-east Greenland

    DEFF Research Database (Denmark)

    Rosing-Schow, Nanna; Bagas, Leon; Kolb, Jochen

    2017-01-01

    Flake graphite mineralisation is hosted in the Kuummiut Terrane of the Paleoproterozoic Nagssugtoqidian Orogen, south-east Greenland. Eclogite-facies peak-metamorphic assemblages record temperatures of 640–830 °C and pressures of 22–25 kbar, and are retrogressed in the high-pressure amphibolite-f...

  10. Mesoproterozoic and Paleoproterozoic subcontinental lithospheric mantle domains beneath southern Patagonia: Isotopic evidence for its connection to Africa and Antarctica

    Czech Academy of Sciences Publication Activity Database

    Mundl, A.; Ntaflos, T.; Ackerman, Lukáš; Bizimis, M.; Bjerg, E. A.; Hauzenberger, Ch. A.

    2015-01-01

    Roč. 43, č. 1 (2015), s. 39-42 ISSN 0091-7613 Institutional support: RVO:67985831 Keywords : lithospheric mantle * Mesoproterozoic * Paleoproterozoic Subject RIV: DD - Geochemistry Impact factor: 4.548, year: 2015

  11. Petrography and geochemistry of iron formations of the Paleoproterozoic Koegas Subgroup, Transvaal Supergroup, Griqualand West, South Africa

    OpenAIRE

    2013-01-01

    M.Sc. (Geology) Nel, B.P. (2013). Petrography and geochemistry of iron formations of the Paleoproterozoic Koegas Subgroup, Transvaal Supergroup, Griqualand West, South Africa. MSc thesis (unpublished), University of Johannesburg, Aucklandpark, pp. 133. The Early Paleoproterozoic Koegas Subgroup comprises a succession of siltstone, mudstone, iron-­‐formation, chert and carbonate rocks that overlies the iron-­‐formations of the Asbestos Hills Subgroup with sharp contact. It is overlain with ...

  12. Plate tectonics hiati as the cause of global glaciations: 2. The late Proterozoic 'Snowball Earth'

    Science.gov (United States)

    Osmaston, M. F.

    2003-04-01

    A fundamental reappraisal of the mechanisms that drive plate tectonics has yielded the remarkable conclusion that, for at least the past 130 Ma, the principal agent has not been ridge-push or slab-pull but a CW-directed torque (probably of electromagnetic origin at the CMB) reaching the deep (>600 km, e.g.[1]) tectospheric keel of the Antarctica craton. Major changes in spreading direction marked both ends of the 122--85 Ma Cretaceous Superchron and started by forming the Ontong Java Plateau. Action of MORs as gearlike linkages has driven Africa and India CCW since Gondwana breakup and continues to drive the Pacific plate CCW. In the Arctic there is now no cratonic keel to pick up any corresponding polar torque, so northern hemisphere plate tectonics is far less active. The thesis of this contribution is that in the Neoproterozoic the lack of cratons at high latitudes would have deprived plate tectonics of this motivation, causing MORs to die (see below) and a major fall in sea-level, leading to global glaciation as outlined in Part 1 for the Huronian events. Like that seen during that first hiatus, dyke-swarm volcanism could have arisen from thermal shrinkage of the global lithosphere, providing CO2 and ash-covering that interrrupted glacial episodes. In oceanic settings this volcanism would have lowered pH and supplied Fe2+ for shallow bio-oxygenic action to deposit as BIF. My multifacet studies of the subduction process convince me that the rapid development of "flat-slab" interface profiles involves the physical removal of hanging-wall material in front of the downbend by basal subduction tectonic erosion (STE). Historically this, and its inferred ubiquity in the Archaean as the precursor to PSM (Part 1), suggests that the required subducting-plate buoyancy is thermal. Accordingly, a redesign [2] of the MOR process has incorporated the heat-containing LVZ as an integral part of the plate and luckily provides a lot more ridge-push to ensure the subduction of buoyant plates. But its action is not indefinitely self-sustaining, so could die out if not "nudged" occasionally. Wholly untrumpeted by seismologists, this built-in ocean-plate-heat is indeed evident as slab-reheating during active subduction. Nearly 100 circum-Pacific tomographic transects kindly provided by E.R.Engdahl consistently show the "slab" high-Vp signature peters out at between 200 and 350 km (plate age-dependent and even at 130 Ma) and a second high-Vp signature then begins close to the top of the TZ and goes on into the lower mantle. This latter signature must be mineralogical, not thermal, and arguably is not mantle but is only a stream of dense stishovitic lumps derived from the TZ-depth partial melting of subducted oceanic crust. Where now is the slab-pull to sustain plate tectonics?

  13. Asynchronous Distance Education Forum - Brainstorming vs. Snowballing: A Case Study for Teaching in Programming Didactics

    Science.gov (United States)

    Patriarcheas, Kiriakos; Xenos, Michalis

    Asynchronous discussion fora all the more become part of the educational process of distance education. The goal of this research is the study of the educational techniques of Brainstorming and Snowballing to their utilisation in the frame of a distance education forum, both as far as participation and creation of learning environment and also educational effectiveness are concerned. This research refers to computer teachers’ training on didactics of programming within the framework of educational micro-worlds. As it is deduced from the data analysis and the study of the messages higher participation and improvement of critical thinking are noted when Brainstorming technique is used, while fairly less time is spent and less off-topic interventions are made when Snowballing technique is used. Meanwhile, Brainstorming is found to be more advantageous than Snowballing concerning the effectiveness both in primary level (trained teachers) and in secondary level of adaptation and knowledge impartment to the students (results of their students).

  14. Termination of BIF deposition in the Paleoproterozoic: the Tongwane Formation, South Africa

    OpenAIRE

    Schroeder, Stefan; Warke, Matthew

    2016-01-01

    The Tongwane Formation (~2.4 Ga) conformably overlies banded iron formations (BIF; Penge Iron Formation) on the Kaapvaal Craton, South Africa. As such, it provides a unique window into depositional processes and environmental conditions in the aftermath of major Archean-Paleoproterozoic BIF deposition, and on the eve of irreversible environmental oxygenation in the Great Oxidation Event (GOE, ~2.35 Ga). This study presents the first sedimentological and bulk-rock geochemical characterization ...

  15. The Great Oxidation Event Recorded in Paleoproterozoic Rocks from Fennoscandia

    Directory of Open Access Journals (Sweden)

    Dmitry V. Rychanchik

    2010-04-01

    Full Text Available With support of the International Continental Scientific Drilling Program (ICDP and other funding organizations, the Fennoscandia Arctic Russia – Drilling Early Earth Project (FAR-DEEP operations have been successfully completed during 2007. A total of 3650 meters of core have been recovered from fifteen holes drilled through sedimentary and volcanic formations in Fennoscandia (Fig. 1, recording several global environmental changes spanning the time interval 2500–2000 Ma, including the Great Oxidation Event (GOE (Holland, 2002. The core was meanwhile curated and archived in Trondheim, Norway, and it has been sampled by an international team of scientists.

  16. Validation of networks derived from snowball sampling of municipal science education actors

    DEFF Research Database (Denmark)

    von der Fehr, Ane; Sølberg, Jan; Bruun, Jesper

    2016-01-01

    predictions based on existing knowledge of the municipalities aligned with SNA data. However, these discrepancies could be explained by development in the municipalities in the time following previous investigations. This study shows that snowball sampling is an applicable method to use for mapping hidden...

  17. Conditional estimation of exponential random graph models from snowball sampling designs

    NARCIS (Netherlands)

    Pattison, Philippa E.; Robins, Garry L.; Snijders, Tom A. B.; Wang, Peng

    2013-01-01

    A complete survey of a network in a large population may be prohibitively difficult and costly. So it is important to estimate models for networks using data from various network sampling designs, such as link-tracing designs. We focus here on snowball sampling designs, designs in which the members

  18. How to find future ecstasy-users: targeted and snowball sampling in an ethically sensitive context

    NARCIS (Netherlands)

    Vervaeke, H.K.E.; Korf, D.J.; Benschop, A.; van den Brink, W.

    2007-01-01

    This article documents the design and the sampling procedures of a prospective longitudinal multidisciplinary study on the neurotoxicity of ecstasy (MDMA): the Netherlands XTC Toxicity Study (NeXT). Targeted and snowball sampling was used to recruit 188 respondents who were ecstasy-naive at

  19. Validation of Networks Derived from Snowball Sampling of Municipal Science Education Actors

    Science.gov (United States)

    von der Fehr, Ane; Sølberg, Jan; Bruun, Jesper

    2018-01-01

    Social network analysis (SNA) has been used in many educational studies in the past decade, but what these studies have in common is that the populations in question in most cases are defined and known to the researchers studying the networks. Snowball sampling is an SNA methodology most often used to study hidden populations, for example, groups…

  20. Sr–Nd isotopic compositions of Paleoproterozoic metavolcanic rocks from the southern Ashanti volcanic belt, Ghana

    OpenAIRE

    Dampare, Samuel; Shibata, Tsugio; Asiedu, Daniel; Okano, Osamu; Manu, Johnson; Sakyi, Patrick

    2009-01-01

    Neodymium (Nd) and strontium (Sr) isotopic data are presented for Paleoproterozoic metavolcanic rocks in the southern part of the Ashanti volcanic belt of Ghana. The metavolcanic rocks are predominantly basalts/basaltic andesites and andesites with minor dacites. Two types of basalts/basaltic andesites (B/A), Type I and Type II, have been identified. The Type I B/A are stratigraphically overlain by the Type II B/A, followed by the andesites and the dacites. The analyzed volcanic rocks commonl...

  1. A highly oxidized atmosphere-ocean system and oceanic molybdenum drawdown during the Paleoproterozoic

    Science.gov (United States)

    Goto, K. T.; Ito, T.; Suzuki, K.; Anbar, A. D.; Gordon, G. W.; Kashiwabara, T.; Takaya, Y.; Shimoda, G.; Nozaki, T.; Kiyokawa, S.; Tetteh, G. M.; Nyame, F. K.

    2014-12-01

    Multiple lines of evidence suggest that the first major oxidation of the atmosphere-ocean system occurred during the Paleoproterozoic. However, the course of this redox transition remains elusive. A number of large Mn deposits are distributed in Paleoproterozoic sedimentary successions. As Mn is a redox-sensitive element characterized by high redox potential, knowledge of the Mn cycle in Paleoproterozoic seawater may provide insight into redox evolution during this period. Here, we investigate the Mn cycle in Paleoproterozoic seawater based on the Re-Os and Mo isotope compositions, and the abundance of major and trace elements, in Mn-rich sedimentary rocks from the Nsuta deposit of the Birimian Supergroup, Ghana. The Mn ore is composed mainly of rhodochrosite and is distributed at the boundaries between sedimentary rocks and tholeiitic volcanic rocks. The Re-Os isochron age (2217 ± 100 Ma) we obtained was consistent with U-Pb zircon ages of the volcanic rocks. The manganophile elements, except for Mo, show no enrichment, which is similar to modern hydrothermal Mn oxides. The PAAS-normalized REE compositions show positive Ce anomaly, indicative of Ce enrichment due to the oxidation of Ce(III) by Mn(IV). These findings suggest that Mn ore formed from primary precipitation of Mn oxides from hydrothermal fluids as they were mixed with bottom seawater at ~2.2 Ga. Thus, the bottom seawater would have been sufficiently oxygenated for the precipitation of Mn oxides at ~2.2 Ga. The Nsuta ore samples exhibit slight Mo enrichment, but Mo/Mn ratios are orders of magnitude lower than those in modern hydrothermal Mn oxides. We also found that the Mo isotopes in the Nsuta ore are ~0.7‰ heavier than those in modern hydrothermal and hydrogenous Mn oxides. As Mo in hydrothermal Mn oxides is sourced primarily from seawater (Goto et al., in prep), these results may reflect smaller oceanic Mo inventory and heavier seawater Mo isotope composition at 2.2 Ga than those of present

  2. The Khida terrane - Geology of Paleoproterozoic rocks in the Muhayil area, eastern Arabian Shield, Saudi Arabia

    Science.gov (United States)

    Stoeser, D.B.; Whitehouse, M.J.; Stacey, J.S.

    2001-01-01

    The bulk of the Arabian Shield of Saudi Arabia is underlain by Neoproterozoic terranes of oceanic affinity that were accreted during Pan-African time (about 680- 640Ma). Geologicalmappingandisotopicinvestigations during the 1980’s,however, provided the first evidence for Paleoproterozoic continental crust within the east- central part of the shield in Saudi Arabia. These studies delineated an older basement domain, herein referred to as the Khida terrane (Fig. l), which is defined as that part of the southern Afif composite terrane underlain by Paleoproterozoicto Archean continental crust (Stoeser and Stacey, 1988). The isotopic and geochronologic work to support our current studies within the Khida terrane are discussed in a companion abstract (Whitehouse et al., this volume). The regional geology and geochronology of the region has been summarized in detail by Johnson (1996). The current study is based on the continued use of samples previously collected in the Khida area by the authors and others as well as new field work conducted by us in 1999. This work further defines the occurrence of late Paleoproterozoic rocks at Jabal Muhayil, which is located at the eastern margin of the exposed terrane (Fig. 1). Our isotopic work is at an early stage and this abstract partly relates geologic problems that remain to be resolved. 

  3. Temporal and social contexts of heroin-using populations. An illustration of the snowball sampling technique.

    Science.gov (United States)

    Kaplan, C D; Korf, D; Sterk, C

    1987-09-01

    Snowball sampling is a method that has been used in the social sciences to study sensitive topics, rare traits, personal networks, and social relationships. The method involves the selection of samples utilizing "insider" knowledge and referral chains among subjects who possess common traits that are of research interest. It is especially useful in generating samples for which clinical sampling frames may be difficult to obtain or are biased in some way. In this paper, snowball samples of heroin users in two Dutch cities have been analyzed for the purpose of providing descriptions and limited inferences about the temporal and social contexts of their lifestyles. Two distinct heroin-using populations have been discovered who are distinguished by their life cycle stage. Significant contextual explanations have been found involving the passage from adolescent peer group to criminal occupation, the functioning of network "knots" and "outcroppings," and the frequency of social contact. It is suggested that the snowball sampling method may have utility in studying the temporal and social contexts of other populations of clinical interest.

  4. Recruiting hard-to-reach United States population sub-groups via adaptations of snowball sampling strategy

    Science.gov (United States)

    Sadler, Georgia Robins; Lee, Hau-Chen; Seung-Hwan Lim, Rod; Fullerton, Judith

    2011-01-01

    Nurse researchers and educators often engage in outreach to narrowly defined populations. This article offers examples of how variations on the snowball sampling recruitment strategy can be applied in the creation of culturally appropriate, community-based information dissemination efforts related to recruitment to health education programs and research studies. Examples from the primary author’s program of research are provided to demonstrate how adaptations of snowball sampling can be effectively used in the recruitment of members of traditionally underserved or vulnerable populations. The adaptation of snowball sampling techniques, as described in this article, helped the authors to gain access to each of the more vulnerable population groups of interest. The use of culturally sensitive recruitment strategies is both appropriate and effective in enlisting the involvement of members of vulnerable populations. Adaptations of snowball sampling strategies should be considered when recruiting participants for education programs or subjects for research studies when recruitment of a population based sample is not essential. PMID:20727089

  5. The Stratigraphy and Lithofacies of the Paleoproterozoic Volcaniclastic Sequences in the Cape Three Points Area- Akodda section of the Southern in Ashanti Belt in the Birimian of southwest Ghana

    Science.gov (United States)

    Yoshimaru, S.; Kiyokawa, S.; Ito, T.; Ikehara, M.; Nyame, F. K.; Tetteh, G. M.

    2015-12-01

    The Paleoproterozoic Era is thought to have experienced one of the most significant changes in earth's environment during earth history. Early continents started to diverge and collide accompanied by first major oxidation of the atmosphere-oceanic system known as the Great Oxidation Environment (GOE). Due to their well-preserved oceanic sedimentary sequences, Paleoproterozoic belts are usually good targets for studies on the history of earth's past environment. In addition, these belts provide great help to understand the nature of the Paleoproterozoic deeper oceanic environments. Birimian greenstone belt in southwestern Ghana is likely to have made up of subduction of oceanic basin to form a volcanic island arc. Birimian rocks are separated by nonconformity from the Tarkwaian Group which is a younger paleoplacer deposit (Perrouty et al., 2012). The Birimian is made up of island-arc volcanic rocks; foreland basin made up of shale, sandstone, quartzite and turbidities derived from 2.17 Ga granite intrusions during Birimian volcanism. In this study, we focused on the coastal area around Cape Three Points at the southernmost part of the Ashanti (Axim-Konongo) belt in Ghana. In the eastern part of the area, excellently preserved Paleoprotorozoic deeper oceanic sedimentary sequences extensively outcrop for over 4km stretch. This volcano-sedimentary sequence has been affected by greenschist facies metamorphism. Structurally, this region preserves S1 cleavage and asymmetrical synform with west vergence and S0 younging to the east. Provisional stratigraphy is very continuous up to more than 2000m thick and, in addition, suggests at least four different fining upward sequences in the area to the east and west of Atwepo, west of Kwetakora and Akodda. These sub-sequences are mainly composed of volcaniclasitc, sandstone, black shale and rare volcanics such as pillow basalt or massive volcanic lava. In other words, this continuous sequence suggests distal submarine

  6. Triassic rejuvenation of unexposed Archean-Paleoproterozoic deep crust beneath the western Cathaysia block, South China

    Science.gov (United States)

    Li, Xi-Yao; Zheng, Jian-Ping; Xiong, Qing; Zhou, Xiang; Xiang, Lu

    2018-01-01

    Jurassic (ca. 150 Ma) Daoxian basalts from the western Cathaysia block (South China) entrained a suite of deep-seated crustal xenoliths, including felsic schist, gneiss and granulite, and mafic two-pyroxene granulite and metagabbro. Zircon U-Pb-Hf isotopic, whole-rock elemental and Sr-Nd-Pb isotopic compositions have been determined for these valuable xenoliths to reveal the poorly-known, unexposed deep crust beneath South China. Detrital zircons from the garnet-biotite schists show several populations of ages at 0.65-0.5 Ga, 1.1-0.75 Ga, 1.6-1.4 Ga, 1.8-1.7 Ga, 2.5-2.4 Ga, 2.8 Ga, and 3.5 Ga, representing a multi-sourced, meta-sedimentary origin with deposition time at the early Cambrian. One mafic granulite contains zircons with concordant U-Pb ages of Neoarchean ( 2520 Ma), as well as Hf model ages of 2.8-2.6 Ga and positive εHf(t) values (up to 6.3), suggesting an accretion of juvenile crust in Neoarchean, probably as the main framework of the lower crust. Geochemical and geochronological evidence shows the mafic granulite and metagabbro were produced by underplating of magmas derived from the depleted asthenosphere and mixed with EM2-type materials during the Late Triassic (205-196 Ma). This magmatic underplating also resulted in the widespread metamorphism of the mafic lower crust and felsic middle crust (e.g., the felsic granulite and gneiss) at 202-201 Ma. We suggest the existence of a highly evolved Archean-Paleoproterozoic basement beneath the western Cathaysia block, which experienced episodic accretion and reworking and the strong rejuvenation during the Triassic. A three-layered structure of the lower crust could exist beneath the Daoxian area during the Jurassic time: its upper layer is an evolved Archean-Paleoproterozoic basement; the middle hybrid layer represents a mixture of Archean-Paleoproterozoic basement with newly accreted/reworked Proterozoic to Phanerozoic materials; and the deeper layer consists of mafic granulites derived from the

  7. Using snowball sampling method with nurses to understand medication administration errors.

    Science.gov (United States)

    Sheu, Shuh-Jen; Wei, Ien-Lan; Chen, Ching-Huey; Yu, Shu; Tang, Fu-In

    2009-02-01

    We aimed to encourage nurses to release information about drug administration errors to increase understanding of error-related circumstances and to identify high-alert situations. Drug administration errors represent the majority of medication errors, but errors are underreported. Effective ways are lacking to encourage nurses to actively report errors. Snowball sampling was conducted to recruit participants. A semi-structured questionnaire was used to record types of error, hospital and nurse backgrounds, patient consequences, error discovery mechanisms and reporting rates. Eighty-five nurses participated, reporting 328 administration errors (259 actual, 69 near misses). Most errors occurred in medical surgical wards of teaching hospitals, during day shifts, committed by nurses working fewer than two years. Leading errors were wrong drugs and doses, each accounting for about one-third of total errors. Among 259 actual errors, 83.8% resulted in no adverse effects; among remaining 16.2%, 6.6% had mild consequences and 9.6% had serious consequences (severe reaction, coma, death). Actual errors and near misses were discovered mainly through double-check procedures by colleagues and nurses responsible for errors; reporting rates were 62.5% (162/259) vs. 50.7% (35/69) and only 3.5% (9/259) vs. 0% (0/69) were disclosed to patients and families. High-alert situations included administration of 15% KCl, insulin and Pitocin; using intravenous pumps; and implementation of cardiopulmonary resuscitation (CPR). Snowball sampling proved to be an effective way to encourage nurses to release details concerning medication errors. Using empirical data, we identified high-alert situations. Strategies for reducing drug administration errors by nurses are suggested. Survey results suggest that nurses should double check medication administration in known high-alert situations. Nursing management can use snowball sampling to gather error details from nurses in a non

  8. U-Pb geochronologic constraints on Paleoproterozoic orogenesis in the northwestern Makkovik Province, Labrador, Canada

    International Nuclear Information System (INIS)

    Ketchum, J.W.F.; Dunning, G.R.; Dunning, G.R.

    1997-01-01

    A 45 km wide, shear-zone-bounded segment of the northwestern Makkovik Province, Labrador, is underlain by Archean gneisses derived from the adjacent Nain craton. This lithotectonic block (Kaipokok domain) was reworked at high metamorphic grade, overthrust by supracrustal sequences (Lower Aillik and Moran Lake groups), and intruded by granitoid plutons during the Paleoproterozoic. Initial amphibolite-facies reworking of the Kaipokok domain at 1896 ± 6 Ma is indicated by U-Pb ages of metamorphic zircon from a foliated Kikkertavak metadiabase dyke. This is one of the oldest Paleoproterozoic tectonic events dated thus far in northeast Laurentia and may be linked with ca. 1890 Ma plutonism documented elsewhere in the Kaipokok domain. Intrusion of granitoid plutons at 1882 -6 +10 , 1877 ± 5, and 1871 -3 +4 Ma in the Kaipokok Bay area postdates early thick- and thin-skinned thrusting (possibly east to northeast directed) that involved Lower Aillik Group strata. U-Pb titanite ages of 1866 - 1847 Ma in part record a metamorphic event that followed this plutonic-tectonic activity. These early events are temporally and kinematically difficult to reconcile with accretion of juvenile Makkovikian terranes in the southeast and may instead be related to early stages of the ca. 1.91 - 1.72 Ga Torngat orogeny along the western margin of the Nain craton. In contrast, high-grade metamorphism, dextral shearing, and northwestward thrusting between 1841 and 1784 Ma, including crystallization of an Iggiuk granitic vein at 1811 ± 8 Ma, are in accord with accretion of Makkovikian terranes in a dextral transpressional regime (Makkovikian orogeny sensu stricto). Coeval sinistral transpression in the Torngat orogen suggests that both orogenic belts accommodated relative northward tectonic escape of the Nain craton during this interval. (author)

  9. The nature and origin of nucleus-like intracellular inclusions in Paleoproterozoic eukaryote microfossils.

    Science.gov (United States)

    Pang, K; Tang, Q; Schiffbauer, J D; Yao, J; Yuan, X; Wan, B; Chen, L; Ou, Z; Xiao, S

    2013-11-01

    The well-known debate on the nature and origin of intracellular inclusions (ICIs) in silicified microfossils from the early Neoproterozoic Bitter Springs Formation has recently been revived by reports of possible fossilized nuclei in phosphatized animal embryo-like fossils from the Ediacaran Doushantuo Formation of South China. The revisitation of this discussion prompted a critical and comprehensive investigation of ICIs in some of the oldest indisputable eukaryote microfossils-the ornamented acritarchs Dictyosphaera delicata and Shuiyousphaeridium macroreticulatum from the Paleoproterozoic Ruyang Group of North China-using a suite of characterization approaches: scanning electron microscopy (SEM), transmission electron microscopy (TEM), and focused ion beam scanning electron microscopy (FIB-SEM). Although the Ruyang acritarchs must have had nuclei when alive, our data suggest that their ICIs represent neither fossilized nuclei nor taphonomically condensed cytoplasm. We instead propose that these ICIs likely represent biologically contracted and consolidated eukaryotic protoplasts (the combination of the nucleus, surrounding cytoplasm, and plasma membrane). As opposed to degradational contraction of prokaryotic cells within a mucoidal sheath-a model proposed to explain the Bitter Springs ICIs-our model implies that protoplast condensation in the Ruyang acritarchs was an in vivo biologically programmed response to adverse conditions in preparation for encystment. While the discovery of bona fide nuclei in Paleoproterozoic acritarchs would be a substantial landmark in our understanding of eukaryote evolution, the various processes (such as degradational and biological condensation of protoplasts) capable of producing nuclei-mimicking structures require that interpretation of ICIs as fossilized nuclei be based on comprehensive investigations. © 2013 John Wiley & Sons Ltd.

  10. Sedimentary phosphate and associated fossil bacteria in a Paleoproterozoic tidal flat in the 1.85 Ga Michigamme Formation, Michigan, USA

    Science.gov (United States)

    Hiatt, Eric E.; Pufahl, Peir K.; Edwards, Cole T.

    2015-04-01

    Phosphorus is a nutrient fundamental to life and when it precipitates in modern environments bacteria are intimately involved in its release, concentration, and mineralization. Preserved fossil bacteria in phosphate crusts and grains from the ca. 1850 million-year-old Bijiki Iron Formation Member of the Michigamme Formation, Michigan provide insight into the longevity and nature of this relationship. The Michigamme Formation accumulated near the end of the Earth's initial phosphogenic episode (ca. 2.2 and 1.8 Ga) to produce one of the first granular phosphorites. Phosphatic lithofacies consist of fine- to medium-sand-sized francolite peloids concentrated on bedding surfaces in peritidal facies. Granular beds are up to 2 cm thick and peloids are often partially to completely replaced by dolomite and chert. The grains contain organic matter and pyrite framboids that suggest bacterial breakdown of organic matter and bacterial sulfate reduction. The peritidal nature of phosphorite in the Michigamme Formation is in sharp contrast to Phanerozoic phosphogenic environments in deeper coastal upwelling settings. Peritidal settings were well suited for phosphogenesis under the very low oxygen and low dissolved sulfate levels of the Paleoproterozoic as cyanobacteria produced oxygen in shallow water and evaporation led to increased sulfate concentrations. Such concomitant processes helped establish focused redox interfaces in the sediment that chemosynthetic bacterial communities (sulfur oxidizers, reducers, forms that concentrate P, and possibly iron oxidizers) could exploit. Phosphate released from organic matter by heterotrophic bacteria and Fe-redox pumping was further concentrated by these chemotrophs; a process that forms late Neoproterozoic to Phanerozoic phosphorites but on a much larger scale. This early example of a granular phosphorite demonstrates that, like their Phanerozoic counterparts, Paleoproterozoic phosphorites are the concentrated indirectly biomineralized

  11. Parcellating an individual subject's cortical and subcortical brain structures using snowball sampling of resting-state correlations.

    Science.gov (United States)

    Wig, Gagan S; Laumann, Timothy O; Cohen, Alexander L; Power, Jonathan D; Nelson, Steven M; Glasser, Matthew F; Miezin, Francis M; Snyder, Abraham Z; Schlaggar, Bradley L; Petersen, Steven E

    2014-08-01

    We describe methods for parcellating an individual subject's cortical and subcortical brain structures using resting-state functional correlations (RSFCs). Inspired by approaches from social network analysis, we first describe the application of snowball sampling on RSFC data (RSFC-Snowballing) to identify the centers of cortical areas, subdivisions of subcortical nuclei, and the cerebellum. RSFC-Snowballing parcellation is then compared with parcellation derived from identifying locations where RSFC maps exhibit abrupt transitions (RSFC-Boundary Mapping). RSFC-Snowballing and RSFC-Boundary Mapping largely complement one another, but also provide unique parcellation information; together, the methods identify independent entities with distinct functional correlations across many cortical and subcortical locations in the brain. RSFC parcellation is relatively reliable within a subject scanned across multiple days, and while the locations of many area centers and boundaries appear to exhibit considerable overlap across subjects, there is also cross-subject variability-reinforcing the motivation to parcellate brains at the level of individuals. Finally, examination of a large meta-analysis of task-evoked functional magnetic resonance imaging data reveals that area centers defined by task-evoked activity exhibit correspondence with area centers defined by RSFC-Snowballing. This observation provides important evidence for the ability of RSFC to parcellate broad expanses of an individual's brain into functionally meaningful units. © The Author 2013. Published by Oxford University Press.

  12. Lesser Himalayan sequences in Eastern Himalaya and their deformation: Implications for Paleoproterozoic tectonic activity along the northern margin of India

    Directory of Open Access Journals (Sweden)

    Dilip Saha

    2013-05-01

    Full Text Available Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence (LHS of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite-slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic–Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here: (1 the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; (2 the older deformation and metamorphism relate to a Pacific type

  13. Paleozoic and Paleoproterozoic Zircon in Igneous Xenoliths Assimilated at Redoubt Volcano, Alaska

    Science.gov (United States)

    Bacon, C. R.; Vazquez, J. A.; Wooden, J. L.

    2010-12-01

    Historically active Redoubt Volcano is a basalt-to-dacite cone constructed upon the Jurassic-early Tertiary Alaska-Aleutian Range batholith. New SHRIMP-RG U-Pb age and trace-element concentration results for zircons from gabbroic xenoliths and crystal-rich andesitic mush from a late Pleistocene pyroclastic deposit indicate that ~310 Ma and ~1865 Ma igneous rocks underlie Redoubt at depth. Two gabbros have sharply terminated prismatic zircons that yield ages of ~310 Ma. Zircons from a crystal mush sample are overwhelmingly ~1865 Ma and appear rounded due to incomplete dissolution. Binary plots of element concentrations or ratios show clustering of data for ~310-Ma grains and markedly coherent trends for ~1865-Ma grains; e.g., ~310-Ma grains have higher Eu/Eu* than most of the ~1865-Ma grains, the majority of which form a narrow band of decreasing Eu/Eu* with increasing Hf content which suggests that ~1865-Ma zircons come from igneous source rocks. It is very unlikely that detrital zircons from a metasedimentary rock would have this level of homogeneity in age and composition. One gabbro contains abundant ~1865 Ma igneous zircons, ~300-310 Ma fluid-precipitated zircons characterized by very low U and Th concentrations and Th/U ratios, and uncommon ~100 Ma zircons. We propose that (1) ~310 Ma gabbro xenoliths from Redoubt Volcano belong to the same family of plutons dated by Aleinikoff et al. (USGS Circular 1016, 1988) and Gardner et al. (Geology, 1988) located ≥500 km to the northeast in basement rocks of the Wrangellia and Alexander terranes and (2) ~1865 Ma zircons are inherited from igneous rock, potentially from a continental fragment that possibly correlates with the Fort Simpson terrane or Great Bear magmatic zone of the Wopmay Orogen of northwestern Laurentia. Possibly, elements of these Paleoproterozoic terranes intersected the Paleozoic North American continental margin where they may have formed a component of the basement to the Wrangellia

  14. Piedra lata terrane of Uruguay: Rb-Sr geochronological data of two new paleoproterozoic (transamazonian) granitoids

    International Nuclear Information System (INIS)

    Cingolani, C; Bossi, J; Varela, R; Maldonado, S.; Pineyro, D.; Schipilov, A

    2001-01-01

    The Precambrian basement of Uruguay consists of three major terranes separated and crosscut by wide NE-striking subvertical transcurrent shear zones. The western terrane as a part of the Rio de la Plata Craton is known as the Piedra Alta Terrane (PAT). This is separated from the Nico Perez Terrane by the Sarandi del Yi-Piri olis subvertical shear zone (Bossi et al., 1993). A mafic dykes complex intruded the PAT at 1.8 Ga and was not later deformed. The PAT has equivalent rocks in the igneous-metamorphic basement of Tandilia region and the Martin Garcia Island, Buenos Aires Province, Argentina (Dalla Salda et al., 1988; Cingolani and Dalla Salda, 2000). The PAT shows no evidence of the Neoproterozoic orogenies and is considered a best preserved Paleoproterozoic block (Transamazonian Cycle). It contains three E-W trending belts of volcano-sedimentary rocks with low grade metamorphism. These are from south to north: Pando, San Jose and Andresito belts (Bossi et al., 1996). Associated with them, three granitic-gneissic zones he Ecilda Paullier, Florida and Feliciano- were recognized with magmatic intrusives emplaced at different crustal levels. The San Jose belt is the largest supracrustal unit and contains abundant volcanic and volcaniclastic rocks of low grade metamorphic (Paso Severino Fm.) with sheets of granitic rocks intercalated (Mutti et al., 1996; Bossi et al., 1996). The associated granitic rocks are of large areal extension, mostly granodiorites and tonalites, and minor monzogranite and gabbro (e.g. Cerro Rospide region), including xenoliths from Paso Severino Fm. Towards the north of the San Jose belt an important Florida granitized zone is developed in the central part of the PAT, where the Pintos massif was recognized. The main purpose of this contribution is to offer new Rb-Sr geochronological data from two granitoid units, The Cerro Rospide intrusive in Paso Severino Fm. and Pintos massif included in medium grade migmatic-metamorphic complex and its

  15. Mantle reservoirs (EM-1, OIB, E-MORB and N-MORB), long duration and polystages history for PGE-bearing paleoproterozoic layered intrusions in the N-E part of Fennoscandian Shield.

    Science.gov (United States)

    Bayanova, Tamara; Nerovich, Ludmila; Serov, Pavel; Kunakkuzin, Evgeniy; Elizarov, Dmitriy

    2015-04-01

    Paleoproterozoic layered PGE -bearing intrusions located in the N-E part of the Fennoscandian Shield and have a total are about 2000 km2. Long multidisciplinary studies using isotope Nd-Sr, U-Pb and 3He/4He systematics permit create a big bank of geochemistry data for different part of the intrusions: barren and main Cu-Ni-Cr-Ti-V and PGE phases, dykes complexes and host rocks. Based on U-Pb isotope data (on baddeleyite and zircon) and Sm-Nd mineral isochrones (on rock-forming and sulphides minerals) there is distinguished long magmatic duration from 2.53 to 2.40 Ga. Using precise U-Pb and Sm-Nd data for different part of the intrusions there are established four main impulses: 2.53, 2.50, 2.45, and 2.40 Ga of magmatic (LIP) activities for gabbronorite, anothosite et.set. rocks. The primary reservoir for all precious and multimetal massifs are considered as enriched mantle EM-1 using ɛNd- ISr system with negative ɛNd values and low ISr data for whole rocks of the intrusions. Dyke complexes are presented as three groups: high Ti-ferrodolerites, low Ti and low Fe-gabbronorites. Complex isotope (U-Pb, Sm-Nd) and geochemistry (REE, ɛNd, ISr) data investigations reflect OIB, E-MORB and N-MORB reservoirs for its origin (Nerovich et all., 2014). Isotope 3He/4He and 3He concentrations for accessory minerals ( ilmenite, magnetite et. set ) from the layered paleoproterozoic intrusions reflect significant lower mantle component and upper mantle contribution. According to the model of binary mixing (Jahn et all, 2000) there were calculated mantle and core component into plume magmatic reservoir connected with the origin of the PGE paleoproterozoic intrusions. The mantle contributions lie in the interval from 85 to 93% and core component are very less. All investigations are devoted to memory of academician RAS, professor F.Mitrofanov (Russia), he was a leader of scientific school for geology, geochemistry and metallogenesis of ore deposits. The studies are

  16. Molybdenum isotopes in modern marine hydrothermal Fe/Mn deposits: Implications for Archean and Paleoproterozoic Mo cycles

    Science.gov (United States)

    Goto, K. T.; Hein, J. R.; Shimoda, G.; Aoki, S.; Ishikawa, A.; Suzuki, K.; Gordon, G. W.; Anbar, A. D.

    2016-12-01

    Molybdenum isotope (δ98/95Mo) variations recorded in Archean and Paleoproterozoic Fe/Mn-rich sediments have been used to constrain ocean redox conditions at the time of deposition (Canfield et al., 2013 PNAS; Planavsky et al., 2014 Nat. Geo.; Kurzweil et al., 2015 GCA). However, except for hydrogenous Fe-Mn crusts (Siebert et al., 2003), δ98/95Mo variation of modern Fe and Mn oxide deposits has been poorly investigated. Marine hydrothermal systems are thought to be the major source of Fe and Mn in Archean and Paleoproterozoic Fe- and Mn-rich sediments. Hence, to accurately interpret Mo isotope data of those ancient sedimentary rocks, it is important to evaluate the possible influence of hydrothermally derived Mo on δ98/95Mo of modern Fe- and Mn-rich sediments. In this study, we analyzed Mo isotopic compositions of one hydrothermal Fe oxide and 15 Mn oxides from five different hydrothermal systems in the modern ocean. The Fe oxide is composed mainly of goethite, and has a δ98/95Mo of 0.7‰, which is 1.4‰ lighter than that of present-day seawater. The observed offset is similar to isotope fractionation observed during adsorption experiments of Mo on goethite (Δ98/95Mogoethite-solution = -1.4 ± 0.5%; Goldberg et al., 2009 GCA). The 15 hydrothermal Mn oxides show large variations in δ98/95Mo ranging from -1.7 to 0.5‰. However, most of the values are similar to those of modern hydrogenous Fe-Mn crusts (Siebert et al., 2003 EPSL), and fall within the range of estimated δ98/95Mo of Mn oxides precipitated from present-day seawater using the isotope offset reported from adsorption experiments (Δ98/95Mo = -2.7 ± 0.3‰; Wasylenki et al., 2008 GCA). These findings indicate that seawater is the dominant source of Mo for modern hydrothermal Fe and Mn deposits. However, the observed large variation indicates that the contribution Mo from local hydrothermal systems is not negligible. The oceanic Mo inventory during the Archean and Paleoproterozoic is thought to be

  17. Insights into a spatially embedded social network from a large-scale snowball sample

    Science.gov (United States)

    Illenberger, J.; Kowald, M.; Axhausen, K. W.; Nagel, K.

    2011-12-01

    Much research has been conducted to obtain insights into the basic laws governing human travel behaviour. While the traditional travel survey has been for a long time the main source of travel data, recent approaches to use GPS data, mobile phone data, or the circulation of bank notes as a proxy for human travel behaviour are promising. The present study proposes a further source of such proxy-data: the social network. We collect data using an innovative snowball sampling technique to obtain details on the structure of a leisure-contacts network. We analyse the network with respect to its topology, the individuals' characteristics, and its spatial structure. We further show that a multiplication of the functions describing the spatial distribution of leisure contacts and the frequency of physical contacts results in a trip distribution that is consistent with data from the Swiss travel survey.

  18. The Atuba complex: a paleoproterozoic belt intensively reworked in the neoproterozoic era

    International Nuclear Information System (INIS)

    Siga Junior, O.; Basei, M.A.S.; Machiavelli, A.; Harara, O.M.; Reis Neto, J.M.

    1996-01-01

    Studies of terranes between the northern Ribeira and southern Dom Feliciano Belts allow the characterization of three geotectonic domains with different evolutions: the Luis Alves, Curitiba and Paranagua terranes. The Atuba complex occurs in Curitiba Domain, which has a northwestern limit with metasediments of the Acungui and Setuva Groups and a southwestern limit with the granulitic gneisses of the Luis Alves domains. The contacts are expressive shear zones. The predominant rocks of the Curitiba Domain are banded, migmatitic gneisses in amphibolite grade with biotite-amphibolite gneissic mesosomes and tonalitic/graodioritic leucosomes, here called the Atuba complex. The migmatites are Paleoproterozoic (2.000±200 Ma) and remigmatized in Neoproterozoic (600±20 Ma). During the latter period temperatures reached more than 500 0 C. The structural pattern indicated shear-controlled tectonics with an important lateral component, and low-angle, south-southeastward transport direction. The terranes of the Atuba complex appear to represent deep-level rocks which were migmatized, granitized and then added to the border of the Luis Alves Microplate during the Neoproterozoic. This late Neoproterozoic tectonic scheme which continued to the Cambro-Ordoviciano seems to be the result of larger scale processes of continental agglutination which ended with the formation of western Gondwanaland. (author). 17 figs., 2 tabs

  19. Weathering model for the quantification of atmospheric oxygen evolution during the Paleoproterozoic

    Science.gov (United States)

    Yokota, Kohei; Kanzaki, Yoshiki; Murakami, Takashi

    2013-09-01

    A weathering model has been developed to quantify atmospheric oxygen evolution during the Paleoproterozoic. The weathering model calculates the concentrations of Fe2+ dissolved from Fe2+-bearing primary minerals and oxidized Fe3+ out of the dissolved Fe2+ at a given partial pressure of atmospheric oxygen (PO2) during weathering and establishes the relationships between PO2 and ϕ, where ϕ is the ratio of oxidized and then precipitated Fe3+ out of the Fe2+ dissolved from primary minerals to the dissolved Fe2+ in a whole weathering profile. The weathering model considers controlling factors of the redistribution of Fe during weathering, that is, the dissolution rate of Fe2+-bearing primary minerals, the oxidation rate of Fe2+, and the groundwater flow rate. The validity of the model was confirmed by applying the model to the experimental data of olivine dissolution carried out under low O2 conditions. The sensitivity analysis of the model has revealed that the formation time of weathering, the mineral dissolution rate and the diffusion of O2 into a weathering profile have no or slight influence on ϕ, resulting in ˜0, 0 and 0.3 changes in log(PO2) caused by four orders of magnitude change of the formation time, more than 10 orders change of the mineral dissolution rate, and assumed change of the O2 diffusion, respectively. On the other hand, the temperature, the pH and the groundwater flow rate have moderate to large effects on ϕ: 0.6, 1.4 and 1.5 changes in log(PO2) for changes of 5 °C in temperature, 0.5 in pH, and one order of magnitude in groundwater flow rate, respectively. Using possible surface temperature, pH and groundwater flow rate estimated from the literature, we calculated the ϕ-PO2 relationships which were then applied to the ϕ values of paleosols (fossil weathering profiles) formed between 2.5 and 1.8 Ga. Taking account of the constraints given by the records of mass independent fractionation in sulfur isotopes and other geological proxies (i

  20. THE PALEOPROTEROZOIC IMANDRA-VARZUGA RIFTING STRUCTURE (KOLA PENINSULA: INTRUSIVE MAGMATISM AND MINERAGENY

    Directory of Open Access Journals (Sweden)

    V. V. Chashchin

    2014-01-01

    Full Text Available The article provides data on the structure of the Paleoproterozoic intercontinental Imandra-Varzuga rifting structure (IVS and compositions of intrusive formations typical of the early stage of the IVS development and associated mineral resources. IVS is located in the central part of the Kola region. Its length is about 350 km, and its width varies from 10 km at the flanks to 50 km in the central part. IVS contains an association of the sedimentary-volcanic, intrusive and dyke complexes. It is a part of a large igneous Paleoproterozoic province of the Fennoscandian Shield spreading for a huge area (about 1 million km2, which probably reflects the settings of the head part of the mantle plume. Two age groups of layered intrusions were associated with the initial stage of the IVS development. The layered intrusions of the Fedorovo-Pansky and Monchegorsk complexes (about 2.50 Ga are confined to the northern flank and the western closure of IVS, while intrusions of the Imandra complex (about 2.45 Ga are located at the southern flank of IVS. Intrusions of older complexes are composed of rock series from dunite to gabbro and anorthosites (Monchegorsk complex and from orthopyroxenite to gabbro and anorthosites (Fedorovo-Pansky complex. Some intrusions of this complexes reveal features of multiphase ones. The younger Imandra complex intrusions (about 2.45 Ga are stratified from orthopyroxenite to ferrogabbro. Their important feature is comagmatical connection with volcanites. All the intrusive complexes have the boninite-like mantle origin enriched by lithophyle components. Rocks of these two complexеs with different age have specific geochemical characteristics. In the rocks of the Monchegorsk and Fedorovo-Pansky complexes, the accumulation of REE clearly depends on the basicity of the rocks, the spectrum of REE is non-fractionated and ‘flat’, and the Eu positive anomaly is slightly manifested. In the rocks of the Imandra complex, the level of

  1. Polymetamorphic evolution of the granulite-facies Paleoproterozoic basement of the Kabul Block, Afghanistan

    Science.gov (United States)

    Collett, Stephen; Faryad, Shah Wali; Mosazai, Amir Mohammad

    2015-08-01

    The Kabul Block is an elongate crustal fragment which cuts across the Afghan Central Blocks, adjoining the Indian and Eurasian continents. Bounded by major strike slip faults and ophiolitic material thrust onto either side, the block contains a strongly metamorphosed basement consisting of some of the only quantifiably Proterozoic rocks south of the Herat-Panjshir Suture Zone. The basement rocks crop-out extensively in the vicinity of Kabul City and consist predominantly of migmatites, gneisses, schists and small amounts of higher-grade granulite-facies rocks. Granulite-facies assemblages were identified in felsic and mafic siliceous rocks as well as impure carbonates. Granulite-facies conditions are recorded by the presence of orthopyroxene overgrowing biotite in felsic rocks; by orthopyroxene overgrowing amphibole in mafic rocks and by the presence of olivine and clinohumite in the marbles. The granulite-facies assemblages are overprinted by a younger amphibolite-facies event that is characterized by the growth of garnet at the expense of the granulite-facies phases. Pressure-temperature (P-T) conditions for the granulite-facies event of around 850 °C and up to 7 kbar were calculated through conventional thermobarometry and phase equilibria modeling. The younger, amphibolite-facies event shows moderately higher pressures of up to 8.5 kbar at around 600 °C. This metamorphism likely corresponds to the dominant metamorphic event within the basement of the Kabul Block. The results of this work are combined with the litho-stratigraphic relations and recent geochronological dating to analyze envisaged Paleoproterozoic and Neoproterozoic metamorphic events in the Kabul Block.

  2. An Integrated Geochronological, Petrological, Geochemical and Paleomagnetic Study of Paleoproterozoic and Mesoproterozoic Mafic Dyke Swarms in the Nain Craton, Labrador

    Science.gov (United States)

    Sahin, Tugce

    The Nain craton comprises the western, Labrador segment of the larger North Atlantic craton (NAC) which exposes Early through Late Archean gneisses. The NAC is bounded on all sides by Paleoproterozoic collisional orogens that involved either considerable structural reworking (Torngat-Nagssugtoqidian-Lewisian) or the accretion of juvenile arc magmas (Ketilidian-Makkovik). The NAC remains poorly understood compared to other Archean crustal blocks now dispersed globally. Compounding this problem is a lack of reliable paleomagnetic poles for NAC units that predate its assembly into the supercontinent Laurentia by ca. 1800 Ma, which could be used to test neighboring relationships with other cratonic fragments. In order to understand the history of the NAC as part of a possible, larger supercontinent, the record of mafic dyke swarms affecting the craton, particularly those that postdate the Late Archean terrane assembly, were examined in this study. Diabase or gabbroic dyke swarms are invaluable in such studies because their geometries offer possible locus points, they often have a punctuated emplacement and precisely datable crystallization histories, and they have cooling histories and oxide mineralogy amenable to recovering robust paleopoles. Coastal Labrador exposes a number of mafic dykes, some of which are demonstrably Paleoproterozoic (e.g. 2235 Ma Kikkertavak dykes; 2121 Ma Tikkigatsiagak dykes) or Mesoproterozoic (e.g. 1280-1270 Ma Nain and Harp dykes) in age (U-Pb; baddeleyite or zircon). The southern half of the Nain craton (Hopedale block) in particular preserves a rich array of mafic dykes. Dyke cross-cutting relationships are numerous and relatively well exposed, permitting multiple opportunities for paleomagnetic field tests (e.g. baked contact). The results presented here allow understanding of the tectonic evolution of the NAC with implications for strengthened Labrador-Greenland correlations, and testing possible Paleoproterozoic supercontinent

  3. Geologic characterization of paleoproterozoics rocks in middle south of Uruguay (PIEDRA ALTA terrains - Craton of Rio de la Plata)

    International Nuclear Information System (INIS)

    Oyhantcabal, P.; Spoturno, J.; Loureiro, J.

    2007-01-01

    An updated synthesis of the Units of the Precambrian Basement (Piedra Alta Terrane; Paleoproterozoic; Transamazonian Cycle) of Montevideo, Canelones, San Jose and southern Florida is presented. This review is based on data from a mapping project (CONICYT 6019) of the area at 1:100 000 scale. Two metamorphic successions are recognised in the San Jose Belt: Paso Severino and Montevideo formations (low and medium grade respectively) and an significant bimodal magmatism recorded in syn- as well as postoregenic intrusions. A system of conjugated shear zones (ENE and NNW; sinistral and dextral respectively) determine the architecture of the Basement. (author)

  4. The lack of selection bias in a snowball sampled case-control study on drug abuse.

    Science.gov (United States)

    Lopes, C S; Rodrigues, L C; Sichieri, R

    1996-12-01

    Friend controls in matched case-control studies can be a potential source of bias based on the assumption that friends are more likely to share exposure factors. This study evaluates the role of selection bias in a case-control study that used the snowball sampling method based on friendship for the selection of cases and controls. The cases selected fro the study were drug abusers located in the community. Exposure was defined by the presence of at least one psychiatric diagnosis. Psychiatric and drug abuse/dependence diagnoses were made according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria. Cases and controls were matched on sex, age and friendship. The measurement of selection bias was made through the comparison of the proportion of exposed controls selected by exposed cases (p1) with the proportion of exposed controls selected by unexposed cases (p2). If p1 = p2 then, selection bias should not occur. The observed distribution of the 185 matched pairs having at least one psychiatric disorder showed a p1 value of 0.52 and a p2 value of 0.51, indicating no selection bias in this study. Our findings support the idea that the use of friend controls can produce a valid basis for a case-control study.

  5. How to find future ecstasy-users: targeted and snowball sampling in an ethically sensitive context.

    Science.gov (United States)

    Vervaeke, Hylke K E; Korf, Dirk J; Benschop, Annemieke; van den Brink, Wim

    2007-08-01

    This article documents the design and the sampling procedures of a prospective longitudinal multidisciplinary study on the neurotoxicity of ecstasy (MDMA): the Netherlands XTC Toxicity Study (NeXT). Targeted and snowball sampling was used to recruit 188 respondents who were ecstasy-naive at baseline. All respondents completed baseline questionnaires and underwent medical and neuropsychological examinations. At the end of a 11- to 26- month follow-up period in which they completed four additional questionnaires, 160 respondents remained (85.1%). A total of 65 participants (40.6%) took ecstasy for the first time during the follow-up period. This paper discusses the ethical dilemmas inherent in a study of this type and the specific problems and solutions that emerged in the sampling. The sampling was tightly constrained by our need to locate respondents who were potential future ecstasy users while also meeting strict medical and technical criteria. The 'intention to use' criterion proved to be a clear-cut inclusion rule that was practical to apply in the fieldwork.

  6. How to stop the snowball growth? A way for sustaining public debt over generations

    Directory of Open Access Journals (Sweden)

    Catrina Ion-Lucian

    2017-08-01

    Full Text Available Why public debts are growing so fast in most developing countries, like a dangerous snowball which is growing and growing and no one can stop it? It is only a negative relation between high debt and real growth of economy? How can we definitively remove the Ricardian anxiety which called debt a “terrible scourge”? These are only few questions asked in the last century in relation with debt “overhang” not only by scholars, but by governments as well. This paper aims to answer to other questions like: Why debt’s rate grows faster than GDP? Why governments borrow? For current spending or for public investments? Who should benefits current loans? Who should pay for them and when? How should be the taxation along the economic cycle: neutral or countercyclical? Need we a model to sustain the public debt over generations, or it is good enough to maintain a good ration between real GDP growth and debt and that’s it?

  7. Sr-Nd evidence of paleoproterozoic mantle metasomatism in the lithospheric mantle beneath northeastern Brazil

    International Nuclear Information System (INIS)

    Hollanda, M.H.B.M.; Pimentel, M.M.; Jardim de Sa, E.F

    2001-01-01

    In the Borborema Province (Northeastern Brazil), the Brasiliano/Pan-African Cycle is expressed by two prominent and penecontemporaneous features: a regional network of transcurrent shear zones and associated large granitoid magmatism. The Rio Grande do Norte Domain (RGND) is an orogenic domain located in the northeastern part of the Borborema Province, and its tectonic evolution is largely related to the Brasiliano orogeny (ca. 600 Ma). This domain includes four major tectonic terranes, which are represented by two metavolcanosedimentary sequences Jaguaribe-Oeste Potiguar and Serido belts, and its gneiss-migmatite Paleoproterozoic basement the Rio Piranhas and Sao Jose de Campestre massifs (Brito Neves et al., 2000). The rocks have been metamorphosed up to the amphibolite facies. Its deformational fabrics are dominated by extensive Brasiliano ductile shear zones displaying predominantly dextral transcurrent kinematic regime. These structures control the emplacement of several Neoproterozoic granitoid intrusions which are made up mainly by porphyritic granitoid suites with subalkaline monzonitic affinity. These occur as isolated plutons of various sizes or as composite intrusions, associated with basic-tointermediate suites. In the latter case, magma mingling and mixing attest that these are contemporaneous igneous suites. Several features suggest coeval relationships with granitic magmas, possibly implying processes such as assimilation or magma mixing. Field evidence of magma mixing include (i) extensive capture of feldspar phenocrysts of the acid mushes by the basic magmas, (ii) common presence of globular to ellipsoidal basic enclaves in the granitic suites, (iii) stockwork-type features consisting of felsic material veining through a diorite host and (iv) syn-plutonic basic dykes intruded into the porphyritic granites (Jardim de S 1994). In this work, Rb-Sr and Sm-Nd isotopic compositions from six distinct basic-to-intermediate suites were investigated to

  8. Paleoproterozoic andesitic volcanism in the southern Amazonian craton (northern Brazil); lithofacies analysis and geodynamic setting

    Science.gov (United States)

    Roverato, Matteo; Juliani, Caetano; Capra, Lucia; Dias Fernandes, Carlos Marcelo

    2016-04-01

    Precambrian volcanism played an important role in geological evolution and formation of new crust. Most of the literature on Precambrian volcanic rocks describes settings belonging to subaqueous volcanic systems. This is likely because subaerial volcanic rocks in Proterozoic and Archean volcano-sedimentary succession are poorly preserved due to erosive/weathering processes. The late Paleoproterozoic Sobreiro Formation (SF) here described, seems to be one of the rare exceptions to the rule and deserves particular attention. SF represents the subaerial expression of an andesitic magmatism that, linked with the upper felsic Santa Rosa F., composes the Uatumã Group. Uatumã Group is an extensive magmatic event located in the Xingú region, southwestern of Pará state, Amazonian Craton (northern Brazil). The Sobreiro volcanism is thought to be related to an ocean-continent convergent margin. It is characterized by ~1880 Ma well-preserved calc-alkaline basaltic/andesitic to andesitic lava flows, pyroclastic rocks and associated reworked successions. The superb preservation of its rock-textures allowed us to describe in detail a large variety of volcaniclastic deposits. We divided them into primary and secondary, depending if they result from a direct volcanic activity (pyroclastic) or reworked processes. Our study reinforces the importance of ancient volcanic arcs and rocks contribution to the terrestrial volcaniclastic sedimentation and evolution of plate tectonics. The volcanic activity that produced pyroclastic rocks influenced the amount of detritus shed into sedimentary basins and played a major role in the control of sedimentary dispersal patterns. This study aims to provide, for the first time, an analysis of the physical volcanic processes for the subaerial SF, based in field observation, lithofacies analysis, thin section petrography and less geochemical data. The modern volcanological approach here used can serve as a model about the evolution of Precambrian

  9. A simulative comparison of respondent driven sampling with incentivized snowball sampling--the "strudel effect".

    Science.gov (United States)

    Gyarmathy, V Anna; Johnston, Lisa G; Caplinskiene, Irma; Caplinskas, Saulius; Latkin, Carl A

    2014-02-01

    Respondent driven sampling (RDS) and incentivized snowball sampling (ISS) are two sampling methods that are commonly used to reach people who inject drugs (PWID). We generated a set of simulated RDS samples on an actual sociometric ISS sample of PWID in Vilnius, Lithuania ("original sample") to assess if the simulated RDS estimates were statistically significantly different from the original ISS sample prevalences for HIV (9.8%), Hepatitis A (43.6%), Hepatitis B (Anti-HBc 43.9% and HBsAg 3.4%), Hepatitis C (87.5%), syphilis (6.8%) and Chlamydia (8.8%) infections and for selected behavioral risk characteristics. The original sample consisted of a large component of 249 people (83% of the sample) and 13 smaller components with 1-12 individuals. Generally, as long as all seeds were recruited from the large component of the original sample, the simulation samples simply recreated the large component. There were no significant differences between the large component and the entire original sample for the characteristics of interest. Altogether 99.2% of 360 simulation sample point estimates were within the confidence interval of the original prevalence values for the characteristics of interest. When population characteristics are reflected in large network components that dominate the population, RDS and ISS may produce samples that have statistically non-different prevalence values, even though some isolated network components may be under-sampled and/or statistically significantly different from the main groups. This so-called "strudel effect" is discussed in the paper. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  10. U-shaped curve of psychosis according to cannabis use: New evidence from a snowball sample.

    Science.gov (United States)

    Brañas, Antía; Barrigón, María L; Garrido-Torres, Nathalia; Perona-Garcelán, Salvador; Rodriguez-Testal, Juan F; Lahera, Guillermo; Ruiz-Veguilla, Miguel

    2016-12-01

    The aim of this study was to investigate the relationship between psychotic-like experiences (PLEs) assessed using the Community Assessment of Psychic Experience (CAPE) questionnaire and the pattern of cannabis use in a non-clinical sample collected by snowball sampling. Our sample was composed of 204 subjects, distributed into three groups by their cannabis use pattern: 68 were non-cannabis users, 40 were moderate cannabis users and 96 were daily cannabis users. We assessed the psychotic experiences in each group with the CAPE questionnaire; and then controlled for the effect of possible confounding factors like sex, age, social exclusion, age of onset of cannabis use, alcohol use and other drug use. We found a significant quadratic association between the frequency of cannabis use and positive (β = -1.8; p = 0.004) and negative dimension scores (β = -1.2; p = 0.04). The first-rank and mania factors showed a significant quadratic association (p < 0.05), while the voices factor showed a trend (p = 0.07). Scores for the different groups tended to maintain a U-shape in their values for the different factors. When we adjusted for gender, age, social exclusion, age of onset of cannabis use, and use of alcohol and other drugs, only the first-rank experiences remained significant. We found there was a U-shaped curve in the association between cannabis use and the positive and negative dimensions of the CAPE score. We also found this association in mania and first-rank experiences. © The Author(s) 2016.

  11. Isotopic characteristics (Nd and Sr) of the intrusive plutonism at the northwestern Amazonian Craton, Venezuela, and implications for the Paleoproterozoic evolution

    International Nuclear Information System (INIS)

    Teixeira, Wilson; Tassinari, Colombro Celso G.; Mondin, M.

    2002-01-01

    Nd and Sr analyses were performed on selected granitoid plutons that intrude Archean and Paleoproterozoic domains of the Guyana shield (Venezuela). The isotopic signatures of these plutons together with the geochronologic background of the country rocks are used to constrain their magma genesis and tectonic setting within the Paleoproterozoic evolutions of mobile belts (Maroni-Itacaiunas and Ventuari-Tapajos provinces) of the Amazonian Craton. The Encrucijada Suite (2187 +- 94 Ma), which intrudes Archean rocks of the Imataca Complex, originated predominantly from partial melt of this crust, as supported by negative epsilon Nd(2.1Ga ) values (-2.2 to - 4.9) and T DM ages between 2.82 and 2.49 Ga. Conversely, the plutons from the Supamo Complex (2230 - 2050 Ma) and Cuchivero Group (1980 - 1830 Ma), occurring within the adjoining Paleoproterozoic provinces, are juvenile in nature (derived from roughly contemporary protoliths). These bodies display T DM ages between 2.13 and 2.22 Ga, as well as positive epsilon Nd(2.1Ga ) values (+0.74 to + 3.05). Isotopic correlation diagrams 143 Nd/144 Nd vs. 147 Sm/144 Nd and 143 Nd/144 Nd vs. time) plotted together with the plutonic rocks and Imataca Complex rocks were evaluated taking into account the geologic background of the NW part of the Amazonian Craton. Interpretation of these isotopic data supports the idea of tectonic juxtaposition between the Imataca Complex and the Maroni-Itacaiunas province during the Transamazonian orogeny (2.25 - 2.05 Ga). On the other hand, the Cuchivero Group plutons have a contrasting isotopic signature compared to the other Paleoproterozoic plutonic rocks. This is consistent with the existence of a tectonic boundary between the Maroni-Itacaiunas and the Ventuari-Tapajos province in the late Paleoproterozoic. (author)

  12. Petro-mineralogical Studies of the Paleoproterozoic Phosphorites in the Sonrai basin, Lalitpur District, Uttar Pradesh, India

    Energy Technology Data Exchange (ETDEWEB)

    Dar, Shamim A., E-mail: sjshamim@gmail.com; Khan, K. F.; Khan, Saif A.; Khan, Samsuddin [Aligarh Muslim University, Department of Geology (India); Masroor Alam, M. [Aligarh Muslim University, Geology Section Department of Civil Engineering (India)

    2015-09-15

    The Paleoproterozoic phosphorites constitute an economically significant component of the Sonrai basin of Lalitpur district. These are associated with ferruginous shale, ironstone, limestone and quartz breccia. Petro-mineralogical studies of samples of the phosphorites, using X-ray diffractometry and scanning electron microscopy, reveal that the collophane (carbonate-fluorapatite) is the dominant phosphate mineral. Calcite, dolomite, quartz, mica and haematite are the dominant gangue constituents. The phosphate minerals occur as oolites mutually replaced by carbonate and silica. The presence of iron oxides has been found in most of the thin sections. There is meagre evidence of organic matter in the form of filaments of microbial phosphate laminae in the samples of phosphorite. The mineral assemblages, their texture and various forms in these phosphorites may be due to some environmental vicissitudes followed by replacement processes and biogenic activities.

  13. Petro-mineralogical Studies of the Paleoproterozoic Phosphorites in the Sonrai basin, Lalitpur District, Uttar Pradesh, India

    International Nuclear Information System (INIS)

    Dar, Shamim A.; Khan, K. F.; Khan, Saif A.; Khan, Samsuddin; Masroor Alam, M.

    2015-01-01

    The Paleoproterozoic phosphorites constitute an economically significant component of the Sonrai basin of Lalitpur district. These are associated with ferruginous shale, ironstone, limestone and quartz breccia. Petro-mineralogical studies of samples of the phosphorites, using X-ray diffractometry and scanning electron microscopy, reveal that the collophane (carbonate-fluorapatite) is the dominant phosphate mineral. Calcite, dolomite, quartz, mica and haematite are the dominant gangue constituents. The phosphate minerals occur as oolites mutually replaced by carbonate and silica. The presence of iron oxides has been found in most of the thin sections. There is meagre evidence of organic matter in the form of filaments of microbial phosphate laminae in the samples of phosphorite. The mineral assemblages, their texture and various forms in these phosphorites may be due to some environmental vicissitudes followed by replacement processes and biogenic activities

  14. UPAYA MENINGKATKAN MINAT BELAJAR SISWA MELALUI MODEL PEMBELAJARAN KOOPERATIF TIPE SNOWBALL THROWING PADA MATA DIKLAT KOMUNIKASI SISWA SMK

    Directory of Open Access Journals (Sweden)

    Dian Pratiwi

    2016-02-01

    Full Text Available Tujuan penelitian untuk meningkatkan minat belajar siswa melalui model pembelajaran kooperatif tipe Snowball Throwing pada mata diklat komunikasi siswa kelas X AP SMK Gatra Praja Pekalongan. Subjek penelitian ini adalah siswa kelas X AP yang berjumlah 37 siswa. jenis penelitian adalah penelitian tindakan kelas, dilakukan dalam dua siklus. Teknik pengumpulan data menggunakan observasi, kuesioner,dan dokumentasi. Hasil penelitian menunjukkan minat belajar hasil dari lembar pengamatan siklus I sebesar 60,33% dengan kategori kurang berminat dan pada siklus II menjadi 75,27% dengan kategori berminat. Sedangkan hasil minat belajar dari angket/kuesioner pada siklus I 68,90% dengan kategori berminat dan pada siklus II menjadi 76,71% dengan kategori berminat. Kesimpulanya Penerapan pembelajaran menggunakan model Snowball Throwing dapat meningkatkan minat belajar siswa kelas X AP pada mata diklat komunikasi SMK Gatra Praja Pekalongan, terbukti setiap siklusnya mengalami peningkatan. This study is aimed at improving students’ interest through cooperative learning model Snowball Throwing at Communication Training Subject in Class X Office Administration of Gatra Praja Vocational High School Pekalongan. Subject of this research was the 37 students of XI AP. This type of research is classroom action research and conducted in two cycles. Data collecting technique used is observation, questionnaires, and documentation. The result of the research shows that the learning interest form of the observation sheet on the first cycle is 60.33% with less interest category and the second cycle, it turns into 75.27% to the category of interest. While the results of the learning interest from the questionnaire in the first cycle is 68.90% of the maximum percentage of the interest category and the second cycle it turns into 76.71% to the category of interest. The conclusion is the application of learning using models Snowball Throwing can increase students’ interest in

  15. Meningkatkan Prestasi Belajar Siswa Kelas VIII.F SMP Negeri 33 Surabaya Pada Mata Pelajaran IPS Materi Pranata Sosial Dengan Model Pembelajaran Snowball Throwing

    Directory of Open Access Journals (Sweden)

    Mudjianingsih Mudjianingsih

    2017-01-01

                          Asks activities in social studies is an important part in carrying out the study, which asks activities serve to gather information from students, to confirm what was already known, and to bring attention to the aspect of the unknown. Based on observations in the classroom conditions VIII F SMP Negeri 33 Surabaya Surabaya are less enthusiastic in asking questions the need for action using the appropriate learning models, one model of learning that can improve student learning outcomes is learning models Snowball Throwing. In this research there are four research purposes, the fourth such purposes include: 1 To determine the application of learning models Snowball Throwing, 2 To determine activity students 3 To determine student learning outcomes, and 3 To know the constraints and solutions in applying learning models Snowball Throwing.                     This study was a classroom action research (PTK with a qualitative approach in the classroom VIII F SMP Negeri 33 Surabaya Surabaya, which amounted to 32 students. In the application of Snowball Throwing consisting of two cycles, each cycle consisting of the planning stage, the stage of action, observation and reflection stages. Data collection techniques interest asked in this study using observation sheet interest to ask, and for student learning outcomes using the test cycle I and II. Data analysis using data reduction, observation data, and drawing conclusions. The results of this study show that: 1 Application of Learning Model Throwing Snowball carried out with 2 cycles, with each cycle consisting of the planning phase, the implementation phase, observation and reflection phase, 2 Complete test results of students in the first cycle was 68.42% , to test cycle II completeness increased to 100%, completeness criteria in this second cycle in the category Very Good, 3 constraints experienced researchers, among others: the seriousness of the students

  16. The Earth is a Planet Too!

    Science.gov (United States)

    Cairns, Brian

    2014-01-01

    When the solar system formed, the sun was 30 dimmer than today and Venus had an ocean. As the sun brightened, a runaway greenhouse effect caused the Venus ocean to boil away. At times when Earth was younger, the sun less bright, and atmospheric CO2 less, Earth froze over (snowball Earth). Earth is in the sweet spot today. Venus is closer to sun than Earth is, but cloud-covered Venus absorbs only 25 of incident sunlight, while Earth absorbs 70. Venus is warmer because it has a thick carbon dioxide atmosphere causing a greenhouse effect of several hundred degrees. Earth is Goldilocks choice among the planets, the one that is just right for life to exist. Not too hot. Not too cold. How does the Earth manage to stay in this habitable range? Is there a Gaia phenomenon keeping the climate in bounds? A nice idea, but it doesnt work. Today, greenhouse gas levels are unprecedented compared to the last 450,000 years.

  17. Sampling Key Populations for HIV Surveillance: Results From Eight Cross-Sectional Studies Using Respondent-Driven Sampling and Venue-Based Snowball Sampling.

    Science.gov (United States)

    Rao, Amrita; Stahlman, Shauna; Hargreaves, James; Weir, Sharon; Edwards, Jessie; Rice, Brian; Kochelani, Duncan; Mavimbela, Mpumelelo; Baral, Stefan

    2017-10-20

    In using regularly collected or existing surveillance data to characterize engagement in human immunodeficiency virus (HIV) services among marginalized populations, differences in sampling methods may produce different pictures of the target population and may therefore result in different priorities for response. The objective of this study was to use existing data to evaluate the sample distribution of eight studies of female sex workers (FSW) and men who have sex with men (MSM), who were recruited using different sampling approaches in two locations within Sub-Saharan Africa: Manzini, Swaziland and Yaoundé, Cameroon. MSM and FSW participants were recruited using either respondent-driven sampling (RDS) or venue-based snowball sampling. Recruitment took place between 2011 and 2016. Participants at each study site were administered a face-to-face survey to assess sociodemographics, along with the prevalence of self-reported HIV status, frequency of HIV testing, stigma, and other HIV-related characteristics. Crude and RDS-adjusted prevalence estimates were calculated. Crude prevalence estimates from the venue-based snowball samples were compared with the overlap of the RDS-adjusted prevalence estimates, between both FSW and MSM in Cameroon and Swaziland. RDS samples tended to be younger (MSM aged 18-21 years in Swaziland: 47.6% [139/310] in RDS vs 24.3% [42/173] in Snowball, in Cameroon: 47.9% [99/306] in RDS vs 20.1% [52/259] in Snowball; FSW aged 18-21 years in Swaziland 42.5% [82/325] in RDS vs 8.0% [20/249] in Snowball; in Cameroon 15.6% [75/576] in RDS vs 8.1% [25/306] in Snowball). They were less educated (MSM: primary school completed or less in Swaziland 42.6% [109/310] in RDS vs 4.0% [7/173] in Snowball, in Cameroon 46.2% [138/306] in RDS vs 14.3% [37/259] in Snowball; FSW: primary school completed or less in Swaziland 86.6% [281/325] in RDS vs 23.9% [59/247] in Snowball, in Cameroon 87.4% [520/576] in RDS vs 77.5% [238/307] in Snowball) than the snowball

  18. An empirical comparison of respondent-driven sampling, time location sampling, and snowball sampling for behavioral surveillance in men who have sex with men, Fortaleza, Brazil.

    Science.gov (United States)

    Kendall, Carl; Kerr, Ligia R F S; Gondim, Rogerio C; Werneck, Guilherme L; Macena, Raimunda Hermelinda Maia; Pontes, Marta Kerr; Johnston, Lisa G; Sabin, Keith; McFarland, Willi

    2008-07-01

    Obtaining samples of populations at risk for HIV challenges surveillance, prevention planning, and evaluation. Methods used include snowball sampling, time location sampling (TLS), and respondent-driven sampling (RDS). Few studies have made side-by-side comparisons to assess their relative advantages. We compared snowball, TLS, and RDS surveys of men who have sex with men (MSM) in Forteleza, Brazil, with a focus on the socio-economic status (SES) and risk behaviors of the samples to each other, to known AIDS cases and to the general population. RDS produced a sample with wider inclusion of lower SES than snowball sampling or TLS-a finding of health significance given the majority of AIDS cases reported among MSM in the state were low SES. RDS also achieved the sample size faster and at lower cost. For reasons of inclusion and cost-efficiency, RDS is the sampling methodology of choice for HIV surveillance of MSM in Fortaleza.

  19. Petrogenesis, detrital zircon SHRIMP U-Pb geochronology, and tectonic implications of the Upper Paleoproterozoic Seosan iron formation, western Gyeonggi Massif, Korea

    Science.gov (United States)

    Kim, Chang Seong; Jang, Yirang; Samuel, Vinod O.; Kwon, Sanghoon; Park, Jung-Woo; Yi, Keewook; Choi, Seon-Gyu

    2018-05-01

    This study involves investigations on the Upper Paleoproterozoic iron formation (viz., Seosan iron formation) from the Seosan Group, Gyeonggi Massif of the southwestern Korean Peninsula. It occurs as thin banded layers within meta-arkosic sandstone, formed by alternating processes of chemical (hydrothermal) and detrital depositions under a shallow marine environment. It mainly consists of alternating layers of iron oxides, mostly hematite, and quartz. Minor amounts of magnetite surrounded by muscovite, clinopyroxene and amphibole indicate hydrothermal alteration since its formation. Meta-arkosic sandstone is composed of recrystallized or porphyroclastic quartz and microcline, with small amounts of hematite and pyrite clusters. The Seosan iron formation has high contents of total Fe2O3 and SiO2 with positive Eu anomalies similar to those of other Precambrian banded iron formations, and its formation is clearly related to hydrothermal alteration since its deposition. Detrital zircon SHRIMP U-Pb geochronology data from a meta-arkosic sandstone (SN-1) and an iron formation (SN-2) show mainly two age groups of ca. 2.5 Ga and ca. 1.9-1.75 Ga. This together with intrusion age of the granite gneiss (ca. 1.70-1.65 Ga) clearly indicate that the iron formations were deposited during the Upper Paleoproterozoic. The dominant Paleoproterozoic detrital zircon bimodal age peaks preserved in the Seosan iron formation compare well with those from the South China Craton sedimentary basins, reflecting global tectonic events related to the Columbia supercontinent in East Asia.

  20. Snowball Vs. House-to-House Technique for Measuring Annual Incidence of Kala-azar in the Higher Endemic Blocks of Bihar, India: A Comparison.

    Science.gov (United States)

    Siddiqui, Niyamat A; Rabidas, Vidya N; Sinha, Sanjay K; Verma, Rakesh B; Pandey, Krishna; Singh, Vijay P; Ranjan, Alok; Topno, Roshan K; Lal, Chandra S; Kumar, Vijay; Sahoo, Ganesh C; Sridhar, Srikantaih; Pandey, Arvind; Das, Pradeep

    2016-09-01

    Visceral Leishmaniasis, commonly known as kala-azar, is widely prevalent in Bihar. The National Kala-azar Control Program has applied house-to-house survey approach several times for estimating Kala-azar incidence in the past. However, this approach includes huge logistics and operational cost, as occurrence of kala-azar is clustered in nature. The present study aims to compare efficiency, cost and feasibility of snowball sampling approach to house-to-house survey approach in capturing kala-azar cases in two endemic districts of Bihar, India. A community based cross-sectional study was conducted in two highly endemic Primary Health Centre (PHC) areas, each from two endemic districts of Bihar, India. Snowball technique (used to locate potential subjects with help of key informants where subjects are hard to locate) and house-to-house survey technique were applied to detect all the new cases of Kala-azar during a defined reference period of one year i.e. June, 2010 to May, 2011. The study covered a total of 105,035 households with 537,153 populations. Out of total 561 cases and 17 deaths probably due to kala-azar, identified by the study, snowball sampling approach captured only 221 cases and 13 deaths, whereas 489 cases and 17 deaths were detected by house-to-house survey approach. Higher value of McNemar's χ² statistics (64; phouse-to-house survey approach than snowball sampling and relative difference (>1) indicates that most of the kala-azar cases missed by snowball sampling were captured by house-to-house approach with 13% of omission. Snowball sampling was not found sensitive enough as it captured only about 50% of VL cases. However, it captured about 77% of the deaths probably due to kala-azar and was found more cost-effective than house-to-house approach. Standardization of snowball approach with improved procedure, training and logistics may enhance the sensitivity of snowball sampling and its application in national Kala-azar elimination programme as cost

  1. The earliest Paleoproterozoic supracrustal rocks in Koillismaa, northern Finland – their petrographic and geochemical characteristics and lithostratigraphy

    Directory of Open Access Journals (Sweden)

    Laura S. Lauri

    2003-01-01

    Full Text Available The 2.44 Ga Koillismaa layered igneous complex (KLIC in northern Finland is interpreted to have formed as a consequence of early Paleoproterozoic continental rifting. Associated with the mafic layered intrusions are felsic to intermediate volcanic and plutonic rocks of approximately the same age. The supracrustal rocks on top of the KLIC have been divided into three stratigraphic groups. The lowermost of these, the Sirniö Group, is thought to predate the KLIC and thus to represent the original roof. The overlying Kynsijärvi andHautavaara Groups are somewhat younger than the layered intrusions. The Sirniö Group comprises two formations of felsic and intermediate volcanic rocks. The Sirniövaara Formation, also called as the Koillismaa granophyre, consists of a thick rhyodacitic unit withgranophyric groundmass and some breccia interlayers. The Sirniövaara rhyodacite consists of plagioclase, quartz and biotite. Minor and accessory phases include ilmenite, magnetite, apatite, titanite, zircon and fluorite. Low-grade metamorphic minerals such as chlorite, epidote, carbonate and sericite are also commonly present. The granophyric texture is considered to have formed as a consequence of contact metamorphism and hydrothermal alteration associated with the emplacement of the KLIC. Above the Sirniövaara Formation is the Unijoki Formation, a heterogeneous group of felsic to intermediate volcanic rocks. The felsic rocks of the Unijoki Formation resemble the Sirniövaara rhyodacite whereas the intermediate rocks generally contain amphibole, instead of biotite, as the predominant mafic mineral. The rocks of the Sirniö Group show A-type geochemical character, e.g., high alkali content, Fe/Mg, 10000*Ga/Al, LREE, Y and Zr. In addition to primary compositional variation, metamorphic, and possibly hydrothermal, disturbance are recorded in the Sirniö Group lithologies. We consider them to be an example of early Paleoproterozoic rift-related volcanic rocks

  2. Geochemical constraints on genesis of Paleoproterozoic A-type granite in the south margin of North China Craton

    Science.gov (United States)

    Xue, Shuo; Xu, Yang; Ling, Ming-Xing; Kang, Qing-Qing; Jiang, Xiao-Yan; Sun, Sai-Jun; Wu, Kai; Zhang, Zhe-Kun; Luo, Ze-Bin; Liu, Yu-Long; Sun, Weidong

    2018-04-01

    Paleoproterozoic A-type granites are widely outcropped in the North China Craton (NCC), particularly in the Trans-North China Orogen. However, their genesis and tectonic significance remain obscure. Here we report systematic studies on geochronology and geochemical characteristics of A-type granite in Huayangchuan, south margin of the NCC. The samples are enriched in total alkali (K2O + Na2O > 8.97 wt%), and depleted in MgO (0.84-0.93 wt%), CaO (1.28-1.90 wt%) and P2O5 (0.18-0.20 wt%), with high FeOT/MgO (5.69-6.67). They are characterized by high Zr + Y + Nb + Ce values (1293-1392 ppm) and 10,000 × Ga/Al ratios (3.14-3.35), which are typical characteristics of A-type granite. The Huayangchuan A-type granite can be further classified as A1-type subgroup based on particular geochemical features, e.g., low Y/Nb (0.87-1.00) and Yb/Ta (0.88-1.10). High precision zircon U-Pb dating of the A-type granite by secondary ion mass spectrometry (SIMS) yields Paleoproterozoic 207Pb/206Pb ages of 1829.5 ± 2.5 Ma. The low zircon ɛHf(t) values (-6.97 to -10.45), along with zircon Hf model age of 2.7-2.9 Ga, indicate that the Huayangchuan A-type granite was derived from partial melting of the ancient continental crust with contribution of enriched mantle components. The low zircon δ18O composition (4.00 to 6.78‰) indicates that the zircons were crystallized from low δ18O magmas, which derived from the crust metasomatized by low δ18O mantle fluids or melts. The E-W trend A1-type granitic plutons in the NCC are generally outcropped in a rift tectonic regime, which is consistent with the development of the mantle plume in the Xiong'er district. The large volume of basaltic magmas, generated by mantle plume head, underplated the lower continental crust and formed the Huayangchuan A-type granite.

  3. Environmental Catastrophes in the Earth's History Due to Solar Systems Encounters with Giant Molecular Clouds

    Science.gov (United States)

    Pavlov, Alexander A.

    2011-01-01

    In its motion through the Milky Way galaxy, the solar system encounters an average density (>=330 H atoms/cubic cm) giant molecular cloud (GMC) approximately every 108 years, a dense (approx 2 x 103 H atoms/cubic cm) GMC every approx 109 years and will inevitably encounter them in the future. However, there have been no studies linking such events with severe (snowball) glaciations in Earth history. Here we show that dramatic climate change can be caused by interstellar dust accumulating in Earth's atmosphere during the solar system's immersion into a dense (approx ,2 x 103 H atoms/cubic cm) GMC. The stratospheric dust layer from such interstellar particles could provide enough radiative forcing to trigger the runaway ice-albedo feedback that results in global snowball glaciations. We also demonstrate that more frequent collisions with less dense GMCs could cause moderate ice ages.

  4. Petrogenesis of siliceous high-Mg series rocks as exemplified by the Early Paleoproterozoic mafic volcanic rocks of the Eastern Baltic Shield: enriched mantle versus crustal contamination

    Science.gov (United States)

    Bogina, Maria; Zlobin, Valeriy; Sharkov, Evgenii; Chistyakov, Alexeii

    2015-04-01

    The Early Paleoproterozoic stage in the Earth's evolution was marked by the initiation of global rift systems, the tectonic nature of which was determined by plume geodynamics. These processes caused the voluminous emplacement of mantle melts with the formation of dike swarms, mafic-ultramafic layered intrusions, and volcanic rocks. All these rocks are usually considered as derivatives of SHMS (siliceous high-magnesian series). Within the Eastern Baltic Shield, the SHMS volcanic rocks are localized in the domains with different crustal history: in the Vodlozero block of the Karelian craton with the oldest (Middle Archean) crust, in the Central Block of the same craton with the Neoarchean crust, and in the Kola Craton with a heterogeneous crust. At the same time, these rocks are characterized by sufficiently close geochemical characteristics: high REE fractionation ((La/Yb)N = 4.9-11.7, (La/Sm)N=2.3-3.6, (Gd/Yb)N =1.66-2.74)), LILE enrichment, negative Nb anomaly, low to moderate Ti content, and sufficiently narrow variations in Nd isotope composition from -2.0 to -0.4 epsilon units. The tectonomagmatic interpretation of these rocks was ambiguous, because such characteristics may be produced by both crustal contamination of depleted mantle melts, and by generation from a mantle source metasomatized during previous subduction event. Similar REE patterns and overlapping Nd isotope compositions indicate that the studied basaltic rocks were formed from similar sources. If crustal contamination en route to the surface would play a significant role in the formation of the studied basalts, then almost equal amounts of contaminant of similar composition are required to produce the mafic rocks with similar geochemical signatures and close Nd isotopic compositions, which is hardly possible for the rocks spaced far apart in a heterogeneous crust. This conclusion is consistent with analysis of some relations between incompatible elements and their ratios. In particular, the

  5. Paleoproterozoic (ca. 1.8 Ga) arc magmatism in the Lützow-Holm Complex, East Antarctica: Implications for crustal growth and terrane assembly in erstwhile Gondwana fragments

    Science.gov (United States)

    Takahashi, Kazuki; Tsunogae, Toshiaki; Santosh, M.; Takamura, Yusuke; Tsutsumi, Yukiyasu

    2018-05-01

    The Lützow-Holm Complex (LHC) of East Antarctica forms a part of the latest Neoproterozoic-Cambrian high-grade metamorphic segment of the East African-Antarctic Orogen. Here we present new petrological, geochemical, and zircon U-Pb geochronological data on meta-igneous rocks from four localities (Austhovde, Telen, Skallevikshalsen, and Skallen) in the LHC, and evaluate the regional Paleoproterozoic (ca. 1.8 Ga) arc magmatism in this terrane for the first time. The geochemical features reveal a volcanic-arc affinity for most of the meta-igneous rocks from Austhovde and Telen, suggesting that the protoliths of these rocks were derived from felsic to mafic arc magmatic rocks. The protoliths of two mafic granulites from Austhovde are inferred as non-volcanic-arc basalt such as E-MORB, suggesting the accretion of remnant oceanic lithosphere together with the volcanic-arc components during the subduction-collision events. The weighted mean 206Pb/238U ages of the dominant population of magmatic zircons in felsic orthogneisses from Austhovde and Telen show 1819 ± 19 Ma and 1830 ± 10 Ma, respectively, corresponding to Paleoproterozoic magmatic event. The magmatic zircons in orthogneisses from other two localities yield upper intercept ages of 1837 ± 54 Ma (Skallevikshalsen), and 1856 ± 37 Ma and 1854 ± 45 Ma (Skallen), which also support Paleoproterozoic magmatism. The earlier thermal events during Neoarchean to Early Paleoproterozoic are also traced by 206Pb/238U ages of xenocrystic zircons in the felsic orthogneisses from Austhovde (2517 ± 17 Ma and 2495 ± 15 Ma) and Telen (2126 ± 16 Ma), suggesting partial reworking of the basement of a 2.5 Ga microcontinent during ca. 1.8 Ga continental-arc magmatism. The timing of peak metamorphism is inferred to be in the range of 645.6 ± 10.4 to 521.4 ± 12.0 Ma based on 206Pb/238U weighted mean ages of metamorphic zircon grains. The results of this study, together with the available magmatic ages as well as geophysical and

  6. The land Piedra Alta : A geotectonic unit in the juvenile Paleoproterozoic craton del Rio de la Plata ( Uruguay )

    International Nuclear Information System (INIS)

    Preciozzi, F.; Sanchez Bettucci, L.; Oyhantcabal, P.; Pecoits, E.; Aubet, N.; Peel, E.; Basei, M.

    2003-01-01

    Brazilian Shield (Rio Grande do Sul) where Paleoproterozoic os land, located in the region Western, are covered by Paleozoic sediments of the Paraná Basin. The Neoproterozoic domains develop east of the Precambrian shield of Uruguay. The Exceptions to this comparative correlation are represented by the Campanero Unit and Field Suspect Punta del Este, only identified in Uruguayan territory. The Piedra Alta (Río de la Plata Craton, ss.) Is composed of a complex gneissic-migmatítico plant, essentially composed of porphyritic foliated granitoids interspersed with different types of mafic rocks Paleoproterozoicas Migmatites and, at least in the southern portion, where four metamorphic belts of different degree and extent are interleaved (Montevideo, San Jose, Cerros de San Juan and Arroyo Grande). Granites, granodiorites, and bodies mafic, of different composition, age and location environment are intruding the whole ground. The last magmatic activity is represented by a swarm of dykes aged mafic ca. 1750 - 1790 Ma (Bossi and Pitched, 1991, Halls et al., 2001) and meta tuffs acid intercalated in the Belt of Los Cerros de San Juan whose ages by the method U / Pb located in the vicinity of 1753 ± 5 Ma (Preciozzi et al, in prep.). The Piedra Alta Terrane no evidence of being affected by events tectonotérmicos Neoproterozoic and is separated from the Block Valentines by the shear zone Sarandi del Yi (Preciozzi et al., 1979). From geochronological studies U / Pb, Rb / Sr, K / Ar and Sm / Nd recent, carried out on the rocks Intrusive and Piedra Alta Land gneisses, it has been possible to observe a set of events that They affected the Land

  7. Dirty snowball - now is too primitive for a scientific description of comets

    Science.gov (United States)

    Kochemasov, G.

    Success of the "Deep Space 1" scientists which acquired excellent pictures of comet Borrelli, brings comets into the family of small celestial bodies with common regularities of shaping. Often attracted accidental impact process never can explain constantly repeated shapes of small bodies. Understanding their shaping is important in view of coming missions to small bodies. "Orbits make structures". This fundamental notion is unfolded into 4 theorems of planetary tectonics [1]: 1. Celestial bodies are dichotomic; 2. -" - are sectoral; 3. -"- are granular; 4. Angular momenta of different level blocks tend to be equal. All these general rules of shaping and structurization are a consequence of interferences of warping any body standing planetary waves due to inertia forces acting in any moving in non-circular orbit body. Dichotomy is the most global tectonic feature due to the fundamental waves (wave 1). It is typical to all planetary spheres. In Earth it is in the core, mantle, crust, atmosphere. At Venus it is very pronounced in the crust and in atmosphere: lying Y-feature and inverse C-feature in the cloud layer. Coherent martian lithosphere- atmosphere dichotomies are well known. In small bodies the dichotomy is specifically pronounced as ubiquitous convexo -concave shape. Most detailed studied at Eros this shape was also observed at comet Halley and recently at Borrelli. Borrelli's convex extended half is strongly jagged (not easy to find a place for landing!), the contracted concave half spits out tremendous tail. Surface areas around the tail outlets are whitish and lighter than surroundings. It seems that the gas-dust material squeezed out of interiors not only disappears in space but leaves traces on the concave surface. The concave hemisphere has shorter radius than the convex one and tends to compensate loosing angular momentum by denser material extracted from interiors (Theorem 4 [1];compare with the basaltic Pacific hemisphere opposed by the granitic

  8. The Petäjäskoski Formation, a new lithostratigraphic unit in the Paleoproterozoic Peräpohja Belt, northern Finland

    OpenAIRE

    Markus Kyläkoski; Eero Hanski; Hannu Huhma

    2012-01-01

    This paper gives the first description of a newly-recognized, basin-wide metasedimentary unit in the Paleoproterozoic (~2.4–1.9 Ga) Peräpohja Belt, northern Finland. The unit, which is named the Petäjäskoski Formation (PFm) after the single location where the rocks are known to be exposed, is situated stratigraphically in the middle part of the Kivalo Group between the quartzites of the>2.22 Ga Palokivalo Formation and the mafic volcanic rocks of the ~2.1 Ga Jouttiaapa Formation.The bulk of t...

  9. Genesis of the Hengling magmatic belt in the North China Craton: Implications for Paleoproterozoic tectonics

    Science.gov (United States)

    Peng, Peng; Guo, Jinghui; Zhai, Mingguo; Windley, Brian F.; Li, Tiesheng; Liu, Fu

    2012-09-01

    The 2200-1880 Ma igneous rocks in the central and eastern parts of the North China Craton (NCC) constitute a new Hengling magmatic belt (HMB), which includes the ~ 2147 Ma Hengling mafic sill/dyke swarm, the ~ 2060 Ma Yixingzhai mafic dyke swarm, and the ~ 1973 Ma Xiwangshan mafic dyke swarm. The three swarms are contiguous and have experienced variable degrees of metamorphism from greenschist to low amphibolite facies (Hengling), medium granulite facies (Yixingzhai), and medium/high-pressure granulite facies (Xiwangshan). They are all tholeiitic in composition typically with 47-52 wt.% SiO2 and 4-10 wt.% MgO, and all show light rare earth element enrichments and Nb- and Ta-depletion. Their Nd TDM ages are in the range of 2.5-3.0 Ga. Specifically, the Hengling and Yixingzhai dykes/sills are depleted in Th, U, Zr, Hf and Ti, whereas the Xiwangshan dykes are enriched in U and weakly depleted in other elements. Variable Sr-anomalies indicate significant feldspar accumulation (positive anomalies) or fractionation. The ɛNd(t) values of the three swarms are: - 3.2-+3.0 (Hengling), - 1.7-+ 1.8 (Yixingzhai) and - 1.4-+ 1.0 (Xiwangshan). These mafic representatives of the HMB originated from the > 2.5 Ga sub-continental lithospheric mantle of the NCC, and with A-type granites and other igneous associations in this belt they likely evolved in an intra-continental rift. The progressive changing compositions of the three swarms are interpreted in terms of their source regions at different depths, i.e., shallower and shallower through time. And the decrease in scale and size of the intrusions and their magma volumes indicate the progressive weakening of magmatism in this rift. The rocks in this belt are different chronologically, petrologically and chemically from those in the Xuwujia magmatic belt (XMB). We propose that the two magmatic belts represent two different magmatic systems in different blocks of the NCC, i.e., an eastern block (with the HMB) and a western block

  10. Peningkatan Hasil Belajar Siswa Materi Usaha Mempertahankan Republik Indonesia Melalui Model Pembelajaran Snowball Throwing Pada Kelas IX.2 SMP Negeri Muara Beliti

    Directory of Open Access Journals (Sweden)

    Holili Holili

    2017-10-01

    Full Text Available This study aims to improve student learning outcomes of class IX.2 State Junior High School Muara Beliti on the material business to defend the Republic of Indonesia by using the Snowball throwing learning. The research method used is Classroom Action Research. The study was conducted in two cycles with each model cycle following the procedure: planning, action, observation, and reflection. The action of two cycles resulted in improving the quality of learning and improving the learning outcomes, the average completeness of students' learning cycle one 68.55% completeness 61.29%. Cycle two averages 80.1% completeness 90%. The end result of the two cycle action succeeded in improving the IPS learning outcomes. Keywords: Learning Outcome, Snowball throwing   http://dx.doi.org/10.17977/um022v2i12017p025

  11. Paleoproterozoic volcanic centers of the São Félix do Xingu region, Amazonian craton, Brazil: Hydrothermal alteration and metallogenetic potential

    Science.gov (United States)

    da Cruz, Raquel Souza; Fernandes, Carlos Marcello Dias; Villas, Raimundo Netuno Nobre; Juliani, Caetano; Monteiro, Lena Virgínia Soares; Lagler, Bruno; Misas, Carlos Mario Echeverri

    2016-06-01

    Geological, petrographic, scanning electron microscopy, and X-ray diffraction studies revealed hydrothermalized lithotypes evidenced by overprinted zones of potassic, propylitic, sericitic, and intermediate argillic alterations types, with pervasive and fracture-controlled styles, in Paleoproterozoic volcano-plutonic units of the São Félix do Xingu region, Amazonian craton, northern Brazil. The Sobreiro Formation presents propylitic (epidote + chlorite + carbonate + clinozoisite + sericite + quartz ± albite ± hematite ± pyrite), sericitic (sericite + quartz + carbonate), and potassic (potassic feldspar + hematite) alterations. The prehnite-pumpellyite pair that is common in geothermal fields also occurs in this unit. The Santa Rosa Formation shows mainly potassic (biotite + microcline ± magnetite), sericitic (sericite + quartz + carbonate ± chlorite ± gold), and intermediate argillic (montmorillonite + kaolinite/halloysite + illite) alterations. These findings strongly suggest the involvement of magma-sourced and meteoric fluids and draw attention to the metallogenetic potential of these volcanic units for Paleoproterozoic epithermal and rare and base metal porphyry-type mineralizations, similar to those already identified in other portions of the Amazonian craton.

  12. Earth evolution as a thermal system

    Science.gov (United States)

    Tang, C.

    2014-12-01

    After fifty years of plate-tectonic theory, the reasons why earth sometime freezed as a snowball or sometime became lethally hot resulting in mass extinction remain enigmatic. This article proposes a new hypothesis on Earth evolution. The unbalance of heat between the input and output is considered as the driving force for the Earth evolution, the lithospheric expansion and associated uplift are the triggers, the self-organized progressive failure leading to collapse of the Earth are the amplifier, and the global scale response in terms of volcanism and magmatism is the globalizer. This shallow process of lithosphere may reach a critical state with a positive feedback loop, and result in the formation of no-plume original Large Igneous Provinces (NPOLIP) in a top-down pattern. Endothermic phase changes during de-compressive melting remove heat from and cool their surroundings, including the upper parts of the lithosphere. The huge loss of Earth's heat during eruption of LIPs, together with the endothermic cooling, may put the thermal cycle to an end and a new start of the cycle initiates. In summary, Earth drives itself to evolve in terms of thermal cycles. Global cooling and warming are the two stages of the many cycles during the Earth evolution. Glaciations are the extreme result of global cooling, whereas the LIPs, sometime accompanied with remarkable sea level dropping, are the extreme result of global warming, with a long recovering age, the interglacialstage, between them. They come and go as thermal cycle evolves, with climate warming, being caused by Earth itself rather than by external forces or human activities, as the most attractive prediction.

  13. Geochemical element mobility during the history of a Paleo-proterozoic clastic sedimentary basin, the Athabasca Basin (Saskatchewan, Canada)

    International Nuclear Information System (INIS)

    Kister, Philippe

    2003-01-01

    In order to understand the mechanisms of migration and deposition of ore elements, it is essential to determine the timing, source, and destination of the geochemical element mass transfers and/or transportation on a scale encompassing the great sedimentary basins. The purpose of this study is to trace and to date the element migrations that occurred during the history of a Paleo-proterozoic clastic sedimentary basin, the Athabasca Basin, which hosts the world's largest and richest uranium deposits. As this geological environment was proved to be efficient to preserve high grade ore deposits for over more than one billion years, it provides an opportunity to study some natural analogues of deep geological nuclear waste storage. Five research topics were studied: 3D modelling of the distribution of normative minerals and trace elements on a basin-wide scale; U-Pb and Rb-Sr systematics; average chemical age estimation; thermodynamic modelling of the major mineralogical assemblages; U-Pb geochronology of uranium oxides. Some elements have remained immobile (Zr) since their initial sedimentary deposition, or were transferred from one phase to another (Al, Th). Other elements have been transported during fluid flow events that occurred: (1) on a basin wide scale during diagenesis (REE, Y, Sr, Fe), (2) at the unconformity and in the vicinity of the fault zones that represent preferential fluid flow pathways between the basement and the sandstone cover (U, Ni, As, B, Mg, K, Fe, Sr, REE), (3) during the late fault reactivation events associated with the basin uplift (U, Pb, Ni, S, Sr, REE). The successive tectonic events related to the geodynamical context that lead to the formation of these high-grade U concentrations (1460 Ma, 1335 Ma and 1275 Ma in the McArthur River deposit), did not however systematically occur in the whole basin (1275 Ma only at Shea Creek). The exceptionally high grade and tonnages of some deposits seem to be related to a larger number of U

  14. Reasons for smoking among male teenagers in tehran, iran: two case-control studies using snowball sampling.

    Science.gov (United States)

    Rezaei, Fatemeh; Nedjat, Saharnaz; Golestan, Banafsheh; Majdzadeh, Reza

    2011-10-01

    Identifying the underlying factors contributing to smoking among teenagers is important in establishing smoking control programs. The present study was designed to identify and compare factors revealed in a preceding qualitative study conducted on 13-15 year-old boys living in two different socio-economic districts in the Northern and Southern parts of Tehran. Two completely similar case-control studies, each with 200 subjects, were conducted using a snowball sampling. The case and control subjects were matched based on the intimacy relations, i.e. six smokers were recruited in each of the Northern and Southern districts; they were then asked to introduce one of their smoker friends as a case and a non-smoker one as a control. Multi-variable conditional logistic regression revealed that having a smoker father is the single effective factor in the two districts. As for boys living in the Northern (wealthier) part of the city, social capital (OR: 0.59, 95% CI: 0.43-0.81) played a protective role against smoking, whereas quitting home after a quarrel (OR: 15.07, 95% CI: 1.54-147.25), monthly allowance (OR: 2.22, 95% CI: 1.29-3.82) and hyperactivity (OR: 1.69, 95% CI: 2.64-240.45) were associated with a higher risk of becoming a smoker. The studied variables can be classified as personal, familial, and school-level factors. Familial intervention is effective for all the factors which revealed to be influential on the risk of becoming a smoker. It could be concluded that interventions on the family level should be used to prevent the cigarette use in Tehran.

  15. A simulative comparison of respondent driven sampling with incentivized snowball sampling – the “strudel effect”

    Science.gov (United States)

    Gyarmathy, V. Anna; Johnston, Lisa G.; Caplinskiene, Irma; Caplinskas, Saulius; Latkin, Carl A.

    2014-01-01

    Background Respondent driven sampling (RDS) and Incentivized Snowball Sampling (ISS) are two sampling methods that are commonly used to reach people who inject drugs (PWID). Methods We generated a set of simulated RDS samples on an actual sociometric ISS sample of PWID in Vilnius, Lithuania (“original sample”) to assess if the simulated RDS estimates were statistically significantly different from the original ISS sample prevalences for HIV (9.8%), Hepatitis A (43.6%), Hepatitis B (Anti-HBc 43.9% and HBsAg 3.4%), Hepatitis C (87.5%), syphilis (6.8%) and Chlamydia (8.8%) infections and for selected behavioral risk characteristics. Results The original sample consisted of a large component of 249 people (83% of the sample) and 13 smaller components with 1 to 12 individuals. Generally, as long as all seeds were recruited from the large component of the original sample, the simulation samples simply recreated the large component. There were no significant differences between the large component and the entire original sample for the characteristics of interest. Altogether 99.2% of 360 simulation sample point estimates were within the confidence interval of the original prevalence values for the characteristics of interest. Conclusions When population characteristics are reflected in large network components that dominate the population, RDS and ISS may produce samples that have statistically non-different prevalence values, even though some isolated network components may be under-sampled and/or statistically significantly different from the main groups. This so-called “strudel effect” is discussed in the paper. PMID:24360650

  16. Comets - cosmic 'snowballs'

    International Nuclear Information System (INIS)

    Luest, R.

    1979-01-01

    Non-periodic comets come from regions at the limit of our solar system and have conserved their original structure and composition since they have originated from a pre-solar nebuly together with the sun and the planets about 4.5 x 10 9 years ago. They are icy bodies of kilometer size whose structure and chemical composition is of great interest also with respect to the origin of the solar system. It is hoped to send a space craft to comet Halley in 1986 to get more detailed informations. (orig.) [de

  17. Rare earths

    Energy Technology Data Exchange (ETDEWEB)

    Cranstone, D A

    1979-01-01

    Rare earth elements are commonly extracted from the minerals monazite, bastnaesite, and xenotine. New uses for these elements are constantly developing; they have found applications in glass polishing, television tube phosphors, high-strength low-alloy steels, magnets, catalysts, refractory ceramics, and hydrogen sponge alloys. In Canada, rare earths have been produced as byproducts of the uranium mining industry, but there was no production of rare earths in 1978 or 1979. The world sources of and markets for the rare earth elements are discussed.

  18. Geochemical elements mobility during the history of a paleo-Proterozoic clastic sedimentary basin, the Athabasca Basin (Saskatchewan, Canada)

    International Nuclear Information System (INIS)

    Kister, P.

    2003-10-01

    In order to understand the mechanisms of migration and deposition of ore elements, it is essential to determine the timing, source, and destination of the geochemical element mass transfers and/or transportation on a scale encompassing the great sedimentary. The purpose of this study was to trace and to date the element migrations that occurred during the history of a Paleo-proterozoic clastic sedimentary basin, the Athabasca Basin, which hosts the world's largest and richest uranium deposits. As this geological environment was proved to be efficient to preserve high grade ore deposits for over more than one billion years, it provides an opportunity to study the mobility of some elements in a context that shows analogies with deep geological nuclear waste disposals. The natural analogies of interest include (i) uranium oxide and spent nuclear fuel; (ii) clay alteration halo and near field barrier, (iii) Athabasca sandstone cover and far-field barrier. Five research axis: (1) 3D modelling of the distribution of the main minerals and of some trace elements (U, Pb, Zr, Th, REE, Y, Rb, Sr) on a basin-wide scale and in the U mineralized zones, using the Gocad software. The models have been compared with detailed mineralogical studies performed on selected samples. (2) Pb-Pb and Rb-Sr systematics by TIMS (3) Mass balance calculation of the average Pb/U ratio at the scale of the deposit to evaluate whether the present day amount of radiogenic lead is sufficient to explain a U deposition in one or several episodes (geostatistical tools on Gocad) (4) Thermodynamic modelling of the mineralogical evolution of the Athabasca basin, considering the main mineral present in the sandstone (Phreeqc and Supcrt softwares) (5) U-Pb geochronology of uranium oxides using a 3 step approach: (i) optical and scanning electron microscopy; (ii) electron microprobe; (iii) ion microprobe (SIMS). The purpose was to study the long term stability of the uranium oxides and to characterise the

  19. A study of the hydrothermal alteration in Paleoproterozoic volcanic centers, São Félix do Xingu region, Amazonian Craton, Brazil, using short-wave infrared spectroscopy

    Science.gov (United States)

    da Cruz, Raquel Souza; Fernandes, Carlos Marcello Dias; Villas, Raimundo Netuno Nobre; Juliani, Caetano; Monteiro, Lena Virgínia Soares; de Almeida, Teodoro Isnard Ribeiro; Lagler, Bruno; de Carvalho Carneiro, Cleyton; Misas, Carlos Mario Echeverri

    2015-10-01

    Hypogene hydrothermal minerals have been identified by short-wave infrared spectroscopy in hydrothermally altered rocks from the Sobreiro and Santa Rosa formations, which belong to a Paleoproterozoic volcano-plutonic system in Amazonian craton. Three clay minerals are spectrally recognized: montmorillonite, kaolinite, and illite. The integration of these data with those available in the literature, including gold occurrences, suggests that those rocks are hydrothermal products of both volcanic thermal sources and later crustal intrusions, as evidenced by variable styles of propylitic, sericitic, potassic, and intermediate argillic alteration. The influence of meteoric fluids is emphasized. This low cost exploratory technique, which can be applied to hand samples, seems to be promising in the separation of hydrothermally altered volcano-plutonic centers in regions submitted to severe weathering conditions, in addition to aid elaborating models for prospecting mineral deposits.

  20. Paleoproterozoic mojaveprovince in northwestern Mexico? Isotopic and U-Pb zircon geochronologic studies of precambrian and Cambrian crystalline and sedimentary rocks, Caborca, Sonora

    Science.gov (United States)

    Lang, Farmer G.; Bowring, S.A.; Matzel, J.; Maldonado, G.E.; Fedo, C.; Wooden, J.

    2005-01-01

    Whole-rock Nd isotopic data and U-Pb zircon geochronology from Precambrian crystalline rocks in the Caborca area, northern Sonora, reveal that these rocks are most likely a segment of the Paleoproterozoic Mojave province. Supporting this conclusion are the observations that paragneiss from the ??? 1.75 Ga Bamori Complex has a 2.4 Ga Nd model age and contains detrital zircons ranging in age from Paleo- proterozoic (1.75 Ga) to Archean (3.2 Ga). Paragneisses with similar age and isotopic characteristics occur in the Mojave province in southern California. In addition, "A-type" granite exposed at the southern end of Cerro Rajon has ca 2.0 Ga Nd model age and a U-Pb zircon age of 1.71 Ga, which are similar to those of Paleoproterozoic granites in the Mojave province. Unlike the U.S. Mojave province, the Caborcan crust contains ca. 1.1 Ga granite (Aibo Granite), which our new Nd isotopic data suggest is largely the product of anatexis of the local Precambrian basement. Detrital zircons from Neoproterozoic to early Cambrian miogeoclinal arenites at Caborca show dominant populations ca. 1.7 Ga, ca. 1.4 Ga, and ca. 1.1 Ga, with subordinate Early Cambrian and Archean zircons. These zircons were likely derived predominately from North American crust to the east and northeast, and not from the underlying Caborcan basement. The general age and isotopic similarities between Mojave province basement and overlying miogeoclinal sedimentary rocks in Sonora and southern California is necessary, but not sufficient, proof of the hypothesis that Sonoran crust is allochthonous and was transported to its current position during the Mesozoic along the proposed Mojave-Sonora megashear. One viable alternative model is that the Caborcan Precambrian crust is an isolated, autochthonous segment of Mojave province crust that shares a similar, but not identical, Proterozoic geological history with Mojave province crust found in the southwest United States ?? 2005 Geological Society of America.

  1. Rare earths

    International Nuclear Information System (INIS)

    1984-01-01

    The conference was held from September 12 to 13, 1984 in Jetrichovice, Czechoslovakia. The participants heard 16 papers of which 4 were inputted in INIS. These papers dealt with industrial separation processes of rare earths, the use of chemical methods of separation from the concentrate of apatite and bastnesite, the effect of the relative permittivity of solvents in the elution of rare earth elements from a cation exchanger, and the determination of the content of different rare earth elements using X-ray fluorescence analysis and atomic absorption spectroscopy. (E.S.)

  2. Dose-response effect between cannabis use and psychosis liability in a non-clinical population: evidence from a snowball sample.

    Science.gov (United States)

    Ruiz-Veguilla, Miguel; Barrigón, María Luisa; Hernández, Laureano; Rubio, José Luis; Gurpegui, Manuel; Sarramea, Fernando; Cervilla, Jorge; Gutiérrez, Blanca; James, Anthony; Ferrin, Maite

    2013-08-01

    This study aimed to explore the associations between daily cannabis use and the specific profiles of subclinical symptoms in a non-clinical population obtained through snowball sampling, taking into account alcohol use, other drug use, social exclusion and age at onset of cannabis use. We included 85 daily cannabis users and 100 non-daily cannabis users. Both the case and the control populations were identified by snowball sampling. Daily cannabis use was associated with more alcohol intake and other drug use, as well as with early onset in the use of cannabis. Daily cannabis use appeared to exert a dose-response effect on first-rank symptoms, mania symptoms and auditory hallucinations, even after adjusting for sex, age, other drug use, social exclusion and age at onset of cannabis use. The paranoid dimension was only associated with the heaviest consumption of cannabis. Initial age of cannabis use modified the effects of daily cannabis use on the first-rank and voices experiences. Daily cannabis use was associated with significantly more first-rank and voices experiences among those subjects who started to use cannabis before 17 years of age. Our study supports the association of psychotic experiences with cannabis use even among non-psychotic subjects. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Earth Rotation

    Science.gov (United States)

    Dickey, Jean O.

    1995-01-01

    The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

  4. Temperature dependent mobility measurements of alkali earth ions in superfluid helium

    Science.gov (United States)

    Putlitz, Gisbert Zu; Baumann, I.; Foerste, M.; Jungmann, K.; Riediger, O.; Tabbert, B.; Wiebe, J.; Zühlke, C.

    1998-05-01

    Mobility measurements of impurity ions in superfluid helium are reported. Alkali earth ions were produced with a laser sputtering technique and were drawn inside the liquid by an electric field. The experiments were carried out in the temperature region from 1.27 up to 1.66 K. The temperature dependence of the mobility of Be^+-ions (measured here for the first time) differs from that of the other alkali earth ions Mg^+, Ca^+, Sr^+ and Ba^+, but behaves similar to that of He^+ (M. Foerste, H. Günther, O. Riediger, J. Wiebe, G. zu Putlitz, Z. Phys. B) 104, 317 (1997). Theories of Atkins (A. Atkins, Phys. Rev.) 116, 1339 (1959) and Cole (M.W. Cole, R.A. Bachmann Phys. Rev. B) 15, 1388 (1977) predict a different defect structure for He^+ and the alkali earth ions: the helium ion is assumed to form a snowball like structure whereas for the alkali earth ions a bubble structure is assumed. If the temperature dependence is a characteristic feature for the different structures, then it seems likely that the Be^+ ion builds a snowball like structure.

  5. Geochemistry, geochronology and Nd isotopes of the Gogó da Onça Granite: A new Paleoproterozoic A-type granite of Carajás Province, Brazil

    Science.gov (United States)

    Teixeira, Mayara Fraeda Barbosa; Dall'Agnol, Roberto; Santos, João Orestes Schneider; de Sousa, Luan Alexandre Martins; Lafon, Jean-Michel

    2017-12-01

    The Gogó da Onça Granite (GOG) comprise a stock located in the Carajás Province in the southeastern part of Amazonian Craton near its border with the Araguaia Belt. Three facies were identified in the pluton: biotite-amphibole granodiorite, biotite-amphibole monzogranite and amphibole-biotite syenogranite. The GGO crosscut discordantly the Archean country rocks and are not foliated. All Gogó da Onça Granite varieties are metaluminous, ferroan A2-subtype granites with reduced character. The major and trace element behavior suggests that its different facies are related by fractional crystallization. Zircon and titanite U-Pb SHRIMP ages show that the pluton crystallized at ∼1880-1870 Ma and is related to the remarkable Paleoproterozoic magmatic event identified in the Carajás Province. Whole-rock Nd isotope data (TDM ages 2.78 to 2.81, εNd values of -9.07 to -9.48) indicate that the GOG magmas derived from an Archaean source compatible with that of some other Paleoproterozoic suites from Carajás Province. The GOG show significant contrasts with the Jamon and Velho Guilherme Paleoproterozoic suites from Carajás Province and the inclusion of the Gogó da Onça granite in any of these suites is not justified. The GOG is more akin to the Serra dos Carajás Suite and to the Seringa and São João granites of Carajás and to the Mesoproterozoic Sherman granite of USA and the Paleoproterozoic Suomenniemi Batholith of Finland. This study puts in evidence the relevance of precise geochronological data and estimation of magma oxidation state in the characterization and correlation of A-type granites.

  6. Petrology, geochemistry and LA-ICP-MS U-Pb geochronology of Paleoproterozoic basement rocks in Bangladesh: An evaluation of calc-alkaline magmatism and implication for Columbia supercontinent amalgamation

    Science.gov (United States)

    Hossain, Ismail; Tsunogae, Toshiaki; Tsutsumi, Yukiyasu; Takahashi, Kazuki

    2018-05-01

    The Paleoproterozoic (1.7 Ga) basement rocks from Maddhapara, Bangladesh show a large range of chemical variations (e.g. SiO2 = 50.7-74.7%) and include diorite, quartz diorite, monzodiorite, quartz monzonite and granite. The pluton overall displays metaluminous, calc-alkaline orogenic suite; mostly I-type suites formed within subduction-related magmatism. The observed major elements show general trends for fractional crystallization. Trace element contents also indicate the possibility of a fractionation or assimilation; explain the entire variation from diorite to monzonite, even granite. The pluton may have evolved the unique chemical features by a process that included partial melting of calc-alkaline lithologies and mixing of mantle-derived magmas, followed by fractional crystallization, and by assimilation of country rocks. The pluton shows evidence of crystal fractionation involving largely plagioclase, amphibole and possibly biotite. Some of the fractionated magmas may have mixed with more potassic melts from distinct parts of the continental lithosphere to produce granites and/or pegmatites. New geochronological results of granitic pegmatite (1722 ± 10 Ma) are indisputably consistent with diorite and tonalite and those data showing credible geochronological sequence (i.e., diorite - tonalite - granitic pegmatite). Identical Paleoproterozoic age (1.7 Ga) with distinctive magmatism of the Maddhapara basement rocks have agreeable relationship with the CITZ, India. The consistent magmatism is also common in the Transamazonian of South America, Trans-Hudson orogeny in North America, Bohemian Massif and the Svecofennian, Poland, have identified the sequential growth of the continent through the amalgamation of juvenile terrains, succeeded by a major collisional orogeny. Such Paleoproterozoic subduction-related orogens in Australia have similar counterparts in Antarctica and other part of the world. These types of Paleoproterozoic magmatism dominantly contributed

  7. STUDI KOMPARATIF MODEL PEMBELAJARAN TALKING STICK DAN SNOWBALL THROWING TERHADAP HASIL BELAJAR TEKNOLOGI INFORMASI DAN KOMUNIKASI (TIK SISWA KELAS XI SMA NEGERI 1 SERIRIT TAHUN AJARAN 2015/2016

    Directory of Open Access Journals (Sweden)

    Ni Made Dwi Antari

    2016-10-01

    Abstract TIK learning must have to prepared student’s activities and creativities to obtained the own knowledge by means of learning process. An appropriate learning model election agree with students characteristics would help an success learning. The comparative study research would have to compared both of learning model, to know which model was better. This research aimed to know (1 The influenced about the result of students’ TIK study used Talking stick and Snowball Throwing learning model (2 the highest result of study between Talking stick and Snowball Throwing learning model (3 the students’ response toward Talking stick and Snowball Throwing learning model application. Kind of this research was quasi experiment by Post Test Only with Non Equivalent Control Group Design. The data accumulation done by multiple choice tests to measured cognitive domain and skill test to psychomotor domain. The students’ result study analyzed by prerequisite test was normality test and homogeneity by the result of the three group which normal distribution and homogeneous, continued by hypothesis test used a strip Anova then continued by t-Sheffe The result of one way onova exist a significance influenced on the used of Talking Stick leaarning model, Snowball Throwing and conventional. Because of thee was a significance difereences between each partner. Afterwards, seen from the result average of study  can be concluded the Talking Stick learning model better than the higest result average of study. Meanwhile, the respond of used questionnaire method, the result of Talking stick model questionnaire known 36% very positive responses, 61% positive responses and 3% positive sufficient responses. Then, Snowball Throwing model known 25% very positive responses, 67% positive responses, and 8% positive sufficient responses.   Keywords : The Comparrative Study, TIK, Talking stick, Snowball Throwing, the                    study result,  students’ respond

  8. Contributions to the petrography, geochemistry and geochronology (U-Pb and Sm-Nd) of the Paleoproterozoic effusive rocks from Iricoume Group, Amazonian Craton, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Suelen Nonata de Souza; Nascimento, Rielva Solimairy Campelo do, E-mail: suelen-marques@hotmail.com, E-mail: rielva@ufam.edu.br [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil). Inst. de Geociencias; Souza, Valmir da Silva; Dantas, Elton Luiz, E-mail: vsouza@unb.br, E-mail: elton@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Inst. de Geociencias; Valerio, Cristovao da Silva, E-mail: cristovao@igeo.ufrr.br [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil). Inst. de Geociencias

    2014-07-01

    The southernmost region of the Guyana shield, Amazonian craton, hosts large record of Paleoproterozoic effusive rocks of the Iricoume Group. They present remarkably well-preserved igneous textures and structures. The SiO{sub 2} contents reveal a bimodal association marked by a compositional gap between acid (SiO{sub 2} > 67 wt%) and intermediate (SiO{sub 2} < 57.7 wt%) rocks. The acid effusive rocks are rhyolites to rhyodacites with high SiO{sub 2}, alkali, Rb, Zr, Nb + Ta, La + Ce and 104 Ga/Al content and low Fe{sub 2}O{sub 3tot}, TiO{sub 2}, CaO, Sr and Co content. They exhibit subalkaline, metaluminous-to-peraluminous compositions, and geochemically compatible to A-type magmatism emplaced in post-collisional to within-plate tectonic settings. The intermediate rocks are andesitic/basalt to andesite relatively high contents of TiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3total}, MgO, CaO, Sr and Co; low SiO{sub 2}, K{sub 2}O, Rb, Zr, Nb + Ta, La + Ce. They have subalkaline and metaluminous geochemical composition and plot on within-plate basalt field. The acid rocks crystallized at 1882 ± 11 Ma in U-Pb analyses for LA-MC-ICPMS zircon data. The Sm-Nd isotopic data on all rocks reveal a Nd TDM model ages between 2.59 and 2.16 Ga and ε{sub Nd}(t) values between -5.78 and 0.03, indicate that the magmatic evolution was related to the reworking of older Paleoproterozoic at the Rhyacian-Siderian period, continental crust (Transamazonian crust-forming event) with some mixing with a limited amount mantle-derived magmas or with contamination by Archean crust. The petrographic, geochemical and geochronological data presented in this paper suggest a within-plate to post-collisional tectonic setting for the Iricoume volcanism, involving lower crust uplift and generation of basalt magma in an extensional regime. (author)

  9. U-Pb SHRIMP and Sm-Nd geochronology of the paleoproterozoic Silvania magmatic arc in the neoproproterozoic Brasilia Belt, Goias, Central Brazil

    International Nuclear Information System (INIS)

    Fischel, D.P.; Pimentel, M.M.; Fuck, R.A; Armstrong, R

    2001-01-01

    The Brasilia Belt is a large Neoproterozoic orogen formed along the western margin of the Sao Francisco/Congo Craton in central Brazil. It comprises: (i) a thick Meso-Neoproterozoic metasedimentary/sedimentary pile with eastward tectonic vergence; (ii) a large Neoproterozoic juvenile arc in the west (Goias Magmatic Arc); and (iii) a micro-continent (or exotic sialic terrain) formed by Archean rock units (the Crixas -Goias granitegreenstones) and associated Proterozoic formations (Almeida et al. 1981, Fuck et al. 1993,1994, Pimentel et al. 2000a, b). The sialic basement on which the Brasilia Belt sediments were deposited is poorly understood, despite being well exposed in some areas of Goias and Tocantins. Gneiss and volcano-sedimentary units form most of this basement. Early studies have suggested that these rock units are dominantly Archean ( Danni et al. 1982, Marini et al. 1984). However, recent Sm- Nd isotopic studies have indicated that most of them are Paleoproterozoic (Sato 1998, Pimentel et al. 1999a, 2000b). Granite gneiss to the south and east of the Barro Alto mafic-ultramafic layered complex has been dated at 2128+/- 15 Ma (Correia et al. 1997). Calc-alkaline granite gneiss from Almas-Dianopolis is dated at ca. 2.2-2.45 Ga old (U-Pb SHRIMP on zircon and titanite, Cruz et al. 2000). The latter is probably the western extension of Paleoproterozoic rocks which underlie the San Francisco Craton to the east of the northern part of the Brasilia Belt. In central Goias, a large part of the Brasilia Belt is underlain by high-grade metamorphic rocks known as the Anapolis-Itaucu Complex, together with surrounding greenschist to amphibolite facies Mesoto Neoproterozoic cover metasediments of the Araxa group. These rocks represent the main constituent of the internal zone of the Brasilia Belt (Fuck et al. 1994, Pimentel et al. 2000b). Between the Araxa Group, and the easternmost part of the Anapolis-Itaucu Complex a volcano-sedimentary association known as Silvania

  10. U-Pb age constraints for the La Tuna Granite and Montevideo Formation (Paleoproterozoic, Uruguay): Unravelling the structure of the Río de la Plata Craton

    Science.gov (United States)

    Pamoukaghlián, Karina; Gaucher, Claudio; Frei, Robert; Poiré, Daniel G.; Chemale, Farid; Frei, Dirk; Will, Thomas M.

    2017-11-01

    The Río de la Plata Craton is a continental block that crops out in Uruguay, eastern Argentina, southernmost Brazil and Paraguay. It comprises in Uruguay the Piedra Alta, Tandilia and Nico Pérez terranes, separated by the Colonia and the Sarandí del Yí megashears. The La Tuna Granite, which intrudes the Araminda metasandstones in the Tandilia Terrane, was considered Cambrian in age and the intruded sandstones were assigned to the Neoproterozoic Piedras de Afilar Formation. We show that the granite is Paleoproterozoic in age and that the host metasandstones do not belong to the Piedras de Afilar Formation, but to the Paleoproterozoic Montevideo Formation. U-Pb LA ICP-MS of zircon ages for the La Tuna Granite yielded a concordant crystallization age of 2156 ± 26 Ma. Furthermore a metamorphic event at 2010 ± 9 Ma is revealed by Pb stepwise leaching dating of monazites. U-Pb detrital zircon ages of the host Araminda metasandstone yield an upper intercept discordia age of 2152 ± 29 Ma, which marks the intrusion of the La Tuna pluton, and which is in accordance with the zircon U-Pb LA ICP MS constraints. A concordant U-Pb detrital zircon age of 2465 ± 40 Ma provides a maximum depositional age constraint for the metapsammites. Comparing quartz arenites of the Ediacaran Piedras de Afilar Formation with the Araminda metaquartzites, we conclude that they are very similar regarding petrology but they differ in age and metamorphic overprint. Detrital zircons in quartz arenites of the Piedras de Afilar Formation show youngest ages of 1.0 Ga. On the other hand, detrital zircons recovered from the Araminda metasandstones and the age of the intruding granite allow interpreting a depositional age between 2465 and 2150 Ma. Nd model ages show crustal residence times in average more than 200 myr older for the Tandilia Terrane both in Uruguay and Argentina, with a significant Neoarchean component, which is lacking in the Piedra Alta Terrane. Whereas the Piedra Alta Terrane was

  11. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  12. The tectonic significance of the Cabo Frio Tectonic Domain in the SE Brazilian margin: a Paleoproterozoic through Cretaceous saga of a reworked continental margin

    Directory of Open Access Journals (Sweden)

    Renata da Silva Schmitt

    Full Text Available ABSTRACT: The Cabo Frio Tectonic Domain is composed of a Paleoproterozoic basement tectonically interleaved with Neoproterozoic supracrustal rocks (Buzios-Palmital successions. It is in contact with the Neoproterozoic-Cambrian Ribeira Orogen along the SE Brazilian coast. The basement was part of at least three continental margins: (a 1.97 Ga; (b 0.59 - 0.53 Ga; (c 0.14 Ga to today. It consists of continental magmatic arc rocks of 1.99 to 1.94 Ga. Zircon cores show a 2.5 - 2.6 Ga inheritance from the ancient margin of the Congo Craton. During the Ediacaran, this domain was thinned and intruded by tholeiitic mafic dykes during the development of an oceanic basin at ca. 0.59 Ma. After the tectonic inversion, these basin deposits reached high P-T metamorphic conditions, by subduction of the oceanic lithosphere, and were later exhumed as nappes over the basement. The Cabo Frio Tectonic Domain collided with the arc domain of the Ribeira Orogen at ca. 0.54 Ga. It is not an exotic block, but the eastern transition between this orogen and the Congo Craton. Almost 400 m.y. later, the South Atlantic rift zone followed roughly this suture, not coincidently. It shows how the Cabo Frio Tectonic Domain was reactivated as a continental margin in successive extensional and convergent events through geological time.

  13. The Atuba complex: a paleoproterozoic belt intensively reworked in the neoproterozoic era; O complexo Atuba: um cinturao paleoproterozoico intensamente retrabalhado no neoproterozoico

    Energy Technology Data Exchange (ETDEWEB)

    Siga Junior, O.; Basei, M.A.S.; Machiavelli, A.; Harara, O.M. [Sao Paulo Univ., SP (Brazil). Inst. de Geociencias; Reis Neto, J.M. [Parana Univ., Curitiba, PR (Brazil). Dept. de Geologia

    1996-11-01

    Studies of terranes between the northern Ribeira and southern Dom Feliciano Belts allow the characterization of three geotectonic domains with different evolutions: the Luis Alves, Curitiba and Paranagua terranes. The Atuba complex occurs in Curitiba Domain, which has a northwestern limit with metasediments of the Acungui and Setuva Groups and a southwestern limit with the granulitic gneisses of the Luis Alves domains. The contacts are expressive shear zones. The predominant rocks of the Curitiba Domain are banded, migmatitic gneisses in amphibolite grade with biotite-amphibolite gneissic mesosomes and tonalitic/graodioritic leucosomes, here called the Atuba complex. The migmatites are Paleoproterozoic (2.000{+-}200 Ma) and remigmatized in Neoproterozoic (600{+-}20 Ma). During the latter period temperatures reached more than 500{sup 0} C. The structural pattern indicated shear-controlled tectonics with an important lateral component, and low-angle, south-southeastward transport direction. The terranes of the Atuba complex appear to represent deep-level rocks which were migmatized, granitized and then added to the border of the Luis Alves Microplate during the Neoproterozoic. This late Neoproterozoic tectonic scheme which continued to the Cambro-Ordoviciano seems to be the result of larger scale processes of continental agglutination which ended with the formation of western Gondwanaland. (author). 17 figs., 2 tabs.

  14. Earth thermics

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, M

    1960-01-01

    The thermodynamics of the Earth are described, including terrestrial heat flow, internal temperatures and thermal history. The value of the geothermal gradient has been considered to be 3/sup 0/C/100 m but measured values are slightly different. The values of terrestrial heat flow are relatively constant and are calculated be about 2.3 x 10 to the minus 6 cal/cm/sup 2/ sec (2.3 HFU). The Earth's internal temperature can be calculated from the adiabatic temperature gradient of adiabatic expansion. Using Simon's equation No. 9, a value of 2100-2500/sup 0/C is obtained, this is much lower than it was previously thought to be. The value of 2.3 HFU can easily be obtained from this internal temperature figure.

  15. Geochemistry and microbial community composition across a range of acid mine drainage impact and implications for the Neoarchean-Paleoproterozoic transition

    Science.gov (United States)

    Havig, Jeff R.; Grettenberger, Christen; Hamilton, Trinity L.

    2017-06-01

    Streams impacted by acid mine drainage (AMD, also known as acid rock drainage) represent local environmental and ecological disasters; however, they may also present an opportunity to study microbial communities in environments analogous to past conditions. Neoarchean continents had streams and rivers replete with detrital pyrites. Following the emergence of oxygenic photosynthesis, Cyanobacteria colonized streams and rivers on continental surfaces. The combination of labile detrital pyrite grains and locally produced O2 generated by Cyanobacteria produced ideal conditions for pyrite oxidation similar to that found at modern AMD-impacted sites. To explore the connection of modern sites to ancient conditions, we sampled sites that exhibited a range of AMD-impact (e.g., pH from 2.1 to 7.9 [Fe2+] up to 5.2 mmol/L [SO42-] from 0.3 to 52.4 mmol/L) and found (i) nearly all analytes correlated to sulfate concentration; (ii) all sites exhibited the predominance of a single taxon most closely related to Ferrovum myxofaciens, an Fe-oxidixing betaproteoabacterium capable of carbon and nitrogen fixation, and (iii) signs of potential inorganic carbon limitation and nitrogen cycling. From these findings and building on the work of others, we present a conceptual model of continental surfaces during the Neoarchean and Paleoproterozoic linking local O2 production to pyrite oxidation on continental surfaces to sulfate production and delivery to nearshore environments. The delivery of sulfate drives sulfate reduction and euxinia—favoring anoxygenic photosynthesis over cyanobacterial O2 generation in near-continent/shelf marine environments.

  16. Northward laramide thrusting in the quitovac region, northwestern sonora, mexico: Implications for the juxtaposition of paleoproterozoic basement blocks and the mojave-sonora megashear hypothesis

    Science.gov (United States)

    Iriondo, Alexander; Martínez-Torres, Luis M.; Kunk, Michael J.; Atkinson, William W.; Premo, Wayne R.; McIntosh, William C.

    2005-01-01

    Restoration of 12%–30% Basin and Range extension allows direct interpretation of ductile fabrics associated with a stack of Laramide thrust faults in the Quitovac region in northwestern Sonora. The inferred direction of displacement of these thrusts varies gradually from N63°W to N23°E and is interpreted to represent a clockwise rotation of the direction of Laramide thrusting through time. The thrust faults represent a piggy-back sequence of thrusting propagating north, toward the foreland. The average direction and sense of displacement of the thrusts is N18°W, and the cumulative 45 km of estimated northward-directed displacement corresponds to ∼86% of shortening.Based on geochronological constraints, onset of thrusting in Quitovac occurred sometime between 75 and 61 Ma, whereas cessation occurred at ca. 39 Ma. The presence of Paleocene-Eocene orogenic gold mineralization, spatially associated with thrusting, strengthens our idea that compressional tectonism associated with the Laramide orogeny is a very important and widespread dynamometamorphic event in the region.Similarities in age, kinematics, and structural stratigraphy indicate that the thrusting in the Quitovac region may be equivalent to the Laramide Quitobaquito Thrust in southwestern Arizona. In both areas, thrust faults juxtapose the Paleoproterozoic Caborca and “North America” basement blocks. This juxtaposition was previously proposed as exclusively related to movements along the hypothetical Upper Jurassic Mojave-Sonora megashear. The Laramide northward displacements and clockwise rotations recorded in the Caborca block rocks in Quitovac contradict the southward displacements (∼800 km) and counterclockwise rotations inherent in the left-lateral Upper Jurassic Mojave-Sonora megashear hypothesis. We conclude that if this megashear exists in northwestern Sonora, its trace should be to the southwest of the Quitovac region.

  17. A profile of acute care in an aging America: snowball sample identification and characterization of United States geriatric emergency departments in 2013.

    Science.gov (United States)

    Hogan, Teresita M; Olade, Tolulope Oyeyemi; Carpenter, Christopher R

    2014-03-01

    The aging of America poses a challenge to emergency departments (EDs). Studies show that elderly patients have poor outcomes despite increased testing, prolonged periods of observation, and higher admission rates. In response, emergency medicine (EM) leaders have implemented strategies for improved ED elder care, enhancing expertise, equipment, policies, and protocols. One example is the development of geriatric EDs gaining in popularity nationwide. To the authors' knowledge, this is the first research to systematically identify and qualitatively characterize the existence, locations, and features of geriatric EDs across the United States. The primary objective was to determine the number, distribution, and characteristics of geriatric EDs in the United States in 2013. This was a survey with potential respondents identified via a snowball sampling of known geriatric EDs, EM professional organizations' geriatric interest groups, and a structured search of the Internet using multiple search engines. Sites were contacted by telephone, and those confirming geriatric EDs presence received the survey via e-mail. Category questions included date of opening, location, volumes, staffing, physical plant changes, screening tools, policies, and protocols. Categories were reported based on general interest to those seeking to understand components of a geriatric ED. Thirty-six hospitals confirmed geriatric ED existence and received surveys. Thirty (83%) responded to the survey and confirmed presence or plans for geriatric EDs: 24 (80%) had existing geriatric EDs, and six (20%) were planning to open geriatric EDs by 2014. The majority of geriatric EDs are located in the Midwest (46%) and Northeast (30%) regions of the United States. Eighty percent serve from 5,000 to 20,000 elder patients annually. Seventy percent of geriatric EDs are attached to the main ED, and 66% have from one to 10 geriatric beds. Physical plant changes include modifications to beds (96%), lighting (90

  18. Sulfur Earth

    Science.gov (United States)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  19. PENGARUH MODEL PEMBELAJARAN KOOPERATIF TIPE SNOWBALL THROWING TERHADAP HASIL BELAJAR SISWA PADA KONSEP SALING KETERGANTUNGAN DALAM EKOSISTEM DI KELAS VII SMP NEGERI 18 PEKANBARU TAHUN AJARAN 2014 / 2015

    Directory of Open Access Journals (Sweden)

    Jumiati Jumiati

    2017-07-01

    Full Text Available The aim of this research was to find out the effect of cooperative learning type snowballthrowing to improve student learning achievement on the reliance mutualin in theecosystem concept. The research was conducted at SMP Negeri 18 Pekanbaru at firstsemester in academic years 2014 / 2015. Design of the research was quasi-experimental,The Matching Only Pretest – Posttest Control Group Design. Sample of the research wastaken two classes with the number of students in each 40 people who were taken by usingsimple random sampling technique. The data were collected by using pretest, posttest andteacher’s and students’ activities observation sheets. The data analysis technique used inthis research was 2 sample independent t test, if the data were normal and homogen. Themean N-gain experimental class was 0.72 high category and the control class was 0.44medium category. Based on the result of statistical test that there were significantdifferences between the mean N-Gain experimental class and control class. Thereby canbe conluded that there were significant application of cooperative learning type snowballthrowing to improve student learning achievement on the reliance mutualin in theecosystem concept class VII SMPN 18 pekanbaru academic year 2014 / 2015.Key words : snowball throwing, learning achievement, ecosystem.

  20. Paleoproterozoic source contributions to the Sao Roque Group sedimentation: LA-MC-ICPMS U-Pb dating and Sm-Nd systematics of clasts from metaconglomerates of the Boturuna Formation

    Energy Technology Data Exchange (ETDEWEB)

    Henrique-Pinto, Renato; Janasi, Valdecir de Assis; Tassinari, Colombo Celso Gaeta [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica; Simonetti, Antonio [University of Notre Dame, South Bend (United States). Dept. of Civil Engineering and Geological Sciences; Heaman, Larry Michael, E-mail: renatohp@usp.br, E-mail: vajanasi@usp.br, E-mail: ccgtassi@usp.br, E-mail: antonio.simonetti.3@nd.edu, E-mail: larry.heaman@ualberta.ca [University of Alberta, Edmonton (Canada). Dept. of Earth and Atmospheric Sciences

    2012-12-15

    The Sao Roque Group is characterized by volcano-sedimentary sequences, in which deposition probably started in the late Paleoproterozoic. U-Pb dating by LA-MC-ICPMS of zircons extracted from predominantly equigranular monzogranites clasts from Morro Doce and Morro do Polvilho regions, yield paleoproterozoic ages of 2199 {+-}8.5 Ma and 2247 {+-}13 Ma, respectively. These represent the ages for the main source of granite for the metaconglomerates from the Boturuna Formation (basal unit of Sao Roque Group). Its polycyclic history is reinforced by the presence of inherited Archean zircons (2694 {+-}29 Ma) found within the clasts. Moreover, these clasts have also been affected by the Neoproterozoic overprinting event as indicated by their lower intercept Concordia ages. Sm-Nd isotope data for the main clast varieties from the Morro Doce metaconglomerates yield T{sub DM} ages of 2.6 to 2.7 Ga, demonstrating that these granites are the recycling products of an Archean crustal component. The metaconglomerate arkosean framework yields slightly lower {epsilon}{sub Nd(t)} values than those for the clasts, indicating that a younger and/or more primitive source also contributed to the Boturuna Formation. (author)

  1. Impact of participant incentives and direct and snowball sampling on survey response rate in an ethnically diverse community: results from a pilot study of physical activity and the built environment.

    Science.gov (United States)

    Perez, Daniel F; Nie, Jason X; Ardern, Chris I; Radhu, Natasha; Ritvo, Paul

    2013-02-01

    Community-wide efforts to encourage healthy behaviours must respond to the needs of existing neighbourhoods, especially those where low physical activity (PA) is associated with social, economic, and cultural challenges. This study reports on the effect of direct and snowball sampling strategies and financial incentive levels on the response rates of a built environment and PA survey in a predominately urban, low-SES new-immigrant community. Women residing in the Jane-Finch neighbourhood of Toronto, Ontario were selected to participate by quasi-random sampling, yielding a response rate of 41.5%. The survey completion rate per contact attempt increased 2-fold when incentives were increased from $10 to $20 and a further threefold following the increase from $20 to $30. Snowball sampled respondents were older, less likely to have full-time employment, and had lower educational attainment than directly sampled participants. With appropriate incentives, face-to-face contact, and snowball sampling, survey-based research is feasible within a low-SES, high minority population.

  2. Origin of Fe-Ti Oxide Mineralization in the Middle Paleoproterozoic Elet'ozero Syenite-Gabbro Intrusive Complex (Northern Karelia, Russia)

    Science.gov (United States)

    Sharkov, E. V.; Chistyakov, A. V.; Shchiptsov, V. V.; Bogina, M. M.; Frolov, P. V.

    2018-03-01

    Magmatic oxide mineralization widely developed in syenite-gabbro intrusive complexes is an important Fe and Ti resource. However, its origin is hotly debatable. Some researchers believe that the oxide ores were formed through precipitation of dense Ti-magnetite in an initial ferrogabbroic magma (Bai et al., 2012), whereas others consider them as a product of immiscible splitting of Fe-rich liquid during crystallization of Fe-Ti basaltic magma (Zhou et al., 2013). We consider this problem with a study of the Middle Paleoproterozoic (2086 ± 30 Ma) Elet'ozero Ti-bearing layered intrusive complex in northern Karelia (Baltic Shield). The first ore-bearing phase of the complex is mainly made up of diverse ferrogabbros, with subordinate clinopyroxenites and peridotites. Fe-Ti oxides (magnetite, Ti-magnetite, and ilmenite) usually account for 10-15 vol %, reaching 30-70% in ore varieties. The second intrusive phase is formed by alkaline and nepheline syenites. Petrographical, mineralogical, and geochemical data indicate that the first phase of the intrusion was derived from a moderately alkaline Fe-Ti basaltic melt, while the parental melt of the second phase was close in composition to alkaline trachyte. The orebodies comprise disseminated and massive ores. The disseminated Fe-Ti oxide ores make up lenses and layers conformable to general layering. Massive ores occur in subordinate amounts as layers and lenses, as well as cross-cutting veins. Elevated Nb and Ta contents in Fe-Ti oxides makes it possible to consider them complex ores. It is shown that the Fe-Ti oxide mineralization is related to the formation of a residual (Fe,Ti)-rich liquid, which lasted for the entire solidification history of the first intrusive phase. The liquid originated through multiple enrichment of Fe and Ti in the crystallization zone of the intrusion owing to the following processes: (1) precipitation of silicate minerals in the crystallization zone with a corresponding increase in the Fe and

  3. The Petäjäskoski Formation, a new lithostratigraphic unit in the Paleoproterozoic Peräpohja Belt, northern Finland

    Directory of Open Access Journals (Sweden)

    Markus Kyläkoski

    2012-12-01

    Full Text Available This paper gives the first description of a newly-recognized, basin-wide metasedimentary unit in the Paleoproterozoic (~2.4–1.9 Ga Peräpohja Belt, northern Finland. The unit, which is named the Petäjäskoski Formation (PFm after the single location where the rocks are known to be exposed, is situated stratigraphically in the middle part of the Kivalo Group between the quartzites of the>2.22 Ga Palokivalo Formation and the mafic volcanic rocks of the ~2.1 Ga Jouttiaapa Formation.The bulk of the PFm comprises phlogopitic-sericitic and albitic schists with abundant hematite as a diagnostic feature. Quartzite and dolomite interbeds are common. Based on drillcore and geophysical data, the succession is several hundreds of meters thick. The unit has prograde, chiefly lower greenschist facies mineral assemblages and, though being commonly intensely deformed, shows well-preserved sedimentary structures that imply deposition in shallow-water tosubaerial environments. Based on the original lithological features, the Petäjäskoski Formation can be defined as a claystone-siltstone-sandstone-dolostone association. On the geochemical and stratigraphic basis, the albite schists likely represent albitized equivalents of the micaceous claystones and siltstones. They are intercalated with stratabound collapse breccias, up to tens of meters in thickness, with clasts composed mainly of bordering albite schist. A mafic sill intruding the Petäjäskoski Formation yielded a U-Pb zircon age of 2140 ± 11 Ma. The older, c. 2220 Ma, differentiated sills are not known to reach the stratigraphic level of thePetäjäskoski Formation and hence, the depositional age of the PFm sediments can be bracketed between c. 2220 and 2140 Ma. Detrital zircon grains dated from a quartzitic sample from the PFmshow an Archean (c. 2650–3470 Ma provenance.The moderate to high MgO (~6–13 wt.%, K2O (~3–8 wt.% and FeOtot(8–15 wt.% contents, low CaO and Na2O contents, and abundant

  4. P-T composition and evolution of paleofluids in the Paleoproterozoic Mag Hill IOCG system, Contact Lake belt, Northwest Territories, Canada

    Science.gov (United States)

    Somarin, A. Karimzadeh; Mumin, A. Hamid

    2014-02-01

    The Echo Bay stratovolcano complex and Contact Lake Belt of the Great Bear Magmatic Zone, Northwest Territories, host a series of coalescing Paleoproterozoic hydrothermal systems that affected an area of several hundred square kilometers. They were caused by intrusion of synvolcanic diorite-monzodioritic plutons into andesitic host rocks, producing several characteristic hydrothermal assemblages. They include early and proximal albite, magnetite-actinolite-apatite, and potassic (K-feldspar) alteration, followed by more distal hematite, phyllic (quartz-sericite-pyrite), and propylitic (chlorite-epidote-carbonate±sericite±albite±quartz) alteration, and finally by late-stage polymetallic epithermal veins. These alteration types are characteristic of iron oxide copper-gold deposits, however, with distal and lower-temperature assemblages similar to porphyry Cu systems. Magnetite-actinolite-apatite alteration formed from high temperature (up to 560 °C) fluids with average salinity of 12.8 wt% NaCl equivalent. The prograde propylitic and phyllic alteration stages are associated with fluids with temperatures varying from 80 to 430 °C and a wide salinity range (0.5-45.6 wt% NaCl equivalent). Similarly, wide fluid temperature (104-450 °C) and salinity (4.2-46.1 wt% NaCl equivalent) ranges are recorded for the phyllic alteration. This was followed by Cu-Ag-U-Zn-Co-Pb sulfarsenide mineralization in late-stage epithermal veins formed at shallow depths and temperatures from 270 °C to as low as 105 °C. The polymetallic veins precipitated from high salinity (mean 30 wt% NaCl equivalent) dense fluids (1.14 g/cm3) with a vapor pressure of 3.8 bars, typical of epithermal conditions. Fluid inclusion evidence indicates that mixed fluids with evolving physicochemical properties were responsible for the formation of the alteration assemblages and mineralization at Mag Hill. An early high temperature, moderate salinity, and magmatic fluid was subsequently modified variably by

  5. Stratigraphy and Age of Paleoproterozoic Birimian Volcaniclastic Sequence in the Cape Three Points area, Axim-Konongo (Ashanti) Belt, Southwest Ghana

    Science.gov (United States)

    Yoshimaru, S.; Kiyokawa, S.; Ito, T.; Ikehara, M.; Horie, K.; Takehara, M.; Sano, T.; Nyame, F. K.; Tetteh, G. M.

    2016-12-01

    This study investigated the depositional environments and bioactivities of well preserved volcaniclastic sequences in the Cape Three Points area in the Paleoproterozoic Axim-Konongo (Ashanti) belt in the Birimian of Ghana. Our current research outlines the stratigraphy, structure, approximate age and depositional setting of the volcaniclastic sequence in the Cape Three Points area in Ghana, West Africa.Axim-Konongo (Ashanti) belt is composed of mainly andesitic basalts, volcaniclastic rocks and belt type granitoids, which are unconformably overlain by Tarkwaian conglomerates and metasedimentary rocks. The rocks show NE-SW strike with maximum depositional age of overlying metasedimentary rocks of 2154±2 Ma (U-Pb zircon; Oberthür et al., 1998). The oldest age of an intrusive into Birimian volcanic rock near Sekondi is 2174±2 Ma (U-Pb zircon; Oberthür et al., 1998). Thick volcaniclastic succession over 4000 m thickness was reconstructed for 1000 m thickness after detailed field investigations. The succession shows approximately N-S strike mainly 60-80° dip to the east and generally upward sequence. The rocks were affected by greenschist facies metamorphism. TiO2/Al2O3 ratios of chromites and whole- rock trace elements compositions with low Nb concentration and high LREE concentration support deposition on mid-deep sea floor in a volcanic arc. New age data were obtained from foliated porphyritic dyke which occurs in the Cape Three Points area. Zircon grains, measured by SHRIMP at National Institute of Polar Research (NIPR), yielded a weighted mean 204Pb-corrected 207Pb/206Pb age of 2265.6±4.6 Ma (95% confidence). Thus, the volcaniclastic sequence was deposited before 2265.6±4.6 Ma and was deformed after 2265 Ma. 2260 Ma is the oldest age at which early volcanic activity in the Birimian terrane occurred (Loh and Hirdes, 1999). References Oberthür T et al. (1998) Precambrian Research 89: 129-143 Loh G and Hirdes W (1999) Exlplanatory Notes for the Geological Map

  6. Geological evolution of the center-southern portion of the Guyana shield based on the geochemical, geochronological and isotopic studies of paleoproterozoic granitoids from southeastern Roraima, Brazil

    International Nuclear Information System (INIS)

    Almeida, Marcelo Esteves

    2006-01-01

    This study focuses the granitoids of center-southern portion of Guyana Shield, southeastern Roraima, Brazil. The region is characterized by two tectonic-stratigraphic domains, named as Central Guyana (GCD) and Uatuma-Anaua (UAD) and located probably in the limits of geochronological provinces (e.g. Ventuari-Tapajos or Tapajos-Parima, Central Amazonian and Maroni-Itacaiunas or Transamazon). The aim this doctoral thesis is to provide new petrological and lithostratigraphic constraints on the granitoid rocks and contribute to a better understanding of the origin and geo dynamic evolution of Guyana Shield. The GCD is only locally studied near to the UAD boundary, and new geological data and two single zircon Pb-evaporation ages in mylonitic biotite granodiorite (1.89 Ga) and foliated hastingsite-biotite granite (1.72 Ga) are presented. These ages of the protholiths contrast with the lithostratigraphic picture in the other areas of Cd (1.96-1.93 Ga). Regional mapping, petrography, geochemistry and zircon geochronology carried out in the Urad have showed widespread Paleoproterozoic calc-alkaline granitic magmatism. These granitoid rocks are distributed into several magmatic associations with different Paleoproterozoic (1.97-1.89 Ga) ages, structural and geochemical affinities. Detailed mapping, petrographic and geochronological studies have distinguished two main sub domains in the UAD. In the northern UAD, the high-K calc-alkaline Martins Pereira (1.97 Ga) and Serra Dourada S-type granites (1.96 Ga) are affected by NE-SW and E-W ductile dextral shear-zones, showing coexistence of magmatic and deformational fabrics related to heterogeneous deformation. Inliers of basement (2.03 Ga) crop out northeast of this area, and are formed by meta volcano-sedimentary sequence (Cauarane Group) and TTG-like calc-alkaline association (Anaua Complex). Xenoliths of meta diorites (Anaua Complex) and para gneisses (Cauarane Group) reinforce the intrusive character of Martins Pereira

  7. THERMAL PHASES OF EARTH-LIKE PLANETS: ESTIMATING THERMAL INERTIA FROM ECCENTRICITY, OBLIQUITY, AND DIURNAL FORCING

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, Nicolas B. [Center for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2131 Tech Drive, Evanston, IL 60208 (United States); Voigt, Aiko [Max Planck Institute for Meteorology, Bundesstr. 53, D-20146 Hamburg (Germany); Abbot, Dorian S., E-mail: n-cowan@nortwestern.edu [Department of Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States)

    2012-09-20

    In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3 Multiplication-Sign the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A

  8. THERMAL PHASES OF EARTH-LIKE PLANETS: ESTIMATING THERMAL INERTIA FROM ECCENTRICITY, OBLIQUITY, AND DIURNAL FORCING

    International Nuclear Information System (INIS)

    Cowan, Nicolas B.; Voigt, Aiko; Abbot, Dorian S.

    2012-01-01

    In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3× the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A pole-on observer

  9. Earth mortars and earth-lime renders

    Directory of Open Access Journals (Sweden)

    Maria Fernandes

    2008-01-01

    Full Text Available Earth surface coatings play a decorative architectural role, apart from their function as wall protection. In Portuguese vernacular architecture, earth mortars were usually applied on stone masonry, while earth renders and plasters were used on indoors surface coatings. Limestone exists only in certain areas of the country and consequently lime was not easily available everywhere, especially on granite and schist regions where stone masonry was a current building technique. In the central west coast of Portugal, the lime slaking procedure entailed slaking the quicklime mixed with earth (sandy soil, in a pit; the resulting mixture would then be combined in a mortar or plaster. This was also the procedure for manufactured adobes stabilized with lime. Adobe buildings with earth-lime renderings and plasters were also traditional in the same region, using lime putty and lime wash for final coat and decoration. Classic decoration on earth architecture from the 18th-19th century was in many countries a consequence of the François Cointeraux (1740-1830 manuals - Les Cahiers d'Architecture Rurale" (1793 - a French guide for earth architecture and building construction. This manual arrived to Portugal in the beginning of XIX century, but was never translated to Portuguese. References about decoration for earth houses were explained on this manual, as well as procedures about earth-lime renders and ornamentation of earth walls; in fact, these procedures are exactly the same as the ones used in adobe buildings in this Portuguese region. The specific purpose of the present paper is to show some cases of earth mortars, renders and plasters on stone buildings in Portugal and to explain the methods of producing earth-lime renders, and also to show some examples of rendering and coating with earth-lime in Portuguese adobe vernacular architecture.

  10. Why Earth Science?

    Science.gov (United States)

    Smith, Michael J.

    2004-01-01

    This article briefly describes Earth science. The study of Earth science provides the foundation for an understanding of the Earth, its processes, its resources, and its environment. Earth science is the study of the planet in its entirety, how its lithosphere, atmosphere, hydrosphere, and biosphere work together as systems and how they affect…

  11. Using risk-tracing snowball approach to increase HIV case detection among high-risk populations in Cambodia: an intervention study.

    Science.gov (United States)

    Chhim, Srean; Macom, John; Pav, Chettana; Nim, Nirada; Yun, Phearun; Seng, Sopheap; Chhim, Kolab; Tuot, Sovannary; Yi, Siyan

    2017-10-18

    Early HIV diagnosis and initiation onto antiretroviral therapy may prevent ongoing spread of HIV. Risk Tracing Snowball Approach (RTSA) has been shown to be effective in detecting new HIV cases in other settings. The main objective of this study is to evaluate the effectiveness of RTSA in increasing the rate of newly identified HIV cases among high-risk populations. Our second objective was to evaluate the effectiveness of RTSA, as compared to the walk-in group, in increasing the number of HIV tests and early case detection. This study was conducted from April 1 to September 30, 2016 at two NGO clinics in Phnom Penh, Cambodia. Respondent driven sampling method was adapted to develop RTSA to reach high-risk populations, including key populations and the general population who have social connections with key populations. Bivariate and multivariate logistic regression analyses were conducted. During the implementation period, 721 clients walked in for HIV testing (walk-in group), and all were invited to be seeds. Of the invited clients, 36.6% agreed to serve as seeds. Throughout the implementation, 6195 coupons were distributed to seeds or recruiters, and resulted in 1572 clients visiting the two clinics with coupons (RTSA group), for a coupon return rate of 25.3%. The rate of newly identified HIV cases among the RTSA group was significantly lower compared to that in walk-in group. However, the highest number of newly identified HIV cases was found during the implementation period, compared to both pre- and post-implementation period. Although statistically not significant, the mean CD4 count of newly identified HIV cases detected through RTSA was almost 200 cells/mm3 higher than that in the walk-in group. Although the rate of newly identified HIV cases among the RTSA group was lower than that in the walk-in group, the inclusion of RTSA in addition to the traditional walk-in method boosted new HIV case detection in the two participating clinics. A higher mean CD4

  12. 40Ar-39Ar dating of Archean iron oxide Cu-Au and Paleoproterozoic granite-related Cu-Au deposits in the Carajás Mineral Province, Brazil: implications for genetic models

    Science.gov (United States)

    Pollard, Peter J.; Taylor, Roger G.; Peters, Lisa; Matos, Fernando; Freitas, Cantidiano; Saboia, Lineu; Huhn, Sergio

    2018-05-01

    this time. The Paleoproterozoic Cu-Au deposits are commonly hosted within Neoarchean IOCG alteration systems and the common occurrence of potassic alteration (especially biotite) in both types of deposits means that special care is required in interpreting the paragenesis of alteration in both types of deposits. The Paleoproterozoic Cu-Au deposits are reduced, and sulfur- and quartz-rich deposits lacking in major amounts of iron oxides and are therefore unlike IOCG deposits. Instead, they share many characteristics in common with widespread Paleoproterozoic Sn-W deposits in the Amazon Craton, including close spatial and temporal relationships with reduced A-type B-Li-F granites, and the occurrence of greisen and quartz-rich vein/breccia systems within and above granite cupolas. The occurrence of sericitic alteration in the Paleoproterozoic Cu-Au deposits is not evidence for an upward transition to sericitic alteration in IOCG deposits in the Carajás Mineral Province.

  13. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  14. Rare earth sulfates

    International Nuclear Information System (INIS)

    Komissarova, L.N.; Shatskij, V.M.; Pokrovskij, A.N.; Chizhov, S.M.; Bal'kina, T.I.; Suponitskij, Yu.L.

    1986-01-01

    Results of experimental works on the study of synthesis conditions, structure and physico-chemical properties of rare earth, scandium and yttrium sulfates, have been generalized. Phase diagrams of solubility and fusibility, thermodynamic and crystallochemical characteristics, thermal stability of hydrates and anhydrous sulfates of rare earths, including normal, double (with cations of alkali and alkaline-earth metals), ternary and anion-mixed sulfates of rare earths, as well as their adducts, are considered. The state of ions of rare earths, scandium and yttrium in aqueous sulfuric acid solutions is discussed. Data on the use of rare earth sulfates are given

  15. Rare earth germanates

    International Nuclear Information System (INIS)

    Bondar', I.A.; Vinogradova, N.V.; Dem'yanets, L.N.

    1983-01-01

    Rare earth germanates attract close attention both as an independent class of compounds and analogues of a widely spread class of natural and synthetic minerals. The methods of rare earth germanate synthesis (solid-phase, hydrothermal) are considered. Systems on the basis of germanium and rare earth oxides, phase diagrams, phase transformations are studied. Using different chemical analysese the processes of rare earth germanate formation are investigated. IR spectra of alkali and rare earth metal germanates are presented, their comparative analysis being carried out. Crystal structures of the compounds, lattice parameters are studied. Fields of possible application of rare earth germanates are shown

  16. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....

  17. Stable Isotope Geochemistry of Extremely Well-Preserved 2.45-Billion-Year-Old Hydrothermal Systems in the Vetreny Belt, Baltic Shield: Insights into Paleohydrosphere

    Science.gov (United States)

    Zakharov, D. O.; Bindeman, I. N.

    2015-12-01

    The early Paleoproterozoic was an eventful period in the Earth's history. The first portions of free oxygen emerged in the atmosphere, Snowball Earth glaciations happened several times and the first supercontinent broke up due to extensive rifting. These events should have affected the stable isotopic composition of the hydrosphere. In this study, we use rocks that were altered in underwater hydrothermal systems to investigate the stable isotopic composition of the hydrosphere 2.39-2.45 billion years ago (hereinafter, Ga). Extremely low-δ18O (down to -27.5‰ SMOW) rocks from 2.39 Ga metamorphosed subglacial hydrothermal systems of the Belomorian belt, Baltic Shield formed at near-equatorial latitudes suggesting a Snowball (or Slushball) Earth glaciation. These results motivated us to look at temporally and geographically close hydrothermal systems from the unmetamorhposed 2.45 Ga Vetreny Belt rift. The length of the rift is 250 km and it is composed of high-Mg basalts, mafic-ultramafic intrusions and sedimentary successions. We examined several localities of high-Mg basalt flows that include astonishingly fresh pillow lavas, often with preserved volcanic glass, eruptive breccias, and hydrothermal alteration zones. Collected samples serve a great textural evidence of water-rock interaction that occurred in situ while basalts were cooling. The preliminary results from coexisting quartz and epidote (T, D18O=311°C), and from coexisting calcite and quartz (T, D18O=190°C) yield values of δ18O of involved water between -1.6 and -0.9 ‰. The values of δ13C in calcites vary between -4.0 and -2.3 ‰. It is likely that hydrothermal fluids operated in the Vetreny Belt rift were derived from seawater that is no different from modern oceanic water in terms of δ18O. Apparently, the rift was a Paleoproterozoic analog of the modern Red Sea, filled with oceanic water. The result is important because the Vetreny Belt rift predates the onset of Snowball Earth glaciation at 2

  18. Two drastically different climate states on an Earth-like land planet with overland water recycling

    Science.gov (United States)

    Kalidindi, S.; Reick, C. H.; Raddatz, T.; Claussen, M.

    2017-12-01

    Prior studies have demonstrated that habitable areas on low-obliquity land planets are confined to the edges of frozen ice caps. Whether such dry planets can maintain long-lived liquid water is unclear. Leconte et al. 2013 argue that on such planets mechanisms like gravity driven ice flows and geothermal flux can maintain liquid water at the edges of thick ice caps and this water may flow back to the lower latitudes through rivers. However, there exists no modelling study which investigates the climate of an Earth-like land planet with an overland recycling mechanism bringing fresh water back from higher to lower latitudes. In our study, by using a comprehensive climate model ICON, we find that an Earth-like land planet with an overland recycling mechanism can exist in two drastically different climate states for the same set of boundary conditions and parameter values: A Cold and Wet (CW) state with dominant low-latitude precipitation and, a Hot and Dry (HD) state with only high-latitude precipitation. For perpetual equinox conditions, both climate states are stable below a certain threshold value of background soil albedo (α) while above that only the CW state is stable. Starting from the HD state and increasing α above the threshold causes an abrupt shift from the HD state to the CW state resulting in a sudden cooling of about 35°C globally which is of the order of the temperature difference between the present-day and the Snowball Earth state. In contrast to the Snowball Earth instability, we find that the sudden cooling in our study is driven by the cloud albedo feedback rather than the snow-albedo feedback. Also, when α in the CW state is reduced back to zero the land planet does not display a closed hysteresis. Our study also has implications for the habitability of Earth-like land planets. At the inner edge of the habitable zone, the higher cloud cover in the CW state cools the planet and may prevent the onset of a runaway greenhouse state. At the outer

  19. Conditions for oceans on Earth-like planets orbiting within the habitable zone: importance of volcanic CO2 degassing

    International Nuclear Information System (INIS)

    Kadoya, S.; Tajika, E.

    2014-01-01

    Earth-like planets in the habitable zone (HZ) have been considered to have warm climates and liquid water on their surfaces if the carbonate-silicate geochemical cycle is working as on Earth. However, it is known that even the present Earth may be globally ice-covered when the rate of CO 2 degassing via volcanism becomes low. Here we discuss the climates of Earth-like planets in which the carbonate-silicate geochemical cycle is working, with focusing particularly on insolation and the CO 2 degassing rate. The climate of Earth-like planets within the HZ can be classified into three climate modes (hot, warm, and snowball climate modes). We found that the conditions for the existence of liquid water should be largely restricted even when the planet is orbiting within the HZ and the carbonate-silicate geochemical cycle is working. We show that these conditions should depend strongly on the rate of CO 2 degassing via volcanism. It is, therefore, suggested that thermal evolution of the planetary interiors will be a controlling factor for Earth-like planets to have liquid water on their surface.

  20. Mission to Planet Earth

    Science.gov (United States)

    Tilford, Shelby G.; Asrar, Ghassem; Backlund, Peter W.

    1994-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

  1. Mission to Planet Earth

    International Nuclear Information System (INIS)

    Wilson, G.S.; Backlund, P.W.

    1992-01-01

    Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the earth and how it works as a system. Increased understanding of the earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. 8 refs

  2. Corrigendum to "Geochemistry and geochronology of orthogneisses in Bode Saadu area, southwestern Nigeria and their implications for the Paleoproterozoic evolution of the area" [J. African Earth Sciences 109 (2015) 131-142

    Science.gov (United States)

    Okonkwo, Chukwuemeka T.; Ganev, Valentin Y.

    2018-04-01

    The authors regret the error in Table 1-Chemical composition of the orthogneisses where the sum of the elements for each sample was mistakenly indicated as LOI (loss on ignition). The correct table is given below.

  3. Precambrian supercontinents, glaciations, atmospheric oxygenation, metazoan evolution and an impact that may have changed the second half of Earth history

    Directory of Open Access Journals (Sweden)

    Grant M. Young

    2013-05-01

    Full Text Available In more than 4 Ga of geological evolution, the Earth has twice gone through extreme climatic perturbations, when extensive glaciations occurred, together with alternating warm periods which were accompanied by atmospheric oxygenation. The younger of these two episodes of climatic oscillation preceded the Cambrian “explosion” of metazoan life forms, but similar extreme climatic conditions existed between about 2.4 and 2.2 Ga. Over long time periods, changing solar luminosity and mantle temperatures have played important roles in regulating Earth's climate but both periods of climatic upheaval are associated with supercontinents. Enhanced weathering on the orogenically and thermally buoyed supercontinents would have stripped CO2 from the atmosphere, initiating a cooling trend that resulted in continental glaciation. Ice cover prevented weathering so that CO2 built up once more, causing collapse of the ice sheets and ushering in a warm climatic episode. This negative feedback loop provides a plausible explanation for multiple glaciations of the Early and Late Proterozoic, and their intimate association with sedimentary rocks formed in warm climates. Between each glacial cycle nutrients were flushed into world oceans, stimulating photosynthetic activity and causing oxygenation of the atmosphere. Accommodation for many ancient glacial deposits was provided by rifting but escape from the climatic cycle was predicated on break-up of the supercontinent, when flooded continental margins had a moderating influence on weathering. The geochemistry of Neoproterozoic cap carbonates carries a strong hydrothermal signal, suggesting that they precipitated from deep sea waters, overturned and spilled onto continental shelves at the termination of glaciations. Paleoproterozoic (Huronian carbonates of the Espanola Formation were probably formed as a result of ponding and evaporation in a hydrothermally influenced, restricted rift setting. Why did metazoan

  4. Digital Earth – A sustainable Earth

    International Nuclear Information System (INIS)

    Mahavir

    2014-01-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth

  5. “Bola de Neve”: Um Fenômeno Pentecostal Contemporâneo ("SnowBall Church”: a Contemporary Pentecostal Phenomenon. DOI: 10.5752/P.2175-5841.2012v10n26p500

    Directory of Open Access Journals (Sweden)

    Lidice Meyer Pinto Ribeiro

    2012-07-01

    Full Text Available Quase que diariamente presenciamos no Brasil o aparecimento de novas alternativas religiosas, assim como uma intensa fragmentação institucional dentro das igrejas protestantes já estabelecidas. Nesse cenário, surgem igrejas autônomas, voltadas a certos públicos específicos, oferecendo produtos simbólicos mais próximos à realidade desses grupos. Enquadra-se entre as voltadas a “tribos urbanas” específicas a “Bola de Neve Church”, oficializada em 1999. Neste artigo, faz-se a análise antropológica da Igreja Evangélica Bola de Neve, situada no bairro Tatuapé, na Zona Leste da cidade de São Paulo, visando a compreender a estrutura de culto, o perfil dos membros e trabalhando o tipo de comunicação que é utilizada, tendo como método de pesquisa o trabalho de campo, leituras específicas sobre o neopentecostalismo no Brasil e entrevistas e análises pessoais dos membros que ali congregam. Também se levanta a possibilidade de essa igreja, bem como outras voltadas a públicos específicos, poder ser interpretada como uma quarta onda do pentecostalismo dentro da teoria das ondas de Paul Freston, onde imperaria a Teologia da Autonomia.Palavras-chave: Bola de neve. Pentecostalismo. Protestantismo. Tribos urbanas.  Abstract: In Brazil, we witness the emergence of new religious alternatives almost daily, as well as a strong institutional fragmentation within the established Protestant churches. In this scenario, emerge autonomous churches with target specific audiences, offering symbolic products that match the needs of those audiences.  For example, churches focused on "urban tribes" such as "Igreja Evangélica Bola de Neve" ("Snowball Church", incorporated in 1999, on the Tatuapé neighborhood of São Paulo, SP, Brazil. This article presents an anthropological analysis of "Snowball church", seeking to understand the structure of worship, the profile of members, and the kind of communication that is used in there. The research

  6. The earth's gravitational field

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    . But to say that gravity acts downwards is not correct. Gravity acts down, no matter where you stand on the Earth. It is better to say that on Earth gravity pulls objects towards the centre of the Earth. So no matter where you are on Earth all objects fall... pull than objects at the poles. In combination, the equatorial bulge and the effects of centrifugal force mean that sea-level gravitational acceleration increases from about 9.780 m/s² at the equator to about 9.832 m/s² at the poles, so an object...

  7. Geomagnetic field of earth

    International Nuclear Information System (INIS)

    Delipetrev, Marjan; Delipetrev, Blagoj; Panovska, Sanja

    2008-01-01

    In this paper is introduced the theory of geomagnetic field of the Earth. A homogenous and isotropic sphere is taken for a model of Earth with a bar magnet at its center as a magnetic potential. The understanding of the real origin of geomagnetic field produced from differential rotation of inner core with respect to the outer core of Earth is here presented. Special attention is given to the latest observed data of the established net of geomagnetic repeat stations in the Republic of Macedonia. Finally, the maps of elements of geomagnetic field and the equation for calculation of normal magnetic field of Earth are provided. (Author)

  8. Rare earth octacyanomolybdates(4)

    International Nuclear Information System (INIS)

    Zubritskaya, D.I.; Sergeeva, A.N.; Pisak, Yu.V.

    1980-01-01

    Optimal conditions for synthesis of rare-earth octacyanomolybdates(4) of the Ln 4 [Mo(CN) 8 ] 3 xnH 2 O composition (where Ln is a rare-earth element, other than Pr, Pm, Lu, Tb) have been worked out. The synthesis has been accomplished by neutralization with octacianomolybdic acid with rare-earth carbonates. The composition and structure of the compounds synthesized have been studied by infrared-spectroscopy. It has been established that rare-earth octacyanomolybdates(4) form three isostructural groups

  9. Capturing near-Earth asteroids around Earth

    Science.gov (United States)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  10. U-Pb SHRIMP and Sm-Nd geochronology of the Silvania Volcanics and Jurubatuba Granite: juvenile paleoproterozoic crust in the basement of the Neo proterozoic Brasilia Belt, Goias, central Brazil

    International Nuclear Information System (INIS)

    Fischel, Danielle P.; Pimentel, Marcio M.; Fuck, Reinhardt A.; Armstrong, Richard

    2001-01-01

    U-Pb SHRIMP and Sm-Nd isotopic ages were determined for felsic meta volcanic rocks from the Silvania Sequence and Jurubatuba Granite in the central part of the Brasilia Belt. Zircon grains from a meta volcanic sample yielded 2115 ± 23 Ma and from the granite yielded 2089 ±14 Ma, interpreted as crystallization ages of these rocks. Six meta volcanic samples of the Silvania Sequence yielded a six-point whole-rock Sm-Nd isochron indicating a crystallization age of 2262 ±110 Ma and positive ε Nd (T) = +3.0 interpreted as a juvenile magmatic event. Nd isotopic analyses on samples from the Jurubatuba Granite have Paleoproterozoic T DM model ages between 2.30 and 2.42 Ga and ε Nd (T) values vary between -0.22 and -0.58. The oldest T DM value refers to a sedimentary xenolith in the granite. These results suggest crystallization ages of Silvania volcanics and Jurubatuba Granite are the first evidence of a ca. 2.14-2.08 juvenile magmatic event in the basement of the central part of the Brasilia Belt that implies the presence of arc/suture hidden in reworked basement of the Brasilia Belt. (author)

  11. Protracted deformation during cooling of the Paleoproterozoic arc system as constrained by {sup 40}Ar/{sup 39}Ar ages of muscovite from brittle faults: the Transamazonan Bacajá Terrane, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Perico, Edimar; Barros, Carlos Eduardo de Mesquita; Mancini, Fernando [Universidade Federal do Paraná – UFPR, Curitiba, PR (Brazil); Rostirolla, Sidnei Pires, E-mail: sidneiprostirolla@gmail.com [Rosneft, Rio de Janeiro, RJ (Brazil)

    2017-07-15

    In the Paleoproterozoic Transamazonas Province, synkinematic granitogenesis has taken place synchronously with compressive tectonic stress. The synkinematic character of the granites is marked by their WNW elongate shape, and by the presence of pervasive and concordant synmagmatic foliation. Ductile shear zones are concordant to the previous regional WNW structures, and tend to be accommodated along contacts between Rhyacian synkinematic granitoids and both Archean orthogneisses and Siderian metabasites. Locally phyllonitic shear zones and brittle-ductile shear zones with cataclasites are oriented subparallel to the preexisting ductile foliation. Late orogenic brittle faults N30E-trending strike-slip faults are either sinistral or destral. {sup 40}Ar/{sup 39}Ar dating of muscovite developed on fault planes gave ages of 1977 ± 8 Ma and 1968 ± 11 Ma. Structural and geochronological data from rocks of the Transamazonas Province permit to conclude that most mylonites and brittle structures were controlled by preexisting structures such as geological contacts and petrographic facies boundaries. Compressive tectonic stress would have initiated at ca. 2100 Ma, since the former magmatic arc (Bacajaí complex), still present at 2070 Ma when syntectonic granites were emplaced and remained until 1975 Ma after granite plutonism and regional cooling. (author)

  12. U-Pb SHRIMP and Sm-Nd geochronology of the Silvania Volcanics and Jurubatuba Granite: juvenile paleoproterozoic crust in the basement of the Neo proterozoic Brasilia Belt, Goias, central Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Fischel, Danielle P.; Pimentel, Marcio M.; Fuck, Reinhardt A. [Brasilia Univ., DF (Brazil). Inst. de Geociencias; Armstrong, Richard [Australian National Univ., Canberra (Australia). Research School of Earth Sciences

    2001-09-15

    U-Pb SHRIMP and Sm-Nd isotopic ages were determined for felsic meta volcanic rocks from the Silvania Sequence and Jurubatuba Granite in the central part of the Brasilia Belt. Zircon grains from a meta volcanic sample yielded 2115 {+-} 23 Ma and from the granite yielded 2089 {+-}14 Ma, interpreted as crystallization ages of these rocks. Six meta volcanic samples of the Silvania Sequence yielded a six-point whole-rock Sm-Nd isochron indicating a crystallization age of 2262 {+-}110 Ma and positive {epsilon}{sub Nd} (T) = +3.0 interpreted as a juvenile magmatic event. Nd isotopic analyses on samples from the Jurubatuba Granite have Paleoproterozoic T{sub DM} model ages between 2.30 and 2.42 Ga and {epsilon}{sub Nd} (T) values vary between -0.22 and -0.58. The oldest T{sub DM} value refers to a sedimentary xenolith in the granite. These results suggest crystallization ages of Silvania volcanics and Jurubatuba Granite are the first evidence of a ca. 2.14-2.08 juvenile magmatic event in the basement of the central part of the Brasilia Belt that implies the presence of arc/suture hidden in reworked basement of the Brasilia Belt. (author)

  13. U-Pb SHRIMP and Sm-Nd geochronology of the Silvânia Volcanics and Jurubatuba Granite: juvenile Paleoproterozoic crust in the basement of the Neoproterozoic Brasília Belt, Goiás, central Brazil

    Directory of Open Access Journals (Sweden)

    FISCHEL DANIELLE P.

    2001-01-01

    Full Text Available U-Pb SHRIMP and Sm-Nd isotopic ages were determined for felsic metavolcanic rocks from the Silvânia Sequence and Jurubatuba Granite in the central part of the Brasília Belt. Zircon grains from a metavolcanic sample yielded 2115 ± 23 Ma and from the granite yielded 2089 ± 14 Ma, interpreted as crystallization ages of these rocks. Six metavolcanic samples of the Silvânia Sequence yielded a six-point whole-rock Sm-Nd isochron indicating a crystallization age of 2262 ± 110 Ma and positive epsilonNd(T = +3.0 interpreted as a juvenile magmatic event. Nd isotopic analyses on samples from the Jurubatuba Granite have Paleoproterozoic T DM model ages between 2.30 and 2.42 Ga and epsilonNd(T values vary between -0.22 and -0.58. The oldest T DM value refers to a sedimentary xenolith in the granite. These results suggest crystallization ages of Silvânia volcanics and Jurubatuba Granite are the first evidence of a ca. 2.14-2.08 juvenile magmatic event in the basement of the central part of the Brasília Belt that implies the presence of arc/suture hidden in reworked basement of the Brasília Belt.

  14. New insight on the paleoproterozoic evolution of the São Francisco Craton: Reinterpretation of the geology, the suture zones and the thicknesses of the crustal blocks using geophysical and geological data

    Science.gov (United States)

    Sampaio, Edson E. S.; Barbosa, Johildo S. F.; Correa-Gomes, Luiz C.

    2017-07-01

    The Archean-Paleoproterozoic Jequié (JB) and Itabuna-Salvador-Curaçá (ISCB) blocks and their tectonic transition zone in the Valença region, Bahia, Brazil are potentially important for ore deposits, but the geological knowledge of the area is still meager. The paucity of geological information restricts the knowledge of the position and of the field characteristics of the tectonic suture zone between these two crustal segments JB and ISCB. Therefore, interpretation of geophysical data is necessary to supplement the regional structural and petrological knowledge of the area as well as to assist mining exploration programs. The analysis of the airborne radiometric and magnetic data of the region has established, respectively, five radiometric domains and five magnetic zones. Modeling of a gravity profile has defined the major density contrasts of the deep structures. The integrated interpretation of the geophysical data fitted to the known geological information substantially improved the suture zone (lower plate JB versus upper plate ISCB) delimitation, the geological map of the area and allowed to estimate the thicknesses of these two blocks, and raised key questions about the São Francisco Craton tectonic evolution.

  15. EARTH FROM SPACE

    Indian Academy of Sciences (India)

    Table of contents. EARTH FROM SPACE · Slide 2 · Earth System · Slide 4 · Global water cycle · Slide 6 · Slide 7 · Direct Observations of Recent Climate Change · Slide 9 · Slide 10 · Snow cover and Arctic sea ice are decreasing · Polar Melting & Global Heat Transport · Antarctica: Melting and Thickening · Slide 14 · Slide 15.

  16. Earth and Universe

    Energy Technology Data Exchange (ETDEWEB)

    Kosygin, Yu A

    1986-12-01

    Rocks, the age of which according to certain data exceeds considerably the recognized age of the Earth and approximates the age of the Universe, have been detected on the Earth. There is a necessity to coordinate the geological data with cosmological structures.

  17. Hands On Earth Science.

    Science.gov (United States)

    Weisgarber, Sherry L.; Van Doren, Lisa; Hackathorn, Merrianne; Hannibal, Joseph T.; Hansgen, Richard

    This publication is a collection of 13 hands-on activities that focus on earth science-related activities and involve students in learning about growing crystals, tectonics, fossils, rock and minerals, modeling Ohio geology, geologic time, determining true north, and constructing scale-models of the Earth-moon system. Each activity contains…

  18. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  19. Earth System Science Project

    Science.gov (United States)

    Rutherford, Sandra; Coffman, Margaret

    2004-01-01

    For several decades, science teachers have used bottles for classroom projects designed to teach students about biology. Bottle projects do not have to just focus on biology, however. These projects can also be used to engage students in Earth science topics. This article describes the Earth System Science Project, which was adapted and developed…

  20. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    In Late Devonian and Early-to-Late Triassic times, the southern continental margin of the Eastern European Platform was the site of a basaltic volcanism in the Donbas and Fore-Caucasus areas respectively. Both volcanic piles rest unconformably upon Paleoproterozoic and Late Paleozoic units respectively, and emplaced ...

  1. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Assuming that there was no imprint of magnetization of a later date,it is concluded that the Indian plate was located in the southern hemisphere,either independently or as part of a supercontinent,for some span of time during Paleoproterozoic and was involved in complex path of movement and rotation subsequently.

  2. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    New paleomagnetic results on ~2367 Ma Dharwar giant dyke swarm, Dharwar craton, southern India: implications for Paleoproterozoic continental reconstruction · N Ramesh Babu M Venkateshwarlu Ravi Shankar E Nagaraju V Parashuramulu · More Details Abstract Fulltext PDF. Here we report new paleomagnetic results ...

  3. Earth as art three

    Science.gov (United States)

    ,

    2010-01-01

    For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!

  4. Earth Science Informatics - Overview

    Science.gov (United States)

    Ramapriyan, H. K.

    2017-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.The talk will present an overview of current efforts in ESI, the role members of IEEE GRSS play, and discuss

  5. Rare earth germanates

    International Nuclear Information System (INIS)

    Bondar', I.A.; Vinogradova, N.V.; Dem'yanets, L.N.

    1983-01-01

    From the viewpoint of structural chemistry and general regularities controlling formation reactions of compounds and phases in melts, solid and gaseous states, recent achievements in the chemistry of rare earth germanates are generalized. Methods of synthesizing germanates, systems on the base of germanium oxides and rare earths are considered. The data on crystallochemical characteristics are tabulated. Individual compounds of scandium germanate are also characterized. Processes of germanate formation using the data of IR-spectroscopy, X-ray phase analysis are studied. The structure and morphotropic series of rare earth germanates and silicates are determined. Fields of their present and possible future application are considered

  6. Project Earth Science

    CERN Document Server

    Holt, Geoff

    2011-01-01

    Project Earth Science: Astronomy, Revised 2nd Edition, involves students in activities that focus on Earth's position in our solar system. How do we measure astronomical distances? How can we look back in time as we gaze across vast distances in space? How would our planet be different without its particular atmosphere and distance to our star? What are the geometries among Earth, the Moon, and the Sun that yield lunar phases and seasons? Students explore these concepts and others in 11 teacher-tested activities.

  7. Earth formation porosity log

    International Nuclear Information System (INIS)

    Smith, H.D.; Smith, M.P.; Schultz, W.E.

    1977-01-01

    A method for determining the porosity of earth formations in the vicinity of a cased well borehole is described, comprising the steps of: irradiating the earth formations in the vicinity of the cased well borehole with fast neutrons from a source of fast neutrons passed into the borehole; and generating a signal representative of the fast neutron population present in the well borehole at a location in the borehole, the signal is functionally related to the porosity of the earth formations in the vicinity of the borehole

  8. Earth before life.

    Science.gov (United States)

    Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi

    2014-01-09

    A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome includes the age of the Earth are consistent with observed data. The appearance of life after the formation of the Earth is consistent with the data set under examination.

  9. Earth's variable rotation

    Science.gov (United States)

    Hide, Raymond; Dickey, Jean O.

    1991-01-01

    Recent improvements in geodetic data and practical meteorology have advanced research on fluctuations in the earth's rotation. The interpretation of these fluctuations is inextricably linked with studies of the dynamics of the earth-moon system and dynamical processes in the liquid metallic core of the earth (where the geomagnetic field originates), other parts of the earth's interior, and the hydrosphere and atmosphere. Fluctuations in the length of the day occurring on decadal time scales have implications for the topographay of the core-mantle boundary and the electrical, magnetic, ande other properties of the core and lower mantle. Investigations of more rapid fluctuations bear on meteorological studies of interannual, seasonal, and intraseasonal variations in the general circulation of the atmosphere and the response of the oceans to such variations.

  10. Near Earth Objects

    DEFF Research Database (Denmark)

    Wolff, Stefan

    2006-01-01

    , Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global climate changes, yet the threat from a collision with a near Earth object has only recently been recognised...... and accepted. The European Space Agency mission Gaia is a proposed space observatory, designed to perform a highly accurate census of our galaxy, the Milky Way, and beyond. Through accurate measurement of star positions, Gaia is expected to discover thousands of extra-solar planets and follow the bending...... of starlight by the Sun, and therefore directly observe the structure of space-time. This thesis explores several aspects of the observation of NEOs with Gaia, emphasising detection of NEOs and the quality of orbits computed from Gaia observations. The main contribution is the work on motion detection...

  11. Earth study from space

    Science.gov (United States)

    Sidorenko, A. V.

    1981-01-01

    The significance that space studies are making to all Earth sciences in the areas of geography, geodesy, cartography, geology, meteorology, oceanology, agronomy, and ecology is discussed. It is predicted that cosmonautics will result in a revolution in science and technology.

  12. Earth's electric field

    International Nuclear Information System (INIS)

    Kelley, M.C.

    1978-01-01

    The earth becomes charged during thunderstorm activity and discharges through the weak conducting atmosphere. Balloon and rocket studies infer that a high altitude electric field penetrates virtually unattenuated through the atmosphere, at least as far as balloon heights. The field has two primary sources. At low and mid latitudes, interaction between the earth's magnetic field and the neutral wind creates electric fields. At latitudes above 60 0 , the high altitude electrical structure is dominated by the interaction between the solar wind and the earth's magnetic field. The auroral light is emitted by atmospheric atoms and molecules excited by electrons with potentials of many thousands volts. The potentials are induced by the solar wind. Recent satellite data shows that the electrons get this energy by passing through a localized electric field about 6000 km above the auroral zone. Several rocket and satellite experiments used to study the earth's electric field are discussed

  13. Near Earth Asteroid Scout

    Data.gov (United States)

    National Aeronautics and Space Administration — Near-Earth Asteroid Scout, or NEA Scout, is a 6U CubeSat developed jointly between NASA’s Marshall Space Flight Center and the Jet Propulsion Laboratory. NASA...

  14. Gambling with the earth

    CERN Multimedia

    Muir, H

    2000-01-01

    The probability that dangerous Earth-devouring particles will be born at a new accelerator in the US may be tiny, but scientists have played down the devastating potential costs in their risk assessments according to a physicist (1 page).

  15. Jupiter and planet Earth

    International Nuclear Information System (INIS)

    1975-01-01

    The evolution of Jupiter and Earth are discussed along with their atmospheres, the radiation belts around both planets, natural satellites, the evolution of life, and the Pioneer 10. Educational study projects are also included

  16. Earth retaining structures manual

    Science.gov (United States)

    2009-10-29

    The objectives of this policy are to obtain statewide uniformity, establish standard : procedures and delineate responsibility for the preparation and review of plans, : design and construction control of earth retaining structures. In addition, it i...

  17. Earliest life on earth

    CERN Document Server

    Golding, Suzanne D

    2010-01-01

    This volume integrates the latest findings on earliest life forms, identified and characterized in some of the oldest rocks on Earth. It places emphasis on the integration of analytical methods with observational techniques and experimental simulations.

  18. Conditions for oceans on Earth-like planets orbiting within the habitable zone: importance of volcanic CO{sub 2} degassing

    Energy Technology Data Exchange (ETDEWEB)

    Kadoya, S. [Department of Earth and Planetary Science, The University of Tokyo, Kiban Bldg. 408, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Tajika, E., E-mail: kadoya@astrobio.k.u-tokyo.ac.jp, E-mail: tajika@astrobio.k.u-tokyo.ac.jp [Department of Complexity Science and Engineering, The University of Tokyo, Kiban Bldg. 409, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan)

    2014-08-01

    Earth-like planets in the habitable zone (HZ) have been considered to have warm climates and liquid water on their surfaces if the carbonate-silicate geochemical cycle is working as on Earth. However, it is known that even the present Earth may be globally ice-covered when the rate of CO{sub 2} degassing via volcanism becomes low. Here we discuss the climates of Earth-like planets in which the carbonate-silicate geochemical cycle is working, with focusing particularly on insolation and the CO{sub 2} degassing rate. The climate of Earth-like planets within the HZ can be classified into three climate modes (hot, warm, and snowball climate modes). We found that the conditions for the existence of liquid water should be largely restricted even when the planet is orbiting within the HZ and the carbonate-silicate geochemical cycle is working. We show that these conditions should depend strongly on the rate of CO{sub 2} degassing via volcanism. It is, therefore, suggested that thermal evolution of the planetary interiors will be a controlling factor for Earth-like planets to have liquid water on their surface.

  19. The Glória quartz-monzodiorite: isotopic and chemical evidence of arc-related magmatism in the central part of the Paleoproterozoic Mineiro belt, Minas Gerais State, Brazil

    Directory of Open Access Journals (Sweden)

    Ciro A. Ávila

    2006-09-01

    Full Text Available The Glória quartz-monzodiorite, one of the mafic plutons of the Paleoproterozoic Mineiro belt, is intrusive into banded gneisses, amphibolites, schists and phyllites of the Rio das Mortes greenstone belt, in the southern portion of the São Francisco Craton, State of Minas Gerais, Brazil. The Glória quartz-monzodiorite yields a SHRIMP U-Pb zircon age of 2188 ± 29 Ma, suggesting a tectonic relationship with the pre-collisional phase of the Mineiro belt. According to the Nd isotopic evidence (epsilonNd(T = -3.4; T DM = 2.68 Ga the original magmas was formed by a mixture among Archean crustal material and Paleoproterozoic juvenile magma. The Glória quartz-monzodiorite shows metaluminous and calc-alkaline tendency with intermediate K content, comparable to that of volcanic-arc rocks. The primary mineralogical assemblage was partly modified by metamorphism, dated between 2131-2121 Ma in nearby coeval plutons. Such metamorphism is significantly older than the reported metamorphic episodes of the Mineiro belt in the Quadrilátero Ferrífero region (2059-2041 Ma in the eastern portion of the study area. This evidence, together with chemical and isotopic data from other mafic and felsic plutons coeval with the Glória quartz-monzodiorite, indicate a tectonic and magmatic migration within the Mineiro belt from west to east.O Quartzo Monzodiorito Glória é um corpo plutônicomáfico associado à evolução Paleoproterozóica do Cinturão Mineiro. Este é intrusivo em gnaisses bandados, anfibolitos, xistos e filitos do Greenstone Belt Rio das Mortes, na porção sudeste do Cráton São Francisco, Estado de Minas Gerais, Brasil. Este corpo possui idade de cristalização SHRIMP (em zircão de 2188 ± 29 Ma, enquanto os isótopos de Nd (épsilonNd(T = -3,4; T DM = 2,68 Ga apontam que sua fonte magmática envolveumaterial juvenil paleoproterozóico contaminada por protólitos arqueanos. As rochas do Quartzo Monzodiorito Glória são metaluminosas, c

  20. Optimal Safety EarthingEarth Electrode Sizing Using A ...

    African Journals Online (AJOL)

    In this paper a deterministic approach in the sizing of earth electrode using the permissible touch voltage criteria is presented. The deterministic approach is effectively applied in the sizing of the length of earth rod required for the safe earthing of residential and facility buildings. This approach ensures that the earthing ...

  1. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  2. Earth and planetary sciences

    International Nuclear Information System (INIS)

    Wetherill, G.W.; Drake, C.L.

    1980-01-01

    The earth is a dynamic body. The major surface manifestation of this dynamism has been fragmentation of the earth's outer shell and subsequent relative movement of the pieces on a large scale. Evidence for continental movement came from studies of geomagnetism. As the sea floor spreads and new crust is formed, it is magnetized with the polarity of the field at the time of its formation. The plate tectonics model explains the history, nature, and topography of the oceanic crust. When a lithospheric plate surmounted by continental crust collides with an oceanic lithosphere, it is the denser oceanic lithosphere that is subducted. Hence the ancient oceans have vanished and the knowledge of ancient earth will require deciphering the complex continental geological record. Geochemical investigation shows that the source region of continental rocks is not simply the depleted mantle that is characteristic of the source region of basalts produced at the oceanic ridges. The driving force of plate tectonics is convection within the earth, but much remains to be learned about the convection and interior of the earth. A brief discussion of planetary exploration is given

  3. The earth's hydrological cycle

    CERN Document Server

    Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M

    2014-01-01

    This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...

  4. Modeling the earth system

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D. [ed.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  5. The Earth System Model

    Science.gov (United States)

    Schoeberl, Mark; Rood, Richard B.; Hildebrand, Peter; Raymond, Carol

    2003-01-01

    The Earth System Model is the natural evolution of current climate models and will be the ultimate embodiment of our geophysical understanding of the planet. These models are constructed from components - atmosphere, ocean, ice, land, chemistry, solid earth, etc. models and merged together through a coupling program which is responsible for the exchange of data from the components. Climate models and future earth system models will have standardized modules, and these standards are now being developed by the ESMF project funded by NASA. The Earth System Model will have a variety of uses beyond climate prediction. The model can be used to build climate data records making it the core of an assimilation system, and it can be used in OSSE experiments to evaluate. The computing and storage requirements for the ESM appear to be daunting. However, the Japanese ES theoretical computing capability is already within 20% of the minimum requirements needed for some 2010 climate model applications. Thus it seems very possible that a focused effort to build an Earth System Model will achieve succcss.

  6. Rare earths and actinides

    International Nuclear Information System (INIS)

    Coqblin, B.

    1982-01-01

    This paper reviews the different properties of rare-earths and actinides, either as pure metals or as in alloys or compounds. Three different cases are considered: (i) First, in the case of 'normal' rare-earths which are characterized by a valence of 3, we discuss essentially the magnetic ordering, the coexistence between superconductivity and magnetism and the properties of amorphous rare-earth systems. (ii) Second, in the case of 'anomalous' rare-earths, we distinguish between either 'intermediate-valence' systems or 'Kondo' systems. Special emphasis is given to the problems of the 'Kondo lattice' (for compounds such as CeAl 2 ,CeAl 3 or CeB 6 ) or the 'Anderson lattice' (for compounds such as TmSe). The problem of neutron diffraction in these systems is also discussed. (iii) Third, in the case of actinides, we can separate between the d-f hybridized and almost magnetic metals at the beginning of the series and the rare-earth like the metals after americium. (orig.)

  7. Earth's Trojan asteroid.

    Science.gov (United States)

    Connors, Martin; Wiegert, Paul; Veillet, Christian

    2011-07-27

    It was realized in 1772 that small bodies can stably share the same orbit as a planet if they remain near 'triangular points' 60° ahead of or behind it in the orbit. Such 'Trojan asteroids' have been found co-orbiting with Jupiter, Mars and Neptune. They have not hitherto been found associated with Earth, where the viewing geometry poses difficulties for their detection, although other kinds of co-orbital asteroid (horseshoe orbiters and quasi-satellites) have been observed. Here we report an archival search of infrared data for possible Earth Trojans, producing the candidate 2010 TK(7). We subsequently made optical observations which established that 2010 TK(7) is a Trojan companion of Earth, librating around the leading Lagrange triangular point, L(4). Its orbit is stable over at least ten thousand years.

  8. How Big is Earth?

    Science.gov (United States)

    Thurber, Bonnie B.

    2015-08-01

    How Big is Earth celebrates the Year of Light. Using only the sunlight striking the Earth and a wooden dowel, students meet each other and then measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. How Big is Earth provides an online learning environment where students do science the same way Eratosthenes did. A notable project in which this was done was The Eratosthenes Project, conducted in 2005 as part of the World Year of Physics; in fact, we will be drawing on the teacher's guide developed by that project.How Big Is Earth? expands on the Eratosthenes project by providing an online learning environment provided by the iCollaboratory, www.icollaboratory.org, where teachers and students from Sweden, China, Nepal, Russia, Morocco, and the United States collaborate, share data, and reflect on their learning of science and astronomy. They are sharing their information and discussing their ideas/brainstorming the solutions in a discussion forum. There is an ongoing database of student measurements and another database to collect data on both teacher and student learning from surveys, discussions, and self-reflection done online.We will share our research about the kinds of learning that takes place only in global collaborations.The entrance address for the iCollaboratory is http://www.icollaboratory.org.

  9. Teaching earth science

    Science.gov (United States)

    Alpha, Tau Rho; Diggles, Michael F.

    1998-01-01

    This CD-ROM contains 17 teaching tools: 16 interactive HyperCard 'stacks' and a printable model. They are separated into the following categories: Geologic Processes, Earthquakes and Faulting, and Map Projections and Globes. A 'navigation' stack, Earth Science, is provided as a 'launching' place from which to access all of the other stacks. You can also open the HyperCard Stacks folder and launch any of the 16 stacks yourself. In addition, a 17th tool, Earth and Tectonic Globes, is provided as a printable document. Each of the tools can be copied onto a 1.4-MB floppy disk and distributed freely.

  10. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  11. IR and the Earth

    DEFF Research Database (Denmark)

    Corry, Olaf; Stevenson, Hayley

    2017-01-01

    , in the end, one finite interconnected space. Together these two starting points make for the basic conundrum of Inter- national Relations and the Earth: how does a divided world live on a single globe? This introduction first provides an overview of the recent rise of ‘the environment’ in international......, ‘what has the environment ever done for IR?’, before the plan for the rest of the book sketches the content and direction of the ensuing chapters that explore the problematique of International Relations and the Earth....

  12. The Earth's Plasmasphere

    Science.gov (United States)

    Gallagher, D. L.

    2015-01-01

    The Earth's plasmasphere is an inner part of the magneteosphere. It is located just outside the upper ionosphere located in Earth's atmosphere. It is a region of dense, cold plasma that surrounds the Earth. Although plasma is found throughout the magnetosphere, the plasmasphere usually contains the coldest plasma. Here's how it works: The upper reaches of our planet's atmosphere are exposed to ultraviolet light from the Sun, and they are ionized with electrons that are freed from neutral atmospheric particles. The results are electrically charged negative and positive particles. The negative particles are electrons, and the positive particles are now called ions (formerly atoms and molecules). If the density of these particles is low enough, this electrically charged gas behaves differently than it would if it were neutral. Now this gas is called plasma. The atmospheric gas density becomes low enough to support the conditions for a plasma around earth at about 90 kilometers above Earth's surface. The electrons in plasma gain more energy, and they are very low in mass. They move along Earth's magnetic field lines and their increased energy is enough to escape Earth's gravity. Because electrons are very light, they don't have to gain too much kinetic energy from the Sun's ultraviolet light before gravity loses its grip on them. Gravity is not all that holds them back, however. As more and more electrons begin to escape outward, they leave behind a growing net positive electric charge in the ionosphere and create a growing net negative electric charge above the ionosphere; an electric field begins to develop (the Pannekoek-Rosseland E-field). Thus, these different interacting charges result in a positively charged ionosphere and negatively charged region of space above it. Very quickly this resulting electric field opposed upward movement of the electrons out of the ionosphere. The electrons still have this increased energy, however, so the electric field doesn't just

  13. "Galileo Calling Earth..."

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    This guide presents an activity for helping students understand how data from the Galileo spacecraft is sent to scientists on earth. Students are asked to learn about the concepts of bit-rate and resolution and apply them to the interpretation of images from the Galileo Orbiter. (WRM)

  14. Bones of the Earth

    Science.gov (United States)

    Correa, Jose Miguel

    2014-01-01

    The film "Bones of the Earth" (Riglin, Cunninham & Correa, 2014) is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective…

  15. Our bubbling Earth

    NARCIS (Netherlands)

    Schuiling, R.D.

    2005-01-01

    In several places on earth large volumes of gas are seen to escape. These gases are usually dominated by CO2. The emissions are associated with volcanic activity, and are attributed to magma degassing. It will be shown that in the case of Milos this explanation is unacceptable for quantitative

  16. Cosmic rays on earth

    International Nuclear Information System (INIS)

    Allkofer, O.C.; Grieder, P.K.F.

    1984-01-01

    A data collection is presented that covers cosmic rays on earth. Included are all relevant data on flux and intensity measurements, energy spectra, and related data of all primary and secondary components of the cosmic radiation at all levels in the atmosphere, at sea level and underground. In those cases where no useful experimental data have been available, theoretical predictions were substituted. (GSCH)

  17. Earth as art 4

    Science.gov (United States)

    ,

    2016-03-29

    Landsat 8 is the latest addition to the long-running series of Earth-observing satellites in the Landsat program that began in 1972. The images featured in this fourth installment of the Earth As Art collection were all acquired by Landsat 8. They show our planet’s diverse landscapes with remarkable clarity.Landsat satellites see the Earth as no human can. Not only do they acquire images from the vantage point of space, but their sensors record infrared as well as visible wavelengths of light. The resulting images often reveal “hidden” details of the Earth’s land surface, making them invaluable for scientific research.As with previous Earth As Art exhibits, these Landsat images were selected solely for their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation—only for your viewing pleasure. What do you see in these unique glimpses of the Earth’s continents, islands, and coastlines?

  18. Google Earth Science

    Science.gov (United States)

    Baird, William H.; Padgett, Clifford W.; Secrest, Jeffery A.

    2015-01-01

    Google Earth has made a wealth of aerial imagery available online at no cost to users. We examine some of the potential uses of that data in illustrating basic physics and astronomy, such as finding the local magnetic declination, using landmarks such as the Washington Monument and Luxor Obelisk as gnomons, and showing how airport runways get…

  19. How life shaped Earth.

    Science.gov (United States)

    Gross, Michael

    2015-10-05

    Earth is much more complex than all the other solar system objects that we know. Thanks to its rich and diverse geology, our planet can offer habitats to a wide range of living species. Emerging insights suggest that this is not just a happy coincidence, but that life itself has in many ways helped to shape the planet.

  20. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...

  1. Understanding Earth's Albedo Effect

    Science.gov (United States)

    Fidler, Chuck

    2012-01-01

    Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…

  2. Earth Science Misconceptions.

    Science.gov (United States)

    Philips, William C.

    1991-01-01

    Presented is a list of over 50 commonly held misconceptions based on a literature review found in students and adults. The list covers earth science topics such as space, the lithosphere, the biosphere, the atmosphere, the hydrosphere, and the cryosphere. (KR)

  3. The earths innermost core

    International Nuclear Information System (INIS)

    Nanda, J.N.

    1989-01-01

    A new earth model is advanced with a solid innermost core at the centre of the Earth where elements heavier than iron, over and above what can be retained in solution in the iron core, are collected. The innermost core is separated from the solid iron-nickel core by a shell of liquid copper. The innermost core has a natural vibration measured on the earth's surface as the long period 26 seconds microseisms. The earth was formed initially as a liquid sphere with a relatively thin solid crust above the Byerly discontinuity. The trace elements that entered the innermost core amounted to only 0.925 ppm of the molten mass. Gravitational differentiation must have led to the separation of an explosive thickness of pure 235 U causing a fission explosion that could expel beyond the Roche limit a crustal scab which would form the centre piece of the moon. A reservoir of helium floats on the liquid copper. A small proportion of helium-3, a relic of the ancient fission explosion present there will spell the exciting magnetic field. The field is stable for thousands of years because of the presence of large quantity of helium-4 which accounts for most of the gaseous collisions that will not disturb the atomic spin of helium-3 atoms. This field is prone to sudden reversals after long periods of stability. (author). 14 refs

  4. The radioactive earth

    International Nuclear Information System (INIS)

    Plant, J.A.; Saunders, A.D.

    1996-01-01

    Uranium, thorium and potassium are the main elements contributing to natural terrestrial radioactivity. The isotopes 238 U, 235 U, 232 Th and 40 K decay with half-lives so long that significant amounts remain in the earth, providing a continuing source of heat. The slow decay of these isotopes also provides the basis for radiometric age dating and isotopic modelling of the evolution of the earth and its crust. There is a complex interplay between their heat production and the processes involved in crust formation. Phenomena such as volcanism, earthquakes, and large-scale hydrothermal activity associated with ore deposition reflect the dissipation of heat energy from the earth, much of which is derived from natural radioactivity. The higher levels of radioactive elements during the early history of the earth resulted in higher heat flow. All three of the radioactive elements are strongly partitioned into the continental crust, but within the crust their distribution is determined by their different chemical properties. The behaviour of U, which has two commonly occurring oxidation states, is more complex than that of Th and K. Uranium deposits are diverse, and are mostly associated with granites, acid volcanics, or detrital sedimentary rocks. The most important U deposits economically are unconformity-type ores of Proterozoic age, in which U is enriched by up to 5 x 10 6 with respect to bulk earth values. In some cases natural radioactivity can be of environmental concern. The most significant risk is posed by accumulations of radon, the gaseous daughter product of U. (author)

  5. The Earth's Biosphere

    Science.gov (United States)

    2002-01-01

    In the last five years, scientists have been able to monitor our changing planet in ways never before possible. The Sea-viewing Wide Field-of-View Sensor (SeaWiFS), aboard the OrbView-2 satellite, has given researchers an unprecedented view of the biological engine that drives life on Earth-the countless forms of plants that cover the land and fill the oceans. 'There is no question the Earth is changing. SeaWiFS has enabled us, for the first time, to monitor the biological consequences of that change-to see how the things we do, as well as natural variability, affect the Earth's ability to support life,' said Gene Carl Feldman, SeaWiFS project manager at NASA's Goddard Space Flight Center, Greenbelt, Md. SeaWiFS data, based on continuous daily global observations, have helped scientists make a more accurate assessment of the oceans' role in the global carbon cycle. The data provide a key parameter in a number of ecological and environmental studies as well as global climate-change modeling. The images of the Earth's changing land, ocean and atmosphere from SeaWiFS have documented many previously unrecognized phenomena. The image above shows the global biosphere from June 2002 measured by SeaWiFS. Data in the oceans is chlorophyll concentration, a measure of the amount of phytoplankton (microscopic plants) living in the ocean. On land SeaWiFS measures Normalized Difference Vegetation Index, an indication of the density of plant growth. For more information and images, read: SeaWiFS Sensor Marks Five Years Documenting Earth'S Dynamic Biosphere Image courtesy SeaWiFS project and copyright Orbimage.

  6. Nd-Sr isotopic geochemistry and U-Pb geochronology of the Fe granitic gneiss and Lajedo Granodiorite: implications for paleoproterozoic evolution of the Mineiro Belt, southern Sao Francisco craton, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Wilson [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Centro de Pesquisas Geocronologicas]. E-mail: wteixeir@usp.br; Avila, Ciro Alexandre [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Museu Nacional. Dept. de Geologia e Paleontologia]. E-mail: avila@mn.ufrj.br; Nunes, Luciana Cabral [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias]. E-mail: luciana@igc.usp.br

    2008-07-01

    The Fe granitic gneiss and Lajedo granodiorite belong to a voluminous felsic-mafic plutonism, tectonically linked to Paleoproterozoic magmatic evolution of the Mineiro Belt, southern portion of the Sao Francisco Craton, central-eastern Brazil. The Fe pluton is located north of the Lenheiros shear zone and is intrusive with respect to the Rio das Mortes greenstone belt and pyroxenite - gabbroic bodies, as indicated by xenoliths of gneiss and amphibolite, in the first case, and pyroxenite in the latter. The Lajedo granodiorite is located south of the Lenheiros shear zone and cuts the metamafic rocks of the Forro peridotite - pyroxenite and mafic and intermediate rocks of the Nazareno greenstone belt, as evidenced by xenoliths from the latter unit. The modal composition of the Fe granitic gneiss lies within the ranges of monzogranite and syenogranite. It is peraluminous and shows a large variation in K{sub 2}O content, which implies a middle-K calc-alkaline to high-K calc-alkaline tendency. The Lajedo modal composition is consistent with granodioritic and tonalitic compositions. It indicates a predominantly peraluminous composition and calc-alkaline character. The U-Pb zircon crystallization age of the Fe granitic gneiss is 2191 {+-} 9 Ma, whereas the Lajedo granodiorite yields 2208 {+-} 26 Ma. The Nd/Sr characteristics of the Fe and Lajedo plutons are consistent with mixtures of enriched mantle (EMI-type), DMM and crustal components during magma genesis in a plutonic arc setting, while the low {sup 87}Sr/{sup 86}Sri ratios point to contribution of mafic rock protoliths during magma genesis. This is also in accordance with the characteristic xenoliths observed within the investigated plutons from the Nazareno and Rio das Mortes greenstone belts. The Fe granitic gneiss and Lajedo granodiorite show tectonic characteristics which are comparable to those of nearby coeval plutons: Brito quartz-diorite (2221 +- 2 Ma), Brumado de Cima granodiorite (2219 {+-} 2 Ma), Brumado

  7. Nd-Sr isotopic geochemistry and U-Pb geochronology of the Fe granitic gneiss and Lajedo Granodiorite: implications for paleoproterozoic evolution of the Mineiro Belt, southern Sao Francisco craton, Brazil

    International Nuclear Information System (INIS)

    Teixeira, Wilson; Avila, Ciro Alexandre; Nunes, Luciana Cabral

    2008-01-01

    The Fe granitic gneiss and Lajedo granodiorite belong to a voluminous felsic-mafic plutonism, tectonically linked to Paleoproterozoic magmatic evolution of the Mineiro Belt, southern portion of the Sao Francisco Craton, central-eastern Brazil. The Fe pluton is located north of the Lenheiros shear zone and is intrusive with respect to the Rio das Mortes greenstone belt and pyroxenite - gabbroic bodies, as indicated by xenoliths of gneiss and amphibolite, in the first case, and pyroxenite in the latter. The Lajedo granodiorite is located south of the Lenheiros shear zone and cuts the metamafic rocks of the Forro peridotite - pyroxenite and mafic and intermediate rocks of the Nazareno greenstone belt, as evidenced by xenoliths from the latter unit. The modal composition of the Fe granitic gneiss lies within the ranges of monzogranite and syenogranite. It is peraluminous and shows a large variation in K 2 O content, which implies a middle-K calc-alkaline to high-K calc-alkaline tendency. The Lajedo modal composition is consistent with granodioritic and tonalitic compositions. It indicates a predominantly peraluminous composition and calc-alkaline character. The U-Pb zircon crystallization age of the Fe granitic gneiss is 2191 ± 9 Ma, whereas the Lajedo granodiorite yields 2208 ± 26 Ma. The Nd/Sr characteristics of the Fe and Lajedo plutons are consistent with mixtures of enriched mantle (EMI-type), DMM and crustal components during magma genesis in a plutonic arc setting, while the low 87 Sr/ 86 Sri ratios point to contribution of mafic rock protoliths during magma genesis. This is also in accordance with the characteristic xenoliths observed within the investigated plutons from the Nazareno and Rio das Mortes greenstone belts. The Fe granitic gneiss and Lajedo granodiorite show tectonic characteristics which are comparable to those of nearby coeval plutons: Brito quartz-diorite (2221 +- 2 Ma), Brumado de Cima granodiorite (2219 ± 2 Ma), Brumado de Baixo

  8. Visualizing Earth Materials

    Science.gov (United States)

    Cashman, K. V.; Rust, A.; Stibbon, E.; Harris, R.

    2016-12-01

    Earth materials are fundamental to art. They are pigments, they are clay, they provide form and color. Earth scientists, however, rarely attempt to make the physical properties of Earth materials visible through art, and similarly many artists use Earth materials without fully understanding their physical and chemical properties. Here we explore the intersection between art and science through study of the physical properties of Earth materials as characterized in the laboratory, and as transferred to paper using different techniques and suspending media. One focus of this collaboration is volcanic ash. Ash is interesting scientifically because its form provides information on the fundamental processes that drive volcanic eruptions, and determines its transport properties, and thus its potential to affect populations far downwind of the volcano. Ash properties also affect its behavior as an art material. From an aesthetic point of view, ash lends a granular surface to the image; it is also uncontrollable, and thus requires engagement between artist and medium. More fundamentally, using ash in art creates an exchange between the medium and the subject matter, and imparts something of the physical, visceral experience of volcanic landscapes to the viewer. Another component of this work uses powdered rock as a printing medium for geologic maps. Because different types of rock create powders with different properties (grain size distributions and shapes), the geology is communicated not only as color, but also by the physical characteristics of the material as it interacts with the paper. More importantly, the use of actual rocks samples as printing material for geologic maps not only makes a direct connection between the map and the material it represents, but also provides an emotional connection between the map, the viewer and the landscape, its colors, textures and geological juxtapositions. Both case studies provide examples not only of ways in which artists can

  9. Towards earth AntineutRino TomograpHy (EARTH)

    NARCIS (Netherlands)

    De Meijer, R. J.; Smit, F. D.; Brooks, F. D.; Fearick, R. W.; Wortche, H. J.; Mantovani, F.

    2006-01-01

    The programme Earth AntineutRino TomograpHy (EARTH) proposes to build ten underground facilities each hosting a telescope. Each telescope consists of many detector modules, to map the radiogenic heat sources deep in the interior of the Earth by utilising direction sensitive geoneutrino detection.

  10. Inaugeral lecture - Meteorite impacts on Earth and on the Earth ...

    African Journals Online (AJOL)

    There is some controversial evidence for the theory that the first life on Earth itself may have been transported here on meteorites from Mars. The possibility of a major meteorite impact on Earth in the near future emphasizes the dramatic nature of these recent discoveries, which are having deep impacts in the Earth sciences ...

  11. Physics of the Earth

    Science.gov (United States)

    Stacey, Frank D.; Davis, Paul M.

    he fourth edition of Physics of the Earth maintains the original philosophy of this classic graduate textbook on fundamental solid earth geophysics, while being completely revised, updated, and restructured into a more modular format to make individual topics even more accessible. Building on the success of previous editions, which have served generations of students and researchers for nearly forty years, this new edition will be an invaluable resource for graduate students looking for the necessary physical and mathematical foundations to embark on their own research careers in geophysics. Several completely new chapters have been added and a series of appendices, presenting fundamental data and advanced mathematical concepts, and an extensive reference list, are provided as tools to aid readers wishing to pursue topics beyond the level of the book. Over 140 student exercises of varying levels of difficulty are also included, and full solutions are available online at www.cambridge.org/9780521873628.

  12. Alkaline earth metals

    International Nuclear Information System (INIS)

    Brown, Paul L.; Ekberg, Christian

    2016-01-01

    The beryllium ion has a relatively small ionic radius. As a consequence of this small size, its hydrolysis reactions begin to occur at a relatively low pH. To determine the stability and solubility constants, however, the Gibbs energy of the beryllium ion is required. In aqueous solution calcium, like the other alkaline earth metals, only exists as a divalent cation. The size of the alkaline earth cations increases with increasing atomic number, and the calcium ion is bigger than the magnesium ion. The hydrolysis of barium(II) is weaker than that of strontium(II) and also occurs in quite alkaline pH solutions, and similarly, only the species barium hydroxide has been detected. There is only a single experimental study on the hydrolysis of radium. As with the stability constant trend, it would be expected that the enthalpy of radium would be lower than that of barium due to the larger ionic radius.

  13. Heat-pipe Earth.

    Science.gov (United States)

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics.

  14. Earth before life

    OpenAIRE

    Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi

    2014-01-01

    Background A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Results Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome i...

  15. Electromagnetic compatibility and earths

    International Nuclear Information System (INIS)

    Duque Henao, Alan; Casas Ospina, Favio

    2001-01-01

    It is such the increment of applications of electric and electronic equipment in the modern companies that the lack of control of the electromagnetic perturbations, brings, get big losses and difficulties in the normal operations. The paper contribute to ago with base in the challenges that day-by-day are confronting, where the settings to earth, to be the foundation of the electric building, are fundamental for a good coexistence among the different equipment s

  16. Earth-ionosphere cavity

    International Nuclear Information System (INIS)

    Tran, A.; Polk, C.

    1976-01-01

    To analyze ELF wave propagation in the earth-ionosphere cavity, a flat earth approximation may be derived from the exact equations, which are applicable to the spherical cavity, by introducing a second-order or Debye approximation for the spherical Hankel functions. In the frequency range 3 to 30 Hz, however, the assumed conditions for the Debye approximation are not satisfied. For this reason an exact evaluation of the spherical Hankel functions is used to study the effects of the flat earth approximation on various propagation and resonance parameters. By comparing the resonance equation for a spherical cavity with its flat earth counterpart and by assuming that the surface impedance Z/sub i/ at the upper cavity boundary is known, the relation between the eigenvalue ν and S/sub v/, the sine of the complex angle of incidence at the lower ionosphere boundary, is established as ν(ν + 1) = (kaS/sub v/) 2 . It is also shown that the approximation ν(ν + 1) approximately equals (ν + 1/2) 2 which was used by some authors is not adequate below 30 Hz. Numerical results for both spherical and planar stratification show that (1) planar stratification is adequate for the computation of the lowest three ELF resonance frequencies to within 0.1 Hz; (2) planar stratification will lead to errors in cavity Q and wave attenuation which increase with frequency; (3) computation of resonance frequencies to within 0.1 Hz requires the extension of the lower boundary of the ionosphere to a height where the ratio of conduction current to displacement current, (sigma/ωepsilon 0 ), is less than 0.3; (4) atmospheric conductivity should be considered down to ground level in computing cavity Q and wave attenuation

  17. Superhydrophobic diatomaceous earth

    Science.gov (United States)

    Simpson, John T [Clinton, TN; D& #x27; Urso, Brian R [Clinton, TN

    2012-07-10

    A superhydrophobic powder is prepared by coating diatomaceous earth (DE) with a hydrophobic coating on the particle surface such that the coating conforms to the topography of the DE particles. The hydrophobic coating can be a self assembly monolayer of a perfluorinated silane coupling agent. The DE is preferably natural-grade DE where organic impurities have been removed. The superhydrophobic powder can be applied as a suspension in a binder solution to a substrate to produce a superhydrophobic surface on the substrate.

  18. Sun, Earth and Sky

    CERN Document Server

    Lang, Kenneth R

    2006-01-01

    This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...

  19. Characterising Super-Earths

    Directory of Open Access Journals (Sweden)

    Valencia D.

    2011-02-01

    Full Text Available The era of Super-Earths has formally begun with the detection of transiting low-mass exoplanets CoRoT-7b and GJ 1214b. In the path of characterising super-Earths, the first step is to infer their composition. While the discovery data for CoRoT-7b, in combination with the high atmospheric mass loss rate inferred from the high insolation, suggested that it was a rocky planet, the new proposed mass values have widened the possibilities. The combined mass range 1−10 M⊕ allows for a volatile-rich (and requires it if the mass is less than 4 M⊕ , an Earth-like or a super-Mercury-like composition. In contrast, the radius of GJ 1214b is too large to admit a solid composition, thus it necessarily to have a substantial gas layer. Some evidence suggests that within this gas layer H/He is a small but non-negligible component. These two planets are the first of many transiting low-mass exoplanets expected to be detected and they exemplify the limitations faced when inferring composition, which come from the degenerate character of the problem and the large error bars in the data.

  20. Afganistan and rare earths

    Directory of Open Access Journals (Sweden)

    Emilian M. Dobrescu

    2013-05-01

    Full Text Available On our planet, over a quarter of new technologies for the economic production of industrial goods, are using rare earths, which are also called critical minerals and industries that rely on these precious items being worth of an estimated nearly five trillion dollars, or 5 percent of world gross domestic product. In the near future, competition will increase for the control of rare earth minerals embedded in high-tech products. Rare minerals are in the twenty-first century what oil accounted for in the twentieth century and coal in the nineteenth century: the engine of a new industrial revolution. Future energy will be produced increasingly by more sophisticated technological equipment based not just on steel and concrete, but incorporating significant quantities of metals and rare earths. Widespread application of these technologies will result in an exponential increase in demand for such minerals, and what is worrying is that minerals of this type are almost nowhere to be found in Europe and in other industrialized countries in the world, such as U.S. and Japan, but only in some Asian countries, like China and Afghanistan.

  1. From the Earliest Evidence of Life to Complex Single-cell Organisms: The First 3 Gyr on Earth

    Science.gov (United States)

    Buick, Roger

    2006-12-01

    Life has probably been present on Earth since the time of the oldest sedimentary rock record 3.8 Gyr ago, as indicated by graphite with light carbon isotope ratios consistent with derivation from organic matter. But certain evidence for life appears only at 3.52 Gyr, in the form of kerogen (insoluble organic matter) in sedimentary carbonate showing a -25‰ carbon isotope fractionation identical to that imparted by biological carbon fixation. Soon after, at 3.48 Gyr, the first visible evidence for life appears as stromatolites (sediment mounds constructed by microbes), as well as the first evidence for a specific metabolism (large negative sulfur isotope fractionations indicating microbial sulfate reduction). By 2.7 Gyr ago, molecular biomarkers (hydrocarbons derived from biomolecules with distinctive carbon skeletons such as steroids) indicate that all 3 Domains of life: bacteria, eukaryotes (organisms with compartmentalized cells like us) and archaea (bacteria-like organisms with different biochemistry, often inhabiting extreme environments); had evolved. The first multicellular eukaryotes appeared by 1.84 Gyr in the form of fossilized filamentous algae, after the atmosphere changed from anoxic to moderately oxygenated at 2.4 Gyr and following a series of extreme “Snowball Earth” glaciations between 2.4-2.2 Gyr. Planktonic algae diversified thereafter and modern algal groups arose 1.2 Gyr ago, apparently at the end of a prolonged period of ocean anoxia when the deep sea was sulfidic and presumably toxic. Animal evolution was delayed until 0.65 Gyr ago when biomarkers for sponges first appear in the record, evidently after a further rise in atmospheric oxygen to modern levels but surprisingly pre-dating the last of another series of “Snowball Earth” glaciations. These sponges co-existed with an enigmatic extinct group of large flat marine organisms called “Ediacaran fossils” that may have been ancestral to modern animal groups but might also have been

  2. "The Bridge" from Earthscope to EarthsCAN to Maintain North American Geoscience Momentum

    Science.gov (United States)

    Boggs, K. J. E.; Hyndman, R. D.; Eaton, D. W. S.

    2016-12-01

    "The Bridge", of seismic instruments across the Yukon-western NWT from the USArray-Alaska extending from the Pacific Ocean to the Beaufort Sea, is a possible proof of concept for the new EarthsCAN research initiative. The proposal is to fill gaps between the USArray-Alaska seismic stations, the McKenzie Mtn Earthscope Project, seismic sites of the Geological Survey of Canada, the Yukon Geological Survey, the University of Ottawa and other industry/government consortia. Workshop results defined important northern Cordillera questions. The Yukon Stable Block (YSB) is underlain in part by the Paleoproterozoic Wernecke Supergroup (not exposed elsewhere in the Cordillera). Cretaceous-Tertiary structures are deflected around the YSB suggesting stronger internal crust in the YSB. New GPS observations (Alaska and NW Canada) indicate that as the Yakutat block is colliding with North America that the Elias block is rotating counterclockwise, and the Alaska panhandle rotating clockwise into North America. Seismic activity also extends 800 km from the plate boundary to current deformation in the Mackenzie and Richardson Mountains. A model to explain neotectonic deformation proposes a strong upper crust, decoupled from the underlying mantle due to elevated basal temperatures, which is pushed against the plate boundary and transmits stresses throughout the Cordillera. Resolving these questions requires high-resolution seismic velocity models of the crust and mantle, dense GPS velocity fields, as well as mapping active faults in the Mackenzie Mountains and across the Cordillera via Lidar images and paleoseismic trenching. The transition from the actively deforming northern Cordillera to the relatively aseismic northern Rockies across a lithospheric-scale transfer zone inherited from former passive margins, similar to the one bounding the YSB in the north, may be an important characteristic of modern Cordilleras that controls tectonic activity.

  3. Cell evolution and Earth history: stasis and revolution.

    Science.gov (United States)

    Cavalier-Smith, Thomas

    2006-06-29

    This synthesis has three main parts. The first discusses the overall tree of life and nature of the last common ancestor (cenancestor). I emphasize key steps in cellular evolution important for ordering and timing the major evolutionary innovations in the history of the biosphere, explaining especially the origins of the eukaryote cell and of bacterial flagella and cell envelope novelties. Second, I map the tree onto the fossil record and discuss dates of key events and their biogeochemical impact. Finally, I present a broad synthesis, discussing evidence for a three-phase history of life. The first phase began perhaps ca 3.5 Gyr ago, when the origin of cells and anoxic photosynthesis generated the arguably most primitive prokaryote phylum, Chlorobacteria (= Chloroflexi), the first negibacteria with cells bounded by two acyl ester phospholipid membranes. After this 'chlorobacterial age' of benthic anaerobic evolution protected from UV radiation by mineral grains, two momentous quantum evolutionary episodes of cellular innovation and microbial radiation dramatically transformed the Earth's surface: the glycobacterial revolution initiated an oxygenic 'age of cyanobacteria' and, as the ozone layer grew, the rise of plankton; immensely later, probably as recently as ca 0.9 Gyr ago, the neomuran revolution ushered in the 'age of eukaryotes', Archaebacteria (arguably the youngest bacterial phylum), and morphological complexity. Diversification of glycobacteria ca 2.8 Gyr ago, predominantly inhabiting stratified benthic mats, I suggest caused serial depletion of 13C by ribulose 1,5-bis-phosphate caboxylase/oxygenase (Rubisco) to yield ultralight late Archaean organic carbon formerly attributed to methanogenesis plus methanotrophy. The late origin of archaebacterial methanogenesis ca 720 Myr ago perhaps triggered snowball Earth episodes by slight global warming increasing weathering and reducing CO2 levels, to yield runaway cooling; the origin of anaerobic methane

  4. Constraints on Climate and Habitability for Earth-like Exoplanets Determined from a General Circulation Model

    International Nuclear Information System (INIS)

    Wolf, Eric T.; Toon, Owen B.; Shields, Aomawa L.; Kopparapu, Ravi K.; Haqq-Misra, Jacob

    2017-01-01

    Conventional definitions of habitability require abundant liquid surface water to exist continuously over geologic timescales. Water in each of its thermodynamic phases interacts with solar and thermal radiation and is the cause for strong climatic feedbacks. Thus, assessments of the habitable zone require models to include a complete treatment of the hydrological cycle over geologic time. Here, we use the Community Atmosphere Model from the National Center for Atmospheric Research to study the evolution of climate for an Earth-like planet at constant CO 2 , under a wide range of stellar fluxes from F-, G-, and K-dwarf main sequence stars. Around each star we find four stable climate states defined by mutually exclusive global mean surface temperatures ( T s ); snowball ( T s ≤ 235 K), waterbelt (235 K ≤ T s ≤ 250 K), temperate (275 K ≤ T s ≤ 315 K), and moist greenhouse ( T s ≥ 330 K). Each is separated by abrupt climatic transitions. Waterbelt, temperate, and cooler moist greenhouse climates can maintain open-ocean against both sea ice albedo and hydrogen escape processes respectively, and thus constitute habitable worlds. We consider the warmest possible habitable planet as having T s ∼ 355 K, at which point diffusion limited water-loss could remove an Earth ocean in ∼1 Gyr. Without long timescale regulation of non-condensable greenhouse species at Earth-like temperatures and pressures, such as CO 2 , habitability can be maintained for an upper limit of ∼2.2, ∼2.4, and ∼4.7 Gyr around F-, G-, and K-dwarf stars respectively, due to main sequence brightening.

  5. Constraints on Climate and Habitability for Earth-like Exoplanets Determined from a General Circulation Model

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Eric T.; Toon, Owen B. [Laboratory for Atmospheric and Space Physics, Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO (United States); Shields, Aomawa L. [University of California, Irvine, Department of Physics and Astronomy, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Kopparapu, Ravi K.; Haqq-Misra, Jacob, E-mail: eric.wolf@colorado.edu [NASA Astrobiology Institute' s Virtual Planetary Laboratory, P.O. Box 351580, Seattle, WA 98195 (United States)

    2017-03-10

    Conventional definitions of habitability require abundant liquid surface water to exist continuously over geologic timescales. Water in each of its thermodynamic phases interacts with solar and thermal radiation and is the cause for strong climatic feedbacks. Thus, assessments of the habitable zone require models to include a complete treatment of the hydrological cycle over geologic time. Here, we use the Community Atmosphere Model from the National Center for Atmospheric Research to study the evolution of climate for an Earth-like planet at constant CO{sub 2}, under a wide range of stellar fluxes from F-, G-, and K-dwarf main sequence stars. Around each star we find four stable climate states defined by mutually exclusive global mean surface temperatures ( T {sub s}); snowball ( T {sub s} ≤ 235 K), waterbelt (235 K ≤ T {sub s} ≤ 250 K), temperate (275 K ≤ T {sub s} ≤ 315 K), and moist greenhouse ( T {sub s} ≥ 330 K). Each is separated by abrupt climatic transitions. Waterbelt, temperate, and cooler moist greenhouse climates can maintain open-ocean against both sea ice albedo and hydrogen escape processes respectively, and thus constitute habitable worlds. We consider the warmest possible habitable planet as having T {sub s} ∼ 355 K, at which point diffusion limited water-loss could remove an Earth ocean in ∼1 Gyr. Without long timescale regulation of non-condensable greenhouse species at Earth-like temperatures and pressures, such as CO{sub 2}, habitability can be maintained for an upper limit of ∼2.2, ∼2.4, and ∼4.7 Gyr around F-, G-, and K-dwarf stars respectively, due to main sequence brightening.

  6. The Rise of Oxygen in the Earth's Atmosphere Controlled by the Efficient Subduction of Organic Carbon

    Science.gov (United States)

    Duncan, M. S.; Dasgupta, R.

    2017-12-01

    Carbon cycling between the Earth's surface environment, i.e., the ocean-atmosphere system, and the Earth's interior is critical for differentiation, redox evolution, and long-term habitability of the planet. This carbon cycle is influenced heavily by the extent of carbon subduction. While the fate of carbonates during subduction has been discussed in numerous studies [e.g., 1], little is known how organic carbon is quantitatively transferred from the Earth's surface to the interior. Efficient subduction of organic carbon would remove reduced carbon from the surface environment over the long-term (≥100s Myrs) while release at subduction zone arc volcanoes would result in degassing of CO2. Here we conducted high pressure-temperature experiments to determine the carbon carrying capacity of slab derived, rhyolitic melts under graphite-saturated conditions over a range of P (1.5-3.0 GPa) and T (1100-1400 °C) at a fixed melt H2O content (2 wt.%) [2]. Based on our experimental data, we developed a thermodynamic model of CO2 dissolution in C-saturated slab melts, that allows us to quantify the extent of organic carbon mobility as a function of slab P, T, and fO2 during subduction through time. Our experimental data and thermodynamic model suggest that the subduction of graphitized organic C, and graphite/diamond formed by reduction of carbonates with depth [e.g., 3], remained efficient even in ancient, hotter subduction zones - conditions at which subduction of carbonates likely remained limited [1]. Considering the efficiency the subduction of organic C and potential conditions for ancient subduction, we suggest that the lack of remobilization in subduction zones and deep sequestration of organic C in the mantle facilitated the rise and maintenance atmospheric oxygen in the Paleoproterozoic and is causally linked to the Great Oxidation Event (GOE). Our modeling shows that episodic subduction and organic C sequestration pre-GOE may also explain occasional whiffs of

  7. Rare Earth Polyoxometalates.

    Science.gov (United States)

    Boskovic, Colette

    2017-09-19

    Longstanding and important applications make use of the chemical and physical properties of both rare earth metals and polyoxometalates of early transition metals. The catalytic, optical, and magnetic features of rare earth metal ions are well-known, as are the reversible multielectron redox and photoredox capabilities of polyoxomolybdates and polyoxotungstates. The combination of rare earth ions and polyoxometalates in discrete molecules and coordination polymers is of interest for the unique combination of chemical and physical properties that can arise. This Account surveys our efforts to synthesize and investigate compounds with rare earth ions and polyoxometalates (RE-POMs), sometimes with carboxylate-based organic coligands. Our general synthetic approach is "bottom-up", which affords well-defined nanoscale molecules, typically in crystalline form and amenable to single-crystal X-ray diffraction for structure determination. Our particular focus is on elucidation of the physical properties conferred by the different structural components with a view to ultimately being able to tune these properties chemically. For this purpose, we employ a variety of spectroscopic, magnetochemical, electrochemical, and scattering techniques in concert with theoretical modeling and computation. Studies of RE-POM single-molecule magnets (SMMs) have utilized magnetic susceptibility, inelastic neutron scattering, and ab initio calculations. These investigations have allowed characterization of the crystal field splitting of the rare earth(III) ions that is responsible for the SMM properties of slow magnetic relaxation and magnetization quantum tunneling. Such SMMs are promising for applications in quantum computing and molecular spintronics. Photophysical measurements of a family of hybrid RE-POMs with organic ligands have afforded insights into sensitization of Tb(III) and Eu(III) emission through both organic and polyoxometalate chromophores in the same molecule. Detailed

  8. Stovetop Earth Pecan Pie

    Science.gov (United States)

    Robin, C. M.

    2005-12-01

    Many fluid mechanical experiments with direct applications to Earth Science are performed with sugary syrups using conceptually straightforward procedures. Corn syrup has indeed proven to be a godsend for those studying convection and related non-linear phenomena. In addition, however, it gives experimentalists a deep physical intuition for the interior workings of hot planets. The basic concepts behind plate tectonics and mantle convection are not difficult; indeed, although they may not be aware of it, most students probably have a basic intuitive understanding of fluid mechanics gained in their daily life. However, the large size and long time scale of geophysical processes may be quite intimidating to young students. Even a simple geophysical experiment requires a complicated array of coolers, heaters and measuring and recording equipment. It is of interest to introduce students to the geodynamical concepts that can be visualized in a high-tech lab using familiar processes and equipment. Using a homemade apparatus and grocery store supplies, I propose using a 'Stove-top Earth pecan pie' to introduce simple geodynamic concepts to middle- and high-school students. The initially cold syrup heats up and the pecans begin to float (continent formation), the syrup begins to convect (mantle convection), and convection slows down after the heat is removed (secular cooling). Even Wilson cycles can be simulated by moving the pan to one side or the other of the stovetop or heating element. The activity formally introduces students to convection and its application to the earth, and makes them think about plate motion, heat transfer, scaling, and experimental procedures. As an added bonus, they can eat their experiments after recess!

  9. Bones of the Earth

    Directory of Open Access Journals (Sweden)

    Jose Miguel Correa

    2014-06-01

    Full Text Available The film Bones of the Earth (Riglin, Cunninham & Correa, 2014 is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective creation is built. A sense of community, on-going inquiry, connections and social commitment inform the creative process. As a result, the video’s nearly five intense minutes are a metaphor for the search for personal meaning, connection with nature and intersubjective positioning in a world that undergoes constant change.

  10. The Solid Earth

    Science.gov (United States)

    Fowler, C. M. R.

    2005-02-01

    The second edition of this acclaimed textbook has been brought fully up-to-date to reflect the latest advances in geophysical research. It is designed for students in introductory geophysics courses who have a general background in the physical sciences, including introductory calculus. New to this edition are a section of color plates and separate sections on the earth's mantle and core. The book also contains an extensive glossary of terms, and includes numerous exercises for which solutions are available to instructors from solutions@cambridge.org. First Edition Hb (1990): 0-521-37025-6 First Edition Pb (1990): 0-521-38590-3

  11. Between Earth and Sky

    DEFF Research Database (Denmark)

    Carter, Adrian

    2009-01-01

    to rescue architecture from the sterile impasse of late-modernism. In his works the basic elements of lived space become present: the earth, the sky and the `between` of human existence." Jørn Utzon's architecture ranges from the modest to the monumental; from the Kingo courtyard houses, the finest...... of form, material and function, motivated by social values. To this essentially regional response, Utzon combines a fascination for the architectural legacies of foreign cultures. These influences include the architecture of the ancient Mayan civilisation, as well as the Islamic world, China and Japan...

  12. Climate in Earth history

    Science.gov (United States)

    Berger, W. H.; Crowell, J. C.

    1982-01-01

    Complex atmosphere-ocean-land interactions govern the climate system and its variations. During the course of Earth history, nature has performed a large number of experiments involving climatic change; the geologic record contains much information regarding these experiments. This information should result in an increased understanding of the climate system, including climatic stability and factors that perturb climate. In addition, the paleoclimatic record has been demonstrated to be useful in interpreting the origin of important resources-petroleum, natural gas, coal, phosphate deposits, and many others.

  13. Earth's ozone layer

    International Nuclear Information System (INIS)

    Lasa, J.

    1991-01-01

    The paper contain the actual results of investigations of the influence of the human activity on the Earth's ozone layer. History of the ozone measurements and of the changes in its concentrations within the last few years are given. The influence of the trace gases on both local and global ozone concentrations are discussed. The probable changes of the ozone concentrations are presented on the basis of the modelling investigations. The effect of a decrease in global ozone concentration on human health and on biosphere are also presented. (author). 33 refs, 36 figs, 5 tabs

  14. Modeling Earth Albedo for Satellites in Earth Orbit

    DEFF Research Database (Denmark)

    Bhanderi, Dan; Bak, Thomas

    2005-01-01

    Many satellite are influences by the Earthøs albedo, though very few model schemes exist.in order to predict this phenomenon. Earth albedo is often treated as noise, or ignored completely. When applying solar cells in the attitude hardware, Earth albedo can cause the attitude estimate to deviate...... with as much as 20 deg. Digital Sun sensors with Earth albedo correction in hardware exist, but are expensive. In addition, albedo estimates are necessary in thermal calculations and power budgets. We present a modeling scheme base4d on Eartht reflectance, measured by NASA's Total Ozone Mapping Spectrometer......, in which the Earth Probe Satellite has recorded reflectivity data daily since mid 1996. The mean of these data can be used to calculate the Earth albedo given the positions of the satellite and the Sun. Our results show that the albedo varies highly with the solar angle to the satellite's field of view...

  15. Destiny's Earth Observation Window

    Science.gov (United States)

    2002-01-01

    Astronaut Michael J. Bloomfield, STS-110 mission commander, looks through the Earth observation window in the Destiny laboratory aboard the International Space Station (ISS). The STS-110 mission prepared the ISS for future spacewalks by installing and outfitting the S0 (S-zero) truss and the Mobile Transporter. The 43-foot-long S0 Truss, weighing in at 27,000 pounds, was the first of 9 segments that will make up the Station's external framework that will eventually stretch 356 feet (109 meters), or approximately the length of a football field. This central truss segment also includes a flatcar called the Mobile Transporter and rails that will become the first 'space railroad,' which will allow the Station's robotic arm to travel up and down the finished truss for future assembly and maintenance. The completed truss structure will hold solar arrays and radiators to provide power and cooling for additional international research laboratories from Japan and Europe that will be attached to the Station. Milestones of the STS-110 mission included the first time the ISS robotic arm was used to maneuver spacewalkers around the Station and marked the first time all spacewalks were based out of the Station's Quest Airlock. It was also the first Shuttle to use three Block II Main Engines. The Space Shuttle Orbiter Atlantis, STS-110 mission, was launched April 8, 2002 and returned to Earth April 19, 2002.

  16. Mapping Earth's electromagnetic dimensionality

    Science.gov (United States)

    Love, J. J.; Kelbert, A.; Bedrosian, P.

    2017-12-01

    The form of a magnetotelluric impedance tensor, obtained for a given geographic site through simultaneous measurement of geomagnetic and geoelectric field variation, is affected by electrical conductivity structure beneath the measurement site. Building on existing methods for characterizing the symmetry of magnetotelluric impedance tensors, a simple scalar measure is developed for measuring the (frequency dependent) proportion of the impedance tensor that is not just a one-dimensional (1D) function of depth ("non-1D-ness"). These measures are applied to nearly 1000 impedance tensors obtained during magnetotelluric surveys, those for the continental United States and obtained principally through the National Science Foundation's EarthScope project. Across geomagnetic/geoelectric variational periods ranging from 30 s to 3,000 s, corresponding to crustal and upper mantle depths, it is shown that local Earth structure is very often not simply 1D-depth-dependent - often less than 50% of magnetotelluric impedance is 1D. For selected variational frequencies, non-1D-ness is mapped and the relationship between electromagnetic dimensionality and known geological and tectonic structures is discussed. The importance of using realistic surface impedances to accurately evaluate magnetic-storm geoelectric hazards is emphasized.

  17. Is dying the earth?

    International Nuclear Information System (INIS)

    Morales Garzon, Gustavo

    1994-01-01

    December 21 of 1968, on board the capsule Apollo 8, three astronauts, James A. Lovell, Frank Borman and William Anders, went toward what would be the first orbital flight around the moon. That experience like Lovell said, it makes us realize the insignificant that we are in comparison with the vastness of the universe. With the revolution lovelockiane, the life doesn't already consist on a group of organisms only adapted to its atmosphere by a certain action for external laws. The terrestrial environment, instead of being a physical world regulated by own autonomous laws, is part of an evolutionary system that contains the life and that it should to the phenomena vital part of its rules, its mechanisms and components. The alive beings connected to each other and to the atmosphere they manufacture and they maintain of continuous their atmosphere forming an everything at planetary level, according to Ricard Guerrero (1988). The theory of the earth then, he says, it has found their owner Darwin in James lovelock. The document treats topics like the science concept that it is the life, the earth and the contemporary environment

  18. School, Earth and Imagination

    Science.gov (United States)

    Merlini, Anna; Grieco, Giovanni; Oneta, Cristina

    2015-04-01

    Geology needs to be explained and narrated to the people, focusing on the goal of making that big change of mindset that will allow individuals and the entire community to tune into the timing and the ways in which the Earth evolves. In order to achieve these important goals it is necessary to educate children from an early age so that they learn to live an environmentally friendly life. With the project "School, Earth and imagination" we introduce, with a fun and new way, notions and topics in geological and environmental sciences in schools at all levels with the final goal of improving both knowledge and sensibility for these topics into the community. Through this project we start from the children (kindergarten and primary school, ages between 3 and 8 years) because they are the foundation of our society, and without foundations nothing can be built. The "School, Earth and imagination" project wants to give the children a real opportunity to approach reality and in general the surrounding environment, for the first time even before the traditional scholastic experience, with a scientific point of view, experimenting some basic physical concepts like temperature, weight, hardness and so on directly through their body. The project is structured and developed in modules that provide a high flexibility in order to meet needs and requirements of different schools in different situations. Each module is part of the journey of Mariolino, a character that represents a very curious child who introduces basic concepts associating them to geological processes. The Journey of Mariolino, as each module, follows an insistent scheme that starts from the presentation of the problem, follows with its discussion through direct questions and ends with experimentation of the hypotheses that children have proposed to validate the solution of the problem. Each module is independent and never ends without giving children a solution and is always structured with a practical activity

  19. Paleoproterozoic (~1.88Ga felsic volcanism of the Iricoumé Group in the Pitinga Mining District area, Amazonian Craton, Brazil: insights in ancient volcanic processes from field and petrologic data

    Directory of Open Access Journals (Sweden)

    Ronaldo Pierosan

    2011-09-01

    Full Text Available The Iricoumé Group correspond to the most expressive Paleoproterozoic volcanism in the Guyana Shield, Amazonian craton. The volcanics are coeval with Mapuera granitoids, and belong to the Uatumã magmatism. They have U-Pb ages around 1880 Ma, and geochemical signatures of α-type magmas. Iricoumé volcanics consist of porphyritic trachyte to rhyolite, associated to crystal-rich ignimbrites and co-ignimbritic fall tuffs and surges. The amount and morphology of phenocrysts can be useful to distinguish lava (flow and dome from hypabyssal units. The morphology of ignimbrite crystals allows the distinction between effusive units and ignimbrite, when pyroclasts are obliterated. Co-ignimbritic tuffs are massive, and some show stratifications that suggest deposition by current traction flow. Zircon and apatite saturation temperatures vary from 799°C to 980°C, are in agreement with most temperatures of α-type melts and can be interpreted as minimum liquidus temperature. The viscosities estimation for rhyolitic and trachytic compositions yield values close to experimentally determined melts, and show a typical exponential decay with water addition. The emplacement of Iricoumé volcanics and part of Mapuera granitoids was controlled by ring-faults in an intracratonic environment. A genesis related to the caldera complex setting can be assumed for the Iricoumé-Mapuera volcano-plutonic association in the Pitinga Mining District.O Grupo Iricoumé corresponde ao mais expressivo vulcanismo Paleoproterozóico do Escudo das Guianas, craton Amazônico. As rochas vulcânicas são coexistentes com os granitóides Mapuera, e pertencem ao magmatismo Uatumã. Possuem idades U-Pb em torno 1888 Ma, e assinaturas geoquímicas de magmas tipo-A. As vulcânicas do Iricoumé consistem de traquitos a riolitos porfiríticos, associados a ignimbritos ricos em cristal e tufos co-ignimbríticos de queda e surge. A quantidade e a morfologia dos fenocristais podem ser

  20. Cosmic rays and Earth's climate

    DEFF Research Database (Denmark)

    Svensmark, Henrik

    2000-01-01

    During the last solar cycle the Earth's cloud cover underwent a modulation in phase with the cosmic ray flux. Assuming that there is a causal relationship between the two, it is expected and found that the Earth's temperature follows more closely decade variations in cosmic ray flux than other...... solar activity parameters. If the relationship is real the state of the Heliosphere affects the Earth's climate....

  1. Rare earth superlattices

    International Nuclear Information System (INIS)

    McMorrow, D.F.

    1997-01-01

    A review is given of recent experiments on the magnetism of rare earth superlattices. Early experiments in this field were concerned mainly with systems formed by combining a magnetic and a non-magnetic element in a superlattice structure. From results gathered on a variety of systems it has been established that the propagation of magnetic order through the non-magnetic spacer can be understood mostly on the basis of an RKKY-like model, where the strength and range of the coupling depends on the details of the conduction electron susceptibility of the spacer. Recent experiments on more complex systems indicate that this model does not provide a complete description. Examples include superlattices where the constituents can either be both magnetic, adopt different crystal structures (Fermi surfaces), or where one of the constituents has a non-magnetic singlet ground state. The results from such systems are presented and discussed in the context of the currently accepted model. (au)

  2. Earth's Magnetic Field

    DEFF Research Database (Denmark)

    This volume provides a comprehensive view on the different sources of the geomagnetic field both in the Earth’s interior and from the field’s interaction with the terrestrial atmosphere and the solar wind. It combines expertise from various relevant areas of geomagnetic and near Earth space...... research with the aim to better characterise the state and dynamics of Earth’s magnetic field. Advances in the exploitation of geomagnetic observations hold a huge potential not only for an improved quantitative description of the field source but also for a better understanding of the underlying processes...... and space observations, and on state-of-the-art empirical models and physics-based simulations. Thus, it provides an in-depth overview over recent achievements, current limitations and challenges, and future opportunities in the field of geomagnetism and space sciences....

  3. Rare earth (3) pivalates

    International Nuclear Information System (INIS)

    Kuz'mina, N.P.; Martynenko, L.I.; Zoan An' Tu; Ch'eu Tkhi Nguet; Troyanov, S.I.; Rykov, A.N.; Korenev, Yu.M.

    1994-01-01

    Depending on synthesis conditions rare earth pivalates can be obtained in the form of either adducts NPiv·HPiv or hydrates MPiv 3 ·mH 2 O. Adducts are the most stable form of pivalates. Heating of adducts result in formation of corresponding MPiv 3 . MPiv 3 ·nHPiv compounds are characterized by IR-spectroscopy and thermal analysis data. Behaviour of MPiv 3 was studied in the regime of vacuum sublemation. Using mass spectroscopy of NdPiv 3 it was shown that gaseous phase above MPiv 3 had complex composition and contained ligomer fragments. X-ray structure analysis of [NdPiv 3 ·3HPiv] was conducted

  4. One Day on Earth

    CERN Multimedia

    2011-01-01

    In collaboration with the CineGlobe Film Festival, the One Day on Earth global film project invites you to share your story of scientific inspiration, scientific endeavors and technological advancement on 11 November 2011 (11.11.11).   Technology in the 21st century continuously inspires us to re-imagine the world. From outer-space to cyberspace, new ideas that we hope will improve the lives of future generations keep us in a state of change. However, these new technologies may alter the nature of our shared existence in ways not yet known. On 11.11.11, we invite you to record the exciting ways that science is a part of your life, together with people around the world who will be documenting their lives on this day of global creation. See www.onedayonearth.org for details on how to participate.

  5. Earth's radiation belts

    International Nuclear Information System (INIS)

    Moslehi Fard, M.

    1984-01-01

    The theory of trapped particles in a magnetic field of approximated dipole is described completely in the first part. Second part contains experimental results. The mechanism of radiation belt source ''albedo neutrons'' and also types of dissipation mechanism about radiation belt is explained. The trapped protons and electrons by radiation belt is discussed and the life-time of trapped particles are presented. Finally the magnetic fields of Moon, Venus, Mars, and Saturn, measured by passengers Mariner 4,10 and pioneer 10,11 are indicated. The experimental and theoretical results for the explanation of trapped plasma around the earth which is looked like two internal and external belt have almost good correspondence

  6. Earth's early biosphere

    Science.gov (United States)

    Des Marais, D. J.

    1998-01-01

    Understanding our own early biosphere is essential to our search for life elsewhere, because life arose on Earth very early and rocky planets shared similar early histories. The biosphere arose before 3.8 Ga ago, was exclusively unicellular and was dominated by hyperthermophiles that utilized chemical sources of energy and employed a range of metabolic pathways for CO2 assimilation. Photosynthesis also arose very early. Oxygenic photosynthesis arose later but still prior to 2.7 Ga. The transition toward the modern global environment was paced by a decline in volcanic and hydrothermal activity. These developments allowed atmospheric O2 levels to increase. The O2 increase created new niches for aerobic life, most notably the more advanced Eukarya that eventually spawned the megascopic fauna and flora of our modern biosphere.

  7. The earth and the moon

    CERN Document Server

    Elkins-Tanton, Linda T

    2010-01-01

    The moon is the only body in the solar system outside of the Earth that has been visited by humans. More than 440 pounds of lunar material are brought by NASA and Soviet space missions to Earth for study. The information gleaned about the moon from this relatively small pile of rocks is mind-boggling and stands as the greatest proof that Martian planetary science would be greatly enhanced by returning samples to Earth. Compositional studies of lunar rocks show that the moon and the Earth are made of similar material, and because lunar material has not been reworked through erosion and plate te

  8. Theory of Earth

    Science.gov (United States)

    Anderson, D. L.

    2014-12-01

    Earth is an isolated, cooling planet that obeys the 2nd law. Interior dynamics is driven from the top, by cold sinking slabs. High-resolution broad-band seismology and geodesy has confirmed that mantle flow is characterized by narrow downwellings and ~20 broad slowly rising updrafts. The low-velocity zone (LVZ) consists of a hot melange of sheared peridotite intruded with aligned melt-rich lamellae that are tapped by intraplate volcanoes. The high temperature is a simple consequence of the thermal overshoot common in large bodies of convecting fluids. The transition zone consists of ancient eclogite layers that are displaced upwards by slabs to become broad passive, and cool, ridge feeding updrafts of ambient mantle. The physics that is overlooked in canonical models of mantle dynamics and geochemistry includes; the 2nd law, convective overshoots, subadiabaticity, wave-melt interactions, Archimedes' principle, and kinetics (rapid transitions allow stress-waves to interact with melting and phase changes, creating LVZs; sluggish transitions in cold slabs keep eclogite in the TZ where it warms up by extracting heat from mantle below 650 km, creating the appearance of slab penetration). Canonical chemical geodynamic models are the exact opposite of physics and thermodynamic based models and of the real Earth. A model that results from inverting the assumptions regarding initial and boundary conditions (hot origin, secular cooling, no external power sources, cooling internal boundaries, broad passive upwellings, adiabaticity and whole-mantle convection not imposed, layering and self-organization allowed) results in a thick refractory-yet-fertile surface layer, with ancient xenoliths and cratons at the top and a hot overshoot at the base, and a thin mobile D" layer that is an unlikely plume generation zone. Accounting for the physics that is overlooked, or violated (2nd law), in canonical models, plus modern seismology, undermines the assumptions and conclusions of these

  9. China's rare-earth industry

    Science.gov (United States)

    Tse, Pui-Kwan

    2011-01-01

    Introduction China's dominant position as the producer of over 95 percent of the world output of rare-earth minerals and rapid increases in the consumption of rare earths owing to the emergence of new clean-energy and defense-related technologies, combined with China's decisions to restrict exports of rare earths, have resulted in heightened concerns about the future availability of rare earths. As a result, industrial countries such as Japan, the United States, and countries of the European Union face tighter supplies and higher prices for rare earths. This paper briefly reviews China's rare-earth production, consumption, and reserves and the important policies and regulations regarding the production and trade of rare earths, including recently announced export quotas. The 15 lanthanide elements-lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 57-71)-were originally known as the rare earths from their occurrence in oxides mixtures. Recently, some researchers have included two other elements-scandium and yttrium-in their discussion of rare earths. Yttrium (atomic number 39), which lies above lanthanum in transition group III of the periodic table and has a similar 3+ ion with a noble gas core, has both atomic and ionic radii similar in size to those of terbium and dysprosium and is generally found in nature with lanthanides. Scandium (atomic number 21) has a smaller ionic radius than yttrium and the lanthanides, and its chemical behavior is intermediate between that of aluminum and the lanthanides. It is found in nature with the lanthanides and yttrium. Rare earths are used widely in high-technology and clean-energy products because they impart special properties of magnetism, luminescence, and strength. Rare earths are also used in weapon systems to obtain the same properties.

  10. Rare earths 1998 market update

    International Nuclear Information System (INIS)

    Tourre, J.M.

    1998-01-01

    The rare earth industry has always been a world of rapid change with the emergence of new markets, new ores and new players, as well as the disappearance of old applications. Rare earth based products are used in a great diversity of applications such as hard disk drives, CD drives, batteries, capacitors, pigments, ceramics, polishing powders, fuel cells, flints, catalyst converter, fluid cracking catalysts, etc. South East Asia holds the largest share of the known reserve of rare earth ores and is one of the major markets for rare earth compounds; in the last ten years, China has become the largest producer of rare earth intermediates as well as an important exporter of separated rare earth elements. Today, China has approximately 150 factories producing rare earth compounds, most of which are experiencing financial difficulties due to the lack of knowledge of true market needs, lack of control of their distribution channels and production over-capacity. Recently the Chinese rare earth producers have recognized the situation and efforts are underway to rationalize rare earth production. Japan has dominated many of the major application markets, and is by far the largest market for metal and alloy products. This will remain the case for the next five years; however, new countries are emerging as significant users of rare earth products such as Korea, Taiwan and Malaysia. During the last ten years rare earth producers adjusted to several radical changes that affected the raw materials, the application mix and the price structure. New producers have emerged, especially from China; some have subsequently stopped their activities while others have focused their efforts in a specific market segment

  11. Two drastically different climate states on an Earth-like terra-planet

    Directory of Open Access Journals (Sweden)

    S. Kalidindi

    2018-06-01

    Full Text Available We study an Earth-like terra-planet (water-limited terrestrial planet with an overland recycling mechanism bringing fresh water back from the high latitudes to the low latitudes. By performing model simulations for such a planet we find two drastically different climate states for the same set of boundary conditions and parameter values: a cold and wet (CW state with dominant low-latitude precipitation and a hot and dry (HD state with only high-latitude precipitation. We notice that for perpetual equinox conditions, both climate states are stable below a certain threshold value of background soil albedo while above the threshold only the CW state is stable. Starting from the HD state and increasing background soil albedo above the threshold causes an abrupt shift from the HD state to the CW state resulting in a sudden cooling of about 35 °C globally, which is of the order of the temperature difference between present day and the Snowball Earth state. When albedo starting from the CW state is reduced down to zero the terra-planet does not shift back to the HD state (no closed hysteresis. This is due to the high cloud cover in the CW state hiding the surface from solar irradiation so that surface albedo has only a minor effect on the top of the atmosphere radiation balance. Additional simulations with present-day Earth's obliquity all lead to the CW state, suggesting a similar abrupt transition from the HD state to the CW state when increasing obliquity from zero. Our study also has implications for the habitability of Earth-like terra-planets. At the inner edge of the habitable zone, the higher cloud cover in the CW state cools the planet and may prevent the onset of a runaway greenhouse state. At the outer edge, the resupply of water at low latitudes stabilizes the greenhouse effect and keeps the planet in the HD state and may prevent water from getting trapped at high latitudes in frozen form. Overall, the existence of bistability in the

  12. Next-generation digital earth

    NARCIS (Netherlands)

    Goodchild, M.F.; Guo, H.; Annoni, A.; Bian, L.; Bie, de K.; Campbell, F.; Craglia, M.; Ehlers, M.; Genderen, van J.; Skidmore, A.K.; Wang, C.; Woodgate, P.

    2012-01-01

    A speech of then-Vice President Al Gore in 1998 created a vision for a Digital Earth, and played a role in stimulating the development of a first generation of virtual globes, typified by Google Earth, that achieved many but not all the elements of this vision. The technical achievements of Google

  13. LIMNOLOGICAL OPTOMETRY: EXAMINING EARTH'S EYE

    Science.gov (United States)

    In Thoreau's Walden, a lake is described as the landscape's most expressive feature and the earth's eye. Collectively, scientists are charged by society to assess, monitor, and remedy maladies of earth's eye in the same way optometrists maintain the health of the human eye. This ...

  14. Melting in super-earths.

    Science.gov (United States)

    Stixrude, Lars

    2014-04-28

    We examine the possible extent of melting in rock-iron super-earths, focusing on those in the habitable zone. We consider the energetics of accretion and core formation, the timescale of cooling and its dependence on viscosity and partial melting, thermal regulation via the temperature dependence of viscosity, and the melting curves of rock and iron components at the ultra-high pressures characteristic of super-earths. We find that the efficiency of kinetic energy deposition during accretion increases with planetary mass; considering the likely role of giant impacts and core formation, we find that super-earths probably complete their accretionary phase in an entirely molten state. Considerations of thermal regulation lead us to propose model temperature profiles of super-earths that are controlled by silicate melting. We estimate melting curves of iron and rock components up to the extreme pressures characteristic of super-earth interiors based on existing experimental and ab initio results and scaling laws. We construct super-earth thermal models by solving the equations of mass conservation and hydrostatic equilibrium, together with equations of state of rock and iron components. We set the potential temperature at the core-mantle boundary and at the surface to the local silicate melting temperature. We find that ancient (∼4 Gyr) super-earths may be partially molten at the top and bottom of their mantles, and that mantle convection is sufficiently vigorous to sustain dynamo action over the whole range of super-earth masses.

  15. Flooding Effect on Earth Walls

    Directory of Open Access Journals (Sweden)

    Meysam Banimahd

    2010-12-01

    Full Text Available Earth building is a sustainable, environmentally friendly and economical method of construction that has been used worldwide for many centuries. For the past three decades, earth has seen a revival as a building material for a modern construction method due to its benefits in terms of low carbon content, low cost and energy involved during construction, as well as the fact that it is a sustainable technology of building. Climate change is influencing precipitation levels and patterns around the world, and as a consequence, flood risk is increasing rapidly. When flooding occurs, earth buildings are exposed to water by submersion, causing an increase in the degree of saturation of the earth structures and therefore a decrease of the suction between particles. This study investigated the effect of cycles of flooding (consecutive events of flooding followed by dry periods on earth walls. A series of characterization tests were carried out to obtain the physical and mechanical properties of the studied earth material. In a second stage, Flooding Simulation Tests (FST were performed to explore the earth walls’ response to repeated flooding events. The results obtained for the tested earth wall/samples with reinforced material (straw reveal hydraulic hysteresis when wall/samples are subject to cycles of wetting and drying.

  16. Introductory mathematics for earth scientists

    CERN Document Server

    Yang, Xin-She

    2009-01-01

    Any quantitative work in earth sciences requires mathematical analysis and mathematical methods are essential to the modelling and analysis of the geological, geophysical and environmental processes involved. This book provides an introduction to the fundamental mathematics that all earth scientists need.

  17. Teaching Waves with Google Earth

    Science.gov (United States)

    Logiurato, Fabrizio

    2012-01-01

    Google Earth is a huge source of interesting illustrations of various natural phenomena. It can represent a valuable tool for science education, not only for teaching geography and geology, but also physics. Here we suggest that Google Earth can be used for introducing in an attractive way the physics of waves. (Contains 9 figures.)

  18. Thermodynamics of the Earth

    International Nuclear Information System (INIS)

    Stacey, Frank D

    2010-01-01

    Applications of elementary thermodynamic principles to the dynamics of the Earth lead to robust, quantitative conclusions about the tectonic effects that arise from convection. The grand pattern of motion conveys deep heat to the surface, generating mechanical energy with a thermodynamic efficiency corresponding to that of a Carnot engine operating over the adiabatic temperature gradient between the heat source and sink. Referred to the total heat flux derived from the Earth's silicate mantle, the efficiency is 24% and the power generated, 7.7 x 10 12 W, causes all the material deformation apparent as plate tectonics and the consequent geological processes. About 3.5% of this is released in seismic zones but little more than 0.2% as seismic waves. Even major earthquakes are only localized hiccups in this motion. Complications that arise from mineral phase transitions can be used to illuminate details of the motion. There are two superimposed patterns of convection, plate subduction and deep mantle plumes, driven by sources of buoyancy, negative and positive respectively, at the top and bottom of the mantle. The patterns of motion are controlled by the viscosity contrasts (>10 4 : 1) at these boundaries and are self-selected as the least dissipative mechanisms of heat transfer for convection in a body with very strong viscosity variation. Both are subjects of the thermodynamic efficiency argument. Convection also drives the motion in the fluid outer core that generates the geomagnetic field, although in that case there is an important energy contribution by compositional separation, as light solute is rejected by the solidifying inner core and mixed into the outer core, a process referred to as compositional convection. Uncertainty persists over the core energy balance because thermal conduction is a drain on core energy that has been a subject of diverse estimates, with attendant debate over the need for radiogenic heat in the core. The geophysical approach to

  19. Rotation of a Moonless Earth

    Science.gov (United States)

    Lissauer, Jack J.; Barnes, Jason W.; Chambers, John E.

    2013-01-01

    We numerically explore the obliquity (axial tilt) variations of a hypothetical moonless Earth. Previous work has shown that the Earth's Moon stabilizes Earth's obliquity such that it remains within a narrow range, between 22.1 deg and 24.5 deg. Without lunar influence, a frequency-map analysis by Laskar et al. showed that the obliquity could vary between 0 deg. and 85 deg. This has left an impression in the astrobiology community that a large moon is necessary to maintain a habitable climate on an Earth-like planet. Using a modified version of the orbital integrator mercury, we calculate the obliquity evolution for moonless Earths with various initial conditions for up to 4 Gyr. We find that while obliquity varies significantly more than that of the actual Earth over 100,000 year timescales, the obliquity remains within a constrained range, typically 20-25 deg. in extent, for timescales of hundreds of millions of years. None of our Solar System integrations in which planetary orbits behave in a typical manner show obliquity accessing more than 65% of the full range allowed by frequency-map analysis. The obliquities of moonless Earths that rotate in the retrograde direction are more stable than those of pro-grade rotators. The total obliquity range explored for moonless Earths with rotation periods shorter than 12 h is much less than that for slower-rotating moonless Earths. A large moon thus does not seem to be needed to stabilize the obliquity of an Earth-like planet on timescales relevant to the development of advanced life.

  20. Changes in earth's dipole.

    Science.gov (United States)

    Olson, Peter; Amit, Hagay

    2006-11-01

    The dipole moment of Earth's magnetic field has decreased by nearly 9% over the past 150 years and by about 30% over the past 2,000 years according to archeomagnetic measurements. Here, we explore the causes and the implications of this rapid change. Maps of the geomagnetic field on the core-mantle boundary derived from ground-based and satellite measurements reveal that most of the present episode of dipole moment decrease originates in the southern hemisphere. Weakening and equatorward advection of normal polarity magnetic field by the core flow, combined with proliferation and growth of regions where the magnetic polarity is reversed, are reducing the dipole moment on the core-mantle boundary. Growth of these reversed flux regions has occurred over the past century or longer and is associated with the expansion of the South Atlantic Anomaly, a low-intensity region in the geomagnetic field that presents a radiation hazard at satellite altitudes. We address the speculation that the present episode of dipole moment decrease is a precursor to the next geomagnetic polarity reversal. The paleomagnetic record contains a broad spectrum of dipole moment fluctuations with polarity reversals typically occurring during dipole moment lows. However, the dipole moment is stronger today than its long time average, indicating that polarity reversal is not likely unless the current episode of moment decrease continues for a thousand years or more.

  1. When the earth shudders

    Energy Technology Data Exchange (ETDEWEB)

    Maltese, G.

    The enormous damage that can be caused by earthquakes (500,000 deaths in Tangshan, China, 1976) makes the art and science of earthquake predicting one of the principal objectives of modern geophysics. In this review of the state-of-the-art in earthquake predicting, brief notes are given on several topics: plate tectonics theory, geographic distribution of earthquakes, elastic potential energy storage of rocks, seismic wave typology, comparison of Mercalli and Richter scales, pre-warning signs in nature (strange behaviour of animals, preliminary reduction of seismic wave velocity, variations in local micro-seismicity and physical properties of rocks, etc.), comparison of earthquake energy release models, historical origin of the science of earthquake predicting, implication of fault slip rates and earthquake recurrence models to probabilistic seismic hazard estimates, the time element in prediction making, analysis of examples of correct predictions, pattern recognition instrumentation, earthquake intensity control through fluid injection, correlations between water reservoir level and seismicity, the creation of government programs for the monitoring of the earth's crust and seismic data acquisition, comparison of earthquake prediction and preparedness approaches in Japan and the USA.

  2. Our sustainable Earth

    International Nuclear Information System (INIS)

    Orbach, Raymond L

    2011-01-01

    Recent evidence demonstrates that the Earth has been warming monotonically since 1980. Transient to equilibrium temperature changes take centuries to develop, as oceans are slow to respond to atmospheric temperature changes. Atmospheric CO 2 concentrations, from ice core and observatory measurements, display consistent increases from historical averages, beginning in about 1880, and can be associated with the industrial revolution. The climactic consequences of this human dominated increase in atmospheric CO 2 define a geologic epoch that has been termed the 'Anthropocene.' The issue is whether this is a short term, relatively minor change in global climate, or an extreme deviation that lasts for thousands of years. Eight 'myths' that posit the former are examined in light of known data. The analysis strongly suggests the latter. In order to stabilize global temperatures, sharp reductions in CO 2 emissions are required: an 80% reduction beginning in 2050. Two examples of economically sustainable CO 2 emission reduction demonstrate that technological innovation has the potential to maintain our standard of living while stabilizing global temperatures.

  3. Space sickness on earth

    Science.gov (United States)

    Nooij, S. A. E.; Bos, J. E.; Groen, E. L.; Bles, W.; Ockels, W. J.

    2007-09-01

    During the first days in space, i.e., after a transition from 1G to 0G, more than 50% of the astro- (and cosmonauts) suffer from the Space Adaptation Syndrome (SAS).The symptoms of SAS, like nausea and dizziness, are especially provoked by head movements. Astronauts have mentioned close similarities between the symptoms of SAS and the symptoms they experienced after a 1 hour centrifuge run on Earth, i.e., after a transition from 3G to 1G (denoted by Sickness Induced by Centrifugation, SIC). During several space missions, we related susceptibility to SAS and to SIC in 11 astronauts and found 4 of them being susceptible to both SIC and SAS, and 7 being not susceptible to SIC nor to SAS. This correspondence in susceptibility suggests that SIC and SAS share the same underlying mechanism. To further study this mechanism, several vestibular parameters have been investigated (e.g. postural stability, vestibularly driven eye movements, subjective vertical). We found some striking changes in individual cases that are possibly due to the centrifuge run. However, the variability between subjects generally is very large, making physiological links to SIC and SAS still hard to find.

  4. Magnetic field of the Earth

    Science.gov (United States)

    Popov, Aleksey

    2013-04-01

    The magnetic field of the Earth has global meaning for a life on the Earth. The world geophysical science explains: - occurrence of a magnetic field of the Earth it is transformation of kinetic energy of movements of the fused iron in the liquid core of Earth - into the magnetic energy; - the warming up of a kernel of the Earth occurs due to radioactive disintegration of elements, with excretion of thermal energy. The world science does not define the reasons: - drift of a magnetic dipole on 0,2 a year to the West; - drift of lithospheric slabs and continents. The author offers: an alternative variant existing in a world science the theories "Geodynamo" - it is the theory « the Magnetic field of the Earth », created on the basis of physical laws. Education of a magnetic field of the Earth occurs at moving the electric charge located in a liquid kernel, at rotation of the Earth. At calculation of a magnetic field is used law the Bio Savara for a ring electric current: dB = . Magnetic induction in a kernel of the Earth: B = 2,58 Gs. According to the law of electromagnetic induction the Faradey, rotation of a iron kernel of the Earth in magnetic field causes occurrence of an electric field Emf which moves electrons from the center of a kernel towards the mantle. So of arise the radial electric currents. The magnetic field amplifies the iron of mantle and a kernel of the Earth. As a result of action of a radial electric field the electrons will flow from the center of a kernel in a layer of an electric charge. The central part of a kernel represents the field with a positive electric charge, which creates inverse magnetic field Binv and Emfinv When ?mfinv = ?mf ; ?inv = B, there will be an inversion a magnetic field of the Earth. It is a fact: drift of a magnetic dipole of the Earth in the western direction approximately 0,2 longitude, into a year. Radial electric currents a actions with the basic magnetic field of a Earth - it turn a kernel. It coincides with laws

  5. Radiation environment of the earth

    International Nuclear Information System (INIS)

    Furukawa, Masahide

    2003-01-01

    The radiation environment of the earth consists of natural and artificial radiation. This paper explains the distribution and some exposure examples of natural radiation and the relation between life and natural radiation. The earth was born before about 46 hundreds of millions of years. In the present earth, there are some natural radiations with long half-life originated by the earth. They are 232 Th (141 hundreds of millions of years of half-life), 238 U (45 hundreds of millions of years of half-life) and 40 K (13 hundreds of millions of years of half-life). Natural radiation (α-, β-, and γ-ray) from natural radionuclides exists everywhere in the earth. Natural radio nuclides are heat source of the earth, which is about 0.035 μcal/g/y. γ-ray from them is called as ''the earth's crust γ-ray'', which is about 55 nGy/h average of the world and about 50 nGy/h in Japan. The distribution of γ-ray is depended on the kinds of soil and rock. 222 Rn and 230 Rn are rare gases and the concentration of them in a room is larger than outside. Natural radiations originated from the cosmos are proton, ionizing components, neutron component with muon and electron, 3 H, 14 C and 10 Be. Effect of cosmic rays on birth of life, change of temperature, amount of cloud and ultra resistant cell are stated. (S.Y.)

  6. Earth Science Enterprise Technology Strategy

    Science.gov (United States)

    1999-01-01

    NASA's Earth Science Enterprise (ESE) is dedicated to understanding the total Earth system and the effects of natural and human-induced changes on the global environment. The goals of ESE are: (1) Expand scientific knowledge of the Earth system using NASA's unique vantage points of space, aircraft, and in situ platforms; (2) Disseminate information about the Earth system; and (3) Enable the productive use of ESE science and technology in the public and private sectors. ESE has embraced the NASA Administrator's better, faster, cheaper paradigm for Earth observing missions. We are committed to launch the next generation of Earth Observing System (EOS) missions at a substantially lower cost than the EOS first series. Strategic investment in advanced instrument, spacecraft, and information system technologies is essential to accomplishing ESE's research goals in the coming decades. Advanced technology will play a major role in shaping the ESE fundamental and applied research program of the future. ESE has established an Earth science technology development program with the following objectives: (1) To accomplish ESE space-based and land-based program elements effectively and efficiently; and (2) To enable ESE's fundamental and applied research programs goals as stated in the NASA Strategic Plan.

  7. Our Sustainable Earth

    Science.gov (United States)

    Orbach, Raymond L.

    2013-03-01

    Recent evidence demonstrates that the Earth has been warming monotonically since 1980. Transient to equilibrium temperature changes take centuries to develop, as the upper levels of the ocean are slow to respond to atmospheric temperature changes. Atmospheric CO2 concentrations, from ice core and observatory measurements, display consistent increases from historical averages, beginning in about 1880. They can be associated with the use of coal ecause of the spread of the industrial revolution from Great Britain to the European continent and beyond. The climactic consequence of this human-dominated increase in atmospheric CO2 has been suggested to define a geologic epoch, termed the ``Anthropocene.'' This could be a short term, relatively minor change in global climate, or an extreme deviation that lasts for thousands of years. In order to stabilize global temperatures, sharp reductions in CO2 emissions are required: an 80% reduction beginning in 2050. U.S. emissions have declined sharply recently because of market conditions leading to the substitution of natural gas for coal for electricity generation. Whether this is the best use for this resource may be questioned, but it nevertheless reduces CO2 production by 67% from a coal-fired power plant, well on the way to the 80% reduction required for global temperature stabilization. Current methods for CO2 capture and storage are not cost effective, and have been slow (if not absent) to introduce at scale. This paper describes research into some potentially economically feasible approaches: cost-effective capture and storage of CO2 from injection of flue gas into subterranean methane-saturated aquifers at the surface; fuels from sunlight without CO2 production; and large-scale electrical energy storage for intermittent (and even constant) electricity generating sources.

  8. Earth - South America (first frame of Earth Spin Movie)

    Science.gov (United States)

    1990-01-01

    This color image of the Earth was obtained by Galileo at about 6:10 a.m. Pacific Standard Time on Dec. 11, 1990, when the spacecraft was about 1.3 million miles from the planet during the first of two Earth flybys on its way to Jupiter. The color composite used images taken through the red, green and violet filters. South America is near the center of the picture, and the white, sunlit continent of Antarctica is below. Picturesque weather fronts are visible in the South Atlantic, lower right. This is the first frame of the Galileo Earth spin movie, a 500- frame time-lapse motion picture showing a 25-hour period of Earth's rotation and atmospheric dynamics.

  9. Earth observation from the manned low Earth orbit platforms

    Science.gov (United States)

    Guo, Huadong; Dou, Changyong; Zhang, Xiaodong; Han, Chunming; Yue, Xijuan

    2016-05-01

    The manned low Earth orbit platforms (MLEOPs), e.g., the U.S. and Russia's human space vehicles, the International Space Station (ISS) and Chinese Tiangong-1 experimental space laboratory not only provide laboratories for scientific experiments in a wide range of disciplines, but also serve as exceptional platforms for remote observation of the Earth, astronomical objects and space environment. As the early orbiting platforms, the MLEOPs provide humans with revolutionary accessibility to the regions on Earth never seen before. Earth observation from MLEOPs began in early 1960s, as a part of manned space flight programs, and will continue with the ISS and upcoming Chinese Space Station. Through a series of flight missions, various and a large amount of Earth observing datasets have been acquired using handheld cameras by crewmembers as well as automated sophisticated sensors onboard these space vehicles. Utilizing these datasets many researches have been conducted, demonstrating the importance and uniqueness of studying Earth from a vantage point of MLEOPs. For example, the first, near-global scale digital elevation model (DEM) was developed from data obtained during the shuttle radar topography mission (SRTM). This review intends to provide an overview of Earth observations from MLEOPs and present applications conducted by the datasets collected by these missions. As the ISS is the most typical representative of MLEOPs, an introduction to it, including orbital characteristics, payload accommodations, and current and proposed sensors, is emphasized. The advantages and challenges of Earth observation from MLEOPs, using the ISS as an example, is also addressed. At last, a conclusive note is drawn.

  10. EarthN: A new Earth System Nitrogen Model

    OpenAIRE

    Johnson, Benjamin W.; Goldblatt, Colin

    2018-01-01

    The amount of nitrogen in the atmosphere, oceans, crust, and mantle have important ramifications for Earth's biologic and geologic history. Despite this importance, the history and cycling of nitrogen in the Earth system is poorly constrained over time. For example, various models and proxies contrastingly support atmospheric mass stasis, net outgassing, or net ingassing over time. In addition, the amount available to and processing of nitrogen by organisms is intricately linked with and prov...

  11. Sun-Earth Day, 2001

    Science.gov (United States)

    Adams, Mitzi L.; Mortfield, P.; Hathaway, D. H.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    To promote awareness of the Sun-Earth connection, NASA's Marshall Space Flight Center, in collaboration with the Stanford SOLAR Center, sponsored a one-day Sun-Earth Day event on April 27, 2001. Although "celebrated" on only one day, teachers and students from across the nation, prepared for over a month in advance. Workshops were held in March to train teachers. Students performed experiments, results of which were shared through video clips and an internet web cast. Our poster includes highlights from student experiments (grades 2 - 12), lessons learned from the teacher workshops and the event itself, and plans for Sun-Earth Day 2002.

  12. The earth's shape and gravity

    CERN Document Server

    Garland, G D; Wilson, J T

    2013-01-01

    The Earth's Shape and Gravity focuses on the progress of the use of geophysical methods in investigating the interior of the earth and its shape. The publication first offers information on gravity, geophysics, geodesy, and geology and gravity measurements. Discussions focus on gravity measurements and reductions, potential and equipotential surfaces, absolute and relative measurements, and gravity networks. The text then elaborates on the shape of the sea-level surface and reduction of gravity observations. The text takes a look at gravity anomalies and structures in the earth's crust; interp

  13. Earth analysis methods, subsurface feature detection methods, earth analysis devices, and articles of manufacture

    Science.gov (United States)

    West, Phillip B [Idaho Falls, ID; Novascone, Stephen R [Idaho Falls, ID; Wright, Jerry P [Idaho Falls, ID

    2011-09-27

    Earth analysis methods, subsurface feature detection methods, earth analysis devices, and articles of manufacture are described. According to one embodiment, an earth analysis method includes engaging a device with the earth, analyzing the earth in a single substantially lineal direction using the device during the engaging, and providing information regarding a subsurface feature of the earth using the analysis.

  14. Safety aspects in rare earths recovery

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2014-01-01

    Recovery of rare earths involves mining of beach sands, mineral separation to obtain monazite and its chemical processing to obtain rare earth composites. The composites are then subjected to further chemical treatment to obtain individual rare earths. Although the separated out rare earths are not radioactive, the process for recovery of rare earths involve both radiological as well as conventional hazards. This paper highlights the safety aspects in the mining, mineral separation and chemical processing of monazite to obtain rare earths

  15. Rare earth metals, rare earth hydrides, and rare earth oxides as thin films

    International Nuclear Information System (INIS)

    Gasgnier, M.

    1980-01-01

    The review deals with pure rare earth materials such as rare earth metals, rare earth hydrides, and rare earth oxides as thin films. Several preparation techniques, control methods, and nature of possible contaminations of thin films are described. These films can now be produced in an extremely well-known state concerning chemical composition, structure and texture. Structural, electric, magnetic, and optical properties of thin films are studied and discussed in comparison with the bulk state. The greatest contamination of metallic rare earth thin films is caused by reaction with hydrogen or with water vapour. The compound with an f.c.c. structure is the dihydride LnH 2 (Ln = lanthanides). The oxygen contamination takes place after annealing at higher temperatures. Then there appears a compound with a b.c.c. structure which is the C-type sesquioxide C-Ln 2 O 3 . At room atmosphere dihydride light rare earth thin films are converted to hydroxide Ln(OH) 3 . For heavy rare earth thin films the oxinitride LnNsub(x)Osub(y) is observed. The LnO-type compound was never seen. The present review tries to set the stage anew for the investigations to be undertaken in the future especially through the new generations of electron microscopes

  16. Children's knowledge of the Earth

    Science.gov (United States)

    Siegal, Michael; Nobes, Gavin; Panagiotaki, Georgia

    2011-03-01

    Children everywhere are fascinated by the sky, stars and Sun. Emerging evidence from cultures throughout the world suggests that even young children can acquire knowledge of the Earth and its place in the Universe.

  17. Encyclopedia of earth system science

    National Research Council Canada - National Science Library

    Nierenberg, William Aaron

    1992-01-01

    .... The very diversity of the articles attests to the complexity of earth system science as a unique interdisciplinary venture to place humanity in a position to move wisely to protect the global habitat...

  18. Measuring Earth's Magnetic Field Simply.

    Science.gov (United States)

    Stewart, Gay B.

    2000-01-01

    Describes a method for measuring the earth's magnetic field using an empty toilet paper tube, copper wire, clear tape, a battery, a linear variable resistor, a small compass, cardboard, a protractor, and an ammeter. (WRM)

  19. Earth Science Education in Morocco

    Science.gov (United States)

    Bouabdelli, Mohamed

    1999-05-01

    The earth sciences are taught in twelve universities in Morocco and in three other institutions. In addition there are three more earth science research institutions. Earth science teaching has been taking place since 1957. The degree system is a four-year degree, split into two two-year blocks and geology is taught within the geology-biology programme for the first part of the degree. 'Classical' geology is taught in most universities, although applied geology degrees are also on offer in some universities. Recently-formed technical universities offer a more innovative approach to Earth Science Education. Teaching is in French, although school education is in Arabic. There is a need for a reform of the curriculum, although a lead is being taken by the technical universities. A new geological mapping programme promises new geological and mining discoveries in the country and prospects of employment for geology graduates.

  20. The Search for Another Earth

    Indian Academy of Sciences (India)

    2016-08-26

    /fulltext/reso/021/07/0641-0652. Keywords. Stars, planets, planetary systems, detection. Abstract. Is there life anywhere else in the vast cosmos?Are there planets similar to the Earth? For centuries,these questions baffled ...

  1. Earth Charter and nuclear energy

    International Nuclear Information System (INIS)

    Grippi, Sidney

    2006-01-01

    The chapter presents Earth Charter, where are listed the principles in 4 sections: 1) respect and take care of the life community; 2) environmental integrity; social and economic welfare; 4) democracy, no-violence and peace

  2. NASA's Earth Science Data Systems

    Science.gov (United States)

    Ramapriyan, H. K.

    2015-01-01

    NASA's Earth Science Data Systems (ESDS) Program has evolved over the last two decades, and currently has several core and community components. Core components provide the basic operational capabilities to process, archive, manage and distribute data from NASA missions. Community components provide a path for peer-reviewed research in Earth Science Informatics to feed into the evolution of the core components. The Earth Observing System Data and Information System (EOSDIS) is a core component consisting of twelve Distributed Active Archive Centers (DAACs) and eight Science Investigator-led Processing Systems spread across the U.S. The presentation covers how the ESDS Program continues to evolve and benefits from as well as contributes to advances in Earth Science Informatics.

  3. A umbrella for the Earth

    International Nuclear Information System (INIS)

    Kunzig, R.

    2009-01-01

    In front of the global warming threat, the 'geo-engineers' foresee some solutions to change the climate of the Earth, like for instance, by hiding part of the solar radiation. Among the solutions one can notice: the injection of sulfur dioxide in the stratosphere, the artificial generation of clouds using sea fog generators, or the putting into orbit of disc-shape screens creating a 100000 km x 12000 km elliptical 'umbrella' between the sun and the Earth. (J.S.)

  4. Rare earth industries: Downstream business

    International Nuclear Information System (INIS)

    2011-01-01

    The value chain of the rare earths business involves mining, extraction, processing, refining and the manufacture of an extensive range of downstream products which find wide applications in such industries including aerospace, consumer electronics, medical, military, automotive, renewable wind and solar energy and telecommunications. In fact the entire gamut of the high-tech industries depends on a sustainable supply of rare earths elements. The explosive demand in mobile phones is an excellent illustration of the massive potential that the rare earths business offers. In a matter of less than 20 years, the number of cell phones worldwide has reached a staggering 5 billion. Soon, going by the report of their growth in sales, the world demand for cell phones may even exceed the global population. Admittedly, the rare earths business does pose certain risks. Top among the risks are the health and safety risks. The mining, extraction and refining of rare earths produce residues and wastes which carry health and safety risks. The residues from the extraction and refining are radioactive, while their effluent waste streams do pose pollution risks to the receiving rivers and waterways. But, as clearly elaborated in a recent report by IAEA experts, there are technologies and systems available to efficiently mitigate such risks. The risks are Rare Earth manageable. However, it is crucial that the risk and waste management procedures are strictly followed and adhered to. This is where effective monitoring and surveillance throughout the life of all such rare earths facilities is crucial. Fortunately, Malaysia's regulatory standards on rare earths follow international standards. In some areas, Malaysia's regulatory regime is even more stringent than the international guidelines. (author)

  5. Rare earth metal alloy magnets

    International Nuclear Information System (INIS)

    Harris, I.R.; Evans, J.M.; Nyholm, P.S.

    1979-01-01

    This invention relates to rare earth metal alloy magnets and to methods for their production. The technique is based on the fact that rare earth metal alloys (for e.g. cerium or yttrium) which have been crumbled to form a powder by hydride formation and decomposition can be used for the fabrication of magnets without the disadvantages inherent in alloy particle size reduction by mechanical milling. (UK)

  6. Rare-earth elements

    Science.gov (United States)

    Van Gosen, Bradley S.; Verplanck, Philip L.; Seal, Robert R.; Long, Keith R.; Gambogi, Joseph; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The rare-earth elements (REEs) are 15 elements that range in atomic number from 57 (lanthanum) to 71 (lutetium); they are commonly referred to as the “lanthanides.” Yttrium (atomic number 39) is also commonly regarded as an REE because it shares chemical and physical similarities and has affinities with the lanthanides. Although REEs are not rare in terms of average crustal abundance, the concentrated deposits of REEs are limited in number.Because of their unusual physical and chemical properties, the REEs have diverse defense, energy, industrial, and military technology applications. The glass industry is the leading consumer of REE raw materials, which are used for glass polishing and as additives that provide color and special optical properties to the glass. Lanthanum-based catalysts are used in petroleum refining, and cerium-based catalysts are used in automotive catalytic converters. The use of REEs in magnets is a rapidly increasing application. Neodymium-iron-boron magnets, which are the strongest known type of magnets, are used when space and weight are restrictions. Nickel-metal hydride batteries use anodes made of a lanthanum-based alloys.China, which has led the world production of REEs for decades, accounted for more than 90 percent of global production and supply, on average, during the past decade. Citing a need to retain its limited REE resources to meet domestic requirements as well as concerns about the environmental effects of mining, China began placing restrictions on the supply of REEs in 2010 through the imposition of quotas, licenses, and taxes. As a result, the global rare-earth industry has increased its stockpiling of REEs; explored for deposits outside of China; and promoted new efforts to conserve, recycle, and substitute for REEs. New mine production began at Mount Weld in Western Australia, and numerous other exploration and development projects noted in this chapter are ongoing throughout the world.The REE-bearing minerals are

  7. Greenhouse Earth: A Traveling Exhibition

    International Nuclear Information System (INIS)

    Booth, W.H.; Caesar, S.

    1992-09-01

    The Franklin Institute Science Museum provided an exhibit entitled the Greenhouse Earth: A Traveling Exhibition. This 3500 square-foot exhibit on global climate change was developed in collaboration with the Association of Science-Technology Centers. The exhibit opened at The Franklin Institute on February 14, 1992, welcoming 291,000 visitors over its three-month stay. During its three-year tour, Greenhouse Earth will travel to ten US cities, reaching two million visitors. Greenhouse Earth aims to deepen public understanding of the scientific issues of global warming and the conservation measures that can be taken to slow its effects. The exhibit features hands-on exhibitry, interactive computer programs and videos, a theater production, a ''demonstration cart,'' guided tours, and lectures. supplemental educational programs at the Institute included a teachers preview, a symposium on climate change, and a ''satellite field trip.'' The development of Greenhouse Earth included front-end and formative evaluation procedures. Evaluation includes interviews with visitors, prototypes, and summative surveys for participating museums. During its stay in Philadelphia, Greenhouse Earth was covered by the local and national press, with reviews in print and broadcast media. Greenhouse Earth is the first large-scale museum exhibit to address global climate change

  8. Next-generation Digital Earth.

    Science.gov (United States)

    Goodchild, Michael F; Guo, Huadong; Annoni, Alessandro; Bian, Ling; de Bie, Kees; Campbell, Frederick; Craglia, Max; Ehlers, Manfred; van Genderen, John; Jackson, Davina; Lewis, Anthony J; Pesaresi, Martino; Remetey-Fülöpp, Gábor; Simpson, Richard; Skidmore, Andrew; Wang, Changlin; Woodgate, Peter

    2012-07-10

    A speech of then-Vice President Al Gore in 1998 created a vision for a Digital Earth, and played a role in stimulating the development of a first generation of virtual globes, typified by Google Earth, that achieved many but not all the elements of this vision. The technical achievements of Google Earth, and the functionality of this first generation of virtual globes, are reviewed against the Gore vision. Meanwhile, developments in technology continue, the era of "big data" has arrived, the general public is more and more engaged with technology through citizen science and crowd-sourcing, and advances have been made in our scientific understanding of the Earth system. However, although Google Earth stimulated progress in communicating the results of science, there continue to be substantial barriers in the public's access to science. All these factors prompt a reexamination of the initial vision of Digital Earth, and a discussion of the major elements that should be part of a next generation.

  9. Rare earths as a future resource

    International Nuclear Information System (INIS)

    Cornell, D.H.

    1988-01-01

    The fourteen rare earth or lanthanide elements have recently emerged as an important natural resource because of the rapidly growing demand in the electronic, chemical and metallurgical industries. The Symposium on rare earth elements as a future resource presented a multidisciplinary review of rare earth chemistry, geology, beneficiation, industrial applications and marketing. Papers by experts in many fields were presented on the following topics: chemical properties of the rare earth elements; the analysis of rare earth elements and minerals; beneficiation and extraction of rare earth elements; economic geochemistry and mineralogy of rare earths; present industrial uses of rare earth elements; the role of rare earth elements in high-temperature superconductors; the technical application of high-temperature superconductors; supply and demand for rare earth products - now and in the future, and the geology of rare earth deposits

  10. Baltic Earth - Earth System Science for the Baltic Sea Region

    Science.gov (United States)

    Meier, Markus; Rutgersson, Anna; Lehmann, Andreas; Reckermann, Marcus

    2014-05-01

    The Baltic Sea region, defined as its river catchment basin, spans different climate and population zones, from a temperate, highly populated, industrialized south with intensive agriculture to a boreal, rural north. It encompasses most of the Scandinavian Peninsula in the west; most of Finland and parts of Russia, Belarus, and the Baltic states in the east; and Poland and small parts of Germany and Denmark in the south. The region represents an old cultural landscape, and the Baltic Sea itself is among the most studied sea areas of the world. Baltic Earth is the new Earth system research network for the Baltic Sea region. It is the successor to BALTEX, which was terminated in June 2013 after 20 years and two successful phases. Baltic Earth stands for the vision to achieve an improved Earth system understanding of the Baltic Sea region. This means that the research disciplines of BALTEX continue to be relevant, i.e. atmospheric and climate sciences, hydrology, oceanography and biogeochemistry, but a more holistic view of the Earth system encompassing processes in the atmosphere, on land and in the sea as well as in the anthroposphere shall gain in importance in Baltic Earth. Specific grand research challenges have been formulated, representing interdisciplinary research questions to be tackled in the coming years. A major means will be scientific assessments of particular research topics by expert groups, similar to the BACC approach, which shall help to identify knowledge gaps and develop research strategies. Preliminary grand challenges and topics for which Working Groups have been installed include: • Salinity dynamics in the Baltic Sea • Land-Sea biogeochemical feedbacks in the Baltic Sea region • Natural hazards and extreme events in the Baltic Sea region • Understanding sea level dynamics in the Baltic Sea • Understanding regional variability of water and energy exchange • Utility of Regional Climate Models • Assessment of Scenario Simulations

  11. EarthLabs - Investigating Hurricanes: Earth's Meteorological Monsters

    Science.gov (United States)

    McDaris, J. R.; Dahlman, L.; Barstow, D.

    2007-12-01

    Earth science is one of the most important tools that the global community needs to address the pressing environmental, social, and economic issues of our time. While, at times considered a second-rate science at the high school level, it is currently undergoing a major revolution in the depth of content and pedagogical vitality. As part of this revolution, labs in Earth science courses need to shift their focus from cookbook-like activities with known outcomes to open-ended investigations that challenge students to think, explore and apply their learning. We need to establish a new model for Earth science as a rigorous lab science in policy, perception, and reality. As a concerted response to this need, five states, a coalition of scientists and educators, and an experienced curriculum team are creating a national model for a lab-based high school Earth science course named EarthLabs. This lab course will comply with the National Science Education Standards as well as the states' curriculum frameworks. The content will focus on Earth system science and environmental literacy. The lab experiences will feature a combination of field work, classroom experiments, and computer access to data and visualizations, and demonstrate the rigor and depth of a true lab course. The effort is being funded by NOAA's Environmental Literacy program. One of the prototype units of the course is Investigating Hurricanes. Hurricanes are phenomena which have tremendous impact on humanity and the resources we use. They are also the result of complex interacting Earth systems, making them perfect objects for rigorous investigation of many concepts commonly covered in Earth science courses, such as meteorology, climate, and global wind circulation. Students are able to use the same data sets, analysis tools, and research techniques that scientists employ in their research, yielding truly authentic learning opportunities. This month-long integrated unit uses hurricanes as the story line by

  12. Towards Big Earth Data Analytics: The EarthServer Approach

    Science.gov (United States)

    Baumann, Peter

    2013-04-01

    Big Data in the Earth sciences, the Tera- to Exabyte archives, mostly are made up from coverage data whereby the term "coverage", according to ISO and OGC, is defined as the digital representation of some space-time varying phenomenon. Common examples include 1-D sensor timeseries, 2-D remote sensing imagery, 3D x/y/t image timeseries and x/y/z geology data, and 4-D x/y/z/t atmosphere and ocean data. Analytics on such data requires on-demand processing of sometimes significant complexity, such as getting the Fourier transform of satellite images. As network bandwidth limits prohibit transfer of such Big Data it is indispensable to devise protocols allowing clients to task flexible and fast processing on the server. The EarthServer initiative, funded by EU FP7 eInfrastructures, unites 11 partners from computer and earth sciences to establish Big Earth Data Analytics. One key ingredient is flexibility for users to ask what they want, not impeded and complicated by system internals. The EarthServer answer to this is to use high-level query languages; these have proven tremendously successful on tabular and XML data, and we extend them with a central geo data structure, multi-dimensional arrays. A second key ingredient is scalability. Without any doubt, scalability ultimately can only be achieved through parallelization. In the past, parallelizing code has been done at compile time and usually with manual intervention. The EarthServer approach is to perform a samentic-based dynamic distribution of queries fragments based on networks optimization and further criteria. The EarthServer platform is comprised by rasdaman, an Array DBMS enabling efficient storage and retrieval of any-size, any-type multi-dimensional raster data. In the project, rasdaman is being extended with several functionality and scalability features, including: support for irregular grids and general meshes; in-situ retrieval (evaluation of database queries on existing archive structures, avoiding data

  13. Rare earth industry in India

    International Nuclear Information System (INIS)

    Singh, D.S.

    2016-01-01

    Rare Earths (RE) comprises of 17 elements i.e. elements from atomic No. 57-71 (lanthanide series) along with yttrium (atomic No. 39) and scandium (atomic No. 21). They exhibit special electronic, magnetic, optical and catalytic properties. The first 7 elements in the lanthanide series from atomic Nos. 57 to 63 (La to Eu) are called Light Rare Earths (LRE), while the remaining elements from atomic Nos. 64 to 71 (Gd to Lu) are grouped as Heavy Rare Earths (HRE). Scandium and Yttrium have properties similar to HRE. The concentration of the REs in the earth's crust is as high as some other elements including that of copper. The only difference is that REs do not occur as separate minerals amenable for easy exploration and mining and are widely distributed across the earth's surface, hence they are called as REs. Resources In India, monazite has been the principal source of RE. It occurs in association with other heavy minerals, such as ilmenite, rutile, zircon etc. in the beach sands and inland placer deposits. The monazite content in this assemblage varies from negligible quantity to as high as 5%. As per AMD resource estimation, the reported resource of monazite in India is about 11.93 million tons which corresponds with about 6.9 million tons of RE oxides. Although India possesses large deposits of monazite, the heavier RE are not present in sufficient quantities in this mineral. (author)

  14. Smarter Earth Science Data System

    Science.gov (United States)

    Huang, Thomas

    2013-01-01

    The explosive growth in Earth observational data in the recent decade demands a better method of interoperability across heterogeneous systems. The Earth science data system community has mastered the art in storing large volume of observational data, but it is still unclear how this traditional method scale over time as we are entering the age of Big Data. Indexed search solutions such as Apache Solr (Smiley and Pugh, 2011) provides fast, scalable search via keyword or phases without any reasoning or inference. The modern search solutions such as Googles Knowledge Graph (Singhal, 2012) and Microsoft Bing, all utilize semantic reasoning to improve its accuracy in searches. The Earth science user community is demanding for an intelligent solution to help them finding the right data for their researches. The Ontological System for Context Artifacts and Resources (OSCAR) (Huang et al., 2012), was created in response to the DARPA Adaptive Vehicle Make (AVM) programs need for an intelligent context models management system to empower its terrain simulation subsystem. The core component of OSCAR is the Environmental Context Ontology (ECO) is built using the Semantic Web for Earth and Environmental Terminology (SWEET) (Raskin and Pan, 2005). This paper presents the current data archival methodology within a NASA Earth science data centers and discuss using semantic web to improve the way we capture and serve data to our users.

  15. Geodynamics of kimberlites on a cooling Earth: Clues to plate tectonic evolution and deep volatile cycles

    Science.gov (United States)

    Tappe, Sebastian; Smart, Katie; Torsvik, Trond; Massuyeau, Malcolm; de Wit, Mike

    2018-02-01

    Kimberlite magmatism has occurred in cratonic regions on every continent. The global age distribution suggests that this form of mantle melting has been more prominent after 1.2 Ga, and notably between 250-50 Ma, than during early Earth history before 2 Ga (i.e., the Paleoproterozoic and Archean). Although preservation bias has been discussed as a possible reason for the skewed kimberlite age distribution, new treatment of an updated global database suggests that the apparent secular evolution of kimberlite and related CO2-rich ultramafic magmatism is genuine and probably coupled to lowering temperatures of Earth's upper mantle through time. Incipient melting near the CO2- and H2O-bearing peridotite solidus at >200 km depth (1100-1400 °C) is the petrologically most feasible process that can produce high-MgO carbonated silicate melts with enriched trace element concentrations akin to kimberlites. These conditions occur within the convecting asthenospheric mantle directly beneath thick continental lithosphere. In this transient upper mantle source region, variable CHO volatile mixtures control melting of peridotite in the absence of heat anomalies so that low-degree carbonated silicate melts may be permanently present at ambient mantle temperatures below 1400 °C. However, extraction of low-volume melts to Earth's surface requires tectonic triggers. Abrupt changes in the speed and direction of plate motions, such as typified by the dynamics of supercontinent cycles, can be effective in the creation of lithospheric pathways aiding kimberlite magma ascent. Provided that CO2- and H2O-fluxed deep cratonic keels, which formed parts of larger drifting tectonic plates, existed by 3 Ga or even before, kimberlite volcanism could have been frequent during the Archean. However, we argue that frequent kimberlite magmatism had to await establishment of an incipient melting regime beneath the maturing continents, which only became significant after secular mantle cooling to below

  16. Models of the earth's core

    Science.gov (United States)

    Stevenson, D. J.

    1981-01-01

    Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.

  17. Revolutions that made the earth

    CERN Document Server

    Lenton, Tim

    2013-01-01

    The Earth that sustains us today was born out of a few remarkable, near-catastrophic revolutions, started by biological innovations and marked by global environmental consequences. The revolutions have certain features in common, such as an increase in the complexity, energy utilization, and information processing capabilities of life. This book describes these revolutions, showing the fundamental interdependence of the evolution of life and its non-living environment. We would not exist unless these upheavals had led eventually to 'successful' outcomes - meaning that after each one, at length, a new stable world emerged. The current planet-reshaping activities of our species may be the start of another great Earth system revolution, but there is no guarantee that this one will be successful. This book explains what a successful transition through it might look like, if we are wise enough to steer such a course. This book places humanity in context as part of the Earth system, using a new scientific synthe...

  18. Free oscillation of the Earth

    Directory of Open Access Journals (Sweden)

    Y. Abedini

    2000-06-01

    Full Text Available   This work is a study of the Earths free oscillations considering a merge of solid and liquid model. At the turn of 19th century Geophysicists presented the theory of the free oscillations for a self-gravitating, isotropic and compressible sphere. Assuming a steel structure for an Earth size sphere, they predicted a period of oscillation of about 1 hour. About 50 years later, the free oscillations of stars was studied by Cowling and others. They classified the oscillation modes of the stars into acoustic and gravity modes on the basis of their driving forces. These are pressure and buoyancy forces respectively. The earliest measurements for the period of the free oscillations of the Earth was made by Benyove from a study of Kamchathca earthquake. Since then, the Geophysicists have been trying to provide a theoretical basis for these measurements. Recently, the theory concerning oscillations of celestial fluids is extended by Sobouti to include the possible oscillations of the Earthlike bodies. Using the same technique, we study the free oscillations of a spherically symmetric, non-rotating and elastic model for the Earth.   We used the actual data of the Earths interior structure in our numerical calculations. Numerical results show that there exist three distinct oscillation modes namely acoustic, gravity and toroidal modes. These modes are driven by pressure, buoyancy and shear forces respectively. The shear force is due to the elastic properties of the solid part of the Earth. Our numerical results are consistent with the seismic data recorded from earthquake measurements.

  19. Universities Earth System Scientists Program

    Science.gov (United States)

    Estes, John E.

    1995-01-01

    This document constitutes the final technical report for the National Aeronautics and Space Administration (NASA) Grant NAGW-3172. This grant was instituted to provide for the conduct of research under the Universities Space Research Association's (USRA's) Universities Earth System Scientist Program (UESSP) for the Office of Mission to Planet Earth (OMTPE) at NASA Headquarters. USRA was tasked with the following requirements in support of the Universities Earth System Scientists Programs: (1) Bring to OMTPE fundamental scientific and technical expertise not currently resident at NASA Headquarters covering the broad spectrum of Earth science disciplines; (2) Conduct basic research in order to help establish the state of the science and technological readiness, related to NASA issues and requirements, for the following, near-term, scientific uncertainties, and data/information needs in the areas of global climate change, clouds and radiative balance, sources and sinks of greenhouse gases and the processes that control them, solid earth, oceans, polar ice sheets, land-surface hydrology, ecological dynamics, biological diversity, and sustainable development; (3) Evaluate the scientific state-of-the-field in key selected areas and to assist in the definition of new research thrusts for missions, including those that would incorporate the long-term strategy of the U.S. Global Change Research Program (USGCRP). This will, in part, be accomplished by study and evaluation of the basic science needs of the community as they are used to drive the development and maintenance of a global-scale observing system, the focused research studies, and the implementation of an integrated program of modeling, prediction, and assessment; and (4) Produce specific recommendations and alternative strategies for OMTPE that can serve as a basis for interagency and national and international policy on issues related to Earth sciences.

  20. Physical Processes Controlling Earth's Climate

    Science.gov (United States)

    Genio, Anthony Del

    2013-01-01

    As background for consideration of the climates of the other terrestrial planets in our solar system and the potential habitability of rocky exoplanets, we discuss the basic physics that controls the Earths present climate, with particular emphasis on the energy and water cycles. We define several dimensionless parameters relevant to characterizing a planets general circulation, climate and hydrological cycle. We also consider issues associated with the use of past climate variations as indicators of future anthropogenically forced climate change, and recent advances in understanding projections of future climate that might have implications for Earth-like exoplanets.

  1. Setting to earth for computer

    International Nuclear Information System (INIS)

    Gallego V, Luis Eduardo; Montana Ch, Johny Hernan; Tovar P, Andres Fernando; Amortegui, Francisco

    2000-01-01

    The program GMT allows the analysis of setting to earth for tensions DC and AC (of low frequency) of diverse configurations composed by cylindrical electrodes interconnected, in a homogeneous land or stratified (two layers). This analysis understands among other aspects: calculation of the setting resistance to earth, elevation of potential of the system (GPR), calculation of current densities in the conductors, potentials calculation in which point on the land surface (profile and surfaces), tensions calculation in passing and of contact, also, it carries out the interpretation of resistivity measures for Wenner and Schlumberger methods, finding a model of two layers

  2. Rare earths and rare earth alloys electrolytic preparation process and device for this process

    International Nuclear Information System (INIS)

    Seon, F.; Barthole, G.

    1986-01-01

    Electrolysis of a molten salt of rare earth or rare earth alloy for preparation of the metal or alloy is described. The molten salt bath comprises at least a rare earth chloride, at least an alkaline or alkaline earth chloride and at least an alkaline or alkaline earth fluoride [fr

  3. Early Earth(s) Across Time and Space

    Science.gov (United States)

    Mojzsis, S.

    2014-04-01

    The geochemical and cosmochemical record of our solar system is the baseline for exploring the question: "when could life appear on a world similar to our own?" Data arising from direct analysis of the oldest terrestrial rocks and minerals from the first 500 Myr of Earth history - termed the Hadean Eon - inform us about the timing for the establishment of a habitable silicate world. Liquid water is the key medium for life. The origin of water, and its interaction with the crust as revealed in the geologic record, guides our exploration for a cosmochemically Earth-like planets. From the time of primary planetary accretion to the start of the continuous rock record on Earth at ca. 3850 million years ago, our planet experienced a waning bolide flux that partially or entirely wiped out surface rocks, vaporized oceans, and created transient serpentinizing atmospheres. Arguably, "Early Earths" across the galaxy may start off as ice planets due to feeble insolation from their young stars, occasionally punctuated by steam atmospheres generated by cataclysmic impacts. Alternatively, early global environments conducive to life spanned from a benign surface zone to deep into crustal rocks and sediments. In some scenarios, nascent biospheres benefit from the exogenous delivery of essential bio-elements via leftovers of accretion, and the subsequent establishment of planetary-scale hydrothermal systems. If what is now known about the early dynamical regime of the Earth serves as any measure of the potential habitability of worlds across space and time, several key boundary conditions emerge. These are: (i) availability and long-term stability of liquid water; (ii) presence of energy resources; (iii) accessibility of organic raw materials; (iv) adequate inventory of radioisotopes to drive internal heating; (v) gross compositional parameters such as mantle/core mass ratio, and (vi) P-T conditions at or near the surface suitable for sustaining biological activity. Life could

  4. The Greatest Show on Earth

    Indian Academy of Sciences (India)

    Darwin and Alfred Russel Wallace: life on earth had evolved ... over long epochs, the pace of change was infinitesimal. ... Thanks to the work of the Japanese theoreti- cian Motoo ... pleasure-minus-expenditure balance is posi- tive. This way of ...

  5. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  6. Earth Day 2012: Greening Government

    Centers for Disease Control (CDC) Podcasts

    2012-04-19

    This podcast describes sustainability efforts at CDC in relation to Earth Day celebrations and details agency greenhouse gas reduction strategies and successes.  Created: 4/19/2012 by Office of the Chief Operating Officer (OCOO)/ Chief Sustainability Office (CSO).   Date Released: 4/23/2012.

  7. NASA Earth Science Education Collaborative

    Science.gov (United States)

    Schwerin, T. G.; Callery, S.; Chambers, L. H.; Riebeek Kohl, H.; Taylor, J.; Martin, A. M.; Ferrell, T.

    2016-12-01

    The NASA Earth Science Education Collaborative (NESEC) is led by the Institute for Global Environmental Strategies with partners at three NASA Earth science Centers: Goddard Space Flight Center, Jet Propulsion Laboratory, and Langley Research Center. This cross-organization team enables the project to draw from the diverse skills, strengths, and expertise of each partner to develop fresh and innovative approaches for building pathways between NASA's Earth-related STEM assets to large, diverse audiences in order to enhance STEM teaching, learning and opportunities for learners throughout their lifetimes. These STEM assets include subject matter experts (scientists, engineers, and education specialists), science and engineering content, and authentic participatory and experiential opportunities. Specific project activities include authentic STEM experiences through NASA Earth science themed field campaigns and citizen science as part of international GLOBE program (for elementary and secondary school audiences) and GLOBE Observer (non-school audiences of all ages); direct connections to learners through innovative collaborations with partners like Odyssey of the Mind, an international creative problem-solving and design competition; and organizing thematic core content and strategically working with external partners and collaborators to adapt and disseminate core content to support the needs of education audiences (e.g., libraries and maker spaces, student research projects, etc.). A scaffolded evaluation is being conducted that 1) assesses processes and implementation, 2) answers formative evaluation questions in order to continuously improve the project; 3) monitors progress and 4) measures outcomes.

  8. Studying the Earth from space

    Science.gov (United States)

    ,

    1981-01-01

    Space age technology contains a key to increased knowledge about the Earth's resources; this key is remote sensing detecting the nature or condition of something without actually touching it. An early and still most useful form of remote sensing is photography which records the

  9. A journey through Earth climates

    International Nuclear Information System (INIS)

    Ramstein, Gilles; Brunet, Michel

    2015-01-01

    The author proposes a history of climates all along Earth's history, describes how cold and warm periods have been alternating during these billions of years. He also tries to highlight lessons learned from this long evolution of climate in order to better understand the current global warming. He discusses whether this disruption is unique in Earth's history, and how it threatens our environment and therefore our survival. The chapters describe how Earth could escape a global glaciation, the thermal regulation by greenhouse effect gases in a world without oxygen, the empowerment of oxygen and the first thermal accident, a new oxygenated and warm world, the second accident or how Earth entered and escaped from periods of total glaciation, the possible stabilisation, the succession of deregulations, crisis and extinctions, the slow way down to the cold, the various paleo-indicators during the Quaternary, the high frequency oscillations of climate during the last million of years, and the uncertain projections

  10. Solar Flare Aimed at Earth

    Science.gov (United States)

    2002-01-01

    At the height of the solar cycle, the Sun is finally displaying some fireworks. This image from the Solar and Heliospheric Observatory (SOHO) shows a large solar flare from June 6, 2000 at 1424 Universal Time (10:24 AM Eastern Daylight Savings Time). Associated with the flare was a coronal mass ejection that sent a wave of fast moving charged particles straight towards Earth. (The image was acquired by the Extreme ultaviolet Imaging Telescope (EIT), one of 12 instruments aboard SOHO) Solar activity affects the Earth in several ways. The particles generated by flares can disrupt satellite communications and interfere with power transmission on the Earth's surface. Earth's climate is tied to the total energy emitted by the sun, cooling when the sun radiates less energy and warming when solar output increases. Solar radiation also produces ozone in the stratosphere, so total ozone levels tend to increase during the solar maximum. For more information about these solar flares and the SOHO mission, see NASA Science News or the SOHO home page. For more about the links between the sun and climate change, see Sunspots and the Solar Max. Image courtesy SOHO Extreme ultaviolet Imaging Telescope, ESA/NASA

  11. The Earth as a Polder

    Indian Academy of Sciences (India)

    that the resources of the earth as a whole will .... tion of land and underground water sources as a ... oil; the different visions and desires of old and .... the world, one showing its political hot spots, ... Guns, Germs, and Steel, and The Rise and.

  12. The Dynamic Earth: Recycling Naturally!

    Science.gov (United States)

    Goldston, M. Jenice; Allison, Elizabeth; Fowler, Lisa; Glaze, Amanda

    2013-01-01

    This article begins with a thought-provoking question: What do you think of when you hear the term "recycle?" Many think about paper, glass, aluminum cans, landfills, and reducing waste by reusing some of these materials. How many of us ever consider the way the systems of Earth dynamically recycle its materials? In the following…

  13. Lessons from Earth's Deep Time

    Science.gov (United States)

    Soreghan, G. S.

    2005-01-01

    Earth is a repository of data on climatic changes from its deep-time history. Article discusses the collection and study of these data to predict future climatic changes, the need to create national study centers for the purpose, and the necessary cooperation between different branches of science in climatic research.

  14. Refresher Course on Earth Sciences

    Indian Academy of Sciences (India)

    Information and Announcements ... Introduction: Geoscience education in India is in the throes of a serious crisis and any paradigm ... considerations: geology needs to be taught as an earth system science, linked with cognate ... viable and employment-generating management of natural resources: the global trend of.

  15. Paleoseismology: evidence of earth activity

    Czech Academy of Sciences Publication Activity Database

    Nováková, Lucie

    2016-01-01

    Roč. 105, č. 5 (2016), 1467-1469 ISSN 1437-3254 Institutional support: RVO:67985891 Keywords : Paleoseismology * Colluvial wedge * White Creek Fault _ * Greendale Fault * San Andreas Fault * Paganica Fault Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.283, year: 2016

  16. The two earths of Eratosthenes.

    Science.gov (United States)

    Carman, Christián Carlos; Evans, James

    2015-03-01

    In the third century B.C.E., Eratosthenes of Cyrene made a famous measurement of the circumference of the Earth. This was not the first such measurement, but it is the earliest for which significant details are preserved. Cleomedes gives a short account of Eratosthenes' method, his numerical assumptions, and the final result of 250,000 stades. However, many ancient sources attribute to Eratosthenes a result of 252,000 stades. Historians have attempted to explain the second result by supposing that Eratosthenes later made better measurements and revised his estimate or that the original result was simply rounded to 252,000 to have a number conveniently divisible by 60 or by 360. These explanations are speculative and untestable. However, Eratosthenes' estimates of the distances of the Sun and Moon from the Earth are preserved in the doxographical literature. This essay shows that Eratosthenes' result of 252,000 stades for the Earth's circumference follows from a solar distance that is attributed to him. Thus it appears that Eratosthenes computed not only a lower limit for the size of the Earth, based on the assumption that the Sun is at infinity, but also an upper limit, based on the assumption that the Sun is at a finite distance. The essay discusses the consequences for our understanding of his program.

  17. Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

    Science.gov (United States)

    Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

    2011-06-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be

  18. Rare earths: occurrence, production and applications

    International Nuclear Information System (INIS)

    Murthy, T.K.S.; Mukherjee, T.K.

    2002-01-01

    The mining and processing of rare earth minerals, particularly of monazite, began in a modest way in 1880s for commercialized production of mantle for gas lighting. For all major applications up to mid-twentieth century- production of lighter flints, misch metal as a metallurgical alloying agent, colouring, decolourizing and polishing agents for glass, petroleum cracking catalysts and arc-carbons, unseparated or partially separated rare earths were adequate. These applications continue till today. With the development and industrial application of powerful techniques like ion exchange and solvent extraction for the separation of rare earths, the decades after 1960 saw increasing utilization of the specific properties of the individual rare earths. Some of these advanced technological applications include: special glass for optical systems including camera lenses, phosphors for colour television, cathode ray tubes and fluorescent lighting, X-ray intensification screens, high intensity permanent magnets, electro optical devices, lasers, hydrogen storage materials, hydride rechargeable batteries, photomagnetic data storage systems, autoexhaust catalysts, special ceramics of unusual toughness, artificial diamonds and nonpoisonous plastic colorants. The topics covered in the book include rare earths: their story identity, rare earth resources, processing of ores and recovery of mixed rare earths products, separation and purification of rare earths, nonmetallic applications of rare earths, rare earth metals: production and applications, rare earth alloys and their applications, analysis of rare earth, processing of rare earth resources in India by Indian Rare Earth Ltd. and availability and market conditions

  19. Development of an earth pressure model for design of earth retaining structures in piedmont soil.

    Science.gov (United States)

    2008-10-01

    Anecdotal evidence suggests that earth pressure in Piedmont residual soils is typically over estimated. Such estimates of earth pressure impact the design of earth retaining structures used on highway projects. Thus, the development of an appropriate...

  20. Behaviour of Rare Earth Elements during the Earth's core formation

    Science.gov (United States)

    Faure, Pierre; Bouhifd, Mohamed Ali; Boyet, Maud; Hammouda, Tahar; Manthilake, Geeth

    2017-04-01

    Rare Earth Elements (REE) are classified in the refractory group, which means that they have a high temperature condensation and their volatility-controlled fractionation is limited to high-temperature processes. Anomalies have been measured for Eu, Yb and Sm, which are the REE with the lowest condensation temperatures in CAIs and chondrules (e.g. [1]). REE are particularly abundant in the sulfides of enstatite chondrites, 100 to 1000 times the CI value [e.g. 2,3], proving that these elements are not strictly lithophile under extremely reducing conditions. However by investigating experimentally the impact of Earth's core formation on the behavior of Sm and Nd, we have shown the absence of fractionation between Sm and Nd during the segregation of the metallic phase [4]. Recently, Wohlers and Wood [5] proposed that Nd and Sm could be fractionated in presence of a S-rich alloy phase. However, their results were obtained at pressure and temperature conditions below the plausible conditions of the Earth's core formation. Clearly, large pressure range needs to be covered before well-constrained model can be expected. Furthermore, our preliminary metal-silicate partitioning results show that Ce and Eu have higher metal/silicate partition coefficients than their neighboring elements, and that the presence of sulphur enhances the relative difference between partition coefficients. In this presentation, we will present and discuss new metal-silicate partition coefficients of all REE at a deep magma ocean at pressures ranging from those of the uppermost upper mantle ( 5 GPa) to a maximum pressure expected in the range of 20 GPa, temperatures ranging from 2500 to about 3000 K, and oxygen fugacities within IW-1 to IW-5 (1 to 5 orders of magnitude lower than the iron-wüstite buffer). We will discuss the effect of S, as well as the effect of H2O on the behaviour of REE during the Earth's core formation: recent models suggest that contrary to currently accepted beliefs, the

  1. WAVE TECTONICS OF THE EARTH

    Directory of Open Access Journals (Sweden)

    Tatiana Yu. Tveretinova

    2010-01-01

    Full Text Available In the Earth's lithosphere, wavy alternation of positive and negative heterochronous structures is revealed; such structures are variable in ranks and separated by vergence zones of fractures and folds. In the vertical profile of the lithosphere, alternating are layers characterized by relatively plastic or fragile rheological properties and distinguished by different states of stress. During the Earth’s evolution, epochs of compression and extension are cyclically repeated, including planetary-scale phenomena which are manifested by fluctuating changes of the planet’s volume. Migration of geological and geophysical (geodynamic processes takes place at the Earth's surface and in its interior. The concept of the wave structure and evolution of the Earth's lithosphere provides explanations to the abovementioned regularities. Wavy nature of tectonic structures of the lithosphere, the cyclic recurrence of migration and geological processes in space and time can be described in terms of the multiple-order wave geodynamics of the Earth's lithosphere that refers to periodical variations of the state of stress. Effects of structure-forming tectonic forces are determined by «interference» of tangential and radial stresses of the Earth. The tangential stresses, which occur primarily due to the rotational regime of the planet, cause transformations of the Earth’s shape, redistributions of its substance in depths, the westward drift of the rock mass in its upper levels, and changes of structural deformation plans. The radial stresses, which are largely impacted by gravity, determine the gravitational differentiation of the substance, vertical flattening and sub-horizontal flow of the rock masses, and associated fold-rupture deformation. Under the uniform momentum geodynamic concept proposed by [Vikulin, Tveritinova, 2004, 2005, 2007, 2008], it is possible to provide consistent descriptions of seismic and volcanic, tectonic and geological processes

  2. Rare Earth Garnet Selective Emitter

    Science.gov (United States)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

  3. EarthN: A new Earth System Nitrogen Model

    OpenAIRE

    Goldblatt, Colin; Johnson, Benjamin

    2018-01-01

    The amount of nitrogen in the atmosphere, oceans, crust, and mantle have important ramifications for Earth’s biologic and geologic history. Despite this importance, the history and cycling of nitrogen in the Earth system is poorly constrained over time. For example, various models and proxies contrastingly support atmospheric mass stasis, net outgassing, or net ingassing over time. In addition, the amount available to and processing of nitrogen by organisms is intricately linked with and prov...

  4. Immersive Earth: Teaching Earth and Space with inexpensive immersive technology

    Science.gov (United States)

    Reiff, P. H.; Sumners, C.; Law, C. C.; Handron, K.

    2003-12-01

    In 1995 we pioneered "Space Update", the Digital Library for the rest of us", software that was so simple that a child could use it without a keyboard and yet would allow one-click updating of the daily earth and space science images without the dangers of having an open web browser on display. Thanks to NASA support, it allowed museums and schools to have a powerful exhibit for a tiny price. Over 40,000 disks in our series have been distributed so far to educators and the public. In 2003, with our partners we are again revolutionizing educational technology with a low-cost hardware and software solution to creating and displaying immersive content. Recently selected for funding as part of the REASoN competition, Immersive Earth is a partnership of scientists, museums, educators, and content providers. The hardware consists of a modest projector with a special fisheye lens to be used in an inflatable dome which many schools already have. This, coupled with a modest personal computer, can now easily project images and movies of earth and space, allows training students in 3-D content at a tiny fraction of the cost of a cave or fullscale dome theater. Another low-cost solution is the "Imove" system, where spherical movies can play on a personal computer, with the user changing the viewing direction with a joystick. We were the first to create immersive earth science shows, remain the leader in creating educational content that people want to see. We encourage people with "allsky" images or movies to bring it and see what it looks like inside a dome! Your content could be in our next show!

  5. Sensing Planet Earth - Chalmers' MOOCs on Earth observation

    Science.gov (United States)

    Hobiger, Thomas; Stöhr, Christian; Murtagh, Donal; Forkman, Peter; Galle, Bo; Mellquist, Johan; Soja, Maciej; Berg, Anders; Carvajal, Gisela; Eriksson, Leif; Haas, Rüdiger

    2016-04-01

    An increasing number of universities around the globe produce and conduct Massive Open Online Courses (MOOCs). In the beginning of 2016, Chalmers University of Technology ran two MOOCs on the topic of Earth observations on the edX platform. Both four week long courses were at introductory level and covered topics related to solid Earth, atmosphere, biosphere, hydrosphere and cryosphere. It was discussed how one can measure and trace global change and use remote sensing tools for disaster monitoring. Research has attempted to assess the learners' motivations to participate in MOOCs, but there is a need for further case studies about motivations, opportunities and challenges for teachers engaging in MOOC development. In our presentation, we are going to report about the experiences gained from both the MOOC production and the actual course run from the instructors' perspective. After brief introduction to MOOCs in general and at Chalmers in particular, we share experiences and challenges of developing lecture and assessment material, the video production and coordination efforts between and within different actors involved in the production process. Further, we reflect upon the actual run of the course including course statistics and feedback from the learners. We discuss issues such as learner activation and engagement with the material, teacher-learner and student-student interaction as well as the scalability of different learning activities. Finally, we will present our lessons-learned and conclusions on the applicability of MOOCs in the field of Earth science teaching.

  6. Life on Earth: From Chemicals in Space?

    Science.gov (United States)

    Chemical and Engineering News, 1973

    1973-01-01

    Discusses experimental evidence for the existence of organic material in the solar system prior to the earth's formation. Indicates that the earth could have received much of its organic compounds from meteors falling on its primitive surface. (CC)

  7. Optical properties of alkaline earth borate glasses

    African Journals Online (AJOL)

    user

    The alkaline earth borate glasses containing heavy metal oxides show good solubility of rare-earth ions. Glasses containing PbO exhibit low glass transition temperature (Tg) and high ..... These oxygen ions carry a partial negative charge and.

  8. Optical properties of alkaline earth borate glasses

    African Journals Online (AJOL)

    user

    ... devices; radiation shields, surgical lasers and their glass ceramic counter ... Alkaline earth oxides improve glass forming capability while heavy metal ... reports on optical properties of MO-B2O3 glasses containing alkaline earth oxides.

  9. Earth Observing System Covariance Realism Updates

    Science.gov (United States)

    Ojeda Romero, Juan A.; Miguel, Fred

    2017-01-01

    This presentation will be given at the International Earth Science Constellation Mission Operations Working Group meetings June 13-15, 2017 to discuss the Earth Observing System Covariance Realism updates.

  10. ``An Earth-Shaking Experience''

    Science.gov (United States)

    Achenbach, Joel

    2005-03-01

    Last month's annual meeting of the American Geophysical Union in San Francisco drew an estimated 11,000 scientists, teachers, journalists and geophysics groupies. The schedule of talks could be found in a bound volume as thick as a phone book. You never see a geophysicist in ordinary life, but apparently the world is crawling with them. They came to talk about everything from the ozone layer to the big wad of iron at the center of the Earth. Also about other planets. And magnetic fields. Solar wind. Water on Mars. To be at this convention was to be immersed to the eyebrows in scientific knowledge. It is intellectually fashionable to fetishize the unknown, but at AGU, a person will get the opposite feeling-that science is a voracious, relentless and tireless enterprise, and that soon there may not remain on this Earth an unturned stone.

  11. Tidal variations of earth rotation

    Science.gov (United States)

    Yoder, C. F.; Williams, J. G.; Parke, M. E.

    1981-01-01

    The periodic variations of the earths' rotation resulting from the tidal deformation of the earth by the sun and moon were rederived including terms with amplitudes of 0.002 millisec and greater. The series applies to the mantle, crust, and oceans which rotate together for characteristic tidal periods; the scaling parameter is the ratio of the fraction of the Love number producing tidal variations in the moment of inertia of the coupled mantle and oceans (k) to the dimensionless polar moment of inertia of the coupled moments (C). The lunar laser ranging data shows that k/C at monthly and fortnightly frequencies equals 0.99 + or - 0.15 and 0.99 + or - 0.20 as compared to the theoretical value of 0.94 + or - 0.04.

  12. Solar influence on Earth's climate

    DEFF Research Database (Denmark)

    Marsh, N.; Svensmark, Henrik

    2003-01-01

    An increasing number of studies indicate that variations in solar activity have had a significant influence on Earth's climate. However, the mechanisms responsible for a solar influence are still not known. One possibility is that atmospheric transparency is influenced by changing cloud properties...... and thereby influence the radiative properties of clouds. If the GCR-Cloud link is confirmed variations in galactic cosmic ray flux, caused by changes in solar activity and the space environment, could influence Earth's radiation budget....... via cosmic ray ionisation (the latter being modulated by solar activity). Support for this idea is found from satellite observations of cloud cover. Such data have revealed a striking correlation between the intensity of galactic cosmic rays (GCR) and low liquid clouds (

  13. Stamping the Earth from space

    CERN Document Server

    Dicati, Renato

    2017-01-01

    This unique book presents a historical and philatelic survey of Earth exploration from space. It covers all areas of research in which artificial satellites have contributed in designing a new image of our planet and its environment: the atmosphere and ionosphere, the magnetic field, radiation belts and the magnetosphere, weather, remote sensing, mapping of the surface, observation of the oceans and marine environments, geodesy, and the study of life and ecological systems. Stamping the Earth from Space presents the results obtained with the thousands of satellites launched by the two former superpowers, the Soviet Union and the United States, and also those of the many missions carried out by the ESA, individual European countries, Japan, China, India, and the many emerging space nations. Beautifully illustrated, it contains almost 1100 color reproductions of philatelic items. In addition to topical stamps and thematic postal documents, the book provides an extensive review of astrophilatelic items. The most...

  14. Mapping Near-Earth Hazards

    Science.gov (United States)

    Kohler, Susanna

    2016-06-01

    How can we hunt down all the near-Earth asteroids that are capable of posing a threat to us? A new study looks at whether the upcoming Large Synoptic Survey Telescope (LSST) is up to the job.Charting Nearby ThreatsLSST is an 8.4-m wide-survey telescope currently being built in Chile. When it goes online in 2022, it will spend the next ten years surveying our sky, mapping tens of billions of stars and galaxies, searching for signatures of dark energy and dark matter, and hunting for transient optical events like novae and supernovae. But in its scanning, LSST will also be looking for asteroids that approach near Earth.Cumulative number of near-Earth asteroids discovered over time, as of June 16, 2016. [NASA/JPL/Chamberlin]Near-Earth objects (NEOs) have the potential to be hazardous if they cross Earths path and are large enough to do significant damage when they impact Earth. Earths history is riddled with dangerous asteroid encounters, including the recent Chelyabinsk airburst in 2013, the encounter that caused the kilometer-sized Meteor Crater in Arizona, and the impact thought to contribute to the extinction of the dinosaurs.Recognizing the potential danger that NEOs can pose to Earth, Congress has tasked NASA with tracking down 90% of NEOs larger than 140 meters in diameter. With our current survey capabilities, we believe weve discovered roughly 25% of these NEOs thus far. Now a new study led by Tommy Grav (Planetary Science Institute) examines whether LSST will be able to complete this task.Absolute magnitude, H, of asynthetic NEO population. Though these NEOs are all larger than 140 m, they have a large spread in albedos. [Grav et al. 2016]Can LSST Help?Based on previous observations of NEOs and resulting predictions for NEO properties and orbits, Grav and collaborators simulate a synthetic population of NEOs all above 140 m in size. With these improved population models, they demonstrate that the common tactic of using an asteroids absolute magnitude as a

  15. Rare earth industries: Upstream business

    International Nuclear Information System (INIS)

    2011-01-01

    Evidently, many factors contribute to the rush to invest in the unprecedented revival of rare earths. One major reason has to do with the rapidly growing world demand. The other reason relates to the attractive price of rare earths which is projected to stay strong in the coming years. This is because supply is predicted to have difficulty keeping pace with demand. Experts believe a major driver of global rare earths demand is the forecasted expansion in the green economy. Climate change is a major driver of the green economy. With climate change, there is concern that the uncontrolled emission of the greenhouse gases, especially carbon dioxide, can lead to catastrophic consequences for the world. This has been documented in countless studies and reports. Another important driver of the green economy is the growing shortfall in many resources. The world is now experiencing declines in key resources to meet a growing global demand. With more than 6 billion people now in the world and growing, the pressure exerted on global resources including energy, water and food is a major concern. Recent demand surge in China and India has dented the supply position of major world resources. The much quoted Stern Report from the UK has warned that, unless immediate steps are taken to reduce greenhouse gas emissions, it may be a costly exercise to undertake the corrections later. Since energy use, especially fossil fuels, is a major contributor to climate change, greener options are being sought. Add to that the fact that the fossil energy resources of the world are declining, the need to seek alternatives becomes even more urgent. One option is to change to renewable energy sources. These include such potentials as solar, wind and biomass. Rare earths have somehow become a critical feature of the technologies in such renewable. Another option is to improve the efficient use of energy in transport, buildings and all the other energy intensive industries. Again the technologies in

  16. Earth Science Capability Demonstration Project

    Science.gov (United States)

    Cobleigh, Brent

    2006-01-01

    A viewgraph presentation reviewing the Earth Science Capability Demonstration Project is shown. The contents include: 1) ESCD Project; 2) Available Flight Assets; 3) Ikhana Procurement; 4) GCS Layout; 5) Baseline Predator B Architecture; 6) Ikhana Architecture; 7) UAV Capability Assessment; 8) The Big Picture; 9) NASA/NOAA UAV Demo (5/05 to 9/05); 10) NASA/USFS Western States Fire Mission (8/06); and 11) Suborbital Telepresence.

  17. Earth's Paleomagnetosphere and Planetary Habitability

    Science.gov (United States)

    Tarduno, J. A.; Blackman, E. G.; Oda, H.; Bono, R. K.; Carroll-Nellenback, J.; Cottrell, R. D.; Nimmo, F.

    2017-12-01

    The geodynamo is thought to play an important role in protecting Earth's hydrosphere, vital for life as we know it, from loss due to the erosive potential of the solar wind. Here we consider the mechanisms and history of this shielding. A larger core dynamo magnetic field strength provides more pressure to abate the solar wind dynamic pressure, increasing the magnetopause radius. However, the larger magnetopause also implies a larger collecting area for solar wind flux during phases of magnetic reconnection. The important variable is not mass capture but energy transfer, which does not scale linearly with magnetosphere size. Moreover, the ordered field provides the magnetic topology for recapturing atmospheric components in the opposite hemisphere such that the net global loss might not be greatly affected. While a net protection role for magnetospheres is suggested, forcing by the solar wind will change with stellar age. Paleomagnetism utilizing the single silicate crystal approach, defines a relatively strong field some 3.45 billion years ago (the Paleoarchean), but with a reduced magnetopause of 5 Earth radii, implying the potential for some atmospheric loss. Terrestrial zircons from the Jack Hills (Western Australia) and other localities host magnetic inclusions, whose magnetization has now been recorded by a new generation of ultra-sensitive 3-component SQUID magnetometer (U. Rochester) and SQUID microscope (GSJ/AIST). Paleointensity data suggest the presence of a terrestrial dynamo and magnetic shielding for Eoarchean to Hadean times, at ages as old as 4.2 billion years ago. However, the magnetic data suggest that for intervals >100,000 years long, magnetopause standoff distances may have reached 3 to 4 Earth radii or less. The early inception of the geodynamo, which probably occurred shortly after the lunar-forming impact, its continuity, and an early robust hydrosphere, appear to be key ingredients for Earth's long-term habitability.

  18. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  19. Physics of the earth crust

    International Nuclear Information System (INIS)

    Lauterbach, R.

    1977-01-01

    This book deals in 12 chapters, amongst other things, with the subjects: Structure of the crust and the upper earth mantle, geology and geophysics of sea beds, satellite and aero-methods of geophysics, state of the art of geothermal research, geophysical potential fields and their anomalies, applied seismology, electrical methods of geophysics, geophysics in engineering and rock engineering, borehole geophysics, petrophysics, and geochemistry. (RW) [de

  20. Metallothermic reduction of rare earth oxides

    International Nuclear Information System (INIS)

    Sharma, R.A.

    1986-01-01

    Rare earth oxides can be reduced to rare earth metals by a novel, high yield, metallothermic process. The oxides are dispersed in a suitable, molten, calcium chloride bath along with sodium metal. The sodium reacts with the calcium chloride to produce calcium metal which reduces the rare earth oxides to rare earth metals. The metals are collected in a discrete layer in the reaction vessel

  1. Rare earth-iron-boron premanent magnets

    International Nuclear Information System (INIS)

    Ghendehari, M.H.

    1988-01-01

    This patent describes a method for producing rare earth-iron-boron permanent magnets containing added rare earth oxide, comprising the steps of: (a) mixing a particulate alloy containing at least one rare earth metal, iron, and boron with at least one particulate rare earth oxide; (b) aligning magnetic domains of the mixture in a magnetic field; (c) compacting the aligned mixture to form a shape; and (d) sintering the compacted shape

  2. External Fuel Tank, Clouds and Earth Limb

    Science.gov (United States)

    1991-01-01

    It's fuel consumed, the expendable external fuel tank was jettisoned moments earlier from the Space Shuttle Atlantis and now begins its plunge back to Earth (20.5N, 36.0W). Backdropped against the void of space and the thin blue line of the Earth's airglow above the Earth Limb, the harshness of the blackness of space is softened by the fleeciness of Earth's cloud cover below.

  3. Space exercise and Earth benefits.

    Science.gov (United States)

    Macias, Brandon R; Groppo, Eli R; Eastlack, Robert K; Watenpaugh, Donald E; Lee, Stuart M C; Schneider, Suzanne M; Boda, Wanda L; Smith, Scott M; Cutuk, Adnan; Pedowitz, Robert A; Meyer, R Scott; Hargens, Alan R

    2005-08-01

    The detrimental impact of long duration space flight on physiological systems necessitates the development of exercise countermeasures to protect work capabilities in gravity fields of Earth, Moon and Mars. The respective rates of physiological deconditioning for different organ systems during space flight has been described as a result of data collected during and after missions on the Space Shuttle, International Space Station, Mir, and bed rest studies on Earth. An integrated countermeasure that simulates the body's hydrostatic pressure gradient, provides mechanical stress to the bones and muscles, and stimulates the neurovestibular system may be critical for maintaining health and well being of crew during long-duration space travel, such as a mission to Mars. Here we review the results of our studies to date of an integrated exercise countermeasure for space flight, lower body negative pressure (LBNP) treadmill exercise, and potential benefits of its application to athletic training on Earth. Additionally, we review the benefits of Lower Body Positive Pressure (LBPP) exercise for rehabilitation of postoperative patients. Presented first are preliminary data from a 30-day bed rest study evaluating the efficacy of LBNP exercise as an integrated exercise countermeasure for the deconditioning effects of microgravity. Next, we review upright LBNP exercise as a training modality for athletes by evaluating effects on the cardiovascular system and gait mechanics. Finally, LBPP exercise as a rehabilitation device is examined with reference to gait mechanics and safety in two groups of postoperative patients.

  4. Rare earth niobate coordination polymers

    Science.gov (United States)

    Muniz, Collin N.; Patel, Hiral; Fast, Dylan B.; Rohwer, Lauren E. S.; Reinheimer, Eric W.; Dolgos, Michelle; Graham, Matt W.; Nyman, May

    2018-03-01

    Rare-earth (RE) coordination polymers are infinitely tailorable to yield luminescent materials for various applications. Here we described the synthesis of a heterometallic rare-earth coordination compound ((CH3)2SO)3(RE)NbO(C2O4)3((CH3)2SO) = dimethylsulfoxide, DMSO, (C2O2= oxalate), (RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb). The structure was obtained from single crystal X-ray diffraction of the La analogue. The Nb˭O and DMSO terminal-bonding character guides assembly of an open framework structure with noncentrosymmetric RE-coordination geometry, and large spacing between the RE centers. A second structure was observed by PXRD for the smaller rare earths (Dy, Ho, Er, Yb); this structure has not yet been determined. The materials were further characterized using FTIR, and photoluminescence measurements. Characteristic excitation and emission transitions were observed for RE = Nd, Sm, Eu, and Tb. Quantum yield (QY) measurements were performed by exciting Eu and Tb analoges at 394 nm (QY 66%) and 464 nm (QY 71%) for Eu; and 370 nm (QY=40%) for Tb. We attribute the high QY and bright luminescence to two main structure-function properties of the system; namely the absence of water in the structure, and absence of concentration quenching.

  5. Mineral evolution and Earth history

    Science.gov (United States)

    Bradley, Dwight C.

    2015-01-01

    The field of mineral evolution—a merger of mineralogy and Earth history—coalesced in 2008 with the first of several global syntheses by Robert Hazen and coworkers in the American Mineralogist. They showed that the cumulative abundance of mineral species has a stepwise trend with first appearances tied to various transitions in Earth history such as the end of planetary accretion at ca. 4.55 Ga and the onset of bio-mediated mineralogy at ca. >2.5 Ga. A global age distribution is best established for zircon. Observed abundance of zircon fluctuates through more than an order of magnitude during successive supercontinent cycles. The pulse of the Earth is also recorded, albeit imperfectly, by the 87Sr/86Sr composition of marine biogenic calcite; the Sr-isotopic ratio of this mineral reflects the balance of inputs of primitive strontium at mid-ocean ridges and evolved strontium that drains off the continents. A global mineral evolution database, currently in the works, will greatly facilitate the compilation and analysis of extant data and the expansion of research in mineralogy outside its traditional bounds and into more interdisciplinary realms.

  6. Apollo 11 Earth Training Exercises

    Science.gov (United States)

    1969-01-01

    In preparation of the nation's first lunar landing mission, Apollo 11 crew members underwent training to practice activities they would be performing during the mission. In this photograph, taken at the Manned Spacecraft Center in Houston, Texas, an engineer, Bob Mason, donned in a space suit, goes through some of those training exercises on the mock lunar surface. He performed activites similar to those planned for astronauts Neil Armstrong and Edwin Aldrin during their moon walk. The Apollo 11 mission launched from the Kennedy Space Center (KSC) in Florida via the Marshall Space Flight Center (MSFC) developed Saturn V launch vehicle on July 16, 1969 and safely returned to Earth on July 24, 1969. Aboard the space craft were astronauts Neil A. Armstrong, commander; Michael Collins, Command Module (CM) pilot; and Edwin E. (Buzz) Aldrin Jr., Lunar Module (LM) pilot. The CM, 'Columbia', piloted by Collins, remained in a parking orbit around the Moon while the LM, 'Eagle'', carrying astronauts Armstrong and Aldrin, landed on the Moon. On July 20, 1969, Armstrong was the first human to ever stand on the lunar surface, followed by Aldrin. During 2½ hours of surface exploration, the crew collected 47 pounds of lunar surface material for analysis back on Earth. With the success of Apollo 11, the national objective to land men on the Moon and return them safely to Earth had been accomplished.

  7. The Earth Observation Technology Cluster

    Science.gov (United States)

    Aplin, P.; Boyd, D. S.; Danson, F. M.; Donoghue, D. N. M.; Ferrier, G.; Galiatsatos, N.; Marsh, A.; Pope, A.; Ramirez, F. A.; Tate, N. J.

    2012-07-01

    The Earth Observation Technology Cluster is a knowledge exchange initiative, promoting development, understanding and communication about innovative technology used in remote sensing of the terrestrial or land surface. This initiative provides an opportunity for presentation of novel developments from, and cross-fertilisation of ideas between, the many and diverse members of the terrestrial remote sensing community. The Earth Observation Technology Cluster involves a range of knowledge exchange activities, including organisation of technical events, delivery of educational materials, publication of scientific findings and development of a coherent terrestrial EO community. The initiative as a whole covers the full range of remote sensing operation, from new platform and sensor development, through image retrieval and analysis, to data applications and environmental modelling. However, certain topical and strategic themes have been selected for detailed investigation: (1) Unpiloted Aerial Vehicles, (2) Terrestrial Laser Scanning, (3) Field-Based Fourier Transform Infra-Red Spectroscopy, (4) Hypertemporal Image Analysis, and (5) Circumpolar and Cryospheric Application. This paper presents general activities and achievements of the Earth Observation Technology Cluster, and reviews state-of-the-art developments in the five specific thematic areas.

  8. Process for lead removal from rare earth

    International Nuclear Information System (INIS)

    Bollat, A.; Sabot, J.L.

    1987-01-01

    An aqueous solution of rare earth chlorides and lead chlorides, with a chloride concentration of at least 2 moles/liter and a pH between 2 and 4, is extracted by an alkylphosphonic acid ester and rare earth(s) is (are) recovered from the organic phase [fr

  9. Dimension of the Earth's general ellipsoid

    Czech Academy of Sciences Publication Activity Database

    Burša, Milan; Kenyon, S.; Kouba, J.; Raděj, K.; Šíma, Zdislav; Vatrt, V.; Vojtíšková, M.

    2002-01-01

    Roč. 91, č. 1 (2002), s. 31-41 ISSN 0167-9295 Institutional research plan: CEZ:AV0Z1003909 Keywords : Earth's dimensions * Earth's ellipsoid * fundamental constants Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.364, year: 2002

  10. In the Red Shadow of the Earth

    Science.gov (United States)

    Hughes, Stephen W.; Hosokawa, Kazuyuki; Carroll, Joshua; Sawell, David; Wilson, Colin

    2015-01-01

    A technique is described for calculating the brightness of the atmosphere of the Earth that shines into the Earth's umbra during a total lunar eclipse making the Moon red. This "Rim of Fire" is due to refracted unscattered light from all the sunrises and sunsets rimming the Earth. In this article, a photograph of the totally eclipsed…

  11. Earth Science: It's All about the Processes

    Science.gov (United States)

    King, Chris

    2013-01-01

    Readers of the draft new English primary science curriculum (DfE, 2012) might be concerned to see that there is much more detail on the Earth science content than previously in the United Kingdom. In this article, Chris King, a professor of Earth Science Education at Keele University and Director of the Earth Science Education Unit (ESEU),…

  12. Common Earth Science Misconceptions in Science Teaching

    Science.gov (United States)

    King, Chris

    2012-01-01

    A survey of the Earth science content of science textbooks found a wide range of misconceptions. These are discussed in this article with reference to the published literature on Earth science misconceptions. Most misconceptions occurred in the "sedimentary rocks and processes" and "Earth's structure and plate tectonics"…

  13. Earth Systems Science: An Analytic Framework

    Science.gov (United States)

    Finley, Fred N.; Nam, Younkeyong; Oughton, John

    2011-01-01

    Earth Systems Science (ESS) is emerging rapidly as a discipline and is being used to replace the older earth science education that has been taught as unrelated disciplines--geology, meteorology, astronomy, and oceanography. ESS is complex and is based on the idea that the earth can be understood as a set of interacting natural and social systems.…

  14. ISS EarthKam: Taking Photos of the Earth from Space

    Science.gov (United States)

    Haste, Turtle

    2008-01-01

    NASA is involved in a project involving the International Space Station (ISS) and an Earth-focused camera called EarthKam, where schools, and ultimately students, are allowed to remotely program the EarthKAM to take images. Here the author describes how EarthKam was used to help middle school students learn about biomes and develop their…

  15. The Chinese Society of Rare Earth is Studying The Feasibility of Marketing Rare Earth Futures

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Lin Donglu,secretary-general of the Chinese Society of Rare Earth recently said,the Chinese Society of Rare Earth undertook the research on subject of the National Social Science Fund Foundation on the reform of Chinese rare earth trading pricing mechanism on promoting RMB globalization,and is focusing on studying the feasibility of marketing rare earth futures variety.

  16. Origin of the earth and moon

    International Nuclear Information System (INIS)

    Ringwood, A.E.

    1981-01-01

    The composition of the Earth's interior and its bearing on the Earth's origin are discussed. It seems likely that the terrestrial planets formed by the accretion of solid planetisimals from the nebula of dust and gas left behind during the formation of the Sun. The scenario proposed is simpler than others. New evidence based upon a comparison of siderophile element abundances in the Earth's mantle and in the Moon imply that the Moon was derived from the Earth's mantle after the Earth's core had segregated

  17. Rare earth elements: end use and recyclability

    Science.gov (United States)

    Goonan, Thomas G.

    2011-01-01

    Rare earth elements are used in mature markets (such as catalysts, glassmaking, lighting, and metallurgy), which account for 59 percent of the total worldwide consumption of rare earth elements, and in newer, high-growth markets (such as battery alloys, ceramics, and permanent magnets), which account for 41 percent of the total worldwide consumption of rare earth elements. In mature market segments, lanthanum and cerium constitute about 80 percent of rare earth elements used, and in new market segments, dysprosium, neodymium, and praseodymium account for about 85 percent of rare earth elements used. Regardless of the end use, rare earth elements are not recycled in large quantities, but could be if recycling became mandated or very high prices of rare earth elements made recycling feasible.

  18. Earth current monitoring circuit for inductive loads

    CERN Document Server

    Montabonnet, V; Thurel, Y; Cussac, P

    2010-01-01

    The search for higher magnetic fields in particle accelerators increasingly demands the use of superconducting magnets. This magnet technology has a large amount of magnetic energy storage during operation at relatively high currents. As such, many monitoring and protection systems are required to safely operate the magnet, including the monitoring of any leakage of current to earth in the superconducting magnet that indicates a failure of the insulation to earth. At low amplitude, the earth leakage current affects the magnetic field precision. At a higher level, the earth leakage current can additionally generate local losses which may definitively damage the magnet or its instrumentation. This paper presents an active earth fault current monitoring circuit, widely deployed in the converters for the CERN Large Hadron Collider (LHC) superconducting magnets. The circuit allows the detection of earth faults before energising the circuit as well as limiting any eventual earth fault current. The electrical stress...

  19. The Earth: A Changing Planet

    Science.gov (United States)

    Ribas, Núria; Màrquez, Conxita

    2013-04-01

    text: We describe a didactic unit that rises from our own living impression about our experience on the planet. Most of us feel the Earth to be a very static place. Rocks don't easily move and most landscapes always look the same over time. Anyone would say (the same way most scientists believed until the beginning of the last century) that our planet has always remained unchanged, never transformed. But then, all of a sudden, as a misfortune for so many humans, natural hazards appear on the scene: an earthquake causing so many disasters, a tsunami carrying away everything in its path, an eruption that can destroy huge surrounding areas but also bring new geographical relief. Science cannot remain oblivious to these events, we must wonder beyond. What does an earthquake mean? Why does it happen? What about an eruption? If it comes from the inside, what can we guess from it? Researching about all of these events, scientists have been able to arrive to some important knowledge of the planet itself: It has been possible to theorize about Earth's interior. It has also been confirmed that the planet has not always been the quiet and stable place we once thought. Continents, as Wegener supposed, do move about and the Tectonic Plates Theory, thanks to the information obtained through earthquakes and eruption, can provide some interesting explanations. But how do we know about our planet's past? How can we prove that the Earth has always been moving and that its surface changes? The Earth's rocks yield the answer. Rocks have been the only witnesses throughout millions of years, since the planet first came to existence. Let's learn how to read them… Shouldn't we realize that rocks are to Geology what books are to History? This discursive process has been distributed in four learning sequences: 1. Land is not as solid nor firm as it would seem, 2. The Earth planet: a puzzle, 3. The rocks also recycle , 4. Field trip to "Sant Miquel del Fai". The subjects take about 30

  20. Earthing the human body influences physiologic processes.

    Science.gov (United States)

    Sokal, Karol; Sokal, Pawel

    2011-04-01

    This study was designed to answer the question: Does the contact of the human organism with the Earth via a copper conductor affect physiologic processes? Subjects and experiments: Five (5) experiments are presented: experiment 1-effect of earthing on calcium-phosphate homeostasis and serum concentrations of iron (N = 84 participants); experiment 2-effect of earthing on serum concentrations of electrolytes (N = 28); experiment 3-effect of earthing on thyroid function (N = 12); experiment 4-effect of earthing on glucose concentration (N = 12); experiment 5-effect of earthing on immune response to vaccine (N = 32). Subjects were divided into two groups. One (1) group of people was earthed, while the second group remained without contact with the Earth. Blood and urine samples were examined. Earthing of an electrically insulated human organism during night rest causes lowering of serum concentrations of iron, ionized calcium, inorganic phosphorus, and reduction of renal excretion of calcium and phosphorus. Earthing during night rest decreases free tri-iodothyronine and increases free thyroxine and thyroid-stimulating hormone. The continuous earthing of the human body decreases blood glucose in patients with diabetes. Earthing decreases sodium, potassium, magnesium, iron, total protein, and albumin concentrations while the levels of transferrin, ferritin, and globulins α1, α2, β, and γ increase. These results are statistically significant. Earthing the human body influences human physiologic processes. This influence is observed during night relaxation and during physical activity. Effect of the earthing on calcium-phosphate homeostasis is the opposite of that which occurs in states of weightlessness. It also increases the activity of catabolic processes. It may be the primary factor regulating endocrine and nervous systems.

  1. Earthing the Human Body Influences Physiologic Processes

    Science.gov (United States)

    Sokal, Karol

    2011-01-01

    Abstract Objectives This study was designed to answer the question: Does the contact of the human organism with the Earth via a copper conductor affect physiologic processes? Subjects and experiments Five (5) experiments are presented: experiment 1—effect of earthing on calcium–phosphate homeostasis and serum concentrations of iron (N = 84 participants); experiment 2—effect of earthing on serum concentrations of electrolytes (N = 28); experiment 3—effect of earthing on thyroid function (N = 12); experiment 4—effect of earthing on glucose concentration (N = 12); experiment 5—effect of earthing on immune response to vaccine (N = 32). Subjects were divided into two groups. One (1) group of people was earthed, while the second group remained without contact with the Earth. Blood and urine samples were examined. Results Earthing of an electrically insulated human organism during night rest causes lowering of serum concentrations of iron, ionized calcium, inorganic phosphorus, and reduction of renal excretion of calcium and phosphorus. Earthing during night rest decreases free tri-iodothyronine and increases free thyroxine and thyroid-stimulating hormone. The continuous earthing of the human body decreases blood glucose in patients with diabetes. Earthing decreases sodium, potassium, magnesium, iron, total protein, and albumin concentrations while the levels of transferrin, ferritin, and globulins α1, α2, β, and γ increase. These results are statistically significant. Conclusions Earthing the human body influences human physiologic processes. This influence is observed during night relaxation and during physical activity. Effect of the earthing on calcium–phosphate homeostasis is the opposite of that which occurs in states of weightlessness. It also increases the activity of catabolic processes. It may be the primary factor regulating endocrine and nervous systems. PMID:21469913

  2. Rb-Sr and Sm-Nd isotopic relations and ages of the Brasiliano granitic magmatism of the eastern region of the Dom Feliciano belt in the Rio Grande do Sul State, South region Brazil: evidences of the reworking of a paleoproterozoic continental crust, South region, Brazil

    International Nuclear Information System (INIS)

    Frantz, Jose Carlos; Koester, Edinei; Teixeira, Roberto Santos; Botelho, Nilson Francisquini; Pimentel, Marcio Martins; Potrel, Alan

    1999-01-01

    The granitoids belonging to the brasiliano cycle from the eastern region at the Dom Feliciano Belt in the Rio Grande do Sul state have had Rb-Sr data that indicated bodies which were intruded between 800 and 585 Ma. The T DM ages are suggesting the participation of an older source in their generation. This source could be represented by a long period enriched mantle, much than would be expected during the evolution of the magmatic arcs, or could be represented by the interaction between an older continental crust and mantle during a continental collision regime. The tectonic evolution of this area., the existence of a long period of time between the granitic intrusions associated to the tangential regime and to the transpressive regime and to the transpressive regime ones, the isotopic relations between Sr and nd and the very low negative values of ε N dt are suggesting a strong participation of an older continental crust. This older continental crust, may be constituted by gneissic protoliths of paleoproterozoic ages and generated during the evolution of the Transamazonic Cycle, has participated in the formation of the sources of the granitic magmatism of this part of the belt. The variations of the T DM ages and of the Nd ratios in the calc-alkaline granitoids are suggesting different proportions of mixture between and older continental crust and mantle or different homogenization grades in the magmas sources. For the peraluminous granites, that have be resulted from continental crustal melt, there are indications of different sources to the different bodies. (author)

  3. Planet earth a beginner's guide

    CERN Document Server

    Gribbin, John

    2012-01-01

    In this incredible expedition into the origins, workings, and evolution of our home planet, John Gribbin, bestselling author of In Search of Schrödinger's Cat, The Scientists, and In Search of the Multiverse, does what he does best: taking four and a half billion years of mind-boggling science and digging out the best bits. From the physics of Newton and the geology of Wegener, to the environmentalism of Lovelock, this is a must read for Earth's scientists and residents alike. Trained as an astrophysicist at Cambridge University, John Gribbin is currently Visiting Fellow in Astronomy at the University of Sussex, England.

  4. Magnetic Rare-Earth Superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Gibbs, D.; Böni, P.

    1988-01-01

    The magnetic structures of several single‐crystal, magnetic rare‐earth superlattice systems grown by molecular‐beam epitaxy are reviewed. In particular, the results of recent neutron diffraction investigations of long‐range magnetic order in Gd‐Y, Dy‐Y, Gd‐Dy, and Ho‐Y periodic superlattices...... are presented. In the Gd‐Y system, an antiphase domain structure develops for certain Y layer spacings, whereas modified helical moment configurations are found to occur in the other systems, some of which are commensurate with the chemical superlattice wavelength. References are made to theoretical interaction...

  5. Earth Summit Science, policy discussed

    Science.gov (United States)

    Leath, Audrey T.

    The United Nations Conference on Environment and Development, the “Earth Summit,” convenes in Rio de Janeiro on June 3. President Bush has pledged to attend part of the 2-week conference. The highlight of the summit will be the signing of an international framework convention to reduce emissions of greenhouse gases. The final elements of the agreement were negotiated in New York last week by representative of 143 countries. In anticipation of the Rio conference, the Senate Committee on Energy and Natural Resources held two standing-roomonly hearings, reviewing the scientific basis for global warming due to greenhouse gases and discussing the details of the proposed convention.

  6. Fire in the Earth system.

    Science.gov (United States)

    Bowman, David M J S; Balch, Jennifer K; Artaxo, Paulo; Bond, William J; Carlson, Jean M; Cochrane, Mark A; D'Antonio, Carla M; Defries, Ruth S; Doyle, John C; Harrison, Sandy P; Johnston, Fay H; Keeley, Jon E; Krawchuk, Meg A; Kull, Christian A; Marston, J Brad; Moritz, Max A; Prentice, I Colin; Roos, Christopher I; Scott, Andrew C; Swetnam, Thomas W; van der Werf, Guido R; Pyne, Stephen J

    2009-04-24

    Fire is a worldwide phenomenon that appears in the geological record soon after the appearance of terrestrial plants. Fire influences global ecosystem patterns and processes, including vegetation distribution and structure, the carbon cycle, and climate. Although humans and fire have always coexisted, our capacity to manage fire remains imperfect and may become more difficult in the future as climate change alters fire regimes. This risk is difficult to assess, however, because fires are still poorly represented in global models. Here, we discuss some of the most important issues involved in developing a better understanding of the role of fire in the Earth system.

  7. Earth Sciences annual report, 1987

    International Nuclear Information System (INIS)

    Younker, L.W.; Donohue, M.L.; Peterson, S.J.

    1988-12-01

    The Earth Sciences Department at Lawrence Livermore National Laboratory conducts work in support of the Laboratory's energy, defense, and research programs. The Department is organized into ten groups. Five of these -- Nuclear Waste Management, Fossil Energy, Containment, Verification, and Research -- represent major programmatic activities within the Department. Five others -- Experimental Geophysics, Geomechanics, Geology/Geological Engineering, Geochemistry, and Seismology/Applied Geophysics -- are major disciplinary areas that support these and other laboratory programs. This report summarizes work carried out in 1987 by each group and contains a bibliography of their 1987 publications

  8. Spanish Earth Observation Satellite System

    Science.gov (United States)

    Borges, A.; Cerezo, F.; Fernandez, M.; Lomba, J.; Lopez, M.; Moreno, J.; Neira, A.; Quintana, C.; Torres, J.; Trigo, R.; Urena, J.; Vega, E.; Vez, E.

    2010-12-01

    The Spanish Ministry of Industry, Tourism and Trade (MITyC) and the Ministry of Defense (MoD) signed an agreement in 2007 for the development of a "Spanish Earth Observation Satellite System" based, in first instance, on two satellites: a high resolution optical satellite, called SEOSAT/Ingenio, and a radar satellite based on SAR technology, called SEOSAR/Paz. SEOSAT/Ingenio is managed by MITyC through the Centre for the Development of Industrial Technology (CDTI), with technical and contractual support from the European Space Agency (ESA). HISDESA T together with the Spanish Instituto Nacional de Técnica Aeroespacial (INTA, National Institute for Aerospace Technology) will be responsible for the in-orbit operation and the commercial operation of both satellites, and for the technical management of SEOSAR/Paz on behalf of the MoD. In both cases EADS CASA Espacio (ECE) is the prime contractor leading the industrial consortia. The ground segment development will be assigned to a Spanish consortium. This system is the most important contribution of Spain to the European Programme Global Monitoring for Environment and Security, GMES. This paper presents the Spanish Earth Observation Satellite System focusing on SEOSA T/Ingenio Programme and with special emphasis in the potential contribution to the ESA Third Party Missions Programme and to the Global Monitoring for Environment and Security initiative (GMES) Data Access.

  9. Isotopes in the earth sciences

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, Robert

    1988-01-01

    This book examines significant aspects of isotope applications in geology and geochemistry commencing with basic matters, such as atomic structure, stable nuclides and their fractionation, as well as the various decay modes of unstable nuclides. Modern mass spectrometry techniques including electrostatic tandem accelerators are followed by a review of radioisotope dating technology. The relatively new method using the rare earth elements samarium and neodymium are covered. Other geochronometers, applicable to both rocks and minerals not dateable otherwise, are included. A review is given of isotopes in the atmosphere, hydrosphere and lithosphere of the Earth. Those of oxygen and hydrogen together with the cosmogenic radionuclides tritium and radiocarbon are discussed in relation to the biosphere. The role of isotopes of carbon, nitrogen and sulphur is described and extended to fossil fuels and rocks as well as meteorites. Related themes such as Phanerozoic oceans, oceanic palaeothermometry, snow and ice stratigraphy and geothermal waters are covered. The field of isotopic palaeoecology is discussed. Radioactive wastes, their accumulation, dangers and disposal are investigated with especial reference to their environmental impacts.

  10. Contextualizing Earth Science Professional Development Courses for Geoscience Teachers in Boston: Earth Science II (Solid Earth)

    Science.gov (United States)

    Pringle, M. S.; Kamerer, B.; Vugrin, M.; Miller, M.

    2009-12-01

    Earth Science II: The Solid Earth -- Earth History and Planetary Science -- is the second of two Earth Science courses, and one of eleven graduate level science Contextualized Content Courses (CCC), that have been developed by the Boston Science Partnership as part of an NSF-funded Math Science Partnership program. A core goal of these courses is to provide high level science content to middle and high school teachers while modeling good instructional practices directly tied to the Boston Public Schools and Massachusetts science curriculum frameworks. All of these courses emphasize hands-on, lab-based, inquiry-driven, student-centered lessons. The Earth Science II team aimed to strictly adhere to ABC (Activity Before Concept) and 5E/7E models of instruction, and limited lecture or teacher-centered instruction to the later “Explanation” stages of all lessons. We also introduced McNeill and Krajick’s Claim-Evidence-Reasoning (CER) model of scientific explanation for middle school classroom discourse, both as a powerful scaffold leading to higher levels of accountable talk in the classroom, and to model science as a social construct. Daily evaluations, dutifully filled out by the course participants and diligently read by the course instructors, were quite useful in adapting instruction to the needs of the class on a real-time basis. We find the structure of the CCC teaching teams - university-based faculty providing expert content knowledge, K-12-based faculty providing age appropriate pedagogies and specific links to the K-12 curriculum - quite a fruitful, two-way collaboration. From the students’ perspective, one of the most useful takeaways from the university-based faculty was “listening to experts model out loud how they reason,” whereas some of the more practical takeaways (i.e., lesson components directly portable to the classroom?) came from the K-12-based faculty. The main takeaways from the course as a whole were the promise to bring more hands

  11. Intelligent Design and Earth History

    Science.gov (United States)

    Elders, W. A.

    2001-05-01

    Intelligent Design (ID), the idea that the Earth's biota was intelligently designed and created, is not a new species recently evolved by allopatric speciation at the fringes of the creationist gene pool. In spite of its new veneer of sophistication, ID is a variant of an already extant species of religious polemics. In the western world, arguments about causative relationships between the complexity of nature and the supernatural can be traced from the fifth century St. Augustine, to the eighteenth century David Hume and the nineteenth century William Paley. Along this descent tree some argued from the existence of supernatural agencies to the creation of nature with its complexities, while others argued from the complexities of nature to the existence of supernatural agencies. Today, Phillip Johnson promotes ID by attacking evolution rather than by presenting evidence for ID. He argues that the evidence for macroevolution is either absent, misinterpreted or fraudulent. His "Wedge Strategy" attempts to separate his "objective science" from the "philosophical mechanistic naturalism" which he posits is responsible for the survival of Darwinism. To make his appeal as wide as possible he tries not to offend anyone (except evolutionists) by deliberately avoiding discussion of biblical literalism or the age of the Earth. Although in 1859 Darwin admitted that the geological evidence was "the most obvious and gravest objection which can be urged against my theory", subsequently geological evidence has become one of the chief supports of his theory. However, the fossil record is now seen to be not simply one of slow gradual descent with modification. Rates of divergence and disappearance of organisms have varied enormously through time. Repeated mass extinctions indicate a strong element of contingency in evolution. Accepting the postulate of an intelligent designer also requires the postulate of an intelligent destroyer. Darwin hinted at this when he referred to, "The

  12. a Walk Through Earth's Time

    Science.gov (United States)

    Turrin, B. D.; Turrin, M.

    2012-12-01

    After "What is this rock?" the most common questions that is asked of Geologists is "How old is this rock/fossil?" For geologists considering ages back to millions of years is routine. Sorting and cataloguing events into temporal sequences is a natural tendency for all humans. In fact, it is an everyday activity for humans, i.e., keeping track of birthdays, anniversaries, appointments, meetings, AGU abstract deadlines etc… However, the time frames that are most familiar to the non scientist (seconds, minutes, hours, days, years) generally extend to only a few decades or at most centuries. Yet the vast length of time covered by Earth's history, 4.56 billion years, greatly exceeds these timeframes and thus is commonly referred to as "Deep Time". This is a challenging concept for most students to comprehend as it involves temporal and abstract thinking, yet it is key to their successful understanding of numerous geologic principles. We have developed an outdoor learning activity for general Introductory Earth Science courses that incorporates several scientific and geologic concepts such as: linear distance or stratigraphic thickness representing time, learning about major events in Earth's history and locating them in a scaled temporal framework, field mapping, abstract thinking, scaling and dimensional analysis, and the principles of radio isotopic dating. The only supplies needed are readily available in local hardware stores i.e. a 300 ft. surveyor's tape marked in feet, and tenths and hundredths of a foot, and the student's own introductory geology textbook. The exercise employs a variety of pedagogical learning modalities, including traditional lecture-based, the use of Art/Drawing, use of Visualization, Collaborative learning, and Kinesthetic and Experiential learning. Initially the students are exposed to the concept of "Deep Time" in a short conventional introductory lecture; this is followed by a 'field day'. Prior to the field exercise, students work with

  13. Google Earth: A Virtual Globe for Elementary Geography

    Science.gov (United States)

    Britt, Judy; LaFontaine, Gus

    2009-01-01

    Originally called Earth Viewer in 2004, Google Earth was the first virtual globe easily available to the ordinary user of the Internet. Google Earth, at earth.google.com, is a free, 3-dimensional computer model of Earth, but that means more than just a large collection of pretty pictures. It allows the viewer to "fly" anywhere on Earth "to view…

  14. Low-energy near Earth asteroid capture using Earth flybys and aerobraking

    Science.gov (United States)

    Tan, Minghu; McInnes, Colin; Ceriotti, Matteo

    2018-04-01

    Since the Sun-Earth libration points L1 and L2 are regarded as ideal locations for space science missions and candidate gateways for future crewed interplanetary missions, capturing near-Earth asteroids (NEAs) around the Sun-Earth L1/L2 points has generated significant interest. Therefore, this paper proposes the concept of coupling together a flyby of the Earth and then capturing small NEAs onto Sun-Earth L1/L2 periodic orbits. In this capture strategy, the Sun-Earth circular restricted three-body problem (CRTBP) is used to calculate target Lypaunov orbits and their invariant manifolds. A periapsis map is then employed to determine the required perigee of the Earth flyby. Moreover, depending on the perigee distance of the flyby, Earth flybys with and without aerobraking are investigated to design a transfer trajectory capturing a small NEA from its initial orbit to the stable manifolds associated with Sun-Earth L1/L2 periodic orbits. Finally, a global optimization is carried out, based on a detailed design procedure for NEA capture using an Earth flyby. Results show that the NEA capture strategies using an Earth flyby with and without aerobraking both have the potential to be of lower cost in terms of energy requirements than a direct NEA capture strategy without the Earth flyby. Moreover, NEA capture with an Earth flyby also has the potential for a shorter flight time compared to the NEA capture strategy without the Earth flyby.

  15. Magnetic Storms at Mars and Earth

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Falkenberg, Thea Vilstrup

    In analogy with magnetic storms at the Earth, periods of significantly enhanced global magnetic activity also exist at Mars. The extensive database of magnetic measurements from Mars Global Surveyor (MGS), covering almost an entire solar cycle, is used in combination with geomagnetic activity...... indices at Earth to compare the occurrence of magnetic storms at Mars and Earth. Based on superposed epochs analysis the time-development of typical magnetic storms at Mars and Earth is described. In contradiction to storms at Earth, most magnetic storms at Mars are found to be associated...... with heliospheric current sheet crossings, where the IMF changes polarity. While most storms at the Earth occur due to significant southward excursions of the IMF associated with CMEs, at Mars most storms seem to be associated with the density enhancement of the heliospheric current sheet. Density enhancements...

  16. Earth's earliest biosphere: Its origin and evolution

    International Nuclear Information System (INIS)

    Schopf, J.W.

    1983-01-01

    Some of the subjects discussed are related to the early biogeologic history, the nature of the earth prior to the oldest known rock record, the early earth and the Archean rock record, the prebiotic organic syntheses and the origin of life, Precambrian organic geochemistry, the biochemical evolution of anaerobic energy conversion, the isotopic inferences of ancient biochemistries, Archean stromatolites providing evidence of the earth's earliest benthos, Archean microfossils, the geologic evolution of the Archean-Early Proterozoic earth, and the environmental evolution of the Archean-Early Proterozoic earth. Other topics examined are concerned with geochemical evidence bearing on the origin of aerobiosis, biological and biochemical effects of the development of an aerobic environment, Early Proterozoic microfossils, the evolution of earth's earliest ecosystems, and geographic and geologic data for processed rock samples. Attention is given to a processing procedure for abiotic samples and calculation of model atmospheric compositions, and procedures of organic geochemical analysis

  17. Earth Surface Processes, Landforms and Sediment Deposits

    Science.gov (United States)

    Bridge, John; Demicco, Robert

    Earth surface processes, landforms and sediment deposits are intimately related - involving erosion of rocks, generation of sediment, and transport and deposition of sediment through various Earth surface environments. These processes, and the landforms and deposits that they generate, have a fundamental bearing on engineering, environmental and public safety issues; on recovery of economic resources; and on our understanding of Earth history. This unique textbook brings together the traditional disciplines of sedimentology and geomorphology to explain Earth surface processes, landforms and sediment deposits in a comprehensive and integrated way. It is the ideal resource for a two-semester course in sedimentology, stratigraphy, geomorphology, and Earth surface processes from the intermediate undergraduate to beginning graduate level. The book is also accompanied by a website hosting illustrations and material on field and laboratory methods for measuring, describing and analyzing Earth surface processes, landforms and sediments.

  18. Geohistory. Global evolution of the earth

    Energy Technology Data Exchange (ETDEWEB)

    Ozima, Minoru

    1987-01-01

    A full understanding of the earth's evolution can be achieved only by considering it as a continuous process starting with the birth of the solar system. This book traces the evolution of the earth, mainly on the basis of radiogenic isotopes from long half-life parent elements, and discusses it in terms of the latest developments in astrophysical theory, which impose unique constraints on the earth's origin and early evolution. By its 'historical' nature, geohistorical study also offers a unique approach to forecasting the future of the earth, yielding useful clues for the understanding of environmental problems, such as radioactive waste disposal. This book aims to provide an outline of global evolution of the planet earth for students of general science and for earth scientists.

  19. Raman scattering of rare earth hexaborides

    International Nuclear Information System (INIS)

    Ogita, Norio; Hasegawa, Takumi; Udagawa, Masayuki; Iga, Fumitoshi; Kunii, Satoru

    2009-01-01

    Raman scattering spectra were measured for the rare-earth hexaborides RB 6 (R = Ce, Gd, or Dy). All Raman-active phonons due to B 6 vibrations were observed in the range 600 - 1400 cm -1 . Anomalous peaks were detected below 200 cm -1 , which correspond to vibrations of rare-earth ion excited by second-order Raman scattering process. The intensity and energy of the rare-earth mode decrease with decreasing temperature. This suggests that the rare-earth ion vibrates in a shallow and anharmonic potential due to the boron cage. Using the reported values of mean square displacement of rare-earth ion, we estimated the anharmonic contribution for the rare-earth vibrations.

  20. "Thinking about a Sustainable Earth"

    Science.gov (United States)

    Ikeshita, Makoto

    2014-05-01

    1.Introduction The Course of study for Junior high school teaching was changed in 2008 in Japan. We should especially mention about this change that ESD, "Education for Sustainable Development," was written as a point of view. ESD is a kind of educations that is studied with a target for a region and that aims at reorganize of consciousness through thinking of how to be a better region. ESD's view was written for Social studies, Science, Foreign Languages, Health and Physical Education, Home Economics and Technical Arts, and the Period for Integrated Studies. Of these subjects, Social studies are the one of core subjects. Social studies for Junior high school consist of Geography, History and Civics. "Problem of us and international society" is the last part of Civics. Teacher helps students to understand international society deeply and think about the role of our country for it. Students research many problems (global environment, resources and energy, poverty etc.) and organize their thoughts on how make a better society as a part of the human family. I taught them to think about how to solve many themes like religious problems, terrorism problems, the North-South problems, and resource and energy problems. It is my practice to let them think about what they should do to solve the global warming problem. 2.The truth of my class I pointed out to the students that the length of summer time in Japan is increasing, and we can anticipate it will continue to increase in the future. After that, I explained to them that occurrence of sudden, heavy downpour of rain is increasing and helped them understand the process of this kind of downpour through some diagrams and pictures. I helped them understand the context of this increase of the length of summer time and heavy downpour within the whole earth's ecosystem. Such increases as these things are causing global warming. I asked them to think about what are the possible problems if global warming progresses. The ideas the

  1. Grid for Earth Science Applications

    Science.gov (United States)

    Petitdidier, Monique; Schwichtenberg, Horst

    2013-04-01

    The civil society at large has addressed to the Earth Science community many strong requirements related in particular to natural and industrial risks, climate changes, new energies. The main critical point is that on one hand the civil society and all public ask for certainties i.e. precise values with small error range as it concerns prediction at short, medium and long term in all domains; on the other hand Science can mainly answer only in terms of probability of occurrence. To improve the answer or/and decrease the uncertainties, (1) new observational networks have been deployed in order to have a better geographical coverage and more accurate measurements have been carried out in key locations and aboard satellites. Following the OECD recommendations on the openness of research and public sector data, more and more data are available for Academic organisation and SMEs; (2) New algorithms and methodologies have been developed to face the huge data processing and assimilation into simulations using new technologies and compute resources. Finally, our total knowledge about the complex Earth system is contained in models and measurements, how we put them together has to be managed cleverly. The technical challenge is to put together databases and computing resources to answer the ES challenges. However all the applications are very intensive computing. Different compute solutions are available and depend on the characteristics of the applications. One of them is Grid especially efficient for independent or embarrassingly parallel jobs related to statistical and parametric studies. Numerous applications in atmospheric chemistry, meteorology, seismology, hydrology, pollution, climate and biodiversity have been deployed successfully on Grid. In order to fulfill requirements of risk management, several prototype applications have been deployed using OGC (Open geospatial Consortium) components with Grid middleware. The Grid has permitted via a huge number of runs to

  2. Korea Earth Observation Satellite Program

    Science.gov (United States)

    Baek, Myung-Jin; Kim, Zeen-Chul

    via Korea Aerospace Research Institute (KARI) as the prime contractor in the area of Korea earth observation satellite program to enhance Korea's space program development capability. In this paper, Korea's on-going and future earth observation satellite programs are introduced: KOMPSAT- 1 (Korea Multi Purpose Satellite-1), KOMPSAT-2 and Communication, Broadcasting and Meteorological Satellite (CBMS) program. KOMPSAT-1 satellite successfully launched in December 1999 with Taurus launch vehicle. Since launch, KOMPSAT-1 is downlinking images of Korea Peninsular every day. Until now, KOMPSAT-1 has been operated more than 2 and half years without any major hardware malfunction for the mission operation. KOMPSAT-1 payload has 6.6m panchromatic spatial resolution at 685 km on-orbit and the spacecraft bus had NASA TOMS-EP (Total Ozone Mapping Spectrometer-Earth Probe) spacecraft bus heritage designed and built by TRW, U.S.A.KOMPSAT-1 program was international co-development program between KARI and TRW funded by Korean Government. be launched in 2004. Main mission objective is to provide geo-information products based on the multi-spectral high resolution sensor called Multi-Spectral Camera (MSC) which will provide 1m panchromatic and 4m multi-spectral high resolution images. ELOP of Israel is the prime contractor of the MSC payload system and KARI is the total system prime contractor including spacecraft bus development and ground segment. KARI also has the contract with Astrium of Europe for the purpose of technical consultation and hardware procurement. Based on the experience throughout KOMPSAT-1 and KOMPSAT-2 space system development, Korea is expecting to establish the infrastructure of developing satellite system. Currently, KOMPSAT-2 program is in the critical design stage. are scheduled to launch in 2008 and in 2014, respectively. The mission of CBMS consists of two areas. One is of space technology test for the communications mission, and the other is of a real

  3. Rare earth metals for automotive exhaust catalysts

    International Nuclear Information System (INIS)

    Shinjoh, Hirohumi

    2006-01-01

    The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of inclusion of rare earth metals in automotive catalysts are discussed

  4. Rare earth industries: Strategies for Malaysia

    International Nuclear Information System (INIS)

    2011-01-01

    Evidently, many reports cite Malaysia as having reasonably substantial amounts of rare earths elements. In fact, based on the rare earths found in the residual tin deposits alone, Malaysia has about 30,000 tonnes. This does not take into account unmapped deposits which experts believe may offer more tonnages of rare earths. Brazil which is reported to have about 48,000 tonnes has announced plans to invest aggressively in the rare earths business. China has on record the largest reserves with about 36 million tonnes. This explains why China has invested heavily in the entire value chain of the rare earths business. Chinas committed investment in rare earths started many years ago when the country's foremost leaders proclaimed the strategic position of rare earths in the world economy. That forecast is now a reality where the rise in the green high-tech economy is seen driving global demand for rare earths in a big way. Malaysia needs to discover and venture into new economic growth areas. This will help fuel the country's drive to achieve a high income status by 2020 as articulated in the New Economic Model (NEM) and the many supporting Economic Transformation Plans that the Government has recently launched. Rare earths may be the new growth area for Malaysia. However, the business opportunities should not just be confined to the mining, extraction and production of rare earths elements alone if Malaysia is to maximise benefits from this industry. The industry's gold mine is in the downstream products. This is also the sector that China wants to expand. Japan which now controls about 50 % of the global market for downstream rare earths-based high-tech components is desperately looking for partners to grow their stake in the business. Malaysia needs to embark on the right strategies in order to build the rare earths industry in the country. What are the strategies? (author)

  5. Cosmology and the expanding Earth hypothesis

    International Nuclear Information System (INIS)

    Tryon, E.P.

    1983-01-01

    The standard model of cosmology is briefly presented, together with a recent conjecture that the initial matter in the universe might have been spontaneously created from nothing as a result of relativistic quantum physics. The possibility of Earth expansion from a continuing creation of matter is then considered. A critique is presented of efforts to relate Earth expansion to the Hubble expansion of the universe. Possible changes in Earth radius as a result of diminishing gravity are also discussed

  6. Rare earth - no case for government intervention

    OpenAIRE

    Georg Zachmann

    2010-01-01

    China has officially restricted exports of rare earth for several years and announced this year it will further tighten exports. Rare earth is a group of 17 different metals, usually found clustered together. These metals have hundreds of different industry applications. For example, they are used in certain high capacity magnets, batteries and lasers. As the rare earth elements are used in sectors that are assumed to have an over-proportionate growth potential (eg. green-technology), policy ...

  7. Anisotropy in the deep Earth

    Science.gov (United States)

    Romanowicz, Barbara; Wenk, Hans-Rudolf

    2017-08-01

    Seismic anisotropy has been found in many regions of the Earth's interior. Its presence in the Earth's crust has been known since the 19th century, and is due in part to the alignment of anisotropic crystals in rocks, and in part to patterns in the distribution of fractures and pores. In the upper mantle, seismic anisotropy was discovered 50 years ago, and can be attributed for the most part, to the alignment of intrinsically anisotropic olivine crystals during large scale deformation associated with convection. There is some indication for anisotropy in the transition zone, particularly in the vicinity of subducted slabs. Here we focus on the deep Earth - the lower mantle and core, where anisotropy is not yet mapped in detail, nor is there consensus on its origin. Most of the lower mantle appears largely isotropic, except in the last 200-300 km, in the D″ region, where evidence for seismic anisotropy has been accumulating since the late 1980s, mostly from shear wave splitting measurements. Recently, a picture has been emerging, where strong anisotropy is associated with high shear velocities at the edges of the large low shear velocity provinces (LLSVPs) in the central Pacific and under Africa. These observations are consistent with being due to the presence of highly anisotropic MgSiO3 post-perovskite crystals, aligned during the deformation of slabs impinging on the core-mantle boundary, and upwelling flow within the LLSVPs. We also discuss mineral physics aspects such as ultrahigh pressure deformation experiments, first principles calculations to obtain information about elastic properties, and derivation of dislocation activity based on bonding characteristics. Polycrystal plasticity simulations can predict anisotropy but models are still highly idealized and neglect the complex microstructure of polyphase aggregates with strong and weak components. A promising direction for future progress in understanding the origin of seismic anisotropy in the deep mantle

  8. Energy from heaven and earth

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    Today, almost everybody is affected by problems relating to energy, above all the high cost of energy. Professor Dr. Edward Teller, one of the outstanding nuclear physicists of our time, has devoted many years of research work to investigate the various aspects of the energy shortage, and to find out appropriate ways and means of solving this problem. Following a series of lectures held in the USA and in Israel, he has now published a book entitled Energy from heaven and earth, which is also available in German under the title Energie fuer ein neues Jahrtausend. In the interview given here, Professor Teller explains some of the statements made in his book. (orig.) [de

  9. Substorms in the earth's magnetosphere

    International Nuclear Information System (INIS)

    Baker, D.N.

    1984-01-01

    Magnetospheres are plasma regions of large scale in space dominated by magnetic field effects. The earth, and many planets in our solar system, are known to have magnetospheric regions around them. Magnetospheric substorms represent the intense, rapid dissipation of energy that has been extracted from the solar wind and stored temporarily in the terrestrial magnetotail. In this paper a widely, but not universally, accepted model of substorms is described. The energy budgets, time scales, and conversion efficiencies for substorms are presented. The primary forms of substorm energy dissipation are given along with the average levels of the dissipation. Aspects of particle acceleration and precipitation, Joule heating mechanisms, ring current formation, and plasmoid escape are illustrated based on in situ observations taken from the large available data base. A brief description is given of possible analogues of substorm-like behavior in other astrophysical systems. 27 references, 12 figures

  10. Earth System Science Education Modules

    Science.gov (United States)

    Hall, C.; Kaufman, C.; Humphreys, R. R.; Colgan, M. W.

    2009-12-01

    The College of Charleston is developing several new geoscience-based education modules for integration into the Earth System Science Education Alliance (ESSEA). These three new modules provide opportunities for science and pre-service education students to participate in inquiry-based, data-driven experiences. The three new modules will be discussed in this session. Coastal Crisis is a module that analyzes rapidly changing coastlines and uses technology - remotely sensed data and geographic information systems (GIS) to delineate, understand and monitor changes in coastal environments. The beaches near Charleston, SC are undergoing erosion and therefore are used as examples of rapidly changing coastlines. Students will use real data from NASA, NOAA and other federal agencies in the classroom to study coastal change. Through this case study, learners will acquire remotely sensed images and GIS data sets from online sources, utilize those data sets within Google Earth or other visualization programs, and understand what the data is telling them. Analyzing the data will allow learners to contemplate and make predictions on the impact associated with changing environmental conditions, within the context of a coastal setting. To Drill or Not To Drill is a multidisciplinary problem based module to increase students’ knowledge of problems associated with nonrenewable resource extraction. The controversial topic of drilling in the Arctic National Wildlife Refuge (ANWR) examines whether the economic benefit of the oil extracted from ANWR is worth the social cost of the environmental damage that such extraction may inflict. By attempting to answer this question, learners must balance the interests of preservation with the economic need for oil. The learners are exposed to the difficulties associated with a real world problem that requires trade-off between environmental trust and economic well-being. The Citizen Science module challenges students to translate scientific

  11. Biological Extinction in Earth History

    Science.gov (United States)

    Raup, David M.

    1986-03-01

    Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

  12. Biological extinction in earth history

    Science.gov (United States)

    Raup, D. M.

    1986-01-01

    Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

  13. The Earth's mantle and geoneutrinos

    International Nuclear Information System (INIS)

    Fiorentini, Giovanni; Fogli, Gian Luigi; Lisi, Eligio; Mantovani, Fabio; Rotunno, Anna Maria; Xhixha, Gerti

    2013-01-01

    The KamLAND and Borexino experiments have observed, each at ∼4σ level, signals of electron antineutrinos produced in the decay chains of thorium and uranium in the Earth's crust and mantle (Th and U geoneutrinos). Various pieces of geochemical and geophysical information allow an estimation of the crustal geoneutrino flux components with relatively small uncertainties. The mantle component may then be inferred by subtracting the estimated crustal flux from the measured total flux. We find that crust-subtracted signals show hints of a residual mantle component, emerging at ∼2.4σ level by combining the KamLAND and Borexino data. The inferred mantle flux, slightly favoring scenarios with relatively high Th and U abundances, within ∼1σ uncertainties is comparable to the predictions from recent mantle models

  14. Looking at the earth from space

    Science.gov (United States)

    Geller, Marvin A.

    1988-01-01

    Some of the scientific accomplishments attained in observing the earth from space are discussed. A brief overview of findings concerning the atmosphere, the oceans and sea ice, the solid earth, and the terrestrial hydrosphere and biosphere is presented, and six examples are examined in which space data have provided unique information enabling new knowledge concerning the workings of the earth to be derived. These examples concern stratospheric water vapor, hemispheric differences in surface and atmosphere parameters, Seasat altimeter mesoscale variability, variability of Antarctic sea ice, variations in the length of day, and spaceborne radar imaging of ancient rivers. Future space observations of the earth are briefly addressed.

  15. HABEBEE: habitability of eyeball-exo-Earths.

    Science.gov (United States)

    Angerhausen, Daniel; Sapers, Haley; Citron, Robert; Bergantini, Alexandre; Lutz, Stefanie; Queiroz, Luciano Lopes; da Rosa Alexandre, Marcelo; Araujo, Ana Carolina Vieira

    2013-03-01

    Extrasolar Earth and super-Earth planets orbiting within the habitable zone of M dwarf host stars may play a significant role in the discovery of habitable environments beyond Earth. Spectroscopic characterization of these exoplanets with respect to habitability requires the determination of habitability parameters with respect to remote sensing. The habitable zone of dwarf stars is located in close proximity to the host star, such that exoplanets orbiting within this zone will likely be tidally locked. On terrestrial planets with an icy shell, this may produce a liquid water ocean at the substellar point, one particular "Eyeball Earth" state. In this research proposal, HABEBEE: exploring the HABitability of Eyeball-Exo-Earths, we define the parameters necessary to achieve a stable icy Eyeball Earth capable of supporting life. Astronomical and geochemical research will define parameters needed to simulate potentially habitable environments on an icy Eyeball Earth planet. Biological requirements will be based on detailed studies of microbial communities within Earth analog environments. Using the interdisciplinary results of both the physical and biological teams, we will set up a simulation chamber to expose a cold- and UV-tolerant microbial community to the theoretically derived Eyeball Earth climate states, simulating the composition, atmosphere, physical parameters, and stellar irradiation. Combining the results of both studies will enable us to derive observable parameters as well as target decision guidance and feasibility analysis for upcoming astronomical platforms.

  16. New dynamic system suggested for earth expansion

    Energy Technology Data Exchange (ETDEWEB)

    Fitzpatrick, J [Asuncion Nacional Univ. (Paraguay). Inst. de Ciencias

    1972-01-01

    It is here suggested that there may have been much more radioactive materials in the deep interior of the earth than bitherto supposed. Trapped heat being generated in the interior would provide a mechanism for earth expansion. An assumption of heat generation in the deep interior of the earth of the order of 0,5 X 10-13 calories per second, per cubic centimeter, would provide sufficient thermal expansion to account for approximately 0.1 mm. change in the radius of the earth per year.

  17. Age of the earth and solar system

    International Nuclear Information System (INIS)

    Manhes, G.

    1977-01-01

    The history of chemical element formation and radiochronology is given. The study of Pb isotope composition evolution enables to estimate the age of the earth. A series of galena of known ages was measured. By means of a model, it is possible to determine the initial isotope composition of Pb on the earth and the age of the earth. On the other hand, the analysis of stony meteorites provides a Pb isotope composition higher than the earth value. A comparison of the data shows a fundamental transition at 4.55 10 9 years [fr

  18. Alaska's rare earth deposits and resource potential

    Science.gov (United States)

    Barker, James C.; Van Gosen, Bradley S.

    2012-01-01

    Alaska’s known mineral endowment includes some of the largest and highest grade deposits of various metals, including gold, copper and zinc. Recently, Alaska has also been active in the worldwide search for sources of rare earth elements (REE) to replace exports now being limitedby China. Driven by limited supply of the rare earths, combined with their increasing use in new ‘green’ energy, lighting, transportation, and many other technological applications, the rare earth metals neodymium, europium and, in particular, the heavy rare earth elements terbium, dysprosium and yttrium are forecast to soon be in critical short supply (U.S. Department of Energy, 2010).

  19. Probing Earth's State of Stress

    Science.gov (United States)

    Delorey, A. A.; Maceira, M.; Johnson, P. A.; Coblentz, D. D.

    2016-12-01

    The state of stress in the Earth's crust is a fundamental physical property that controls both engineered and natural systems. Engineered environments including those for hydrocarbon, geothermal energy, and mineral extraction, as well those for storage of wastewater, carbon dioxide, and nuclear fuel are as important as ever to our economy and environment. Yet, it is at spatial scales relevant to these activities where stress is least understood. Additionally, in engineered environments the rate of change in the stress field can be much higher than that of natural systems. In order to use subsurface resources more safely and effectively, we need to understand stress at the relevant temporal and spatial scales. We will present our latest results characterizing the state of stress in the Earth at scales relevant to engineered environments. Two important components of the state of stress are the orientation and magnitude of the stress tensor, and a measure of how close faults are to failure. The stress tensor at any point in a reservoir or repository has contributions from both far-field tectonic stress and local density heterogeneity. We jointly invert seismic (body and surface waves) and gravity data for a self-consistent model of elastic moduli and density and use the model to calculate the contribution of local heterogeneity to the total stress field. We then combine local and plate-scale contributions, using local indicators for calibration and ground-truth. In addition, we will present results from an analysis of the quantity and pattern of microseismicity as an indicator of critically stressed faults. Faults are triggered by transient stresses only when critically stressed (near failure). We show that tidal stresses can trigger earthquakes in both tectonic and reservoir environments and can reveal both stress and poroelastic conditions.

  20. Optical MEMS for Earth observation

    Science.gov (United States)

    Liotard, Arnaud; Viard, Thierry; Noell, Wilfried; Zamkotsian, Frédéric; Freire, Marco; Guldimann, Benedikt; Kraft, Stefan

    2017-11-01

    Due to the relatively large number of optical Earth Observation missions at ESA, this area is interesting for new space technology developments. In addition to their compactness, scalability and specific task customization, optical MEMS could generate new functions not available with current technologies and are thus candidates for the design of future space instruments. Most mature components for space applications are the digital mirror arrays, the micro-deformable mirrors, the programmable micro diffraction gratings and tiltable micromirrors. A first selection of market-pull and techno-push concepts is done. In addition, some concepts are coming from outside Earth Observation. Finally two concepts are more deeply analyzed. The first concept is a programmable slit for straylight control for space spectro-imagers. This instrument is a push-broom spectroimager for which some images cannot be exploited because of bright sources in the field-of-view. The proposed concept consists in replacing the current entrance spectrometer slit by an active row of micro-mirrors. The MEMS will permit to dynamically remove the bright sources and then to obtain a field-of-view with an optically enhanced signal-to-noise ratio. The second concept is a push-broom imager for which the acquired spectrum can be tuned by optical MEMS. This system is composed of two diffractive elements and a digital mirror array. The first diffractive element spreads the spectrum. A micromirror array is set at the location of the spectral focal plane. By putting the micro-mirrors ON or OFF, we can select parts of field-of-view or spectrum. The second diffractive element then recombines the light on a push-broom detector. Dichroics filters, strip filter, band-pass filter could be replaced by a unique instrument.

  1. Google Earth Grand Tour Themes

    Science.gov (United States)

    De Paor, D. G.; Whitmeyer, S. J.; Bentley, C.; Dordevic, M. M.

    2014-12-01

    As part of an NSF TUES Type 3 project entitled "Google Earth for Onsite and Distance Education (GEODE)," we are assembling a "Grand Tour" of locations on Earth and other terrestrial bodies that every geoscience student should know about and visit at least in virtual reality. Based on feedback from colleagues at previous meetings, we have identified nine Grand Tour themes: "Plates and Plumes," "Rocks and Regions," "Geology Through Time," "The Mapping Challenge*," "U.S. National Parks*," "The Magical Mystery Tour*," "Resources and Hazards," "Planets and Moons," and "Top of the Pops." Themes marked with an asterisk are most developed at this stage and will be demonstrated in real time. The Mapping Challenge invites students to trace geological contacts, measure bedding strike and dip and the plunge, trend, and facing of a fold. There is an advanced tool for modeling periclinal folds. The challenge is presented in a game-like format with an emphasis on puzzle-solving that will appeal to students regardless of gender. For the tour of U.S. national parks, we divided the most geologically important parks into four groups—Western Pacific, West Coast, Rockies, and East Coast. We are combining our own team's GigaPan imagery with imagery already available on the Internet. There is a great deal of imagery just waiting to be annotated for geological education purposes. The Magical Mystery Tour takes students to Google Streetview locations selected by instructors. Students are presented with questions or tasks and are given automatic feedback. Other themes are under development. Within each theme, we are crowd-sourcing contributions from colleagues and inviting colleagues to vote for or against proposed locations and student interactions. The GEODE team includes the authors and: Heather Almquist, Stephen Burgin, Cinzia Cervato, Gene Cooper, Paul Karabinos, Terry Pavlis, Jen Piatek, Bill Richards, Jeff Ryan, Ron Schott, Kristen St. John, and Barb Tewksbury.

  2. Comet Hyakutake to Approach the Earth in Late March 1996

    Science.gov (United States)

    1996-03-01

    the very distant `Oort Cloud' of comets that surrounds the solar system. In this sense it is different from the periodical comets which move in closed orbits around the Sun with revolution periods between a few years and some decades. Its `dirty snowball' nucleus of ices and dust has therefore not been heated by the Sun for a very long time, perhaps never, if this is its first visit to the inner regions of the solar system. Hence it is particularly difficult to predict its future performance. Nevertheless, the available observations seem to indicate that it is a quite `active' comet and that it may therefore become comparatively bright when it approaches the Earth and later at perihelion. But how bright ? Imaging as well as spectroscopic observations have been performed in order to better characterize Comet Hyakutake. On CCD-frames obtained of the comet in early February with telescopes at the ESO La Silla Observatory and elsewhere, an elongation is clearly visible (cf. ESO Press Photo 11/96 ) in the anti-sunward direction of the coma (the cloud of gas and dust that surrounds the cometary nucleus). A real tail has not yet developed, but this is expected to happen soon. The size of the coma was measured as at least 7 arcmin, corresponding to a projected diameter of nearly 500,000 kilometres. It is also of interest that until recently the coma otherwise appeared absolutely symmetrical - there was no indication of `jets', i.e. no large vents on the surface of the nucleus had yet become active. However, on images obtained with the ESO 3.6-metre telescope in the morning of February 13, a `jet'-like feature is seen which emerges south-east of the nucleus (i.e. from the sunlit side) and curls counter-clockwise towards the opposite side (the `tail'-direction). This is probably the first evidence of localized dust production on the surface of the nucleus. CCD observations were made on February 9 at the Lowell Observatory (Flagstaff, U.S.A.) through special optical filters

  3. The "Earth Physics" Workshops Offered by the Earth Science Education Unit

    Science.gov (United States)

    Davies, Stephen

    2012-01-01

    Earth science has a part to play in broadening students' learning experience in physics. The Earth Science Education Unit presents a range of (free) workshops to teachers and trainee teachers, suggesting how Earth-based science activities, which show how we understand and use the planet we live on, can easily be slotted into normal science…

  4. EOS Reference Handbook 1999: A Guide to NASA's Earth Science Enterprise and the Earth Observing System

    Science.gov (United States)

    King, M. D. (Editor); Greenstone, R. (Editor)

    2000-01-01

    The content of this handbook includes Earth Science Enterprise; The Earth Observing System; EOS Data and Information System (EOSDIS); Data and Information Policy; Pathfinder Data Sets; Earth Science Information Partners and the Working Prototype-Federation; EOS Data Quality: Calibration and Validation; Education Programs; International Cooperation; Interagency Coordination; Mission Elements; EOS Instruments; EOS Interdisciplinary Science Investigations; and Points-of-Contact.

  5. Torsional Oscillations of the Earths's Core

    Science.gov (United States)

    Hide, Raymond; Boggs, Dale H.; Dickey, Jean O.

    1997-01-01

    Torsional oscillations of the Earth's liquid metallic outer core are investigated by diving the core into twenty imaginary e1qui-volume annuli coaxial with the axis of ratation of the Earth and determining temproal fluctuations in the axial component of angular memonetum of each annulus under the assumption of iso-rotation on cylindrical surfaces.

  6. Forging Inclusive Solutions: Experiential Earth Charter Education

    Science.gov (United States)

    Hill, Linda D.

    2010-01-01

    Forging Inclusive Solutions describes the aims, methodology and outcomes of Inclusive Leadership Adventures, an experiential education curriculum for exploring the Earth Charter. Experiential education builds meaningful relationships, skills, awareness and an inclusive community based on the Earth Charter principles. When we meet people where they…

  7. Chemical analysis of rare earth elements

    International Nuclear Information System (INIS)

    Tsukahara, Ryoichi; Sakoh, Takefumi; Nagai, Iwao

    1994-01-01

    Recently attention has been paid to ICP-AES or ICP-MS, and the reports on the analysis of rare earth elements by utilizing these methods continue to increase. These reports have become to take about 30% of the reports on rare earth analysis, and this is because these methods are highly sensitive to rare earth elements, and also these methods have spread widely. In ICP-AES and ICP-MS, mostly solution samples are measured, therefore, solids must be made into solution. At the time of quantitatively determining the rare earth elements of low concentration, separation and concentration are necessary. Referring to the literatures reported partially in 1990 and from 1991 to 1993, the progress of ICP-AES and ICP-MS is reported. Rare earth oxides and the alloys containing rare earth elements are easily decomposed with acids, but the decomposition of rocks is difficult, and its method is discussed. The separation of the rare earth elements from others in geochemical samples, cation exchange process is frequently utilized. Also solvent extraction process has been studied. For the separation of rare earth elements mutually, chromatography is used. The spectral interference in spectral analysis was studied. The comparison of these methods with other methods is reported. (K.I)

  8. Rare earth oxyhydrides and preparation process

    International Nuclear Information System (INIS)

    Diaz, H.

    1986-01-01

    Rare earth oxyhydrides of formula RE 1-q Th q Ni 5-p M p O x H y are claimed. RE is a rare earth, Th can be replaced by Yt, M is Cu, Mn, Al, Fe, Cr or Co, o O C and the hydrides are oxidized. They are catalysts for various chemical reactions [fr

  9. Multiple Modes of Inquiry in Earth Science

    Science.gov (United States)

    Kastens, Kim A.; Rivet, Ann

    2008-01-01

    To help teachers enrich their students' understanding of inquiry in Earth science, this article describes six modes of inquiry used by practicing geoscientists (Earth scientists). Each mode of inquiry is illustrated by using examples of seminal or pioneering research and provides pointers to investigations that enable students to experience these…

  10. Ivestigating Earth Science in Urban Schoolyards

    Science.gov (United States)

    Endreny, Anna; Siegel, Donald I.

    2009-01-01

    The Urban Schoolyards project is a two year partnership with a university Earth Science Department and the surrounding urban elementary schools. The goal of the project was to develop the capacity of elementary teachers to teach earth science lessons using their schoolyards and local parks as field sites. The university personnel developed lessons…

  11. Elementary Children's Retrodictive Reasoning about Earth Science

    Science.gov (United States)

    Libarkin, Julie C.; Schneps, Matthew H.

    2012-01-01

    We report on interviews conducted with twenty-one elementary school children (grades 1-5) about a number of Earth science concepts. These interviews were undertaken as part of a teacher training video series designed specifically to assist elementary teachers in learning essential ideas in Earth science. As such, children were interviewed about a…

  12. The Near-Earth Space Radiation Environment

    Science.gov (United States)

    Xapsos, Michael

    2008-01-01

    This viewgraph presentation reviews the effects of the Near-Earth space radiation environment on NASA missions. Included in this presentation is a review of The Earth s Trapped Radiation Environment, Solar Particle Events, Galactic Cosmic Rays and Comparison to Accelerator Facilities.

  13. SPACE: Enhancing Life on Earth. Proceedings Report

    Science.gov (United States)

    Hobden, Alan (Editor); Hobden, Beverly (Editor); Bagley, Larry E. (Editor); Bolton, Ed (Editor); Campaigne, Len O. (Editor); Cole, Ron (Editor); France, Marty (Editor); Hand, Rich (Editor); McKinley, Cynthia (Editor); Zimkas, Chuck (Editor)

    1996-01-01

    The proceedings of the 12th National Space Symposium on Enhancing Life on Earth is presented. Technological areas discussed include: Space applications and cooperation; Earth sensing, communication, and navigation applications; Global security interests in space; and International space station and space launch capabilities. An appendices that include featured speakers, program participants, and abbreviation & acronyms glossary is also attached.

  14. Theory of Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1977-01-01

    A mean-field random alloy theory combined with a simple calculation of the exchange interaction J(c,Q) is shown to quantitatively account for the phase diagrams for alloys of rare-earth metals with Y, Lu, Sc, and other rare-earth metals. A concentration-dependent J(c,Q) explains the empirical 2...

  15. Rare Earth Elements Distribution in Beryl

    International Nuclear Information System (INIS)

    El Gawish, H.K.; Nada, N.; Ghaly, W.A.; Helal, A.I.

    2012-01-01

    Laser ablation method is applied to a double focusing inductively coupled plasma mass spectrometer to determine the rare earth element distribution in some selected beryl samples. White, green and blue beryl samples are selected from the Egyptian eastern desert. Distributions of chondrite- normalized plot for the rare earth element in the selected beryl samples are investigated

  16. Satellite to study earth's magnetic field

    Science.gov (United States)

    1979-01-01

    The Magnetic Field Satellite (Magsat) designed to measure the near earth magnetic field and crustal anomalies is briefly described. A scalar magnetometer to measure the magnitude of the earth's crustal magnetic field and a vector magnetometer to measure magnetic field direction as well as magnitude are included. The mission and its objectives are summarized along with the data collection and processing system.

  17. Earth's Most Important Producers: Meet the Phytoplankton!

    Science.gov (United States)

    Marrero, Meghan E.; Stevens, Nicole

    2011-01-01

    The ocean is home to some of Earth's most important producers. Single-celled organisms in the ocean are responsible for more than half of Earth's productivity, as well as most of its oxygen. Phytoplankton are single-celled, plantlike organisms. That is, they have chloroplasts and perform photosynthesis, but are not true plants, which are typically…

  18. Venus tectonics: another Earth or another Mars

    International Nuclear Information System (INIS)

    McGill, G.E.

    1979-01-01

    The presence of presumably primordial large craters has led to the suggestion that Venus may have a thick lithosphere like that of Mars despite its similarities to Earth in size and density. However, crust and upper mantle temperatures on Venus are very likely higher than on Earth so that a dry Venus could have a lithosphere with a thickness similar to that of Earth. If a trace of volatiles is present in the mantle, the lithosphere of Venus could be thinner. Due to the absence of liquid water, erosion and deposition will be much slower on Venus than on Earth, favoring retention of primordial cratered surfaces on portions of the crust that have not been destroyed or buried by tectonic and volcanic activity. Geochemical models of solar system origin and petrological considerations suggest that K is about as abundant in Venus as in Earth. The abundance of 40 Ar in the atmosphere of Venus lies somewhere between the Earth value and one-tenth of the Earth value. Because erosional liberation of 40 Ar on Venus will be relatively inefficient, this range for 40 Ar abundance at least permits an active tectonic history, and if the 40 Ar abundance is towards the high end of the range, it may well require an active tectonic history. Thus we are not constrained to a Mars-like model of Venus tectonics by craters and possible mantle dryness; an Earth-like model is equally probable

  19. Ancient and Medieval Earth in Armenia

    Science.gov (United States)

    Farmanyan, S. V.

    2015-07-01

    Humankind has always sought to recognize the nature of various sky related phenomena and tried to give them explanations. The purpose of this study is to identify ancient Armenians' pantheistic and cosmological perceptions, world view, notions and beliefs related to the Earth. The paper focuses on the structure of the Earth and many other phenomena of nature that have always been on a major influence on ancient Armenians thinking. In this paper we have compared the term Earth in 31 languages. By discussing and comparing Universe structure in various regional traditions, myths, folk songs and phraseological units we very often came across to "Seven Heavens" (Seven heavens is a part of religious cosmology found in many major religions such as Islam, Judaism, Hinduism and Christianity (namely Catholicism) and "Seven Earths". Armenians in their turn divided Earth and Heavens into seven layers. And in science too, both the Earth and the Heavens have 7 layers. The Seven Heavens refer to the layers of our atmosphere. The Seven Earths refer to the layers of the Earth (from core to crust), as well as seven continents. We conclude that the perception of celestial objects varies from culture to culture and preastronomy had a significant impact on humankind, particularly on cultural diversities.

  20. Earth Sciences Division, collected abstracts-1977

    International Nuclear Information System (INIS)

    Quitiquit, W.A.; Ledbetter, G.P.; Henry, A.L.

    1978-01-01

    This report is a compilation of abstracts of papers, internal reports, and talks presented during 1977 at national and international meetings by members of the Earth Sciences Division, Lawrence Livermore Laboratory. It is arranged alphabetically by author and includes a cross-reference by subject indicating the areas of research interest of the Earth Sciences Division

  1. RoboEarth: connecting robots worldwide

    NARCIS (Netherlands)

    Zweigle, O.; Molengraft, van de M.J.G.; D'Andrea, R.; Häussermann, K.

    2009-01-01

    In this paper, we present the core concept and the benefits of an approach called RoboEarth which will be highly beneficial for future robotic applications in science and industry. RoboEarth is a world-wide platform which robots can use to exchange position and map information as well as

  2. Earth Charter, ESD and Chinese Philosophies

    Science.gov (United States)

    Liu, Yunhua; Constable, Alicia

    2010-01-01

    This article examines the relationship between the Earth Charter and education for sustainable development (ESD), as part of the UN Decade of Education for Sustainable Development. The areas of shared interest between the two are assessed and the invaluable nature of the Earth Charter as a resource outlining global values and principles for a…

  3. 21 CFR 573.340 - Diatomaceous earth.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Diatomaceous earth. 573.340 Section 573.340 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additive Listing § 573.340 Diatomaceous earth. (a) Identity. The additive consists of siliceous skeletal...

  4. Virtual Exploration of Earth's Evolution

    Science.gov (United States)

    Anbar, A. D.; Bruce, G.; Semken, S. C.; Summons, R. E.; Buxner, S.; Horodyskyj, L.; Kotrc, B.; Swann, J.; Klug Boonstra, S. L.; Oliver, C.

    2014-12-01

    Traditional introductory STEM courses often reinforce misconceptions because the large scale of many classes forces a structured, lecture-centric model of teaching that emphasizes delivery of facts rather than exploration, inquiry, and scientific reasoning. This problem is especially acute in teaching about the co-evolution of Earth and life, where classroom learning and textbook teaching are far removed from the immersive and affective aspects of field-based science, and where the challenges of taking large numbers of students into the field make it difficult to expose them to the complex context of the geologic record. We are exploring the potential of digital technologies and online delivery to address this challenge, using immersive and engaging virtual environments that are more like games than like lectures, grounded in active learning, and deliverable at scale via the internet. The goal is to invert the traditional lecture-centric paradigm by placing lectures at the periphery and inquiry-driven, integrative virtual investigations at the center, and to do so at scale. To this end, we are applying a technology platform we devised, supported by NASA and the NSF, that integrates a variety of digital media in a format that we call an immersive virtual field trip (iVFT). In iVFTs, students engage directly with virtual representations of real field sites, with which they interact non-linearly at a variety of scales via game-like exploration while guided by an adaptive tutoring system. This platform has already been used to develop pilot iVFTs useful in teaching anthropology, archeology, ecology, and geoscience. With support the Howard Hughes Medical Institute, we are now developing and evaluating a coherent suite of ~ 12 iVFTs that span the sweep of life's history on Earth, from the 3.8 Ga metasediments of West Greenland to ancient hominid sites in East Africa. These iVFTs will teach fundamental principles of geology and practices of scientific inquiry, and expose

  5. Exploring Earth Systems Through STEM

    Science.gov (United States)

    Chen, Loris; Salmon, Jennifer; Burns, Courtney

    2015-04-01

    During the 2010 school year, grade 8 science teachers at Dwight D. Eisenhower Middle School in Wyckoff, New Jersey, began using the draft of A Framework for K-12 Science Education to transition to the Next Generation Science Standards. In an evolutionary process of testing and revising, teachers work collaboratively to develop problem-based science, technology, engineering, and mathematics (STEM) units that integrate earth science, physical science, and life science topics. Students explore the interconnections of Earth's atmosphere, lithosphere, hydrosphere, and biosphere through problem-based learning. Problem-based learning engages students in (1) direct observations in the field and classroom, (2) collection and analysis of data from remote sensors and hand-held sensors, and (3) analysis of physical, mathematical, and virtual models. Students use a variety of technologies and applications in their investigations, for example iPad apps, Google Classroom, and Vernier sensors. Data from NASA, NOAA, non-government organizations, and scientific research papers inspire student questions and spark investigations. Teachers create materials and websites to support student learning. Teachers curate reading, video, simulations, and other Internet resources for students. Because curriculum is standards-based as opposed to textbook-based, teacher participation in workshops and institutes frequently translates into new or improved study units. Recent programs include Toyota International Teacher Program to Costa Rica, Japan Society Going Global, Siemens STEM Academy, U.S. Naval Academy SET Sail, and NJSTA Maitland P. Simmons Memorial Award Summer Institute. Unit themes include weather and climate, introduction to general chemistry and biochemistry, and cells and heredity. Each if the three 12-week units has embedded engineering challenges inspired by current events, community needs, and/or the work of scientists. The unit segments begin with a problem, progress to

  6. Applicability of neutrino beams to Earth exploration

    International Nuclear Information System (INIS)

    Dolgoshein, B.A.; Kalinovskij, A.N.

    1985-01-01

    The projects on applicability of neutrino beams from high energy accelerators for geological exploration and study of the Earth structure are discussed. The GENIUS (Geological Exploration by Neutrino Induced Underground Sound) project is among them. It covers detecting and studying space-time characteristics of acoustic signal arising in case of neutrino interaction with Earth depth rocks discussed. The GEMINI (Geological Exploration with Muons Induced by neutrino interactions) project represents one more possibility for using geotron neutrino beam for the purpose of geological exploration. The GEOSCAN project represents the possibility for applying high energy neutrino beams for the purpose of the Earth translusence to determine the changes in the density of internal part of the Earth. The necessity of detailed investigations of the problem of applicability of neutrino beams in the field of the Earth exploration is pointed out

  7. Rare Earth Metals: Resourcefulness and Recovery

    Science.gov (United States)

    Wang, Shijie

    2013-10-01

    When we appreciate the digital revolution carried over from the twentieth century with mobile communication and the Internet, and when we enjoy our high-tech lifestyle filled with iDevices, hybrid cars, wind turbines, and solar cells in this new century, we should also appreciate that all of these advanced products depend on rare earth metals to function. Although there are only 136,000 tons of annual worldwide demand, (Cho, Rare Earth Metals, Will We Have Enough?)1 rare earth metals are becoming such hot commodities on international markets, due to not only to their increasing uses, including in most critical military hardware, but also to Chinese growth, which accounts for 95% of global rare earth metal production. Hence, the 2013 technical calendar topic, planned by the TMS/Hydrometallurgy and Electrometallurgy Committee, is particularly relevant, with four articles (including this commentary) contributed to the JOM October Issue discussing rare earth metals' resourcefulness and recovery.

  8. Super computer displays future of the earth

    International Nuclear Information System (INIS)

    Yokokawa, Mitsuo; Tani, Keiji

    2000-01-01

    Science and Technology Agency has promoted a project of estimation of the earth environment fluctuation since Fiscal 1997. As one of series, it is developing a very high speed parallel computer 'the earth 'simulator' with 5TFLOPS of effective performance (40TFLOPS of peak performance). Abstract of the hardware, basic software and application software is explained. Hardware is constructed by a distributed memory type parallel computer and single-stage crossbars network. Main storage capacity is 10 TB. The basic software consisted of hierarchical structure with operating system, compiler, operation and management software. In the earth simulator, 640 nodes are connected by magnetic disk units, so that input/output of calculation is parallel processor, the most important development item. The earth simulator project is developing a software, NJR (NASDA-JAMSTEC-RIST) program, which is atmosphere and ocean large circulation joint model library system. An example of analysis showed a global distribution of rain a day in the earth. (S.Y.)

  9. Delivery of information from earth observation satellites

    International Nuclear Information System (INIS)

    MacDonald, J.S.

    1992-01-01

    Satellite-based systems for measuring the surface of the earth and its atmosphere from space have evolved rapidly in the past decade. The amount of data available in the future promises to be truly staggering. This paper addresses the requirements for handling data from earth observation systems. It begins with the premise that our objective is to acquire an understanding of the state and evolution of our planet, and proceeds from there to argue that earth observation satellite systems are, in reality, systems for delivering information. This view has implications on how we approach the design of such systems, and how we handle the data they produce in order to derive maximum benefit from them. The paper examines these issues and puts forth some of the technical requirements for future satellite-based earth observation systems, based on the concept that earth observation is a quantitative measurement discipline that is driven by requirements for information. (Author). 8 refs., 3 figs

  10. Models of the earth's core

    International Nuclear Information System (INIS)

    Stevenson, D.J.

    1981-01-01

    The combination of seismology, high pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to strong constraints on core models. The synthesis presented here is devoted to the defense of the following properties: (1) core formation was contemporaneous with earth accretion; (2) the outer, liquid core is predominately iron but cannot be purely iron; (3) the inner core-outer core boundary represents a thermodynamic equilibrium between a liquid alloys and a predominanately iron solid; (4) thermodynamic and transport properties of outer core can be estimated from liquid-state theories; and (5) the outer core is probably adiabatic and uniform in composition. None of these propositions are universally accepted by geophysicists. But, the intent of this paper is to present a coherent picture which explains most of the data with the fewest ad hoc assumptions. Areas in which future progress is both essential and likely are geo- and cosmochronology, seismological determinations of core structure, fluid dynamics of the core and mantle, and condensed matter physics

  11. Recycling of Rare Earth Elements

    Science.gov (United States)

    Lorenz, Tom; Bertau, Martin

    2017-01-01

    Any development of an effective process for rare earth (RE) recycling has become more and more challenging, especially in recent years. Since 2011, when commodity prices of REs had met their all-time maximum, prices have dropped rapidly by more than 90 %. An economic process able to offset these fluctuations has to take unconventional methods into account beside well-known strategies like acid/basic leaching or solvent extraction. The solid-state chlorination provides such an unconventional method for mobilizing RE elements from waste streams. Instead of hydrochloric acid this kind of chlorination decomposes NH4Cl thermally to release up to 400 °C hot HCl gas. After cooling the resulting solid metal chlorides may be easily dissolved in pH-adjusted water. Without producing strongly acidic wastes and with NH4Cl as cheap source for hydrogen chloride, solid-state chlorination provides various advantages in terms of costs and disposal. In the course of the SepSELSA project this method was examined, adjusted and optimized for RE recycling from fluorescent lamp scraps as well as Fe14Nd2B magnets. Thereby many surprising influences and trends required various analytic methods to examine the reasons and special mechanisms behind them.

  12. The road to Earth twins

    Science.gov (United States)

    Mayor, M.; Lovis, C.; Pepe, F.; Ségransan, D.; Udry, S.

    2011-06-01

    A rich population of low-mass planets orbiting solar-type stars on tight orbits has been detected by Doppler spectroscopy. These planets have masses in the domain of super-Earths and Neptune-type objects, and periods less than 100 days. In numerous cases these planets are part of very compact multiplanetary systems. Up to seven planets have been discovered orbiting one single star. These low-mass planets have been detected by the HARPS spectrograph around 30% of solar-type stars. This very high occurrence rate has been recently confirmed by the results of the Kepler planetary transit space mission. The large number of planets of this kind allows us to attempt a first characterization of their statistical properties, which in turn represent constraints to understand the formation process of these systems. The achieved progress in the sensitivity and stability of spectrographs have already led to the discovery of planets with masses as small as 1.5 M⊕. Karl Schwarzschild Award Lecture 2010

  13. Aquifer response to earth tides

    International Nuclear Information System (INIS)

    Kanehiro, B.Y.; Narasimhan, T.N.

    1981-01-01

    The relation presented in the first part of this paper are applicable to packed-off wells and other situations where appreciable flow to the well does not exist. Comparisons of aquifer properties determined from the response to earth tides and from the more standard pumping tests for the two California fields are reasonably good. The case of an open well makes the problem more complicated, since there may be an appreciable amount of flow to the well. This flow to the well is seen as either a phase lag or as a difference in the ratio of the well signal to the tide for the semidiurnal and diurnal components of the tide. The latter is probably the better and more accurate indicator of flow to the well. Analyses of such situations, however, become involved and are probably best done as case-by-case studies. The numerical solutions show that treating the inverse problem through numerical modeling is at least feasible for any individual situation. It may be possible to simplify the inverse problem through the generation of type curves, but general type curves that are applicable to diverse situations are not likely to be practical. 7 figures

  14. The climate: Earth and men

    International Nuclear Information System (INIS)

    Poitou, Jean; Braconnot, Pascale; Masson-Delmotte, Valerie

    2015-01-01

    In this book, the authors first present the climate system as it operates under the influence of the atmosphere and oceans: Earth heated by the Sun, temperatures and movements within the atmosphere, surface and deep circulation in the oceans, exchanges between the atmosphere and the oceans. They present the various actors of climate and their interactions: water cycle, carbon cycle, greenhouse effect, clouds, aerosols, ocean, cryosphere-climate interaction, interaction between continental biosphere and climate, interactions between climate, continents and lithosphere, feedbacks and climate sensitivity. They comment the variety of climates and their variability when considered on a large scale (role of the Sun, ocean-atmosphere oscillations in El Nino and La Nina, North Atlantic oscillation, other examples of oscillations). The next part addresses climate modelling: model fundamentals (parameters and other components, coupling between components), model adjustment (simulation types, multi-model sets, and model assessment), models of intermediate complexity, regional models. The authors discuss the warming phenomenon: history of temperature measurements, clues of global warming, how to make climate change. They propose a presentation and discussion of anthropogenic and natural factors which disturb the climate: CO 2 and other greenhouse gases, changes in soil uses, other possible causes of climate disturbance (aerosol, aircraft wakes, volcanoes, and sun), combination of these disturbances, and identification of anthropogenic disturbances. They discuss past climate evolutions, and finally discuss how the climate could evolve in the future

  15. Sedimentary manganese metallogenesis in response to the evolution of the Earth system

    Science.gov (United States)

    Roy, Supriya

    2006-08-01

    The concentration of manganese in solution and its precipitation in inorganic systems are primarily redox-controlled, guided by several Earth processes most of which were tectonically induced. The Early Archean atmosphere-hydrosphere system was extremely O 2-deficient. Thus, the very high mantle heat flux producing superplumes, severe outgassing and high-temperature hydrothermal activity introduced substantial Mn 2+ in anoxic oceans but prevented its precipitation. During the Late Archean, centered at ca. 2.75 Ga, the introduction of Photosystem II and decrease of the oxygen sinks led to a limited buildup of surface O 2-content locally, initiating modest deposition of manganese in shallow basin-margin oxygenated niches (e.g., deposits in India and Brazil). Rapid burial of organic matter, decline of reduced gases from a progressively oxygenated mantle and a net increase in photosynthetic oxygen marked the Archean-Proterozoic transition. Concurrently, a massive drawdown of atmospheric CO 2 owing to increased weathering rates on the tectonically expanded freeboard of the assembled supercontinents caused Paleoproterozoic glaciations (2.45-2.22 Ga). The spectacular sedimentary manganese deposits (at ca. 2.4 Ga) of Transvaal Supergroup, South Africa, were formed by oxidation of hydrothermally derived Mn 2+ transferred from a stratified ocean to the continental shelf by transgression. Episodes of increased burial rate of organic matter during ca. 2.4 and 2.06 Ga are correlatable to ocean stratification and further rise of oxygen in the atmosphere. Black shale-hosted Mn carbonate deposits in the Birimian sequence (ca. 2.3-2.0 Ga), West Africa, its equivalents in South America and those in the Francevillian sequence (ca. 2.2-2.1 Ga), Gabon are correlatable to this period. Tectonically forced doming-up, attenuation and substantial increase in freeboard areas prompted increased silicate weathering and atmospheric CO 2 drawdown causing glaciation on the Neoproterozoic Rodinia

  16. State of rare earth impurities in gallium and indium antimonides

    International Nuclear Information System (INIS)

    Evgen'ev, S.B.; Kuz'micheva, G.M.

    1990-01-01

    State of rare earth impurities in indium and gallium antimonides was studied. Results of measuring density and lattice parameter of samples in GaSb-rare earth and InSb-rare earth systems are presented. It is shown that during rare earth dissolution in indium and gallium antimonides rare earth atoms occupy interstitial positions or, at least, are displaced from lattice points

  17. The Australian Computational Earth Systems Simulator

    Science.gov (United States)

    Mora, P.; Muhlhaus, H.; Lister, G.; Dyskin, A.; Place, D.; Appelbe, B.; Nimmervoll, N.; Abramson, D.

    2001-12-01

    Numerical simulation of the physics and dynamics of the entire earth system offers an outstanding opportunity for advancing earth system science and technology but represents a major challenge due to the range of scales and physical processes involved, as well as the magnitude of the software engineering effort required. However, new simulation and computer technologies are bringing this objective within reach. Under a special competitive national funding scheme to establish new Major National Research Facilities (MNRF), the Australian government together with a consortium of Universities and research institutions have funded construction of the Australian Computational Earth Systems Simulator (ACcESS). The Simulator or computational virtual earth will provide the research infrastructure to the Australian earth systems science community required for simulations of dynamical earth processes at scales ranging from microscopic to global. It will consist of thematic supercomputer infrastructure and an earth systems simulation software system. The Simulator models and software will be constructed over a five year period by a multi-disciplinary team of computational scientists, mathematicians, earth scientists, civil engineers and software engineers. The construction team will integrate numerical simulation models (3D discrete elements/lattice solid model, particle-in-cell large deformation finite-element method, stress reconstruction models, multi-scale continuum models etc) with geophysical, geological and tectonic models, through advanced software engineering and visualization technologies. When fully constructed, the Simulator aims to provide the software and hardware infrastructure needed to model solid earth phenomena including global scale dynamics and mineralisation processes, crustal scale processes including plate tectonics, mountain building, interacting fault system dynamics, and micro-scale processes that control the geological, physical and dynamic

  18. USGEO Common Framework For Earth Observation Data

    Science.gov (United States)

    Walter, J.; de la Beaujardiere, J.; Bristol, S.

    2015-12-01

    The United States Group on Earth Observations (USGEO) Data Management Working Group (DMWG) is an interagency body established by the White House Office of Science and Technology Policy (OSTP). The primary purpose of this group is to foster interagency cooperation and collaboration for improving the life cycle data management practices and interoperability of federally held earth observation data consistent with White House documents including the National Strategy for Civil Earth Observations, the National Plan for Civil Earth Observations, and the May 2013 Executive Order on Open Data (M-13-13). The members of the USGEO DMWG are working on developing a Common Framework for Earth Observation Data that consists of recommended standards and approaches for realizing these goals as well as improving the discoverability, accessibility, and usability of federally held earth observation data. These recommendations will also guide work being performed under the Big Earth Data Initiative (BEDI). This talk will summarize the Common Framework, the philosophy behind it, and next steps forward.

  19. NASA'S Earth Science Data Stewardship Activities

    Science.gov (United States)

    Lowe, Dawn R.; Murphy, Kevin J.; Ramapriyan, Hampapuram

    2015-01-01

    NASA has been collecting Earth observation data for over 50 years using instruments on board satellites, aircraft and ground-based systems. With the inception of the Earth Observing System (EOS) Program in 1990, NASA established the Earth Science Data and Information System (ESDIS) Project and initiated development of the Earth Observing System Data and Information System (EOSDIS). A set of Distributed Active Archive Centers (DAACs) was established at locations based on science discipline expertise. Today, EOSDIS consists of 12 DAACs and 12 Science Investigator-led Processing Systems (SIPS), processing data from the EOS missions, as well as the Suomi National Polar Orbiting Partnership mission, and other satellite and airborne missions. The DAACs archive and distribute the vast majority of data from NASA’s Earth science missions, with data holdings exceeding 12 petabytes The data held by EOSDIS are available to all users consistent with NASA’s free and open data policy, which has been in effect since 1990. The EOSDIS archives consist of raw instrument data counts (level 0 data), as well as higher level standard products (e.g., geophysical parameters, products mapped to standard spatio-temporal grids, results of Earth system models using multi-instrument observations, and long time series of Earth System Data Records resulting from multiple satellite observations of a given type of phenomenon). EOSDIS data stewardship responsibilities include ensuring that the data and information content are reliable, of high quality, easily accessible, and usable for as long as they are considered to be of value.

  20. The Earth in energy troubles

    International Nuclear Information System (INIS)

    Pierret, Ch.; Carroue, L.; Goodchild, M.F.; Charvet, J.P.; Simon, A.; Ane, J.M.; Auburtin, E.; Barre, B.; Bonin, S.; Fumey, G.; Daviet, S.; Goupil, Ph.; Helfer, M.; Raison, J.; Velut, S.; Vidal, D.; Radvanyi, J.; Tapia, St. de; Pourtier, R.; Sebille-Lopez, Ph.; Clairet, S.; Poirson, A.C.; Guillaume, J.; Collignon, B.; Bauquis, P.R.; Brunel, S.; Guillaume, J.; Hourcade, B.; Marchand-Vaguet, Y.; Pitte, J.R.; Marchand-Vaguet, Y.; Laherrere, J.; Letourneau, M.; Lemarchand, N.; Beltran, A.; Bret, B.; Feckoua, L.; Helfer, M.; Lacoste, R.; Manzagol, C.; Tessier, F.; Vanneph, A.; Claessens, M.; Berdevet, M.; Tabeaud, M.; Laherrere, J.; Arnould, P.; Berque, A.; Brucher, W.; Deshaies, M.; Douguedroit, A.; Husson, J.P.; Lemartinel, J.; Mancebo, F.; Baron-Yelles, N.; Pitte, J.R.; Sede Marceau, J.H. de; Vigneau, J.P.; Tabeaud, M.; Fremont, A.; Crozet, Y.; Maupu, J.L.; Orfeuil, J.P.; Savy, M.; Viel, D.; Hammer, A.; Sanjuan, Th.; Lagarec, D.; Raillon, F.; Koninck, R. de; Bailly, A.; Bruneau, M.; Boulanger, Ph.; Bret, B.; Fournet-Guerin, C.; Hourcade, J.Ch.; Pitte, J.R.; Sanjuan, Th.; Verdeil, E.; Butler, S. de; Saint Germain, F.; Bouette, N.; Detot, A.; Caracchioli, Ph.; Bouette, N.; Smaghue, N.; Pousin, J.; Buysse, Ph.; Riallant, Y.; Durand, H.; Genter, A.; Dieulin, C.; Pronier, O.; Badea, A.; Tetart, F.; Genevois, S.; Leobet, M.; Angsthelm, B.; Calugaru, C.; Domergue, Ph.; Iacu, C.; Muntele, L.; Goodchild, M.F.; Costa, P.

    2007-01-01

    of transportation systems in Freiburg im Brisgau city (Germany); 6 - development stakes - access to energy; fatality or inequality: the energy appetite of China, between development and geopolitics; energy and health; wood fuel: the real energy crisis of the poorest southern countries; Madagascar: the lack of energy as a break to development; the challenges of the Three Gorges dam in China; geopolitics and electric power in Middle East and Lebanon; 7 - pedagogical courses: geography teaching using the map library of the French documentation; harvesting and criticizing the energy information coming from Internet; the Earth's energy troubles; petroleum in Africa, revealer of a development problem; petroleum, geopolitical stake of the present day world; the Penly nuclear power plant (Normandy, France); hydroelectric power in the Durance basin: some complex spatial stakes; wind power and land planning; the Earth's petroleum troubles; how petroleum fluxes can reveal the organization of worldwide trades; Picardie: a region in front of renewable energies; 8 - geomatics: wind farms and landscape; geothermal energy: potentialities, challenges and perspectives; Spot Image's projects of monitoring of hydrocarbon pollutions; geo-referenced databases for the agricultural and environmental management of Romania; virtual globes or educative geographical information systems: what is new for geography teaching; geo-portals: a scientific and technical tool; conflicts and petroleum, the Darfour example; the coal from Oltenie mining area (Romania): solution or puzzling problem; energy and society, which transportation policy; geo-history of petroleum in Romania; Citizens as sensors: the world of volunteered geography; the natural environment of the Danube delta. (J.S.)

  1. Testing Reproducibility in Earth Sciences

    Science.gov (United States)

    Church, M. A.; Dudill, A. R.; Frey, P.; Venditti, J. G.

    2017-12-01

    Reproducibility represents how closely the results of independent tests agree when undertaken using the same materials but different conditions of measurement, such as operator, equipment or laboratory. The concept of reproducibility is fundamental to the scientific method as it prevents the persistence of incorrect or biased results. Yet currently the production of scientific knowledge emphasizes rapid publication of previously unreported findings, a culture that has emerged from pressures related to hiring, publication criteria and funding requirements. Awareness and critique of the disconnect between how scientific research should be undertaken, and how it actually is conducted, has been prominent in biomedicine for over a decade, with the fields of economics and psychology more recently joining the conversation. The purpose of this presentation is to stimulate the conversation in earth sciences where, despite implicit evidence in widely accepted classifications, formal testing of reproducibility is rare.As a formal test of reproducibility, two sets of experiments were undertaken with the same experimental procedure, at the same scale, but in different laboratories. Using narrow, steep flumes and spherical glass beads, grain size sorting was examined by introducing fine sediment of varying size and quantity into a mobile coarse bed. The general setup was identical, including flume width and slope; however, there were some variations in the materials, construction and lab environment. Comparison of the results includes examination of the infiltration profiles, sediment mobility and transport characteristics. The physical phenomena were qualitatively reproduced but not quantitatively replicated. Reproduction of results encourages more robust research and reporting, and facilitates exploration of possible variations in data in various specific contexts. Following the lead of other fields, testing of reproducibility can be incentivized through changes to journal

  2. Earth Science Mining Web Services

    Science.gov (United States)

    Pham, Long; Lynnes, Christopher; Hegde, Mahabaleshwa; Graves, Sara; Ramachandran, Rahul; Maskey, Manil; Keiser, Ken

    2008-01-01

    To allow scientists further capabilities in the area of data mining and web services, the Goddard Earth Sciences Data and Information Services Center (GES DISC) and researchers at the University of Alabama in Huntsville (UAH) have developed a system to mine data at the source without the need of network transfers. The system has been constructed by linking together several pre-existing technologies: the Simple Scalable Script-based Science Processor for Measurements (S4PM), a processing engine at he GES DISC; the Algorithm Development and Mining (ADaM) system, a data mining toolkit from UAH that can be configured in a variety of ways to create customized mining processes; ActiveBPEL, a workflow execution engine based on BPEL (Business Process Execution Language); XBaya, a graphical workflow composer; and the EOS Clearinghouse (ECHO). XBaya is used to construct an analysis workflow at UAH using ADam components, which are also installed remotely at the GES DISC, wrapped as Web Services. The S4PM processing engine searches ECHO for data using space-time criteria, staging them to cache, allowing the ActiveBPEL engine to remotely orchestras the processing workflow within S4PM. As mining is completed, the output is placed in an FTP holding area for the end user. The goals are to give users control over the data they want to process, while mining data at the data source using the server's resources rather than transferring the full volume over the internet. These diverse technologies have been infused into a functioning, distributed system with only minor changes to the underlying technologies. The key to the infusion is the loosely coupled, Web-Services based architecture: All of the participating components are accessible (one way or another) through (Simple Object Access Protocol) SOAP-based Web Services.

  3. Impact on the earth, ocean and atmosphere

    International Nuclear Information System (INIS)

    Ahrens, T.J.; O'Keefe, J.D.

    1987-01-01

    Several hundred impact craters produced historically and at times as early as 1.9 x 10/sup 9/ years ago with diameters in the range 10/sup -2/ to 10/sup 2/ km are observed on the surface of the earth. Earth-based and spacecraft observations of the surfaces of all the terrestrial planets and their satellites, as well as many of the icy satellites of the outer planets, indicated that impact cratering was a dominant process on planetary surfaces during the early history of the solar system. Moreover, the recent observation of a circumstellar disk around the nearby star, β-Pictoris, appears to be similar to the authors' own hypothesized protosolar disk. A disk of material around our sun has been hypothesized to have been the source of the solid planetesimals from which the earth and the other planets accreted by infall and capture. Thus it appears that the earth and the other terrestrial planets formed as a result of infall and impact of planetesimals. Although the present planets grew rapidly via accretion to their present size (in --10/sup 7/ years), meteorite impacts continue to occur on the earth and other planets. Until recently meteorite impact has been considered to be a process that was important on the earth and the other planets only early in the history of the solar system. This is no longer true. The Alvarez hypothesis suggests that the extinction of some 90% of all species, including 17 classes of dinosaurs, is associated with the 1 to 150 cm thick layer of noble-element rich dust which is found all over the earth exactly at the Cretaceous-Tertiary boundary. The enrichment of noble elements in this dust is in meteorite-like proportions. This dust is thought to represent the fine impact ejecta from a --10 km diameter asteroid interacting with the solid earth. The Alvarez hypothesis associates the extinction with the physics of a giant impact on the earth

  4. Venus and the Archean Earth: Thermal considerations

    International Nuclear Information System (INIS)

    Sleep, N.H.

    1989-01-01

    The Archean Era of the Earth is not a direct analog of the present tectonics of Venus. In this regard, it is useful to review the state of the Archean Earth. Most significantly, the temperature of the adiabatic interior of the Earth was 200 to 300 C hotter than the current temperature. Preservation biases limit what can be learned from the Archean record. Archean oceanic crust, most of the planetary surface at any one time, has been nearly all subducted. More speculatively, the core of the Earth has probably cooled more slowly than the mantle. Thus the temperature contrast above the core-mantle boundary and the vigor of mantle plumes has increased with time on the Earth. The most obvious difference between Venus and the present Earth is the high surface temperature and hence a low effective viscosity of the lithosphere. In addition, the temperature contrast between the adiabatic interior and the surface, which drives convection, is less on Venus than on the Earth. It appears that the hot lithosphere enhanced tectonics on the early Venus significantly enough that its interior cooled faster than the Earth's. The best evidence for a cool interior of Venus comes from long wavelength gravity anomalies. The low interior temperatures retard seafloor spreading on Venus. The high surface temperatures on Venus enhance crustal deformation. That is, the lower crust may become ductile enough to permit significant flow between the upper crust and the mantle. There is thus some analogy to modern and ancient areas of high heat flow on the Earth. Archean crustal blocks typically remained stable for long intervals and thus overall are not good analogies to the deformation style on Venus

  5. Geological evolution of the center-southern portion of the Guyana shield based on the geochemical, geochronological and isotopic studies of paleoproterozoic granitoids from southeastern Roraima, Brazil; Evolucao geologica da porcao centro-sul do escudo das Guianas com base no estudo geoquimico, geocronologico e isotopico dos granitoides paleoproterozoicos do sudeste de Roraima, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Marcelo Esteves

    2006-07-01

    This study focuses the granitoids of center-southern portion of Guyana Shield, southeastern Roraima, Brazil. The region is characterized by two tectonic-stratigraphic domains, named as Central Guyana (GCD) and Uatuma-Anaua (UAD) and located probably in the limits of geochronological provinces (e.g. Ventuari-Tapajos or Tapajos-Parima, Central Amazonian and Maroni-Itacaiunas or Transamazon). The aim this doctoral thesis is to provide new petrological and lithostratigraphic constraints on the granitoid rocks and contribute to a better understanding of the origin and geo dynamic evolution of Guyana Shield. The GCD is only locally studied near to the UAD boundary, and new geological data and two single zircon Pb-evaporation ages in mylonitic biotite granodiorite (1.89 Ga) and foliated hastingsite-biotite granite (1.72 Ga) are presented. These ages of the protholiths contrast with the lithostratigraphic picture in the other areas of Cd (1.96-1.93 Ga). Regional mapping, petrography, geochemistry and zircon geochronology carried out in the Urad have showed widespread Paleoproterozoic calc-alkaline granitic magmatism. These granitoid rocks are distributed into several magmatic associations with different Paleoproterozoic (1.97-1.89 Ga) ages, structural and geochemical affinities. Detailed mapping, petrographic and geochronological studies have distinguished two main sub domains in the UAD. In the northern UAD, the high-K calc-alkaline Martins Pereira (1.97 Ga) and Serra Dourada S-type granites (1.96 Ga) are affected by NE-SW and E-W ductile dextral shear-zones, showing coexistence of magmatic and deformational fabrics related to heterogeneous deformation. Inliers of basement (2.03 Ga) crop out northeast of this area, and are formed by meta volcano-sedimentary sequence (Cauarane Group) and TTG-like calc-alkaline association (Anaua Complex). Xenoliths of meta diorites (Anaua Complex) and para gneisses (Cauarane Group) reinforce the intrusive character of Martins Pereira

  6. Earth Sciences Division collected abstracts: 1979

    International Nuclear Information System (INIS)

    Henry, A.L.; Schwartz, L.L.

    1980-01-01

    This report is a compilation of abstracts of papers, internal reports, and talks presented during 1979 at national and international meetings by members of the Earth Sciences Division, Lawrence Livermore Laboratory. The arrangement is alphabetical (by author). For a given report, a bibliographic reference appears under the name of each coauthor, but the abstract iself is given only under the name of the first author or the first Earth Sciences Division author. A topical index at the end of the report provides useful cross references, while indicating major areas of research interest in the Earth Sciences Division

  7. Thermochemistry of rare-earth trifluorides

    International Nuclear Information System (INIS)

    Kim, K.Y.; Johnson, C.E.

    1981-01-01

    Using the most recent crystallographic data, the Born-Lande equation was employed to calculate lattice energies of the rare-earth trifluorides. The excellent agreement ( 0 sub(f)(MX 3 ,c,298.15K) can be estimated. The magnitude of the monotonic change of ΔH 0 sub(f)(MX 3 ) for the rare-earth trihalides series (14 4f electrons) is comparable to the energy change between Sc and Ti in which only one 3d electron is added. This energy change is consistent with the chemical evidence that the electrons in the f-orbitals of rare earths contribute negligibly to the bonding. (author)

  8. Clouds and the earth's radiation balance

    Energy Technology Data Exchange (ETDEWEB)

    Schmetz, J; Raschke, E

    1986-01-01

    Cloud formation mechanisms and cloud effects must be known for all regions of the earth for two important purposes of weather and climate research: First, the circulation characteristics of the atmosphere can be defined and understood only if the energy transfer between the atmosphere and the earth's surface is known; secondly, the energy transfer calculations should be as realistic as possible. The article discusses the influence of clouds on the radiation balance of the earth/atmosphere radiation balance, and the effects on weather and climate.

  9. Might electrical earthing affect convection of light

    International Nuclear Information System (INIS)

    Budrikis, Z.L.

    1982-01-01

    Partial convection of light by moving media was predicted by Fresnel and verified by Fizeau, Zeeman and others. It is accepted as an important argument in favour of the Special Theory of Relativity. The suggestion is made here that the convection is partial only when the propagating medium is moved with respect to its electrically earthed surroundings and that it would be total if an earthed shield was co-moving with the medium. This is based on a reinterpretation of Maxwell's equations wherein they are seen as macroscopic relationships that are in each case valid only in respect of a particular inertial frame of reference, the local electrical earth frame. (Auth.)

  10. The earth's radius and the G variation

    International Nuclear Information System (INIS)

    Canuto, V.M.; City Coll., New York

    1981-01-01

    It has been assumed that if the gravitational constant G was larger in the past, the Earth's radius had to be smaller. The assertion holds provided the input from microphysics (in particular the equation of state) is independent of G. While this is true for some theories of gravity with variable G it is not so in the scale covariant theory, where the pressure can be affected by a variable G in a way that, for a constant mass of the Earth, a larger G in the past implies a larger Earth's radius. Comparison with recent palaeomagnetic data is presented. (author)

  11. Space and Earth Science Data Compression Workshop

    Science.gov (United States)

    Tilton, James C. (Editor)

    1991-01-01

    The workshop explored opportunities for data compression to enhance the collection and analysis of space and Earth science data. The focus was on scientists' data requirements, as well as constraints imposed by the data collection, transmission, distribution, and archival systems. The workshop consisted of several invited papers; two described information systems for space and Earth science data, four depicted analysis scenarios for extracting information of scientific interest from data collected by Earth orbiting and deep space platforms, and a final one was a general tutorial on image data compression.

  12. Near-Earth Objects. Chapter 27

    Science.gov (United States)

    Harris, Alan W.; Drube, Line; McFadden, Lucy A.; Binzel, Richard P.

    2014-01-01

    A near-Earth object (NEO) is an asteroid or comet orbiting the Sun with a perihelion distance of less than 1.3 Astronomical Units (AU) (1 AU, an astronomical unit, is the mean distance between the Earth and the Sun, around 150 million kilometers). If the orbit of an NEO can bring it to within 0.05 AU of the Earth's orbit, and it is larger than about 120 meters, it is termed a potentially hazardous object (PHO); an object of this size is likely to survive passage through the atmosphere and cause extensive damage on impact. (The acronyms NEA and PHO are used when referring specifically to asteroids.)

  13. Recovery of rare earths from red mud

    International Nuclear Information System (INIS)

    Bautista, R.G.

    1992-01-01

    The prospect for the recovery of rare earths from red mud, the bauxite tailings from the production of alumina is examined. The Jamaican red mud by far has the higher trace concentrations of lanthanum, cerium, neodymium, and yttrium. Scandium is also present. The dissolution of the rare earth is a major extraction problem because of the large volume of other materials. The recovery processes that have been proposed include the production of co-products such as iron, alumina, and titanium concentrates, with the rare earths going with the titanium. In this paper a critical examination of the possible processes are presented with the recommended research projects to be carried out

  14. Geohistory: Global evolution of the earth

    International Nuclear Information System (INIS)

    Ozima, M.

    1987-01-01

    This book traces the evolution of the Earth, mainly on the basis of radiogenic isotopes from half-life parent elements, and discusses it in terms of the latest developments in astrophysical theory, which impose unique constraints on the origin and early evolution of the earth. Owing to its historical nature, this geohistorical study offers an approach to forecasting the future of the Earth yielding clues for the understanding of environmental problems, such as radioactive waste to disposal and climate changes due to CO/sub 2/ increase

  15. How Inge Lehmann Discovered the Inner Core of the Earth

    Science.gov (United States)

    Rousseau, Christiane

    2013-01-01

    The mathematics behind Inge Lehmann's discovery that the inner core of the Earth is solid is explained using data collected around the Earth on seismic waves and their travel time through the Earth.

  16. An Earth-sized planet with an Earth-like density.

    Science.gov (United States)

    Pepe, Francesco; Cameron, Andrew Collier; Latham, David W; Molinari, Emilio; Udry, Stéphane; Bonomo, Aldo S; Buchhave, Lars A; Charbonneau, David; Cosentino, Rosario; Dressing, Courtney D; Dumusque, Xavier; Figueira, Pedro; Fiorenzano, Aldo F M; Gettel, Sara; Harutyunyan, Avet; Haywood, Raphaëlle D; Horne, Keith; Lopez-Morales, Mercedes; Lovis, Christophe; Malavolta, Luca; Mayor, Michel; Micela, Giusi; Motalebi, Fatemeh; Nascimbeni, Valerio; Phillips, David; Piotto, Giampaolo; Pollacco, Don; Queloz, Didier; Rice, Ken; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Szentgyorgyi, Andrew; Watson, Christopher A

    2013-11-21

    Recent analyses of data from the NASA Kepler spacecraft have established that planets with radii within 25 per cent of the Earth's (R Earth symbol) are commonplace throughout the Galaxy, orbiting at least 16.5 per cent of Sun-like stars. Because these studies were sensitive to the sizes of the planets but not their masses, the question remains whether these Earth-sized planets are indeed similar to the Earth in bulk composition. The smallest planets for which masses have been accurately determined are Kepler-10b (1.42 R Earth symbol) and Kepler-36b (1.49 R Earth symbol), which are both significantly larger than the Earth. Recently, the planet Kepler-78b was discovered and found to have a radius of only 1.16 R Earth symbol. Here we report that the mass of this planet is 1.86 Earth masses. The resulting mean density of the planet is 5.57 g cm(-3), which is similar to that of the Earth and implies a composition of iron and rock.

  17. Recovering heavy rare earth metals from magnet scrap

    Science.gov (United States)

    Ott, Ryan T.; McCallum, Ralph W.; Jones, Lawrence L.

    2017-08-08

    A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.

  18. Rare earth mobility in hydrothermal ore-forming systems

    International Nuclear Information System (INIS)

    Cornell, D.H.; Schade, J.; Scheepers, R.; Watkeys, M.K.

    1988-01-01

    Rocks and ores which form by magmatic processes display a range of chondrite-normalised rare earth profiles. One REE (rare earth elements) profile feature which seems unrelated to magmatic processes is the birdwing profile, in which both heavy and light rare earths are enriched relative to the middle rare earths. Birdwing rare earth profiles are an easily identified geochemical anomaly. It is proposed that rare earth geochemistry could be applied in geochemical prospecting for ore formed by hydrothermal processes. 5 figs

  19. Statistical modeling of Earth's plasmasphere

    Science.gov (United States)

    Veibell, Victoir

    The behavior of plasma near Earth's geosynchronous orbit is of vital importance to both satellite operators and magnetosphere modelers because it also has a significant influence on energy transport, ion composition, and induced currents. The system is highly complex in both time and space, making the forecasting of extreme space weather events difficult. This dissertation examines the behavior and statistical properties of plasma mass density near geosynchronous orbit by using both linear and nonlinear models, as well as epoch analyses, in an attempt to better understand the physical processes that precipitates and drives its variations. It is shown that while equatorial mass density does vary significantly on an hourly timescale when a drop in the disturbance time scale index ( Dst) was observed, it does not vary significantly between the day of a Dst event onset and the day immediately following. It is also shown that increases in equatorial mass density were not, on average, preceded or followed by any significant change in the examined solar wind or geomagnetic variables, including Dst, despite prior results that considered a few selected events and found a notable influence. It is verified that equatorial mass density and and solar activity via the F10.7 index have a strong correlation, which is stronger over longer timescales such as 27 days than it is over an hourly timescale. It is then shown that this connection seems to affect the behavior of equatorial mass density most during periods of strong solar activity leading to large mass density reactions to Dst drops for high values of F10.7. It is also shown that equatorial mass density behaves differently before and after events based on the value of F10.7 at the onset of an equatorial mass density event or a Dst event, and that a southward interplanetary magnetic field at onset leads to slowed mass density growth after event onset. These behavioral differences provide insight into how solar and geomagnetic

  20. The Evolution of the Earth's Magnetic Field.

    Science.gov (United States)

    Bloxham, Jeremy; Gubbins, David

    1989-01-01

    Describes the change of earth's magnetic field at the boundary between the outer core and the mantle. Measurement techniques used during the last 300 years are considered. Discusses the theories and research for explaining the field change. (YP)

  1. Geomagnetism solid Earth and upper atmosphere perspectives

    CERN Document Server

    Basavaiah, Nathani

    2011-01-01

    This volume elaborates several important aspects of solid Earth geomagnetism. It covers all the basics of the subject, including biomagnetism and instrumentation, and offers a number of practical applications with carefully selected examples and illustrations.

  2. Geo-neutrinos and earth's interior

    International Nuclear Information System (INIS)

    Fiorentini, Gianni; Lissia, Marcello; Mantovani, Fabio

    2007-01-01

    The deepest hole that has ever been dug is about 12 km deep. Geochemists analyze samples from the Earth's crust and from the top of the mantle. Seismology can reconstruct the density profile throughout all Earth, but not its composition. In this respect, our planet is mainly unexplored. Geo-neutrinos, the antineutrinos from the progenies of U, Th and 40 K decays in the Earth, bring to the surface information from the whole planet, concerning its content of natural radioactive elements. Their detection can shed light on the sources of the terrestrial heat flow, on the present composition, and on the origins of the Earth. Geo-neutrinos represent a new probe of our planet, which can be exploited as a consequence of two fundamental advances that occurred in the last few years: the development of extremely low background neutrino detectors and the progress on understanding neutrino propagation. We review the status and the prospects of the field

  3. The Age-of-the-Earth-Debate.

    Science.gov (United States)

    Badash, Lawrence

    1989-01-01

    Summarizes the development of the Earth's age calculation including the work of Archbishop Ussher, James Hutton, Lord Kelvin, Ernest Rutherford, Bertram Boltwood, and Arthur Holmes. Describes the changes in radioisotope dating methods. (YP)

  4. Earth Rotation Dynamics: Review and Prospects

    Science.gov (United States)

    Chao, Benjamin F.

    2004-01-01

    Modem space geodetic measurement of Earth rotation variations, particularly by means of the VLBI technique, has over the years allowed studies of Earth rotation dynamics to advance in ever-increasing precision, accuracy, and temporal resolution. A review will be presented on our understanding of the geophysical and climatic causes, or "excitations", for length-of-day change, polar motion, and nutations. These excitations sources come from mass transports that constantly take place in the Earth system comprised of the atmosphere, hydrosphere, cryosphere, lithosphere, mantle, and the cores. In this sense, together with other space geodetic measurements of time-variable gravity and geocenter motion, Earth rotation variations become a remote-sensing tool for the integral of all mass transports, providing valuable information about the latter on a wide range of spatial and temporal scales. Future prospects with respect to geophysical studies with even higher accuracy and resolution will be discussed.

  5. Leeuwenhoek's "Proof" of the Earth's Rotation.

    Science.gov (United States)

    Kruglak, Haym; Johnson, Rand H.

    1995-01-01

    Leeuwenhoek's demonstration proving the Earth's rotation, which leads to some significant errors in reasoning, can be reproduced from this article and used to provide an interesting discussion in undergraduate astronomy and physics courses or clubs. (LZ)

  6. ArXives of Earth science

    Science.gov (United States)

    2018-03-01

    Preprint servers afford a platform for sharing research before peer review. We are pleased that two dedicated preprint servers have opened for the Earth sciences and welcome submissions that have been posted there first.

  7. Foundations for a multiscale collaborative Earth model

    KAUST Repository

    Afanasiev, M.; Peter, Daniel; Sager, K.; Simut, S.; Ermert, L.; Krischer, L.; Fichtner, A.

    2015-01-01

    . The CSEM as a computational framework is intended to help bridging the gap between local, regional and global tomography, and to contribute to the development of a global multiscale Earth model. While the current construction serves as a first proof

  8. SWARM - An earth Observation Mission investigating Geospace

    DEFF Research Database (Denmark)

    Friis-Christensen, Eigil; Lühr, H.; Knudsen, D.

    2008-01-01

    The Swarm mission was selected as the 5th mission in ESA's Earth Explorer Programme in 2004. This mission aims at measuring the Earth's magnetic field with unprecedented accuracy. This will be done by a constellation of three satellites, where two will fly at lower altitude, measuring the gradient...... of the magnetic field, and one satellite will fly at higher altitude. The measured magnetic field is the sum of many contributions including both magnetic fields and currents in the Earth's interior and electrical currents in Geospace. In order to separate all these sources electric field and plasma measurements...... will also be made to complement the primary magnetic field measurements. Together these will allow the deduction of information on a series of solid earth processes responsible for the creation of the fields measured. The completeness of the measurements on each satellite and the constellation aspect...

  9. Near-Earth Space Radiation Models

    Science.gov (United States)

    Xapsos, Michael A.; O'Neill, Patrick M.; O'Brien, T. Paul

    2012-01-01

    Review of models of the near-Earth space radiation environment is presented, including recent developments in trapped proton and electron, galactic cosmic ray and solar particle event models geared toward spacecraft electronics applications.

  10. Electromagnetic sounding of the Earth's interior

    CERN Document Server

    Spichak, Viacheslav V

    2015-01-01

    Electromagnetic Sounding of the Earth's Interior 2nd edition provides a comprehensive up-to-date collection of contributions, covering methodological, computational and practical aspects of Electromagnetic sounding of the Earth by different techniques at global, regional and local scales. Moreover, it contains new developments such as the concept of self-consistent tasks of geophysics and , 3-D interpretation of the TEM sounding which, so far, have not all been covered by one book. Electromagnetic Sounding of the Earth's Interior 2nd edition consists of three parts: I- EM sounding methods, II- Forward modelling and inversion techniques, and III - Data processing, analysis, modelling and interpretation. The new edition includes brand new chapters on Pulse and frequency electromagnetic sounding for hydrocarbon offshore exploration. Additionally all other chapters have been extensively updated to include new developments. Presents recently developed methodological findings of the earth's study, including seism...

  11. Earth Sciences Division annual report 1981

    International Nuclear Information System (INIS)

    1982-09-01

    Separate abstracts were prepared for the 59 papers of the 1981 annual report of the Earth Sciences Division at Lawrence Berkeley Laboratory. The general topics covered included nuclear waste isolation, geophysics and reservoir engineering, and geosciences

  12. The future of Earth observation in hydrology

    KAUST Repository

    McCabe, Matthew; Rodell, Matthew; Alsdorf, Douglas E.; Miralles, Diego G.; Uijlenhoet, Remko; Wagner, Wolfgang; Lucieer, Arko; Houborg, Rasmus; Verhoest, Niko E. C.; Franz, Trenton E.; Shi, Jiancheng; Gao, Huilin; Wood, Eric F.

    2017-01-01

    In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles

  13. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.G.

    1975-01-01

    This patent describes a sintered product having substantially stable permanent magnet properties in air at room temperature. It comprises compacted particulate cobalt--rare earth alloy consisting essentially of a Co 5 R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase, where R is a rare earth metal. The Co 5 R intermetallic phase is present in an amount of at least 65 percent by weight of the sintered product and the CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase is present in a positive amount having a value ranging up to about 35 percent by weight of the product. The sintered product has a density of at least 87 percent and has pores which are substantially noninterconnecting and wherein the component grains have an average size less than 30 microns

  14. Thermodynamics of rare earths in steelmaking

    International Nuclear Information System (INIS)

    Vahed, A.; Kay, D.A.R.

    1976-01-01

    The standard free energies of formation of the oxides, sulfides and oxysulfides of cerium and lanthanum under steelmaking conditions have been calculated and used to predict the behavior of rare earths in steelmaking. Deoxidation and desulfurization constants, expressed in terms of Henrian activities, have been used to construct a precipitation diagram which indicates the sequence of rare earth inclusion formation. An enrichment of lanthanum in (RE)-oxysulfide and cerium in (RE)-sulfide is predicted. It is also predicted that rare earths should be able to reduce the soluble oxygen and sulfur contents of liquid steel well below the contents presently found in most industrial and laboratory practices. A simple method of calculating steelmaking additions for complete rare earth control of inclusion composition is presented

  15. Earth System Science: An Integrated Approach.

    Science.gov (United States)

    Environment, 2001

    2001-01-01

    Details how an understanding of the role played by human activities in global environmental change has emerged. Presents information about the earth system provided by research programs. Speculates about the direction of future research. (DDR)

  16. The Earth's Magnetism: An Introduction for Geologists

    Science.gov (United States)

    Harlan, Stephen S.

    2007-03-01

    Roberto Lanza and Antonio Meloni Springer; XII + 278 pp.; ISBN: 3-540-27979-2 2006; $79.95. The nature of the geomagnetic field is one of the cornerstones of the study of the geophysical properties of the Earth. Despite the importance of geomagnetism to the understanding of the Earth and to the various subdisciplines of geophysics, and despite its being an essential part of any Earth scientist's education, it has been suggested that most geophysics textbooks and curricula devote only limited attention to the subject. With this in mind, Roberto Lanza and Antonio Meloni have authored The Earth's Magnetism: An Introduction for Geologists with the goal of producing a textbook that would provide a holistic approach to the subject and a general overview of many of the fundamental subjects that compose geomagnetism and its applications to geology. The text is meant to supplement more substantial treatments of various subjects and the geomagnetic literature.

  17. Quantitative Modeling of Earth Surface Processes

    Science.gov (United States)

    Pelletier, Jon D.

    This textbook describes some of the most effective and straightforward quantitative techniques for modeling Earth surface processes. By emphasizing a core set of equations and solution techniques, the book presents state-of-the-art models currently employed in Earth surface process research, as well as a set of simple but practical research tools. Detailed case studies demonstrate application of the methods to a wide variety of processes including hillslope, fluvial, aeolian, glacial, tectonic, and climatic systems. Exercises at the end of each chapter begin with simple calculations and then progress to more sophisticated problems that require computer programming. All the necessary computer codes are available online at www.cambridge.org/9780521855976. Assuming some knowledge of calculus and basic programming experience, this quantitative textbook is designed for advanced geomorphology courses and as a reference book for professional researchers in Earth and planetary science looking for a quantitative approach to Earth surface processes. More details...

  18. Thermal structure of the accreting earth

    International Nuclear Information System (INIS)

    Turcotte, D.L.; Pflugrath, J.C.

    1985-01-01

    The energy associated with the accretion of the earth and the segregation of the core is more than sufficient to melt the entire earth. In order to understand the thermal evolution of the early earth it is necessary to study the relevant heat transfer mechanisms. In this paper we postulate the existence of a global magma ocean and carry out calculations of the heat flux through it in order to determine its depth. In the solid mantle heat is transferred by the upward migration of magma. This magma supplies the magma ocean. The increase in the mantle liquidus with depth (pressure) is the dominant effect influencing heat transfer through the magma ocean. We find that a magma ocean with a depth of the order of 20 km would have existed as the earth accreted. We conclude that the core segregated and an atmosphere was formed during accretion

  19. Learning to Improve Earth Observation Flight Planning

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper describes a method and system for integrating machine learning with planning and data visualization for the management of mobile sensors for Earth science...

  20. Volatile accretion history of the Earth.

    Science.gov (United States)

    Wood, B J; Halliday, A N; Rehkämper, M

    2010-10-28

    It has long been thought that the Earth had a protracted and complex history of volatile accretion and loss. Albarède paints a different picture, proposing that the Earth first formed as a dry planet which, like the Moon, was devoid of volatile constituents. He suggests that the Earth's complement of volatile elements was only established later, by the addition of a small veneer of volatile-rich material at ∼100 Myr (here and elsewhere, ages are relative to the origin of the Solar System). Here we argue that the Earth's mass balance of moderately volatile elements is inconsistent with Albarède's hypothesis but is well explained by the standard model of accretion from partially volatile-depleted material, accompanied by core formation.