Sample records for barberton greenstone belt

  1. Archaean greenstone belt tectonism and basin development: some insights from the Barberton and Pietersburg greenstone belts, Kaapvaal Craton, South Africa

    NASA Astrophysics Data System (ADS)

    de Wit, Maarten J.

    The sediments in two of South Africa's major Archaean greenstone belts, the Barberton and Pietersburg greenstone belts, span an age range of some 800 million years. Both greenstone belts represent remnants of extensive fold and thrust belts with complex, but different polyphase tectonic histories. The oldest sediments were deposited between circa 3470 and 3490 M.a. on oceanic like crust preserved in the Barberton belt, possibly at the same time as sedimentation on similar oceanic crust preserved in the Pietersburg belt. Thereafter, the geologic evolution of these two belts diverged considerably. In the Barberton belt, there is clear evidence that the oceanic crust and sediments were obducted onto an intra-arc basin environment within 50 million years of its formation. The sequence was later further imbricated by northwest directed thrust stacking between 3300-3200 M.a. Basin development during both periods of thrusting took place in close proximity to active "calc-alkaline" arc systems. Deformation of the sediments within these basins took place while the same sediments were being deposited. Sedimentation took place predominantly in subaqueous environments, ranging from submarine mid-fans below the photic zone to tidal flats and deltaic plains. The sediments represent a polyhistory successor-type basin: early basins developed along a complex subduction related plate boundary; these basins later evolved into foreland depositories along and within collisional environments of an accretionary orogen. Late in the history of the Barberton greenstone belt (circa 3100 M.a.), the rocks were in places thermally reactivated and probably subjected to extensional processes; these processes overlapped in time with the main episodes of economic gold mineralization, and are of "early Witwatersrand-basin" age. The oceanic-like crust (including associated sediments) preserved in the Pietersburg belt was not significantly deformed until at least 500 million years after its formation: tectonic imbrication of this crust occurred between about 2900 and 2700 M.a., during north-directed thrusting. Sedimentary basins formed in response to this thrusting and associated bulk-flattening, and the sediments in these basins were deformed during sedimentation. Sedimentation took place predominantly in subaerial environments, in alluvial fans of an active foreland basin. It is likely therefore that the oceanic-like crust had previously been tectonically emplaced onto a continental environment as an allochthonous sheet, but the timing of this is not clear. The foreland basin of the Pietersburg belt which developed on top of this simatic basement is almost certainly part of the greater upper Witwatersrand basinal systems; it was most likely formed in an intermontane tectonic setting of the Cordillera-type such as that along the Mesozoic-Cenozoic margins of western North America. Late in the history of the Pietersburg belt ( circa 2.7 G.a.), the rocks were tectonically deformed in a major strike-slip fault system with both transpressional and transtensional kinematics. Sediments which were deposited and deformed in local contemporaneous basins, form an integral part of the greenstone belt's lithotectonic sequence, and are probably of Ventersdorp age. Unravelling the kinematic details of the basin evolution in both greenstone belts is now a major challenge for further understanding of the tectonic evolution of these belts, and almost the entire 800 million years of Archaean history of the Kaapvaal craton as recorded in these belts. A better understanding of the intimate relationship of tectonism to basin formation from greenstone belt studies, is of fundamental importance to understanding the famous Witwatersrand gold deposits and the source of this gold. This major task can only be achieved through better integrated and focused field and laboratory studies, in which precise chronostratigraphy must play a central role.

  2. Do graded units of accretionary spheroids in the Barberton Greenstone Belt indicate Archaean deep water environment?

    Microsoft Academic Search

    Ian G. Stanistreet; Maarten J. de Wit; Rodney E. P. Fripp

    1981-01-01

    We report here a re-analysis of the sedimentology of the Msauli Chert (`oolite') which shows that environmental conditions during the early depositional phase of the Fig Tree Group in the Barberton Greenstone Belt were of a deep water nature. The unit is compared with Quaternary sediments deposited in the Pacific Ocean at bathyal to abyssal depths.

  3. Incipient basin inversion of the Middle Archean Moodies Basin, Barberton Supergroup, Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Kirstein, Jens; Heubeck, Christoph; Lippold, Wigbert

    2010-05-01

    The Moodies Group of the Barberton Greenstone Belt is one of the oldest and best-preserved quartz-rich sedimentary sequences on Earth. Its strata, approx. 3 km thick, record an initial extensional setting, followed by a strong shortening pulse which resulted in the dominant large-scale final deformation of the greenstone belt. We investigated the apparently rapid transition from Moodies extensional to compressive setting through detailed mapping, correlation of measured sections and the analysis of a prominent basaltic lava which extends for approx. 60 km along strike, in order to constrain the tectonic and depositional setting of some of the earliest stable life-providing habitats on Earth. In the middle Moodies Group, large-scale cross-bedded coarse-grained sandstones, interpreted as an offshore dune field, are abruptly overlain by a discontinuous cobble and boulder conglomerate of up to 4 m thickness, possibly representing local small alluvial fans above a cryptic disconformity. A basaltic lava, reaching approx. 50 m thick, regionally exists above this unit and forms the most prominent marker unit in the Moodies Group. In most places, the lava is metasomatically altered to a fine-grained mesh of illite, sericite, chlorite and very fine-grained quartz. In its upper third, it contains abundant amygdules approx. 0.5 - 1 cm in diameter. We did not record significant thickness changes hinting at eruption centers, feeder channels, flow markers nor pillows. Two thin but regionally continuous dacitic tuffs overlying the lava yielded concordant single-zircon ages of 3229+-6 Ma (Heubeck et al., in prep.) which are statistically indistinguishable from underlying Fig Tree Group volcanics and suggest high depositional and subsidence rates (mm/yr or higher) of intervening Moodies Group strata. Overlying clastic sediments up to 1 km thick show a very high lateral and vertical variability in grain size and petrography. Their facies ranges from alluvial conglomeratic wedges, fluvial gravelly sandstones, nearshore cross-bedded sandstones, tuffaceous shales to thin BIFs; sandstones show isolated occurrences of laminated curly biomats. The rapid facies changes attest to the termination of a uniform sedimentation regime and suggest the incipient breakup of the basin in numerous subbasins. The boulder conglomerate below the base of the basaltic lava likely represents the tectonic turning point in the evolution of the Moodies Basin by marking a pronounced increase in local depositional slope, the subsequent initiation of horizontal shortening, basin margin uplift and erosion, and final tight greenstone belt shortening. The eruption of the basaltic lava may be related to brittle segmentation of the basement, causing small-scale faulting, alluvial fan development on a former shelf, and allowing magma ascent.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  5. Accretionary history of the Archean Barberton Greenstone Belt (3.55-3.22 Ga), southern Africa

    NASA Technical Reports Server (NTRS)

    Lowe, D. R.

    1994-01-01

    The 3.55-3.22 Ga Barberton Greenstone Belt, South Africa and Swaziland, and surrounding coeval plutons can be divided into four tectono-stratigraphic blocks that become younger toward the northwest. Each block formed through early mafic to ultramafic volcanism (Onverwacht Group), probably in oceanic extensional, island, or plateau settings. Volcanism was followed by magmatic quiescence and deposition of fine-grained sediments, possibly in an intraplate setting. Late evolution involved underplating of the mafic crust by tonalitic intrusions along a subduction-related magmatic arc, yielding a thickened, buoyant protocontinental block. The growth of larger continental domains occurred both through magmatic accretion, as new protocontinental blocks developed along the margins of older blocks, and when previously separate blocks were amalgamated through tectonic accretion. Evolution of the Barberton Belt may reflect an Early Archean plate tectonic cycle that characterized a world with few or no large, stabilized blocks of sialic crust.

  6. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    Microsoft Academic Search

    M. J. Dewit

    1986-01-01

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type

  7. Palaeomagnetism of Archaean rocks of the Onverwacht Group, Barberton Greenstone Belt (southern Africa): Evidence for a stable and potentially reversing geomagnetic

    E-print Network

    Utrecht, Universiteit

    Greenstone Belt (Kaapvaal Craton, southern Africa). Our palaeomagnetic measurements strengthen a recently) in the Kaapvaal Craton of southern Africa and the Pilbara Granite-Greenstone terrain in western Australia, bothPalaeomagnetism of Archaean rocks of the Onverwacht Group, Barberton Greenstone Belt (southern

  8. Tourmaline mineralization in the Barberton greenstone belt, South Africa: early Archean metasomatism by evaporite-derived boron

    Microsoft Academic Search

    Gary R. Byerly; Martin R. Palmer

    1991-01-01

    Tourmaline-rich rocks are common in the lowgrade, interior portions of the Barberton greenstone belt of South Africa, where shallow-marine sediments and underlying altered basaltic and komatiitic lavas contain up to 50% tourmaline. The presence of tourmaline-bearing rip-up clasts, intraformational tourmalinite pebbles, and tourmaline-coated grains indicates that boron mineralization was a low-temperature, surficial process. The association of these lithologies with stromatolites,

  9. Growth of early archaean crust in the ancient Gneiss complex of Swaziland and adjacent Barberton Greenstone Belt, Southern Africa

    NASA Technical Reports Server (NTRS)

    Kroener, A.; Compston, W.; Tegtmeyer, A.; Milisenda, C.; Liew, T. C.

    1988-01-01

    The relationship between early Archean greenstones and high grade gneisses in the Ancient Gneiss Complex of Swaziland and the neighboring Barberton greenstone belt in Southern Africa is discussed. New high precision zircon analyses reveal a complex history in individual zircons from tonalitic orthogneisses, with ages as old as 3644 + 4 Ma. This suggests the presence of continental crust prior to the formation of the supracrustal rocks of the Barberton greenstone belt, which have been previously considered the earliest rocks in the area. The author suggested that these data are incompatible with the intraoceanic settings that have been widely accepted for this terrane, and favors either a marginal basin or rift environment. By using the detailed age information obtained from zircons in combination with Ar-40 and Ar-39 and paleomagnetic measurements, the author estimated that plate velocities for this part of Africa craton were about 10 to 70 mm/yr, during the period 3.4 to 2.5 Ga. This is not incompatible with the idea that Archean plate velocities may have been similiar to those of today.

  10. Early terrestrial impact events: Archean spherule layers in the Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Ozdemir, Seda; Koeberl, Christian; Schulz, Toni; Reimold, W. Uwe; Hofmann, Axel

    2015-04-01

    In addition to the oldest known impact structure on Earth, the 2.02-billion-year-old Vredefort Structure in South Africa, the evidence of Early Earth impact events are Archean spherule beds in South Africa and Australia. These spherules have been interpreted as condensation products from impact plumes and molten impact ejecta or/and impact ejecta that were melted during atmospheric re-entry [e.g., 1,2]. The 3.2-3.5 Ga spherule layers in the Barberton Greenstone Belt in South Africa currently represent the oldest known remnants of impact deposits on Earth. Aiming at identification of extraterrestrial components and to determine the diagenetic and metamorphic history of spherule layer intersections recently recovered in the CT3 drill core from the northeastern part of the Barberton Greenstone Belt, we have studied samples from these layers in terms of petrography and geochemistry. All samples, including spherule layer intersections and intercalating country rocks, were studied for mineral identification by optical and electron microscopy, as well as electron microprobe analysis (EPMA) at Natural History Museum Vienna and Museum für Naturkunde Berlin (MfN). Major and trace element compositions were determined via X-ray fluorescence spectrometry at MfN and instrumental neutron activation analysis (INAA) at University of Vienna. Os isotopes were measured by thermal ionization mass spectrometry (N-TIMS) at University of Vienna. Eighteen spherule beds are distributed over 150 meter drill core in CT3. Spherules are variably, deformed or undeformed. The high number of these layers may have been caused by tectonic duplication. Spherule beds are intercalated with shale, chert, carbonate, and/or sulfide deposits (country rocks). The size range of spherules is 0.5 to 2 mm, and some layers exhibit gradation. Shapes of spherules differ from spherical to ovoid, as well as teardrops, and spherules commonly show off-center vesicles, which have been interpreted as a primary characteristic pointing toward an impact origin [3]. Mineralogical and petrographic studies indicate that most of the mineralogy of the spherule layers is secondary due to secondary overprint by alteration and metamorphism. The mineral assemblages comprise quartz, K-feldspar, various muscovite types, phyllosilicates, Mg-siderite, Ti/Fe-Ti oxides, sulfides such as pyrite, pyrrhotite, chalkopyrite, sphalerite, and galena. INAA data show that some spherule layer intersections have extremely high siderophile element contents, with up to 1.60 wt% Ni, 0.69 wt% Cr, 0.05 wt% Co, 2.06 ppm Ir and 0.02 ppm Au, which is considered extraterrestrial component. This is further supported by their chondritic to slightly supercondritic 187Os/188Os ratios (ranging from 0.11 to 0.19), contrasting more radiogenic values of the spherule layer intercalations in comparison to country rocks, and Os concentrations up to ~4312 ppb. References: [1] Artemieva, N.A., and Simonson, B.M., 2012, LPSC 43, abstract #1372. [2] Johnson, B.C., and Melosh, H.J., 2014, Icarus, 228, 347-363. [3] Glass, B.P. and Simonson, B.M., 2012, Elements 8, 15-60.

  11. Continental growth on Early Earth: Crustal electrical conductivity models of the Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Weckmann, U.; Kutter, S.; De Wit, M.

    2014-12-01

    The Barberton Greenstone Belt (BGB, South Africa) is one of the few Archean remnants where the tectonic evolution of the Early Earth can be studied. The first formation of the crust is a controversially discussed topic among geoscientists. Tectonics on the Early Earth might have been similar to the plate movement and their driving forces that we observe today. However, regarding that some fundamental conditions like the thermal setting were considerably different at this time other processes like vertical mass transport might have played the governing role in tectonics. Therefore contrasting evolutionary models of the BGB exist, mainly based on a number of geological and petrological studies. However, there is only little information on its deeper architecture. For a better understanding of past processes and the character of the tectonic regime which led to the formation of the BGB, magnetotelluric (MT) surveys were carried out as a part of the German-South African Inkaba yeAfrica research initiative. At approximately 200 MT sites aligned along six profiles (approx. 80 to 110 km length) data was collected during two field experiments in 2009 and 2010. The MT method images the electrical conductivity of rocks and is particularly sensitive to imprints of tectonic processes resulting in persistent mineralization e.g. along shear planes. Against the surrounding of significantly conductive geological units like the Phanerozoic Transvaal cover, the rocks of the BGB are generally characterized by high electrical resistivities. Particularly plutons such as the Dalmein Pluton can be traced deeply into the crust. Contrary, faults of the BGB appear as zones of high conductivity down to a depth of 5 to 10 km. We will present 3D inversion results indicating an extension of the plutons of the western BGB beneath the Transvaal cover and a sharp conductivity contrast of the BGB compared to the eastern batholiths. We will discuss existing models of the evolution of the BGB in view of our 3D electrical conductivity images.

  12. Depositional and tectonic setting of the Archean Moodies Group, Barberton Greenstone Belt, South Africa

    NASA Technical Reports Server (NTRS)

    Heubeck, C.; Lowe, D. R.

    1994-01-01

    The 3.22-3.10 Ga old Moodies Group, uppermost unit of the Swaziland Supergroup in the Barberton Greenstone Belt (BGB), is the oldest exposed, well-preserved quartz-rich sedimentary sequence on earth. It is preserved in structurally separate blocks in a heavily deformed fold-and-thrust belt. North of the Inyoka Fault, Moodies strata reach up to 3700 m in thickness. Detailed mapping, correlation of measured sections, and systematic analysis of paleocurrents show that the lower Moodies Group north of the Inyoka Fault forms a deepening- and fining-upward sequence from a basal alluvial conglomerate through braided fluvial, tidal, and deltaic sandstones to offshore sandy shelf deposits. The basal conglomerate and overlying fluvial facies were derived from the north and include abundant detritus eroded from underlying Fig Tree Group dacitic volcanic rocks. Shoreline-parallel transport and extensive reworking dominate overlying deltaic, tidal, and marine facies. The lithologies and arrangement of Moodies Group facies, sandstone petrology, the unconformable relationship between Moodies strata and older deformed rocks, presence of at least one syndepositional normal fault, and presence of basaltic flow rocks and airfall fall tuffs interbedded with the terrestrial strata collectively suggest that the lower Moodies Group was deposited in one or more intramontane basins in an extensional setting. Thinner Moodies sections south of the Inyoka Fault, generally less than 1000 m thick, may be correlative with the basal Moodies Group north of the Inyoka Fault and were probably deposited in separate basins. A northerly derived, southward-thinning fan-delta conglomerate in the upper part of the Moodies Group in the central BGB overlies lower strata with an angular unconformity. This and associated upper Moodies conglomerates mark the beginning of basin shortening by south- to southeast-directed thrust faulting along the northern margin of the BGB and suggest that the upper Moodies Group was deposited in a foreland basin. Timing, orientation, and style of shortening suggest that this deformation eventually incorporated most of the BGB into a major fold-and-thrust belt.

  13. Single zircon dating constraining the maximum age of the barberton greenstone belt, Southern Africa

    Microsoft Academic Search

    Alfred Kröner; Wolfgang Todt

    1988-01-01

    One of the central issues in early Precambrian crustal evolution is the age and genetic relationship between greenstone belt supracrustal assemblages and nearby high-grade gneiss terranes. The crucial question, in most cases, is which of the two is older. We report zircon ages, using the new single grain evaporation technique, from a metaquartzite and a felsic volcanic flow of the

  14. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Astrophysics Data System (ADS)

    Dewit, M. J.

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  15. Melting conditions and sources of 3.5 Ga komatiites from ICDP Drilling in the Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Coetz, Grace; Blichert-Toft, Janne; Wilson, Allan; Arndt, Nicholas

    2014-05-01

    We measured major and trace element concentrations and Sm-Nd and Lu-Hf isotope systematics in 18 samples of komatiites from the core recovered from the ICDP drilling project in the Barberton Greenstone Belt, South Africa. Two fractions of magmatic clinopyroxene from a surface sample were also analysed. All samples are of the Al-depleted Barberton-type komatiite and all show the geochemical signature of residual garnet in the source (low Al/Ti, depleted HREE). One sequence, however, is unusual in that it reveals petrographic and geochemical evidence that orthopyroxene as well as olivine was on the liquidus. For the Lu-Hf systems, the whole-rock data and the clinopyroxene separates define a linear array whose slope corresponds to an age of 3419±25 Ma which is within error of the accepted age of the rocks (3.48 Ga). The Sm-Nd scatterchron gives a younger age of 3371±20 Ma. Initial isotopic values for the clinopyroxene separates provide high-precision results, with epsilon Nd(T) = -1.1 and -1.5 and epsilon Hf(T) = +3.3 and +4.1. The positive epsilon Hf value is in line with other results from komatiites from the Barberton Belt but the negative epsilon Nd value is surprising in that it indicates an enriched source with low Sm/Nd. The peculiar characteristics of this source - low Sm/Nd and high Lu/Hf - is found in the trace element compositions of the komatiites, which have moderately enriched LREE and negative Hf anomalies. The enriched LREE are consistent with that of a liquid extracted after deep melting but the origin of the Hf deficit remains uncertain. The orthopyroxene-phyric komatiites are isotopically indistinguishable from the other komatiites indicating that its Si-rich character probably was acquired during melting rather than being derived from an older source. All these komatiites were produced by about 30% batch melting, at about 300 km depth, under conditions in which garnet remained in the residue during the melting process.

  16. Exceptional preservation of aragonite in a circa 3.3 billion year old microbial mat from the Barberton greenstone belt, South Africa

    NASA Astrophysics Data System (ADS)

    Westall, Frances; Cavalazzi, Barbara; Lemelle, Laurence; Marrochhi, Yves; Rouzaud, Jean-Noel; Simionovici, Alexandre; Andreazza, Caroline; Foucher, Frédéric; Thiel, Volker; Hofmann, Axel

    2010-05-01

    Exceptional preservation of aragonite in a circa 3.3 billion year old microbial mat from the Barberton greenstone belt, South Africa Frances Westall, Barbara Cavalazzi, Laurence Lemelle, Yves Marrocchi, Jean-Noël Rouzaud, Alexandre Simionovici, Murielle Salomé, Smail Mostefaoui, Caroline Andreazza, Frédéric Foucher, Jan Toporski, Andrea Jauss, Volker Thiel, Axel Hofmann, Anders Meibom, François Robert Aragonite occurs as a biologically-formed mineral precipitate within modern calcifying microbial mats. It is, however, rarely preserved in the geological record because, as one of the least stable polymorphs of calcium carbonate, it readily converts to calcite in present environmental conditions at the Earth's surface. In an in situ investigation at the micro- to nanometer-scale, we show that 5-10 nm sized nanocrystals of aragonite are preserved within the organic framework of a partially calcified microbial mat from the ~ 3.3 billion year-old Josefsdal Chert in the Barberton greenstone belt, South Africa. Transformation of the aragonite to calcite was blocked by a combination of chemical inhibitors within the crystal lattice, organic molecules coating the nanocrystals and, in particular, to the precocious permeation of the mat by hydrothermal silica. Apart from its exceptional preservation for 3.3 billion years, the identification of aragonite in the Josefsdal microbial mat is the earliest evidence for in situ calcification of a microbial mat. Furthermore, the indications of associated sulphur-reducing bacteria (SRB) activity with calcification strongly support a photosynthetic origin for the mat. This is the most direct evidence for photosynthesis in early Archaean rocks.

  17. REE geochemistry of 3.2 Ga BIF from the Mapepe Formation, Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Yahagi, T. R.; Yamaguchi, K. E.; Haraguchi, S.; Sano, R.; Teraji, S.; Kiyokawa, S.; Ikehara, M.; Ito, T.

    2012-12-01

    Banded iron formations (BIFs) are chemical sediments interbedded with Fe- and Si-rich layers, characteristically present in the early history of the Earth. A popular hypothesis for the formation of BIFs postulates that dissolved oxygen produced by photosynthesizers such as cyanobacteria oxidized dissolved ferrous Fe supplied by submarine hydrothermal activities. During precipitation of Fe-oxide minerals, phosphorus and rare earth elements (REEs) were most likely adsorbed on their surface. Therefore, chemical compositions of REEs that adsorbed onto Fe-oxide have useful information on the seawater chemistry at the time of deposition. Especially, information on the redox state of seawater and the extent of the contribution of hydrothermal activity during BIF deposition are expected to have been recorded. Occurrence of BIF has been traditionally tied to the chemical evolution of the atmosphere. Rise of atmospheric oxygen, or as known as GOE (Great Oxidation Event: e.g., Holland, 1994), has been widely believed to have occurred at around 2.4 Ga ago. Contrary, however, some studies have suggested that such oxygenation could have occurred much earlier (e.g., Hoashi et al., 2009). In this study, we used 3.2 Ga old BIF from the Mapepe Formation at the bottom of the Fig Tree Group of the Swaziland Supergroup in the northeastern part of the Barberton Greenstone Belt, South Africa. We aimed to constrain the marine environment, and by inference atmospheric environment, at the time of BIF deposition from REE geochemistry. Major elements and REE compositions of 37 samples were measured using XRF and ICP-MS, respectively. Samples with less than 1.0 wt% Al2O3 are considered to be "pure" BIFs with minimal amount of continental contamination, and are expected to have inherited marine REE signatures. Abundance of REE normalized by C1 chondrite for the analyzed samples commonly exhibits positive Eu anomaly and LREE

  18. Petrography of sandstones from drill cores BARB4 and BARB5, Paleoarchean Mapepe Formation, Barberton greenstone belt, South Africa: Implications for provenance and tectonic reconstructions.

    NASA Astrophysics Data System (ADS)

    Drabon, N.; Lowe, D. R.; Heubeck, C. E.

    2014-12-01

    Paleogeographic and tectonic reconstructions in the Barberton greenstone belt (BGB) are challenged by syn- and post-depositional tectonics. The Barberton Drilling Project extracted two drill cores from the sedimentary rocks of the 3.26-3.22 Ga Mapepe Formation of the Fig Tree Group. The cores were taken from the Manzimnyama Syncline (BARB4) and the Barite Valley structural belt (BARB5), which are separated by belts of faulted older Onverwacht and younger Moodies strata. Stratigraphically, there is no clear correlation of Mapape strata in these two belts. Both BARB4 and BARB5 contain 25 to 300 m thick units of lithic sandstone that may represent correlative units. A comparative provenance analysis allows testing a possible correlation and evaluating the nature of tectonic uplifts that sourced the sediments. The sandstones have experienced pervasive metasomatic alteration and most primary silicate minerals except coarse quartz have been transformed into micromosaics of microquartz, phyllosilicates, and trace impurities. The majority of framework grains are chert, impure chert, and lithic grains while monocrystalline quartz and altered feldspar are minor components. The single thick sandstone in BARB4 displays a relatively uniform framework mode with average 38.7 % total quartz, 2.4% feldspars, and 58.9 % lithics and an increasing percentage of mafic to ultramafic grains upsection. In contrast, BARB5 includes three distinct sandstones with varying framework modes. The litharenite at 0 to 95m core depth was mainly sourced from an immediately underlying dacitic tuff. The chertarenite at 320 to 390m core depth is composed of 73% carbonaceous chert grains. All grain types appear to have been derived by erosion of sedimentary and volcanic rocks of the BGB as well as penecontemporaneous volcanism. Erosion did not reach deeper-seated plutonic rocks. The framework mode of the BARB4 sandstones represents a composite of common silicified BGB rocks and resembles those of other sediments in the southern domain of the BGB. In contrast, BARB5 sandstones derived locally by shallow erosion of underlying volcanic and sedimentary rocks. The distinct signatures suggest that these units are not correlative and were not derived from a common source. They may be a result of local uplifts of different parts of the greenstone sequence.

  19. High-resolution geology, petrology and age of a tectonically accreted section of Paleoarchean oceanic crust, Barberton greenstone belt, South Africa

    NASA Astrophysics Data System (ADS)

    Grosch, Eugene; Vidal, Olivier; McLoughlin, Nicola; Whitehouse, Martin

    2015-04-01

    The ca. 3.53 to 3.29 Ga Onverwacht Group of the Barberton greenstone belt (BGB), South Africa records a rare sequence of exceptionally well-preserved volcanic, intrusive and volcani-clastic Paleaoarchean rocks. Numerous conflicting models exist for the geologic evolution and stratigraphy of this early Archean greenstone belt, ranging from plume-type dynamics to modern-style plate tectonics. Although much work has focussed on the komatiites of the ca. 3.48 Ga Komati Formation since their discovery in 1969, far less petrological attention has been given to the younger oceanic rock sequences of the Kromberg type-section in the mid-Onverwacht Group. In this study, we present new field observations from a detailed re-mapping of the Kromberg type-section, and combine this with high-resolution lithological observations from continuous drill core of the Barberton Scientific Drilling Project [1]. The new mapping and field observations are compared to a recent preliminary study of the Kromberg type-section [2]. A U-Pb detrital provenance study was conducted on a reworked, volcani-clastic unit in the upper Kromberg type-section for the first time. This included U-Pb age determination of 110 detrital zircons by secondary ion microprobe analyses (SIMS), providing constraints on maximum depositional age, provenance of the ocean-floor detritus, and timing for the onset of Kromberg ocean basin formation. These new zircon age data are compared to a previous U-Pb detrital zircon study conducted on the structurally underlying sediments of the ca. 3.43 Ga Noisy formation [3]. A multi-pronged petrological approach has been applied to various rock units across the Kromberg, including thermodynamic modelling techniques applied to metabasalts and metapyroxenites for PT-estimates, bulk- and in-situ isotope geochemistry providing constraints on protolith geochemistry and metamorphic history. Consequently, it is shown that this previously poorly studied Kromberg oceanic rock sequence of the mid-Onverwacht, is a key area in resolving stratigraphy models and understanding the geologic evolution of the BGB. The combined field and petrological data provide new insight into mid-Paleoarchean ocean basin formation and subsequent tectonic destruction. [1]. Grosch et al., (2009b). EOS 90, 350-351. [2] Furnes et al., (2011) Precam. Research 186, 28-50. [3] Grosch et al. (2011) Precam. Research 191, 85-99.

  20. Compositional Grading in an Impact-produced Spherule Bed, Barberton Greenstone Belt, South Africa: A Key to Condensation History of Rock Vapor Clouds

    NASA Technical Reports Server (NTRS)

    Krull, A. E.; Lowe, D. R.; Byerly, G. R.

    2003-01-01

    The chemical and physical processes by which spherules form during the condensation of impact-produced rock vapor clouds are poorly understood. Although efforts have been made to model the processes of spherule formation, there is presently a paucity of field data to constrain the resulting theoretical models. The present study examines the vertical compositional variability in a single early Archean spherule bed in the Barberton Greenstone Belt (BGB), South Africa, in order to better identify the process by which impact vapor clouds condense and spherules form and accumulate. The BGB spherule beds are suitable for this type of study because of their great thickness, often exceeding 25cm of pure spherules, due to the massive sizes of the impactors. Two main problems complicate analysis of vertical compositional variability of graded spherule beds: (1) differential settling of particles in both the vapor and water column due to density and size differences and (2) turbulence within the vapor cloud. The present study compares sections of spherule bed S3 from four different depositional environments in the Barberton Greenstone Belt: (1) The Sheba Mine section (SAF-381) was deposited under fairly low energy conditions in deep water, providing a nice fallout sequence, and also has abundant Ni-rich spinels; (2) Jay's Chert section (SAF-380) was deposited in subaerial to shallow-water conditions with extensive post-depositional reworking by currents. The spherules also have preserved spinels; (3) the Loop Road section (loc. SAF-295; samp. KSA-7) was moderately reworked and has only rare preservation of spinels; and (4) the shallow-water Barite Syncline section (loc. SAF-206; samp KSA-1) has few to no spinels preserved and is not reworked. Although all of the spherule beds have been altered by silica diagenesis and K-metasomatism, most of the compositional differences between these sections appear to reflect their diagenetic histories, possibly related to their differing depositional environments. Sulfate diagenesis in the Barite Syncline and Loop road sections may account for the loss of spinels.

  1. Physics of crustal fracturing and chert dike formation triggered by asteroid impact, ˜3.26 Ga, Barberton greenstone belt, South Africa

    NASA Astrophysics Data System (ADS)

    Sleep, Norman H.; Lowe, Donald R.

    2014-04-01

    asteroid impacts, reflected in the presence of spherule beds in the 3.2-3.5 Ga Barberton greenstone belt (BGB), South Africa, generated extreme seismic waves. Spherule bed S2 provides a field example. It locally lies at the contact between the Onverwacht and Fig Tree Groups in the BGB, which formed as a result of the impact of asteroid (possibly 50 km diameter). Scaling calculations indicate that very strong seismic waves traveled several crater diameters from the impact site, where they widely damaged Onverwacht rocks over much of the BGB. Lithified sediments near the top of the Onverwacht Group failed with opening-mode fractures. The underlying volcanic sequence then failed with normal faults and opening-mode fractures. Surficial unlithified sediments liquefied and behaved as a fluid. These liquefied sediments and some impact-produced spherules-filled near-surface fractures, today represented by swarms of chert dikes. Strong impact-related tsunamis then swept the seafloor. P waves and Rayleigh waves from the impact greatly exceeded the amplitudes of typical earthquake waves. The duration of extreme shaking was also far longer, probably hundreds of seconds, than that from strong earthquakes. Dynamic strains of ˜10-3 occurred from the surface and downward throughout the lithosphere. Shaking weakened the Onverwacht volcanic edifice and the surface layers locally moved downhill from gravity accommodated by faults and open-mode fractures. Coast-parallel opening-mode fractures on the fore-arc coast of Chile, formed as a result of megathrust events, are the closest modern analogs. It is even conceivable that dynamic stresses throughout the lithosphere initiated subduction beneath the Onverwacht rocks.

  2. Sulfur isotope mass-independent fractionation in impact deposits of the 3.2 billion-year-old Mapepe Formation, Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    van Zuilen, M. A.; Philippot, P.; Whitehouse, M. J.; Lepland, A.

    2014-10-01

    Theoretical and experimental studies have shown that atmospheric SO2 isotopologue self-shielding effects in the 190-220 nm region of the solar spectrum are the likely cause for mass independent fractionation of sulfur isotopes (S-MIF). The main products of this photochemical reaction - SO3 and S0 - typically define a compositional array of ca. ?33S/?34S = 0.06-0.14. This is at odds with the generally observed trend in Archean sulfides, which broadly defines an array of ca. ?33S/?34S = 0.9. Various explanations have been proposed, including a diminution of ?34S caused by chemical and biogenic mass-dependent fractionation of sulfur isotopes (S-MDF), mixing with photolytic products produced during felsic volcanic events, or partial blocking of the low-wavelength part of the spectrum due to the presence of reduced atmospheric gases or an organic haze. Early in Earth history large meteorite impacts would have ejected dust and gas clouds into the atmosphere that shielded solar radiation and affected global climate. It is thus likely that at certain time intervals of high meteorite flux the atmosphere was significantly perturbed, having an effect on atmospheric photochemistry and possibly leaving anomalous sulfur isotopic signatures in the rock record. Here we describe the sulfur isotopic signatures in sulfides of spherule beds S2, S3 and S4 of the Barberton Greenstone Belt, South Africa. In particular, in spherule bed S3 - and to a lesser extent S4 - a trend of ca. ?33S/?34S = 0.23 is observed that closely follows the expected trend for SO2-photolysis in the 190-220 nm spectral range. This suggests that an impact dust cloud (deposited as spherule beds), which sampled the higher region of the atmosphere, specifically incorporated products of SO2 photolysis in the 190-220 nm range, and blocked photochemical reactions at higher wavelengths (250-330 nm band). By implication, the generally observed Archean trend appears to be the result of mixing of different MIF-S sources arising from a variety of photochemical reactions that took place in the lower part of the atmosphere.

  3. A petrological study of Paleoarchean rocks of the Onverwacht Group: New insights into the geologic evolution of the Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Grosch, E. G.; Mcloughlin, N.; Abu-Alam, T. S.; Vidal, O.

    2012-12-01

    This study presents a multi-disciplinary petrological approach applied to surface samples and a total of 800 m of scientific drill core that furthers our understanding of the geologic evolution of the ca. 3.5 to 3.2 Ga Onverwacht Group of the Barberton greenstone belt (BGB), South Africa. Detrital zircon grains in coarse (diamictite) to fine-grained clastic sedimentary rocks of the Noisy formation (drill core KD2a) that unconformably overlies the volcanic ca. 3472 Ma Hooggenoeg Formation, are investigated by laser ablation LA-ICP-MS to constrain their 207Pb/206Pb ages for depositional age and provenance. A wide range in 207Pb/206Pb ages between ca. 3600 and 3430 Ma is reported, corresponding to surrounding TTG plutons and the ca.3667-3223 Ma Ancient Gneiss Complex. The youngest detrital zircon grain identified has an age of 3432 ± 10 Ma. Given the short time interval for a major change in geologic environment between ca. 3472 Ma and ca. 3432 Ma, it is argued here, that the Noisy formation is the earliest tectonic basin in the BGB, which developed during major tectonic uplift at ca. 3432 Ma. In the overlying ca. 3334 Ma Kromberg type-section, application of a chlorite thermodynamic multi-equilibrium calculation, dioctahedral mica hydration-temperature curve and pseudosection modelling, indicates a wide range in metamorphic conditions from sub-greenschist to the uppermost greenschist facies across the Kromberg type-section. A central mylonitic fuchsite-bearing zone, referred to as the Kromberg Section Mylonites, records at least two metamorphic events: a high-T, low-P (420 ± 30oC, < 3kbar) metamorphism, and a lower-T event (T = 240-350oC, P = 2.9 ± 0.15kbar) related to retrograde metamorphism. An inverted metamorphic field gradient is documented beneath the KSM suggesting thrust repetition of the Kromberg sequence over the clastic rocks of the Noisy formation at ca. 3.2 Ga. This study also presents the first SIMS multiple sulfur isotope dataset on sulfides from the BGB and is used to test current models of mid-Archean biogeochemical sulfur cycling. In-situ ?34SCDT and ?33S values of volcanic, detrital, diagenetic and hydrothermal pyrite of the Kromberg and Noisy Formations are presented. The Kromberg cherts and mafic-ultramafic hydrothermal vein pyrites exhibit ?33S of -0.20 to +2.50‰, and ?34SCDT from -6.00 to +1.50‰ recording mixing between atmospheric sulfur and hydrothermal magmatic fluids. The Noisy sedimentary sequence contains detrital and diagenetic pyrites with a significant variation in ?33S of -0.62 to +1.4‰ and ?34SCDT between -7.00 and +12.6‰ in the upper turbidite unit, to more narrow isotopic ranges with magmatic-atmospheric values in the underlying polymictitic diamictite. A sedimentary quartz-pyrite vein in the diamictite records the largest range and most negative ?34SCDT values so far reported from an Archean terrain (?34SCDT = -55.04 to +27.46‰), and suggests shallow-level boiling and hydrogen release into early (ca. 3432 Ma) tectonic sedimentary basins during sulfide precipitation and a new possible environment for early microbial life.

  4. Rare-earth element distributions in volcanic rocks from Archean greenstone belts

    Microsoft Academic Search

    Kent C. Condie; W. R. A. Baragar

    1974-01-01

    Rare-earth element distributions in Archean volcanic rocks from the South Pass (Wyoming), Yellowknife (NW Canada) and Abitibi (Quebec) greenstone belts and from the Upper Fig Tree Group of the Barberton (S. Africa) greenstone belt reveal two distinct types of Archean volcanism. One type, herein referred to as the arc-type, is characterized by flat (or slightly enriched) REE distributions in tho

  5. Greenstone Belt Assessment

    NSDL National Science Digital Library

    Pamela Nelson

    This lab utilizes rock samples and images of rocks found in Greenstone Belts that formed globally during the Precambrian Era. The students examine and describe each of the samples visually using terminology regarding their rock texture and associated features. The students then describe or suggest what the rock properties suggest about the process of formation of the rock and the depositional or geologic environment in which the rock formed. Students then collate the data given the relative ages of the rocks and hypothesize how or where these rock units and features could possibly have formed in this association.

  6. Terrestrial Biomarkers for Early Life on Earth as Analogs for Possible Martian Life Forms: Examples of Minerally Replaced Bacteria and Biofilms From the 3.5 - 3.3-Ga Barberton Greenstone Belt, South Africa

    NASA Technical Reports Server (NTRS)

    Westall, F.; McKay, D. S.; Gibson, E. K.; deWit, M. J.; Dann, J.; Gerneke, D.; deRonde, C. E. J.

    1998-01-01

    The search for extraterrestrial life and especially martian life hinges on a variety of methods used to identify vestiges of what we could recognize as life, including chemical signatures, morphological fossils, and biogenic precipitates. Although the possibility of extant life on Mars (subsurface) is being considered, most exploration efforts may be directed toward the search for fossil life. Geomorphological evidence points to a warmer and wetter Mars early on in its history, a scenario that encourages comparison with the early Earth. For this reason, study of the early terrestrial life forms and environment in which they lived may provide clues as to how to search for extinct martian life. As a contribution to the early Archean database of terrestrial microfossils, we present new data on morphological fossils from the 3.5-3.3-Ga Barberton greenstone belt (BGB), South Africa. This study underlines the variety of fossil types already present in some of the oldest, best-preserved terrestrial sediments, ranging from minerally replaced bacteria and bacteria molds of vaRious morphologies (coccoid, coccobacillus, bacillus) to minerally replaced biofilm. Biofilm or extracellular polymeric substance (EPS) is produced by bacteria and appears to be more readily fossilisable than bacteria themselves. The BGB fossils occur in shallow water to subaerial sediments interbedded with volcanic lavas, the whole being deposited on oceanic crust. Penecontemporaneous silicification of sediments and volcanics resulted in the chertification of the rocks, which were later subjected to low-grade metamorphism (lower greenschist).

  7. Workshop on Techtonic Evolution of Greenstone Belts

    NASA Technical Reports Server (NTRS)

    Dewit, M. J. (editor); Ashwal, Lewis D. (editor)

    1986-01-01

    Topics addressed include: greenstone belt externalities; boundaries; rock terranes; synthesis and destiny; tectonic evolution; rock components and structure; sedimentology; stratigraphy; volcanism; metamorphism; and geophysics.

  8. The Jamestown Ophiolite Complex, Barberton mountain belt - A section through 3.5 Ga oceanic crust

    NASA Technical Reports Server (NTRS)

    De Wit, Maarten J.; Hart, Roger A.; Hart, Rodger J.

    1987-01-01

    The Jamestown Ophiolite Complex of the Barberton greenstone belt, South Africa, is investigated, and the intrusive nature of mafic-ultramafic units from the Komati and Kromberg formations into overlying pillow lavas and sediments is documented. Evidence is presented for multiple intrusive events within the igneous sections, including crosscutting intrusives, multiple injection of magma in the Komati section, and sheeted intrusions in the Kromberg section. The thinness of the Jamestown complex suggests that, locally at least, the ca 3.5 Ga oceanic crust was also thin, consistent with the regionally extensive metasomatic alteration.

  9. Chronology of early Archaean granite-greenstone evolution in the Barberton Mountain Land, South Africa, based on precise dating by single zircon evaporation

    NASA Technical Reports Server (NTRS)

    Kruener, Alfred; Byerly, Gary R.; Lowe, Donald R.

    1991-01-01

    Precise Pb-207/Pb-206 single zircon evaporating ages are reported for low-grade felsic metavolcanic rocks within the Onverwacht and Fig Tree Groups of the Barberton Greenstone Belt (BGB), South Africa, as well as for granitoid plutons bordering the belt. Dacitic tuffs of the Hooggenoeg Formation in the upper part of the Onverwacht Group are shown to yield ages between 3445 + or - 3 and 3416 + or - 5 Ma and to contain older crustal components represented by a 3504 + or - 4 Ma old zircon xenocryst. Fig Tree dacitic tuffs and agglomerates have euhedral zircons between 3259 + or - 3 Ma in age which are interpreted to reflect the time of crystallization. The comagmatic relationships between greenstone felsic volcanic units and the surrounding plutonic suites are keynoted. The data adduced show that the Onverwacht and Fig Tree felsic units have distinctly different ages and thus do not constitute a single, tectonically repeated unit as proposed by others. It is argued that conventional multigrain zircon dating may not accurately identify the time of felsic volcanic activity in ancient greenstones, and that the BGB in the Kaapval craton of southern Africa and greenstones in the Pilbara Block of Western Australia may have been part of a larger crustal unit in early Archaean times.

  10. Chronology of early Archaean granite-greenstone evolution in the Barberton Mountain Land, South Africa, based on precise dating by single zircon evaporation.

    PubMed

    Krüner, A; Byerly, G R; Lowe, D R

    1991-04-01

    We report precise 207Pb/206Pb single zircon evaporation ages for low-grade felsic metavolcanic rocks within the Onverwacht and Fig Tree Groups of the Barberton Greenstone Belt (BGB), South Africa, and from granitoid plutons bordering the belt. Dacitic tuffs of the Hooggenoeg Formation in the upper part of the Onverwacht Group yield ages between 3445 +/- 3 and 3416 +/- 5 Ma and contain older crustal components represented by a 3504 +/- 4 Ma old zircon xenocryst. Fig Tree dacitic tuffs and agglomerates have euhedral zircons between 3259 +/- 5 and 3225 +/- 3 Ma in age which we interpret to reflect the time of crystallization. A surprisingly complex xenocryst population in one sample documents ages from 3323 +/- 4 to 3522 +/- 4 Ma. We suspect that these xenocrysts were inherited, during the passage of the felsic melts to the surface, from various sources such as greenstones and granitoid rocks now exposed in the form of tonalite-trondhjemite plutons along the southern and western margins of the BGB, and units predating any of the exposed greenstone or intrusive rocks. Several of the granitoids along the southern margin of the belt have zircon populations with ages between 3490 and 3440 Ma. coeval with or slightly older than Onverwacht felsic volcanism, while the Kaap Valley pluton along the northwestern margin of the belt is coeval with Fig Tree dacitic volcanism. These results emphasize the comagmatic relationships between greenstone felsic volcanic units and the surrounding plutonic suites. Some of the volcanic plutonic units contain zircon xenocrysts older than any exposed rocks. These indicate the existence of still older units, possibly stratigraphically lower and older portions of the greenstone sequence itself, older granitoid intrusive rocks, or bodies of older, unrelated crustal material. Our data show that the Onverwacht and Fig Tree felsic units have distinctly different ages and therefore do not represent a single, tectonically repeated unit as proposed by others. Unlike the late Archaean Abitibi greenstone belt in Canada, which formed over about 30 Ma. exposed rocks in the BGB formed over a period of at least 220 Ma. The complex zircon populations encountered in this study imply that conventional multigrain zircon dating may not accurately identify the time of felsic volcanic activity in ancient greenstones. A surprising similarity in rock types, tectonic evolution, and ages of the BGB in the Kaapvaal craton of southern Africa and greenstones in the Pilbara Block of Western Australia suggests that these two terrains may have been part of a larger crustal unit in early Archaean times. PMID:11538384

  11. Workshop on the Tectonic Evolution of Greenstone Belts

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The Workshop on the Tectonic Evolution of Greenstone Belts, which is part of the Universities Space Research Association, Lunar and Planetary Institute, of Houston, Texas, met there on Jan. 16-18, 1986. A number of plate tectonic hypotheses have been proposed to explain the origin of Archean and Phanerozoic greenstone/ophiolite terranes. These hypotheses are explored in the abstracts.

  12. Recent Advancements in Full Tensor Gravity Gradiometry for Resource Exploration: A Case study from West Africa - Birmian Greenstone Belt

    NASA Astrophysics Data System (ADS)

    Brewster, J.; Mataragio, J.

    2014-12-01

    Over the years significant progress has been made in understanding the regional geologic models of the Greenstone Belts associated with gold mineralization in the fields of exploration geochemistry, geophysics and data integration. Improved knowledge of the geological models together with advancements in exploration techniques have resulted in the discovery of many near surface, and relatively large gold mines around the world such as the Abitibi, Isua, Barberton, Lake Victoria, Sadiola, and Yatela. However, the search for new deposits becomes more difficult due to the fact that most easily detectable, near surface deposits have been discovered. Many of the remaining deposits tend to be remotely located and deep underground. Effective exploration for new economically viable deposits requires approaches that integrate multiple techniques capable of resolving smaller, deeper and remotely located resources. Gravity surveys have been widely used to map and define geometry and structure of greenstones belts at a regional scale. Structure and hydrothermally altered zones can be mapped, either directly by gravity in weathered environments or inferred in terrains where geological units of different density are offset and/or altered Gravity gradiometry is increasingly becoming a standard method of commercial minerals exploration. Gradiometry presents a significant increase in spatial resolution when compared to previous airborne gravity methods. Airborne full tensor gravity gradiometry surveys have been flown in the past for prospect-level gold exploration in Quebec, Nunavut, Nevada, Brazil, Mali, Zambia and New Zealand and Nevada. The application of airborne gravity gradiometry for prospect-level gold exploration over greenstone belts is discussed in this paper. The high resolution system capability to detect small, high frequency targets is the key for successful results. In addition, this paper presents and discusses data enhancement and 3D inversion results. It is expected that the result of data enhancement and 3D inversion will help resolve subsurface structures associated with gold mineralization and updates the existing geological model over the property.

  13. Workshop on the Tectonic Evolution of Greenstone Belts (supplement containing abstracts of invited talks and late abstracts)

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Topics addressed include: greenstone belt tectonics, thermal constaints, geological structure, rock components, crustal accretion model, geological evolution, synsedimentary deformation, Archean structures and geological faults.

  14. Subaqueous calderas in the Archean Abitibi greenstone belt: An overview and W.U. Mueller a,

    E-print Network

    Long, Bernard

    Subaqueous calderas in the Archean Abitibi greenstone belt: An overview and new ideas W.U. Mueller Available online 6 January 2009 Keywords: Archean calderas VMS deposits Abitibi belt Volcanology Carbonate Archean volcanogenic massive sulfide (VMS) deposits, yet documentation of Archean subaqueous calderas

  15. Smaller gold deposits in the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil

    Microsoft Academic Search

    D. S. Vial; G. C. Abreu; G. Schubert; L. C. Ribeiro-Rodrigues

    2007-01-01

    The Quadrilátero Ferrífero is a classic gold province on a global scale, with hundreds of individual gold occurrences in the Archean greenstone belt comprising the Rio das Velhas Supergroup. There are numerous small gold deposits, including Faria, Esperança III, Bicalho, Bela Fama, Juca Vieira, Brumal, Boa Vista, Fernandes, Moita, Roça Grande, Bico de Pedra and Pari, as well as the

  16. The geology and mineralisation at the Golden Pride gold deposit, Nzega Greenstone Belt, Tanzania

    Microsoft Academic Search

    I. M. A. Vos; F. P. Bierlein; J. S. Standing; G. Davidson

    2009-01-01

    The Golden Pride gold deposit (˜3 Moz) is located in the central part of the Nzega Greenstone Belt at the southern margin of the Lake Victoria Goldfields in Tanzania. It represents an inferred Late Archaean, orogenic gold deposit and is hosted in intensely deformed meta-sedimentary rocks in the hanging wall of the approximately E-W striking Golden Pride Shear Zone. The

  17. Evidence for a complex archean deformational history; southwestern Michipicoten Greenstone Belt, Ontario

    NASA Technical Reports Server (NTRS)

    Mcgill, George E.; Shrady, Catherine H.

    1986-01-01

    The Michipicoten Greenstone Belt extends for about 150 km ENE from the northeastern angle of Lake Superior. In common with many other Archean greenstone belts, it is characterized by generally steep bedding dips and a distribution of major lithologic types suggesting a crudely synclinal structure for the belt as a whole. Detailed mapping and determination of structural sequence demonstrates that the structure is much more complex. The Archean history of the belt includes formation of at least three regionally significant cleavages, kilometer-scale overturning, extensive shearing, and diabase intrusion. Most well defined, mappable 'packages' of sedimentary rocks appear to be bounded by faults. These faults were active relatively early in the structural history of the belt, when extensive overturning also occurred. Steepening of dips, NW-SE shortening, development of steep NE cleavage, and pervasive shearing all postdate the early faulting and the regional overturning, obscuring much of the detail needed to define the geometry of the earlier structures. The results obtained so far suggest, however, that the Michipicoten Greenstone Belt underwent an early stage of thrusting and associated isoclinal folding, probably in a convergent tectonic environment.

  18. The Finlayson Lake Greenstone Belt, Superior Province, Canada: A Structural Perspective

    NASA Astrophysics Data System (ADS)

    Backeberg, N. R.; Rowe, C. D.

    2012-12-01

    Archean greenstone belts are key to understanding the evolution and tectonic framework of the oldest preserved continental fragments in the Earth's stable cratons. Detailed structural studies of Archean greenstone belts are needed in the literature. We present a detailed structural study of the 2.931 - 3.003 Ga Finlayson Lake greenstone belt, which is located in the south-central Wabigoon Subprovince of the Superior Province in Canada. The Finlayson belt is situated between three TTG gneiss domes of similar ages: the 3.002 Ga Marmion gneiss; the 2.982 Ma Eye-Dashwa gneiss; and the 2.936 Ga Hardtack gneiss. Although greenstone belts globally show unique features and we do not assume that the Finlayson belt is a general class for all other greenstone belts, we aim to produce a structural framework and deformational history that is wholly supported by field data. Previous work documented tectonic foliation and way-up indicators with variable lithological and chronological boundary interpretations (Stone and Kamineni 1992, Stone 2008). The dominant fabric that we see throughout the Finlayson belt is a strong flattening foliation trending between 044o and 080o with approximately vertical dip. No clear gradation in the intensity of foliation has been observed across the belt and zones of lesser and stronger foliation intensity are intercalated. All lithological boundaries and structural features in the Finlayson belt (except those on the far western margin) lie approximately parallel to the eastern boundary with the Marmion gneiss. Transects across the belt reveal no discrete sutures, meso-scale folds or faults. Way-up indicators from pillow basalts remain generally consistent, although the western and central portion of the belt are oppositely facing and are also distinguished by their petrography. The prevalent metamorphic grade in the Finlayson belt is lower amphibolite facies with peak epidote-hornblende mineralogy preserved. Peak metamorphism is coeval with the formation of the dominant structural fabric. Retrograde chlorite partially replaces amphibole grains in the interior of the belt, whereas completely retrogressed chlorite schists are found on the eastern margin. Post-kinematic euhedral epidote overprints the foliation fabric, typically replacing titanite grains and including excess titanium as rutile. Late-stage quartz-carbonate veins fill brittle fractures that crosscut the foliation fabric and retrograde assemblages. The veins are predominantly emplaced parallel to the foliation fabric and are also mutually crosscutting. Post-veining dykes are typically undeformed, but folded dykes are observed in the central portion of the belt with a shortening axis approximately parallel to the foliation fabric. Using mapped transects across the Finlayson belt, defining deformational crosscutting relations and way-up reversals, we hope to tie in the structural details together with petrographical observations and metamorphic history. This will provide valuable insight into the evolution and structural reconstruction of the Mesoarchean Finlayson Lake greenstone belt within the framework of Archean terranes.

  19. The geology and mineralisation at the Golden Pride gold deposit, Nzega Greenstone Belt, Tanzania

    Microsoft Academic Search

    I. M. A. Vos; F. P. Bierlein; J. S. Standing; G. Davidson

    2009-01-01

    The Golden Pride gold deposit (?3 Moz) is located in the central part of the Nzega Greenstone Belt at the southern margin\\u000a of the Lake Victoria Goldfields in Tanzania. It represents an inferred Late Archaean, orogenic gold deposit and is hosted\\u000a in intensely deformed meta-sedimentary rocks in the hanging wall of the approximately E–W striking Golden Pride Shear Zone.\\u000a The hanging-wall

  20. Gold deposits in the late Archaean Nzega-Igunga greenstone belt, central plateau of tanzania

    SciTech Connect

    Feiss, P.G.; Siyomana, S.

    1985-01-01

    2.2 m oz of gold have been produced, since 1935, from late Archaean (2480-2740 Ma) greenstone belts of the Central Plateau, Tanzania. North and east of Nzega (4/sup 0/12'S, 3/sup 0/11'E), 18% of the exposed basement, mainly Dodoman schists and granites, consists of metavolcanics and metasediments of the Nyanzian and Kavirondian Series. Four styles of mineralization are observed. 1. Stratabound quartz-gold veins with minor sulfides. Host rocks are quartz porphyry, banded iron formation (BIF), magnetite quartzite, and dense, cherty jasperite at the Sekenke and Canuck mines. The Canuck veins are on strike from BIF's in quartz-eye porphyry of the Igusule Hills. 2. Stratabound, disseminated gold in coarse-grained, crowded feldspar porphyry with lithic fragments and minor pyrite. At Bulangamilwa, the porphyry is conformable with Nyanzian-aged submarine (.) greenstone, volcanic sediment, felsic volcanics, and sericite phyllite. The deposits are on strike with BIF of the Wella Hills, which contains massive sulfide with up to 15% Pb+Zn. 3. Disseminated gold in quartz-albite metasomes in Nyanzian greenstones. At Kirondatal, alteration is associated with alaskites and feldspar porphyry dikes traceable several hundred meters into post-Dodoman diorite porphyry. Gold is with pyrite, arsenopyrite, pyrrhotite, minor chalcopyrite, and sphalerite as well as tourmalinite and silica-cemented breccias. 4. Basal Kavirondian placers in metaconglomerates containing cobbles and boulders of Dodoman and Nyanzian rocks several hundred meters up-section from the stratabound, disseminated mineralization at Bulangamilwa.

  1. Genesis of greenstone?hosted Cu–Au mineralisation at Hill 800, Mt Useful Slate Belt, eastern Victoria

    Microsoft Academic Search

    A. A. Morey; F. P. Bierlein; D. P. Cherry; G. Turner

    2002-01-01

    A group of structurally emplaced Cambrian metavolcanic inliers, informally known as the Barkly River greenstones, in the Mt Useful Slate Belt, eastern Victoria, host several base? and precious?metal anomalies. To date, the most significant anomaly is the Hill 800 prospect, where disseminated and stockwork\\/stringer chalcopyrite + sphalerite + galena ± native Au mineralisation have been recognised. This ore assemblage is

  2. Mafic to felsic magmatism and crustal recycling in the Obonga Lake greenstone belt, western Superior Province: evidence from geochemistry, Nd isotopes and U–Pb geochronology

    Microsoft Academic Search

    Kirsty Y Tomlinson; Donald W Davis; John A Percival; David J Hughes; Phil C Thurston

    2002-01-01

    The central Wabigoon Subprovince of the western Superior Province contains Mesoarchean granitoid and supracrustal rocks (3.01–2.83 Ga) and 2.78–2.69 Ga granitoid plutons and supracrustal sequences. It is a key area for understanding the relationship between greenstone belts and surrounding granitoid rocks that may have acted as basement. The Obonga Lake greenstone belt contains two distinct assemblages: (1) a Ta>Nb>Th. They

  3. Abstract, 2011 Advances in Earth Science Research Conference 2011 Petrogenesis of the Metavolcanic Rocks of the North Caribou Greenstone Belt: Implications for

    E-print Network

    are commonly associated with orogenic gold deposits in Archean greenstone belts. The occurrence of biotite deposits including the Musselwhite gold mine, which is hosted by highly deformed and altered a large continuous belt and dismembered during later deformation. The belt contains numerous gold

  4. Volcanic environments of ore formation in the late Archaean Abitibi greenstone belt of Canada

    SciTech Connect

    Ludden, J.N.

    1985-01-01

    The tectonic and petrological evolution of the late Archaean Abitibi greenstone belt indicate both emergent and submergent volcanism played a role in its metallogenesis. At approximately 2700 m.y. the southern volcanic zone (SVZ) of the Abitibi belt was dominated by a rift-related tectonic and volcanic evolution in a transcurrent (wrench) fault regime. The tholeiitic and komatiitic magmas and associated differentiated volcanic rocks had access to shallow crustal levels allowing the development of submarine hydrothermal systems and syngenetic Cu-Zn (Noranda type) massive sulfide ore bodies. These deposits formed along a 300 km. axis in submerging, fault bounded, basins. In contrast, the northern volcanic zone (the Chibougamau-Chapais area) formed at 2720 m.y and was characterized by emergent volcanoes emplaced on a continental crust and cored by coeval diorite-tonalite plutons. Mafic magma was inhibited from the crust by fractionated and contaminated magmas. This resulted in the emplacement of hydrous calc-alkaline magmas and associated porphyry-type epigenetic Cu(Au) massive sulfides. Au-lode deposits are predominantly located near major shear-zones in the SVZ. The are forming solutions were released as a result of burial due to wrench faulting. The dynamic regime of the rifted SVZ may have resulted in the syngenetic massive sulfides, the Au-lode deposits, metamorphism and sedimentation being synchronous on a regional scale, whilst on a local scale, Au-lodes superimpose and replace massive sulfides, iron formation and metamorphic isograds.

  5. Single zircon age constraints on the tectonic juxtaposition of the Archean Abitibi greenstone belt and Pontiac subprovince, Quebec, Canada

    SciTech Connect

    Feng, R.; Kerrich, R. (Univ. of Saskatchewan, Saskatoon (Canada))

    1991-11-01

    Zircons from metasediments and granitoids in the high-grade Lacorne block within the low-grade Archean Abitibi greenstone belt have been dated by single zircon Pb-evaporation technique, yielding {sup 207}Pb/{sup 206}Pb minimum ages. Detrital zircons in the mature clastic metasediments of the Lacorne block display a range of ages from 2,691 {plus minus} 8 Ma to 3,042 {plus minus} 6 Ma. The younger zircon ages thus impose an upper limit for deposition and indicate that the high-grade Lacorne block is not basement to the Abitibi supracrustal sequence (2,747-2,680 Ma). Existence of abundant (69%) older detrital zircons (> 2,750 Ma) suggest in turn that the Abitibi supracrustal rocks are not the source of the Lacorne sediments. Two generations of granitoids occur in the Lacorne block, an early monosodiorite-monzonite-granodiorite-syenite series and a younger S-type garnet-muscovite granite series. This contrasts with granitoid magmatism in the Abitibi greenstone belt which ended at {approximately}2675 Ma. The Pontiac subprovince to the south of the Abitibi greenstone belt shares all of the above features of the Lacorne block, including detrital zircon ages as well as the composition and timing of granitoid magmatism. This is interpreted detrital zircon ages as well as the composition and timing of granitoid magmatism. This is interpreted to indicate that the Lacorne block was originally part of the same tectonic terrane as the Pontiac subprovince. After development of the MMGS magmatism (21,670-2,680 Ma), the Pontiac subprovince locally underthrust the Abitibi greenstone belt, and crustal thickening promoted partial melting of underthrust Pontiac metasediments to form the {approximately}2,644 {plus minus} 13 Ma S-type granites.

  6. Volcanic facies and preliminary geochemical observations of the Goren greenstone belt, Burkina Faso

    NASA Astrophysics Data System (ADS)

    Peters, Luke

    2013-04-01

    Volcanic facies and preliminary geochemical observations of the Goren greenstone belt, Burkina Faso L.F.H. Peters and K.A.A Hein School of Geosciences, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa. The Goren Greenstone Belt (GGB) is a Palaeoproterozoic volcano-sedimentary belt situated in the northeast of Burkina Faso in the West African craton (WAC). Basalt is the main volcanic constituent of the GGB, specifically mid-ocean ridge basalts (MORBS), which have undergone pervasive greenschist facies metamorphism during at least 2 deformation including the Tangaean Event (2170-2130 Ma) and Eburnean Orogeny (2130-1980 Ma). Remarkably, many of the primary textures and minerals remain intact in less deformed regions of the GBB. Textural characteristics and petrographic analyses include aphyric and aphanitic textures, amygdales, hyaloclastic brecciation, pillow structures and preserved (chloritised) volcanic glass. Despite the ubiquitous presence of chlorite and epidote, plagioclase and clinopyroxene microlites are fairly common albeit altered. Phenocrysts (< 1 mm) of plagioclase and CPX are present in some samples but aphyric texture is dominant. These textures indicate that the basalts represent coherent units of sub-aqueous extrusion from a proximal volcanic facies setting relative to the original magma conduit. A repetitious succession of Fe-rich meta-siltstones, fine-grained, carbonaceous, Fe-rich exhalatives and volcaniclastic units is intercalated with the basalts. The volcaniclastic units contrast with the MORBs, which raises questions about the source region of the volcaniclastics. In hand sample, the volcaniclastic rocks show an array of various sized fragments, compared to the fine-grained nature of the MORBs. They are dominated by euhedral, zoned, brown volcanic hornblende, large (2.5-5 mm) euhedral plagioclase crystals, and sub-angular to rounded quartz grains in a poorly sorted volcanogenic sedimentary sequence. Due to the alteration of the original mineralogy, whole rock geochemical analyses of the MORBs were approached with caution, focusing on immobile and trace elements. The REE chemistry displayed a flat trend with an average value of 10x chondrite. The sample suite shows both slight enrichments and depletions of light-REE relative to heavy-REE. This is typical of N-type MORBS. A multi-element diagram illustrates a distinct, negative phosphorus anomaly, which is consistent with previous studies throughout the WAC. However, the volcaniclastic unit has larger phosphorus and significantly lower Ti (ppm) values in comparison to the MORBs. The Mg # of the basalts range from 42-57 suggesting fractionation of the melt had already begun by the time eruption took place. We interpret the volcaniclastic units as an erosional product of a pre-existing volcanic arc, deposited in a back-arc basin which has undergone extension.

  7. Lithostratigraphy and structure of the early Archaean Doolena Gap Greenstone Belt, East Pilbara Terrane (EPT), Western Australia

    NASA Astrophysics Data System (ADS)

    Wiemer, D.; Schrank, C. E.; Murphy, D. T.

    2014-12-01

    We present a detailed lithostratigraphic and structural analysis of the Archean Doolena Gap greenstone belt to shed light on the tectonic evolution of the EPT. The study area is divided into four structural domains: i) marginal orthogneisses of the MGC (Muccan Granitoid Complex), ii) a dominantly mafic mylonitic shear zone (South Muccan Shear Zone, SMSZ) enveloping the MGC, iii) a Central Fold Belt of dominantly mafic greenschists (CFB), and iv) a lower greenschist- to sub-greenschist southern domain. Toward the dome margin, abrupt increases in deformation intensity occur across domain boundaries. Domain boundaries and intra-domain shear zones are marked by significant carbonate +/- quartz alteration and high-strain non-coaxial deformation with dome-up kinematics. The southern domain comprises pillow basalts of the Mount Ada Formation (MAF), conformably overlain by clastic sediments and minor pillow basalts of the Duffer Formation (DF). The MAF and DF are overlain by an up to 1km thick package of quartzite (Strelley Pool Formation) across an angular unconformity. Isoclinal folds (F2) within the CFB to the North deform an early foliation (S1) within dominantly mafic schists and associated carbonate veins. F2 folds are preserved within lozenges that are parallel to the axial planes of F2 folds in a regional E-W trending foliation (S2) and to the SMSZ. Lozenges are often bound by zones of significant carbonate alteration. The lozenges are folded recumbently (F3), with sub-vertical fold axes pointing towards the dome. The F3 axes are parallel to mineral stretching lineations on S2 indicating dome-up movement. The entire belt is cut by late NE-SW-striking faults that exhibit dominantly brittle deformation in the southern domain but ductile drag folding (F4) in the CFB. Therefore, the southern domain must have overlain the CFB during this D4 event. We propose a protracted structural history of the greenstone belt where successive deformation events relate to the episodic emplacement of the MGC. We demonstrate that the greenstone keel is mainly characterised by an anastomosing shear zone network, induced by hydro-chemical weakening of mafic schists. This implies that previous estimates of stratigraphic thickness are significantly overestimated.

  8. Lithofacies associations and structural evolution of the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil: A review of the setting of gold deposits

    Microsoft Academic Search

    O. F. Baltazar; M. Zucchetti

    2007-01-01

    The Rio das Velhas greenstone belt is located in the Quadrilátero Ferrífero region, in the southern extremity of the São Francisco Craton, central-southern part of the State of Minas Gerais, SE Brazil. The metavolcano–sedimentary rocks of the Rio das Velhas Supergroup in this region are subdivided into the Nova Lima and Maquiné Groups. The former occurs at the base of

  9. Structural evolution of the Agnew–Wiluna greenstone belt, Eastern Yilgarn Craton and implications for komatiite-hosted Ni sulfide exploration

    Microsoft Academic Search

    P. Duuring; W. Bleeker; S. W. Beresford; M. L. Fiorentini; N. M. Rosengren

    2012-01-01

    The Agnew–Wiluna greenstone belt in the Yilgarn Craton of Western Australia is a narrow package of complexly deformed Archean supracrustal rocks that hosts two of the world's largest komatiite-hosted nickel sulfide deposits, the Mt Keith and Perseverance deposits. These deposits and several others in the belt are centred on thick lenses of adcumulate-textured komatiite interpreted to represent areas of channelised

  10. The Fazenda Gavião granodiorite and associated potassic plutons as evidence for Palaeoproterozoic arc-continent collision in the Rio Itapicuru greenstone belt, Brazil

    NASA Astrophysics Data System (ADS)

    Costa, Felipe G.; Oliveira, Elson P.; McNaughton, Neal J.

    2011-08-01

    Several granitic plutons have intruded the Palaeoproterozoic Rio Itapicuru greenstone belt, São Francisco craton, Brazil, in the time interval 2163-2080 Ma, but their tectonic significance is poorly understood. The Fazenda Gavião granodiorite (FGG) is one of a set of plutons emplaced along the western boundary of the greenstone belt with Archaean migmatite-gneiss basement. The pluton is mostly composed of hornblende granodiorite, occasionally crosscut by syn-plutonic mafic dykes. The FGG is metaluminous, medium- to high-K calc-alkaline with relatively constant silica abundances (SiO2 ? 63-66 wt%), high Sr (900-800 ppm) and high Ba (1000-1500 ppm). The associated mafic dykes are ultrapotassic, with high abundances of Ba, Sr, MgO, Ni, Cr, and light rare earth elements, suggesting derivation from partial melts of an enriched mantle source. The FGG originated probably by fractional crystallization from a primitive K-rich mafic magma that interacted with crustal melts. Its zircon U-Pb SHRIMP age of 2106 ± 6 Ma indicates that the FGG is younger than the early (2163-2127 Ma) tonalite-trondhjemite-granodiorite (TTG) and calc-alkaline arc plutons of the greenstone belt, and is closely related in time and space with potassic to ultrapotassic plutons (ca. 2110-2105 Ma). The negative ?Nd(t) of FGG and coeval K-rich plutons of the Rio Itapicuru greenstone belt contrasts markedly with the positive ?Nd(t) of the older arc plutons, indicating a major change of isotope signatures in granites of the Rio Itapicuru greenstone belt with time. This isotope shift may be related to magma contamination with older continental material and/or derivation of the parental potassic magma from enriched lithospheric mantle sources. We suggest that the K-rich plutons were emplaced during or shortly after Palaeoproterozoic arc-continent collision.

  11. Systematic decrease of high ? 13C values with burial in late Archaean (2.8 Ga) diagenetic dolomite: evidence for methanogenesis from the Crixás Greenstone Belt, Brazil

    Microsoft Academic Search

    George R. Dix; Margaret L. Thomson; Fred J. Longstaffe; Robert H. McNutt

    1995-01-01

    Remnants of Fe-poor (2700–4400 ppm) dolomite crystals, crystal aggregates, and microconcretions are cryptically distributed within stratiform bodies (tens of metres across) of metamorphic Fe-rich (3–6 wt% Fe) dolomite that occur in graphitic schists of the 2.8 Ga Ribeira˜o das Antas Formation in the Crixás Greenstone Belt, Brazil. Fe-poor dolomite is a diagenetic carbonate formed during burial of organic-bearing, muddy sediments.

  12. Brazil's premier gold province. Part II: geology and genesis of gold deposits in the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero

    Microsoft Academic Search

    Lydia Lobato; Luiz Ribeiro-Rodrigues; Frederico Vieira

    2001-01-01

    Orogenic, gold deposits are hosted by rocks of the Archean Rio das Velhas greenstone belt in the Quadrilátero Ferrífero region, Minas Gerais state, Brazil, one of the major gold provinces in the world. The gold deposits occur at the base of the mafic-ultramafic succession, with the most important orebodies controlled by E-W-striking, strike-slip faults. The main mineralization styles are (1)

  13. Reconstructed Oceanic Sedimentary Sequence in the Cape Three Points Area, Southern Axim-Konongo (Ashanti) Greenstone Belt in the Paleoproterozoic Birimian of Ghana.

    NASA Astrophysics Data System (ADS)

    Kiyokawa, S.; Ito, T.; Frank, N. K.; George, T. M.

    2014-12-01

    The Birimian greenstone belt likely formed through collision between the West African and Congo Cratons ~2.2 Ga. Accreted greenstone belts that formed through collision especially during the Palaeoproterozoic are usually not only good targets for preservation of oceanic sedimentary sequences but also greatly help understand the nature of the Paleoproterozoic deeper oceanic environments. In this study, we focused on the coastal area around Cape Three Points at the southernmost part of the Axim-Konongo (Ashanti) greenstone belt in Ghana where excellently preserved Paleoprotrozoic deeper oceanic sedimentary sequences extensively outcrop. The Birimian greenstone belt in both the Birimian rock (partly Sefwi Group) and Ashanti belts are separated from the Tarkwaian Group which is a paleoplacer deposit (Perrouty et al., 2012). The Birimian rock was identified as volcanic rich greenstone belt; Kumasi Group is foreland basin with shale and sandstone, quartzite and turbidite derived from 2.1 Ga granite in the Birimian; Tarkwaian Group is composed of coarse detrital sedimentary rocks deposited along a strike-slip fault in the Birimian. In the eastern part of the Cape Three Point area, over 4km long of volcanic-sedimentary sequence outcrops and is affected by greenschist facies metamorphism. Four demarcated zones along the coast as Kutike, Atwepo, Kwtakor and Akodaa zones. The boundaries of each zone were not observed, but each zone displays a well preserved and continuous sedimentary sequence. Structurally, this region is west vergent structure and younging direction to the East. Kutike zone exhibits synform structure with S0 younging direction. Provisional stratigraphic columns in all the zones total about 500m thick. Kutike, Atwepo zones (> 200m thick) have coarsening upward characteristics from black shale to bedded volcanic sandstone. Kwtakor zone (> 150m) is the thickest volcaniclastic sequence and has fining upward sections. Akodaa zone (> 150m) consists of finer bed of volcaniclastics with black shales and has fining upward character. This continuous sequence indicate distal portion of submarine volcaniclastic section in an oceanic island arc between the West African and Congo Cratons.

  14. Estimation of uncertainties in a 3D geological model of the Sandstone Greenstone Belt, Yilgarn Craton, Western Australia

    NASA Astrophysics Data System (ADS)

    Wellmann, Florian; Murdie, Ruth; Gessner, Klaus

    2015-04-01

    Geological models representing the structure of the subsurface are becoming a regular product of geological surveys. 3-D models combine information from geological field mapping and interpretations of geophysical data, including gravity, aerial magnetic surveys, and seismic and magnetotelluric studies. It is widely accepted that the sparse data at depth and the ambiguity of structural interpretations of geophysical data lead to inherent model uncertainties. The analysis and visualisation of model uncertainties is therefore the scope of current research. We apply here a recently developed method to estimate uncertainties in 3D structural geological models to a model of the Sandstone Greenstone Belt in the Archean Yilgarn Craton in Western Australia. The geological modelling method is based on an implicit potential-field approach in order to handle complex structures in this region, including multiply deformed stratigraphic units and complex fault networks. We then identify uncertainties in relevant geological parameters and apply a random method to sample probable structural model realisations. The ensemble of generated models is then used as a basis for uncertainty investigations. We apply several methods for uncertainty quantification and visualisation, including unit probabilities, stratigraphic distances, and cell information entropies. The analysis shows that it is feasible to use these measures as indications of model uncertainties in 3D visualisations, as well as composite measures of uncertainties on maps. With the range of novel approaches analysing uncertainties in structural geological models, we are optimistic that uncertainty evaluations can form an integral part of future geological modelling products of geological surveys.

  15. A Detailed Record of Archean Biogochemical Cycles and Seawater Chemistry Preserved in Black Shales of the Abitibi Greenstone Belt

    NASA Astrophysics Data System (ADS)

    Scott, C.; Planavsky, N. J.; Bates, S. M.; Wing, B. A.; Lyons, T. W.

    2011-12-01

    Geological and biological evolution are intimately linked within the Earth System through the medium of seawater. Thus, in order to track the co-evolution of Life and Earth during the Archean Eon we must determine how biogeochemical cycles responded to and initiated changes in the composition of Archean seawater. Among our best records of biogeochemical cycles and seawater chemistry are organic carbon-rich black shales. Here we present a detailed multi-proxy study of 2.7 Ga black shales from the Abitibi Greenstone Belt, Canada. Abitibi shales demonstrate extreme enrichments in total organic carbon (up to 15 wt. %) and total sulfur (up to 6 wt. %) reflecting vigorous biogeochemical cycling in the basin, likely driven by cyanobacteria. The speciation of reactive Fe minerals indicates that pyrite formed in a sulfidic water column (euxinia) and that dissolved Fe was the limiting reactant. The deposition of more than 50 m of euxinic black shales suggests that the Fe-rich conditions reflected by Archean BIF deposition were not necessarily ubiquitous. Biologically significant trace metals fall into two categories. Metals that can be delivered to seawater in large quantities from hydrothermal sources (e.g., Cu and Zn) are enriched in the shales, reflecting their relative abundance in seawater. Conversely, metals that are primarily delivered to the ocean during oxidative weathering of the continents (e. g., Mo and V) are largely absent from the shales, reflecting depleted seawater inventories. Thus, trace metal supply at 2.7 Ga was still dominated by geological processes. Biological forcing of trace metal inventories, through oxidative weathering of the continents, was not initiated until 2.5 Ga, when Mo enrichments are first observed in the Mt. McRae Shale, Hamersley Basin. Multiple sulfur isotope analysis (32S, 33S, 34S) of disseminated pyrite displays large mass independent fractionations (?33S up to 6 %) reflecting a sulfur cycle dominated by atmospheric processes under low oxygen conditions. Pyrite sulfur isotopes generally display a positive correlation between the magnitude of MIF (?33S) and enrichments in ?34S, producing a slope of ~1.1, a common feature for Archean pyrites. The preservation of large quantities of pyrite sulfur with a characteristically Archean isotopic signature suggests that a volcanic source of sulfur is sufficient to drive localized and long-lived euxinic conditions provided that organic matter is abundant and dissolved Fe is scarce. The most remarkable characteristic of black shales from the Abitibi Greenstone Belt is the preservation of large concentrations of organic carbon. This suggests that fixed N was at least locally abundant for extended periods of time in the Archean. Future work on Archean biogeochemical cycles, and their influence on Earth's delayed oxygenation, should attempt to determine if N fixation was localized or global in nature.

  16. Atmospheric record in the Hadean Eon from multiple sulfur isotope measurements in Nuvvuagittuq Greenstone Belt (Nunavik, Quebec)

    PubMed Central

    Thomassot, Emilie; O’Neil, Jonathan; Francis, Don; Cartigny, Pierre; Wing, Boswell A.

    2015-01-01

    Mass-independent fractionation of sulfur isotopes (S-MIF) results from photochemical reactions involving short-wavelength UV light. The presence of these anomalies in Archean sediments [(4–2.5 billion years ago, (Ga)] implies that the early atmosphere was free of the appropriate UV absorbers, of which ozone is the most important in the modern atmosphere. Consequently, S-MIF is considered some of the strongest evidence for the lack of free atmospheric oxygen before 2.4 Ga. Although temporal variations in the S-MIF record are thought to depend on changes in the abundances of gas and aerosol species, our limited understanding of photochemical mechanisms complicates interpretation of the S-MIF record in terms of atmospheric composition. Multiple sulfur isotope compositions (?33S, ?34S, and ?36S) of the >3.8 billion-year-old Nuvvuagittuq Greenstone Belt (Ungava peninsula) have been investigated to track the early origins of S-MIF. Anomalous S-isotope compositions (?33S up to +2.2‰) confirm a sedimentary origin of sulfide-bearing banded iron and silica-rich formations. Sharp isotopic transitions across sedimentary/igneous lithological boundaries indicate that primary surficial S-isotope compositions have been preserved despite a complicated metamorphic history. Furthermore, Nuvvuagittuq metasediments recorded coupled variations in 33S/32S, 34S/32S, and 36S/32S that are statistically indistinguishable from those identified several times later in the Archean. The recurrence of the same S-isotope pattern at both ends of the Archean Eon is unexpected, given the complex atmospheric, geological, and biological pathways involved in producing and preserving this fractionation. It implies that, within 0.8 billion years of Earth’s formation, a common mechanism for S-MIF production was established in the atmosphere. PMID:25561552

  17. Atmospheric record in the Hadean Eon from multiple sulfur isotope measurements in Nuvvuagittuq Greenstone Belt (Nunavik, Quebec).

    PubMed

    Thomassot, Emilie; O'Neil, Jonathan; Francis, Don; Cartigny, Pierre; Wing, Boswell A

    2015-01-20

    Mass-independent fractionation of sulfur isotopes (S-MIF) results from photochemical reactions involving short-wavelength UV light. The presence of these anomalies in Archean sediments [(4-2.5 billion years ago, (Ga)] implies that the early atmosphere was free of the appropriate UV absorbers, of which ozone is the most important in the modern atmosphere. Consequently, S-MIF is considered some of the strongest evidence for the lack of free atmospheric oxygen before 2.4 Ga. Although temporal variations in the S-MIF record are thought to depend on changes in the abundances of gas and aerosol species, our limited understanding of photochemical mechanisms complicates interpretation of the S-MIF record in terms of atmospheric composition. Multiple sulfur isotope compositions (?(33)S, ?(34)S, and ?(36)S) of the >3.8 billion-year-old Nuvvuagittuq Greenstone Belt (Ungava peninsula) have been investigated to track the early origins of S-MIF. Anomalous S-isotope compositions (?(33)S up to +2.2‰) confirm a sedimentary origin of sulfide-bearing banded iron and silica-rich formations. Sharp isotopic transitions across sedimentary/igneous lithological boundaries indicate that primary surficial S-isotope compositions have been preserved despite a complicated metamorphic history. Furthermore, Nuvvuagittuq metasediments recorded coupled variations in (33)S/(32)S, (34)S/(32)S, and (36)S/(32)S that are statistically indistinguishable from those identified several times later in the Archean. The recurrence of the same S-isotope pattern at both ends of the Archean Eon is unexpected, given the complex atmospheric, geological, and biological pathways involved in producing and preserving this fractionation. It implies that, within 0.8 billion years of Earth's formation, a common mechanism for S-MIF production was established in the atmosphere. PMID:25561552

  18. A mid-Archaean ophiolite complex, Barberton Mountain land

    NASA Astrophysics Data System (ADS)

    Dewit, M. J.; Hart, R.; Hart, R.

    New field observations and structurally restored geologic sections through the southern part of 3.5-3.6 Ga Barberton greenstone belt show that its mafic to ultramafic rocks form a pseudostratigraphy comparable to that of Phanerozoic ophiolites; this ancient ophiolite is referred to as the Jamestown ophiolite complex. It consists of an intrusive-extrusive mafic-ultramafic section, underlain by a high-temperature tectono-metamorphic residual peridotitic base, and is capped by a chert-shale sequence which it locally intrudes. Geochemical data support an ophiolitic comparison. Fraction of high temperature melting PGE's 2500 C in the residual rocks suggest a lower mantle origin for the precursors of this crust. An oceanic rather than arc-related crustal section can be inferred from the absence of contemporaneous andesites. The entire simatic section has also been chemically altered during its formation by hyrothermal interaction with the Archean hydrosphere. The most primitive parent liquids, from which the extrusive sequence evolved, may have been picritic in character. Rocks with a komatiitic chemistry may have been derived during crystal accumulation from picrite-crystal mushes (predominantly olivine-clinopyroxene) and/or by metasomatism during one or more subsequent episodes of hydration-dehydration. The Jamestown ophiolite complex provides the oldest record with evidence for the formation of oceanic lithosphere at constructive tectonic boundaries.

  19. Metallogeny of precious and base metal mineralization in the Murchison Greenstone Belt, South Africa: indications from U-Pb and Pb-Pb geochronology

    NASA Astrophysics Data System (ADS)

    Jaguin, J.; Poujol, M.; Boulvais, P.; Robb, L. J.; Paquette, J. L.

    2012-10-01

    The 3.09 to 2.97 Ga Murchison Greenstone Belt is an important metallotect in the northern Kaapvaal Craton (South Africa), hosting several precious and base metal deposits. Central to the metallotect is the Antimony Line, striking ENE for over 35 km, which hosts a series of structurally controlled Sb-Au deposits. To the north of the Antimony Line, hosted within felsic volcanic rocks, is the Copper-Zinc Line where a series of small, ca. 2.97 Ga Cu-Zn volcanogenic massive sulfide (VMS)-type deposits occur. New data are provided for the Malati Pump gold mine, located at the eastern end of the Antimony Line. Crystallizations of a granodiorite in the Malati Pump Mine and of the Baderoukwe granodiorite are dated at 2,964 ± 7 and 2,970 ± 7 Ma, respectively (zircon U-Pb), while pyrite associated with gold mineralization yielded a Pb-Pb age of 2,967 ± 48 Ma. Therefore, granodiorite emplacement, sulfide mineral deposition and gold mineralization all happened at ca. 2.97 Ga. It is, thus, suggested that the major styles of orogenic Au-Sb and the Cu-Zn VMS mineralization in the Murchison Greenstone Belt are contemporaneous and that the formation of meso- to epithermal Au-Sb mineralization at fairly shallow levels was accompanied by submarine extrusion of felsic volcanic rocks to form associated Cu-Zn VMS mineralization.

  20. Geochemical systematics of Arc - Back-arc basalt association in NeoArchean (?) Gadwal greenstone belt, eastern Dharwar craton, India

    NASA Astrophysics Data System (ADS)

    Khanna, T.; Yogodzinski, G. M.; Bizimis, M.; Chakravadhanula, M.; Vysetti, B.; Kanaparthi, R.; Kanakdande, P.

    2010-12-01

    The Gadwal greenstone belt of southern India, hosts a spectrum of arc lithologies ranging from basalt-andesite-dacite-rhyolite, and boninite - Nb-enriched basalt- adakite association, which have been reported rarely from Archean volcanic successions in other cratonic provinces. Basalts of this study, are Mg-tholeiites with SiO2~ 52 wt%, MgO~ 7 wt%, CaO~ 10 wt%, TiO2< 1 wt%, K2O< 0.6 wt%, and variable Mg# 46-56. The remaining lithologies follow calc-alkaline fractionation trends. The basalts have been divided into two types based on high field strength elements (HFSE), rare earth elements (REE) and their interelemental ratios. Type I basalts have flat to slightly depleted REE patterns and overlap with modern intraoceanic back-arc basalts from Tonga and Lau basin. Type II basalts have slightly concave REE patterns (La/Sm~1.4, Gd/Yb<1) similar to boninites and low Ti-arc tholeiites that occur along with boninites. On primitive mantle normalized diagram the Type II basalts exhibit negative Nb, P, Zr and Ti anomalies consistent with formation in an arc setting. Collectively the basalts span the compositional spectrum from back-arc (Nb/Th~11 and Nb/U~41) to arc (Nb/Th~1.2 and Nb/U~2.5). Unlike ocean-island and normal mid ocean ridge basalts these Mg-tholeiites have low (Nb/La)pm ~ 0.7-0.5, (Zr/Sm)pm ~0.7-0.9, (Ti/Gd)pm ~0.8-0.6 and (P/Nd)pm ~0.7. Consequently the HFSE, REE and incompatible trace element systematics of these basalts closely resemble modern oceanic arc - back-arc systems and reflect across-arc variation. Radiogenic isotope studies are in progress with an aim to establish the age for this arc-backarc sequence, and decipher the operation of Phanerozoic style plate tectonic processes in the Archean, and the style of crustal growth in this part of the Dharwar craton.

  1. Early Archean spherule beds of possible impact origin from Barberton, South Africa: A detailed mineralogical and geochemical study

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Reimold, Wolf Uwe; Boer, Rudolf H.

    1992-01-01

    The Barberton Greenstone belt is a 3.5- to 3.2-Ga-old formation situated in the Swaziland Supergroup near Barberton, northeast Transvaal, South Africa. The belt includes a lower, predominantly volcanic sequence, and an upper sedimentary sequence (e.g., the Fig Tree Group). Within this upper sedimentary sequence, Lowe and Byerly identified a series of different beds of spherules with diameters of around 0.5-2 mm. Lowe and Byerly and Lowe et al. have interpreted these spherules to be condensates of rock vapor produced by large meteorite impacts in the early Archean. We have collected a series of samples from drill cores from the Mt. Morgan and Princeton sections near Barberton, as well as samples taken from underground exposures in the Sheba and Agnes mines. These samples seem much better preserved than the surface samples described by Lowe and Byerly and Lowe et al. Over a scale of just under 30 cm, several well-defined spherule beds are visible, interspaced with shales and/or layers of banded iron formation. Some spherules have clearly been deposited on top of a sedimentary unit because the shale layer shows indentions from the overlying spherules. Although fresher than the surface samples (e.g., spherule bed S-2), there is abundant evidence for extensive alteration, presumably by hydrothermal processes. In some sections of the cores sulfide mineralization is common. For our mineralogical and petrographical studies we have prepared detailed thin sections of all core and underground samples (as well as some surface samples from the S-2 layer for comparison). For geochemical work, layers with thicknesses in the order of 1-5 mm were separated from selected core and underground samples. The chemical analyses are being performed using neutron activation analysis in order to obtain data for about 35 trace elements in each sample. Major elements are being determined by XRF and plasma spectrometry. To clarify the history of the sulfide mineralization, sulfur isotopic compositions are being determined.

  2. Origins of apparent conglomerates of the Nuvvuagittuq Greenstone Belt (Nunavik, Québec): Sulfur and oxygen isotope evidence and chronological implications

    NASA Astrophysics Data System (ADS)

    Kitayama, Y.; Thomassot, E.; O'Neil, J.; Francis, D.; Wing, B. A.

    2011-12-01

    Recent work on the Nuvvuagittuq Greenstone Belt (NGB, Nunavik, Québec) raises the possibility that the Hadean may be studied underfoot at least back to the Canadian Period (4.2 to 4.3Ga) [1]. Many mafic volcanic and intrusive lithologies from the NGB yield a range of stratigraphically controlled 142Nd and 143Nd isochron ages from ~4.1 to 4.3Ga [2]. These ages would make the belt the oldest known supracrustal sequence on Earth. However, chronological inconsistencies are present in the NGB, with zircons from rare intrusive felsic horizons and from apparent metaconglomerates yielding ages of ~3.8Ga [3;4]. While the conglomeratic units host a remarkable pebble-like structure, this horizon also reflects a complex metamorphic history that makes a straightforward assessment of its protolith difficult. To evaluate the possible sedimentary origin of the conglomeratic units, we have undertaken a detailed S- and O-isotope study of sulfides and quartz from both the quartz-rich clasts and the surrounding biotite-rich matrix. Quartz grains in clasts in the conglomeratic units have substantially 18O-enriched compositions (16.9% ? ?18O ? 26.7%). These values fall in the upper end of the range previously measured from Archean cherts, potentially linking the ultimate origin of the silica in the clasts to direct precipitation from silica-saturated seawater. The prospect of an ultimate surficial origin is consistent with our measurements of significant mass-independent S isotope fractionation in trace sulfides in the clasts, which is an isotopic characteristic of atmospheric sulfur on early Earth. Despite the clear bulk compositional differences between the biotite-rich matrix and the quartz-rich clasts, quartz and sulfide grains in the matrix share the O- and S-isotopic characteristics of their counterparts in the clasts. Quartz grains in the matrix have ?18O values of 19.9 to 22.3% and sulfide grains in the matrix record significant mass-independent S isotope fractionation. In fact, the entire population of S isotope analyses exhibits an impressive degree of homogeneity characterized by a mean ?33S value of 0.49±0.15%. It is unlikely that this homogeneity represents overprinting by an externally derived sulfur-bearing fluid as rare cross-cutting sulfide veins in the conglomeratic units possess a mean ?33S value of 0.07±0.08%. To a first-order then, our O- and S-isotope analyses suggest an ultimate sedimentary origin for the quartz and sulfide grains in the conglomeratic units. In this presentation, we will explore how these observations constrain the sedimentary origin of the conglomeratic units in light of: (1) the isotopic homogeneity of the rock; (2) the isotopic characteristics of other lithologies in the NGB, and (3) the geochronological implications of potential depositional models for the conglomeratic units. [1] Goldblatt et al. (2010). Solid Earth, 1, 1-3 [2] O'Neil et al. (2008). Science 321, 1828-1831 [3] David et al. (2009). GSA Bulletin 121, 150-163. [4] Cates and Mojzsis (2007), EPSL 255, 9-21

  3. Implications of in situ calcification for photosynthesis in a ~3.3 Ga-old microbial biofilm from the Barberton greenstone belt, South Africa

    E-print Network

    Paris-Sud XI, Université de

    Andreazza7 , Frédéric Foucher1 , Jan Toporski8 , Andrea Jauss8 , Volker Thiel9 , Gordon Southam10 , Lachlan 1 Centre de Biophysique Moléculaire-CNRS-OSUC, Rue Charles Sadron, 45071 Orléans cedex 2, France@uj.ac.za Corresponding author Frances Westall Centre de Biophysique Moléculaire, CNRS, Rue Charles Sadron, 45071 Orléans

  4. Field and Geochemical Characteristics of the ca. 3.0-billion-years-old Ivisaartoq Greenstone Belt, West Greenland: Geodynamic Implications

    NASA Astrophysics Data System (ADS)

    Polat, A.

    2005-12-01

    The 3.0 Ga Ivisaartoq greenstone belt is the largest Mesoarchean (~3075 Ma) supracrustal assemblage in southern West Greenland. The belt is composed mainly of pillow basalts ultramafic flows, gabbros, and serpentinites. Pillow basalts display well-preserved core and rim structures. Many pillow cores have cavities at the centre, which are filled mainly with diopside-quartz-plagioclase-epidote assemblage, indicating Mesoarchean seafloor hydrothermal alteration processes. Pillow cores and gabbros have pre-alteration ocelli structures, composed predominantly of plagioclase-quartz assemblage. These ocelli structures are morphologically and mineralogically similar to those found in other Archean belts. Accordingly, they have been interpreted to represent immiscible liquids. The diopside-quartz-plagioclase-epidote metasomatic assemblage in the pillow cores is interpreted as metamorphosed epidosite formed under upper-greenschist to lower-amphibolite facies metamorphic conditions during hydrothermal alteration of the Mesoarchean oceanic crust. Early seafloor hydrothermal alteration was followed by amphibolite facies regional metamorphism, characterized by diopside-garnet-hornblende-plagioclase-quartz-vesuvianite calc-silicate metasomatic assemblage. Given the preservation of primary ocelli-matrix texture in the outer pillow cores, they are considered as the least altered sections of the pillow basalts. On chondrite- and primitive mantle-normalized diagrams, these pillow cores have the following trace element characteristics: (1) moderately enriched LREE patterns; (2) near-flat HREE patterns; and (3) variably negative Nb, Ti, and Zr anomalies. Ultramafic flows, with picritic geochemical characteristics, and gabbros also have similar trace element characteristics, consistent with a subduction zone geochemical signature. Given the observations that epidosites and subduction zone geochemical signatures have been identified in several Phanerozoic ophiolites, the Ivisaartoq belt is interpreted as the crustal section of a dismembered Mesoarchean supra-subduction zone ophiolite.

  5. Allochthonous 2.78 Ga oceanic plateau slivers in a 2.72 Ga continental arc sequence: Vizien greenstone belt, northeastern Superior Province, Canada

    NASA Astrophysics Data System (ADS)

    Skulski, T.; Percival, J. A.

    1996-04-01

    Embedded within the vast granitoid terrane of the Minto block of northeastern Superior Province are Late Archean greenstone belts of the Goudalie domain that preserve a long-lived record of continent-ocean interaction. The Vizien greenstone belt is one such belt and it contains four fault-bounded structural panels. The 2786 Ma mafic-ultramafic sequence is an allochthonous package of pillowed basaltic andesite, komatiite and volcaniclastic rocks cut by peridotite and gabbro sills. The mafic rocks are LREE-depleted tholeiites which have primitive mantle (PRIM)-normalized abundances of Th < Nb < La, and ?Nd values of +1.5 to + 3.2 reflecting extraction from a depleted mantle source. The 2724 Ma lac Lintelle continental calc-alkaline volcanic sequence consists of massive basalt, plagioclase-porphyritic andesite, dacite, rhyolite, capped by quartz-rich sandstones/conglomerates with 2.97 Ga Nd model ages. Lac Lintelle volcanic rocks are LREE enriched, with low TiO 2 (< 1%) and Zr (< 200 ppm), PRIM-normalized enrichment in Th > La > Nb, and a range of ?Nd values from -0.1 to +1.7. The ~ 2722 Ma lac Serindac bimodal, subaerial tholeiitic volcanic sequence contains andesite (locally with tonalite xenoliths), basalt, gabbro sills, lenses of quartz-rich sedimentary rocks and a thick, upper rhyolite sequence. The lac Serindac tholeiites are LREE-enriched, have PRIM-normalized Th > La > Nb, high Zr (to 300 ppm) and Ti contents, and low ?Nd values from +0.8 in basalt to -1.4 in rhyolite. The < 2718 Ma basement-cover sequence comprises 2.94 Ga tonalitic gneiss unconformably overlain by clastic sediments and a thin upper sequence of 2700 Ma gabbro, siliceous high-Mg basalt (SHMB) and andesite. The SHMB are characterised by LREE depletion and ?Nd values of +2.6, whereas the andesite is LREE-enriched and has ?Nd values of -0.3. The 2786 Ma mafic-ultramafic sequence is interpreted as a sliver of plume-related oceanic plateau crust. The 2724 lac Lintelle sequence represents a continental arc formed on the eastern protocraton. The ~ 2722 Ma lac Serindac volcanic sequence represents late continental rift deposits. The various 2.8-2.7 Ga supracrustal sequences were accreted, deformed and metamorphosed to mid-amphibolite facies during late-stage assembly of the Minto block between 2.718 and 2.693 Ga.

  6. Age of felsic volcanism and the role of ancient continental crust in the evolution of the Neoarchean Rio das Velhas Greenstone belt (Quadrilátero Ferrífero, Brazil): U–Pb zircon dating of volcaniclastic graywackes

    Microsoft Academic Search

    C. M. Noce; M. Zuccheti; O. F. Baltazar; R. Armstrong; E. Dantas; F. E. Renger; L. M. Lobato

    2005-01-01

    A felsic eruptive event within the Rio das Velhas Greenstone belt is mainly represented by volcaniclastic and resedimented volcaniclastic rocks, besides rare lava flows of dacitic composition. The volcaniclastic rocks comprise four lithofacies: (1) monomictic and polymictic breccias, (2) conglomerate–graywacke, (3) graywacke–sandstone, and (4) graywacke–argillite. SHRIMP and ID-TIMS U–Pb zircon dating of three graywacke samples dated the eruptive event at

  7. Emplacement of pillow lavas from the ~ 2.8 Ga Chitradurga Greenstone Belt, South India: A physical volcanological, morphometric and geochemical perspective

    NASA Astrophysics Data System (ADS)

    Duraiswami, Raymond A.; Inamdar, Mustaqueem M.; Shaikh, Tahira N.

    2013-08-01

    The physical volcanology and morphometric analyses of pillowed lava flows from the Chitradurga basin of Chitradurga Greenstone Belt, South India have been undertaken. In the Chitradurga hills individual pillowed flows alternate with massive submarine sheet flows. The pillows from such flows are separated by chert and occur as spheroidal, elongated or reniform units that are devoid of vesicles, vesicle bands or pipe vesicles. The Mardihalli flow is exposed as a small elongated mound in the basin and consists of a massive core that is draped by pillows along the flow crest and flanks. The pillows from Mardihalli occur as spheroidal to elongate units with smooth, spalled or wrinkled surfaces with vesicular interiors. Repeated budding of larger pillows have produced a series of interconnected pillow units indicating fluid lava that was emplaced on steeply dipping flanks. Based on the morphological features the pillowed flows from the Chitradurga basin were emplaced at low effusion rates (? 5 m3/s). Pillows in these flows formed from low viscosity lavas that underwent negligible to moderate inflation due to rapid chilling. Sporadic occurrences of pillow breccias, hyaloclastite and chert breccias in the pillowed flow fields indicate disruption of pillows due to lava surges and slumping. It is envisaged that the Chitradurga basin witnessed distinct episodes of submarine tholeiite eruptions that produced pillowed lavas that variably interacted with sea water to produce geochemistries. The field and stratigraphic relationships of the volcanics and associated clastic sediments suggest that the pillow lavas were emplaced in a shallow marine marginal inter/back arc basin.

  8. Using the Abitibi Greenstone Belt to understand Martian hydrothermal systems and the potential for biosignature preservation in high temperature aqueous environments

    NASA Astrophysics Data System (ADS)

    Hurowitz, J. A.; Abelson, J.; Allwood, A.; Anderson, R. B.; Atkinson, B.; Beaty, D.; Bristow, T. F.; Ehlmann, B. L.; Eigenbrode, J. L.; Grotzinger, J. P.; Hand, K. P.; Halevy, I.; Knoll, A.; McCleese, D. J.; Milliken, R.; Russell, M.; Stolper, D. A.; Stolper, E. M.; Tosca, N. J.

    2011-12-01

    Impact and magmatic driven hydrothermal systems have long been postulated to exist on Mars. Recent observations of high-temperature mineral associations, e.g., smectite-chlorite-carbonate-serpentine, provide evidence consistent with the presence of hydrothermal environments in the ancient Martian rock record. In light of these discoveries, it is instructive to examine fossil hydrothermal systems on Earth to better understand the conditions under which putative Martian hydrothermal mineral assemblages may have formed. Such investigations may prove to be important in the era of Mars Sample Return, as we possess little scientific understanding of the biosignature preservation potential of ancient terrestrial hydrothermal systems. Motivated by these issues, the Agouron Institute organized a Geobiology Field School in July, 2011 to study the 2.7 Ga Abitibi greenstone belt in Ontario, CA. The Abitibi hosts world-renowned economic volcanogenic massive sulfide mineral deposits, and is characterized by a rich suite of lithologies emplaced predominantly in sub-oceanic settings, including komatiites, basalts, and rhyolitic volcanic rocks and banded iron formation, most of which have been hydrothermally altered, remineralized, and tectonically deformed under greenschist facies conditions. During a 10-day excursion to the Abitibi, guided by the Ontario Geological Survey, our team examined these assemblages, performed in-situ analyses using field portable active mid-IR and reflectance VIS-NIR spectrometers, an X-ray diffractometer, and an X-ray fluorescence spectrometer to inform an extensive sampling campaign. These samples have been returned to our laboratories for in-depth analysis. We will report on the outcome of our field campaign and discuss the unique opportunity provided by examination of the Abitibi to compare and contrast the effects of hydrothermal alteration and mineralization on an ocean planet with an active biosphere to a planet where the presence of large, long-lived water bodies and biology remain open questions.

  9. Early Cambrian Post-collisional volcanosedimentary Rey Bouba greenstone belt in northern Cameroun: LA-MC-ICP-MS U-Pb geochronology and implications for the geodynamic evolution of the Central African Fold Belt (CAFB).

    NASA Astrophysics Data System (ADS)

    Bouyo, Merlain

    2014-05-01

    The Rey Bouba Greenstone Belt (RBGB) is a greenschist volcanosedimentary basin representing the youngest accretion event that characterized the geodynamic evolution of the CAFB of Northern Cameroon. LA-MC-ICP-MS U-Pb detrital zircon data indicate that both older PP to MP and younger NP to Early Cambrian sources from ca 2000 to ca 540 Ma, with main provenance being zircon grains from Cryogenian igneous rocks (between ca 850 and ca 650 Ma) were involved in the formation of the RBGB basin. Considering the age of metamorphism inferred from high pressure granulites at ca 600 Ma within the CAFB of northern Cameroon as the most direct evidence for the timing of continental collision, we conclude that the deformation associated with migmatites and post-collisional granites which fed the Rey Bouba basin mostly with NP zircon lasts until post 540 Ma, in correlation with the final amalgamation of the Gondwana Supercontinent during Latest Neoproterozoic-Earliest Cambrian. Therefore, the RBGB may represent the youngest post-collisional metavolcanosedimentary basin within the CAFB.

  10. Septate-tubular textures in 2.0-Ga pillow lavas from the Pechenga Greenstone Belt: a nano-spectroscopic approach to investigate their biogenicity.

    PubMed

    Fliegel, D; Wirth, R; Simonetti, A; Furnes, H; Staudigel, H; Hanski, E; Muehlenbachs, K

    2010-12-01

    Pillow lava rims and interpillow hyaloclastites from the upper part of the Pechenga Greenstone Belt, Kola Peninsula, N-Russia contain rare tubular textures 15-20 ?m in diameter and up to several hundred ?m long in prehnite-pumpellyite to lower greenschist facies meta-volcanic glass. The textures are septate with regular compartments 5-20 ?m across and exhibit branching, stopping and no intersecting features. Synchrotron micro-energy dispersive X-ray was used to image elemental distributions; scanning transmission X-ray microscopy, Fe L-edge and C K-edge were used to identify iron and carbon speciation at interfaces between the tubular textures and the host rock. In situ U-Pb radiometric dating by LA-MC-ICP-MS (laser ablation multicollector inductively coupled plasma mass spectrometry) of titanite from pillow lavas yielded a metamorphic age of 1790 ± 89 Ma. Focused ion-beam milling combined with transmission electron microscopy was used to analyze the textures in three dimensions. Electron diffraction showed that the textures are mineralized by orientated pumpellyite. On the margins of the tubes, an interface between mica or chlorite and the pumpellyite shows evidence of dissolution reactions where the pumpellyite is replaced by mica/chlorite. A thin poorly crystalline Fe-phase, probably precipitated out of solution, occurs at the interface between pumpellyite and mica/chlorite. This sequence of phases leads to the hypothesis that the tubes were initially hollow, compartmentalized structures in volcanic glass that were mineralized by pumpellyite during low-grade metamorphism. Later, a Fe-bearing fluid mineralized the compartments between the pumpellyite and lastly the pumpellyite was partially dissolved and replaced by chlorite during greenschist metamorphism. The most plausible origin for a septate-tubular texture is a progressive etching of the host matrix by several generations of microbes and subsequently these tubes were filled by authigenic mineral precipitates. This preserves the textures in the rock record over geological time. The micro textures reported here thus represent a pumpellyite-mineralized trace fossil that records a Paleoproterozoic sub-seafloor biosphere. PMID:20698893

  11. Sulfur-and oxygen-isotope constraints on the sedimentary history of apparent conglomerates from the Nuvvuagittuq Greenstone

    E-print Network

    Long, Bernard

    igneous rocks of the Nuvvuagittuq Greenstone Belt (NGB) crystallized before 3.8 Ga and possibly as early or less. These appear to be inconsistent with the ages of the mafic igneous rocks, as the quartz Earth as some mafic volcanic rocks from the Nuvvuagittuq Greenstone Belt (NGB, Ungava peninsula, Nunavik

  12. Greenstone Digital Library Software

    NSDL National Science Digital Library

    1969-12-31

    Greenstone is a suite of software designed to build and distribute digital library collections. Produced by the New Zealand Digital Library Project at the University of Waikato, this innovative tool was created to "empower users, particularly in universities, libraries, and other public service institutions, to build their own digital libraries." The software consists of the Collector, which helps create new collections, modify or add to existing ones, or delete collections; and the Administration, which allows the addition of new users, summarizes the collections in the system, and gives technical information on the installation. Also included is a section comprising the Greenstone manuals, and a section that tells about the Greenstone software and where the New Zealand Digital Library Project originated. The software runs on Windows and Unix, and both source codes and binaries are available for downloading on the site.

  13. Stable isotope and Rare Earth Element evidence for recent ironstone pods within the Archean Barberton

    E-print Network

    Hren, Michael

    Stable isotope and Rare Earth Element evidence for recent ironstone pods within the Archean greenstone belt. We examined oxygen and hydrogen isotopes and Rare Earth Element (REE) concentrations pro- vide a valuable geochemical record of the conditions on the surface of the early Earth. Many

  14. Cosmos greenstone terrane: Insights into an Archaean volcanic arc, associated with komatiite-hosted nickel sulphide mineralisation, from U-Pb dating, volcanic stratigraphy and geochemistry 

    E-print Network

    De Joux, Alexandra; Joux, Alexandra de

    2014-06-30

    The Neoarchaean Agnew-Wiluna greenstone belt (AWB) of the Kalgoorlie Terrane, within the Eastern Goldfields Superterrane (EGS) of the Yilgarn Craton, Western Australia, contains several world-class, komatiite-hosted, ...

  15. Insights into early Earth from the Pt-Re-Os isotope and highly siderophile element abundance systematics of Barberton komatiites

    NASA Astrophysics Data System (ADS)

    Puchtel, Igor S.; Walker, Richard J.; Touboul, Mathieu; Nisbet, Euan G.; Byerly, Gary R.

    2014-01-01

    Highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundance and Pt-Re-Os isotopic data are reported for well-preserved komatiites from the Komati and Weltevreden Formations of the Barberton Greenstone Belt in South Africa. The Re-Os data for whole-rock samples and olivine and chromite separates define isochrons with ages of 3484 ± 38 and 3263 ± 12 Ma for the Komati and Weltevreden systems, respectively. The respective initial 187Os/188Os = 0.10335 ± 15 (?187Os = +0.34 ± 0.15) and 0.10442 ± 4 (?187Os = -0.14 ± 0.04) are well within the range defined by chondritic meteorites. When considered together with the Re-Os data for late Archean komatiite systems, these data indicate that the mantle sources of most Archean komatiites evolved with essentially uniform long-term Re/Os that is well within the chondritic range. By contrast, the initial 186Os/188Os = 0.1198283 ± 9 (?186Os = -0.12 ± 0.08) and 0.1198330 ± 8 (?186Os = +0.22 ± 0.07) for the Komati and Weltevreden systems, respectively, are outside of known chondritic evolution paths, indicating that the mantle sources of these two komatiite systems evolved with fractionated time-integrated Pt/Os. The new 186,187Os isotopic data for these early Archean komatiite systems, combined with published 142,143Nd and 176Hf isotopic data for these systems, are consistent with formation and long-term isolation of deep-seated mantle domains with fractionated time-integrated Sm/Nd, Lu/Hf, and Pt/Os ratios, at ca. 4400 Ma. These domains may have been generated as a result of late-stage crystallization of a primordial magma ocean involving Mg-perovskite, Ca-perovskite and Pt-alloys acting as the fractionating phases. The inferred fractionated mantle domains were sampled by the early Archean komatiites, but were largely mixed away by 2.7 Ga, as evidenced by uniform time-integrated Sm/Nd, Lu/Hf, and Pt/Os ratios inferred for the sources of most late Archean komatiite systems. The calculated total Pt + Pd abundances present in the sources of the early Archean komatiite systems fall only 7-14% short of those present in estimates for the modern primitive mantle. These are also within the range of the total Pt + Pd abundances present in the sources of late Archean komatiite systems, indicating little change in the HSE abundances in the Archean mantle between 3.5 and 2.7 Ga. The new HSE data for the early Archean komatiite systems may implicate late accretion of HSE to the mantle prior to completion of crystallization of a final terrestrial magma ocean, followed by sluggish mixing of diverse, post-magma ocean domains characterized by variably fractionated lithophile element and HSE abundances.

  16. Mars mission relevant investigations on a ~ 3.5 Ga Mars analogue rock from the Pilbara and Barberton

    NASA Astrophysics Data System (ADS)

    Westall, F.; Pullan, D.; Schröder, C.; Klingelhöfer, G.; Fernández-Sánchez, J.; Jorge, S.; Edwards, H.; Cressey, G.

    2007-08-01

    Volcaniclastic sediments deposited in shallow water basins on the early Earth represent ideal analogues for Noachian volcanic sediments since the environmental conditions and settings for both were quite similar: important volcanic and hydrothermal activity (somewhat less on Mars), period of late heavy bombardment (~4.0 Ga), water bodies with a slightly acidic pH, higher salt content, atmosphere with minimal O2 (<0.2 % PAL), high UV flux to the surface. Life apparently thrived in these conditions on Earth, leaving structural and geochemical signatures in the Early Archaean sediments. Within the framework of the PAFS-net* programme, using space qualified instrumentation, we analysed previously well-characterised volcanic sedimentary rocks from a number of locations in the 3.5-3.3 Ga-old greenstone belts of the Pilbara (Australia) and Barberton (South Africa). They included mud flat sediments containing traces of probable chemolithotrophic and anoxygenic photosynthetic microorganisms, a small stromatolite (some microfossil traces) and a banded iron formation sample (also some microfossil traces). All the sediments were silicified by early diagenetic processes. The instruments used were the Beagle2 Development Model (DM) stereo camera for proximal (~100 cm) and macroscopic (~10 cm) imaging, the Beagle 2 microscope for microscopic (~1 cm) imaging, a Nuance multi-spectral imager, a TN Technologies Spectrace 9000 commercial energy dispersive XRF spectrometer, a Philips PW1710 diffractometer for XRD, and the Beagle2 spare Mössbauer spectrometer. The camera systems were well able to depict the fine-scale sedimentological structures of the rock samples that, in the case of the volcaniclastic sediment and the stromatolite, can be used to interpret a shallow water environment of deposition (the flaser-linsen bedding of the former and the convex, sinuous layering of the latter). The massively quartz-rich (chert) composition of the silicified sediments was picked up by the XRD and the Raman spectrometers. The silicified volcanics also contain feldspar, identified by the Raman, whereas the XRF analyses showed that they are K-feldspars. The traces of Ba and Cu in this sample are probably related to the mostly hydothermal origin of the silica that cemented the volcanic sediments. Raman spectroscopy also identified a greater abundance of carbon (matured kerogen) in the black layers of this sample (finer grained volcaniclastics). The stromatolite sample, on the other hand, consists largely of quartz although Raman showed some dolomite and carbon (mature kerogen) in the grey layers (silicified stromatolitic layers). The layering in the laminated volcaniclastic sediment was too fine for the Mössbauer spectrometer to pick up any details. The Mössbauer was able to detect a very thin layer of Fe oxide <<0.2 mm on the surface of the stromatolite. Compositional layering in the BIF was clearly visible using multispectral imaging with the Nuance camera and the Mössbauer could identify highly crystalline and chemically pure goethite in the Fe-rich layers with minor goethite and hematite occurring in the quartz-rich layers. The combination of the instrumentation used for imaging and chemical analysis was quite sufficient to identify the sedimentary origin of the finely laminated volcaniclastic and stromatolite rocks and to demonstrate their pervasive silicification. The presence of carbon in these rocks would, in a Mars scenario, make them ideal subjects for organo-geochemical analysis. The same suite of instruments was also able to demonstrate the origin of the BIF, again, a suitable candidate for further analysis. * Planetary Analogue Field Study network (main coordinator D. Pullan)

  17. Magnetic susceptibility, magnetic mineralogy and magnetic fabrics in a late Archean granitoid-gneiss belt

    Microsoft Academic Search

    K. Benn; P. Rochette; J. L. Bouchez; K. Hattori

    1993-01-01

    The Opatica belt is a late Archean granitoid-gneiss terrane situated within the northern Abitibi Subprovince, along the northern margin of the Abitibi greenstone belt, Quebec. This belt is composed of several suites of tonalite-granodiorite- granite composition, variably deformed under epidote-amphibolite to upper-amphibolite grade conditions. Specimens from 87 sampling sites within the Opatica belt show a wide range in variation of

  18. New insights into typical Archaean structures in greenstone terranes of western Ontario

    NASA Technical Reports Server (NTRS)

    Schwerdtner, W. M.

    1986-01-01

    Ongoing detailed field work in selected granitoid complexes of the western Wabigoon and Wawa Subprovinces, southern Canadian Shield, has led to several new conclusions: (1) Prominent gneiss domes are composed of prestrained tonalite-granodiorite and represent dense hoods of magmatic granitoid diapirs; (2) the deformation history of the prestrained gneiss remains to be unraveled; (3) the gneiss lacked a thick cover of mafic metavolcanics or other dense rocks at the time of magmatic diaprisim; (4) the synclinoral structure of large greenstone belts is older than the late gneiss domes and may have been initiated by volcano-tectonic processes; (5) small greenstone masses within the gneiss are complexly deformed, together with the gneiss; and, (6) no compelling evidence has been found of ductile early thrusting in the gneiss terranes. Zones of greenstone enclaves occur in hornblende-rich contaminated tonalite and are apt to be deformed magmatic septa. Elsewhere, the tonalite gneiss is biotite-rich and hornblende-poor. These conclusions rest on several new pieces of structural evidence; (1) oval plutons of syenite-diorite have magmatic strain fabrics and sharp contacts that are parallel to an axial-plane foliation in the surrounding refolded gneiss; (2) gneiss domes are lithologically composite and contain large sheath-like structures which are deformed early plutons, distorted earlier gneiss domes, or early ductile nappes produced by folding of planar plutonic septa, and (3) the predomal attitudes of gneissosity varied from point to point.

  19. Greenstone: A Platform for Distributed Digital Library Applications

    Microsoft Academic Search

    David Bainbridge; George Buchanan; John R. Mcpherson; Steve Jones; Abdelaziz Mahoui; Ian H. Witten

    2001-01-01

    This paper examines the issues surrounding distributed Dig- ital Library protocols. First, it reviews three prominent digital library protocols: Z39.50, SDLIP, and Dienst, plus Greenstone's own protocol. Then, we summarise the implementation in the Greenstone Digital Libary of a number of different protocols for distributed digital libraries, and de- scribe sample applications of the same: a digital library for children,

  20. Greenstone: A Comprehensive Open-Source Digital Library Software System

    Microsoft Academic Search

    Ian H. Witten; Rodger J. McNab; Stefan J. Boddie; David Bainbridge

    1999-01-01

    This paper describes the Greenstone digital library software, a comprehensive, open-source system for the construction and presentation of information collections. Collections built with Greenstone offer effective full-text searching and metadata-based browsing facilities that are attractive and easy to use. Moreover, they are easily maintainable and can be augmented and rebuilt entirely automatically. The system is extensible: software \\

  1. Greenstone: a comprehensive open-source digital library software system

    Microsoft Academic Search

    Ian H. Witten; Stefan J. Boddie; David Bainbridge; Rodger J. McNab

    2000-01-01

    This paper describes the Greenstone digital library software, a comprehensive, open-source system for the construction and presentation of information collections. Collections built with Greenstone offer effective full-text searching and metadata-based browsing facilities that are attractive and easy to use. Moreover, they are easily maintainable and can be augmented and rebuilt entirely automatically. The system is extensible: software \\

  2. Burial and exhumation during Archean sagduction in the East Pilbara Granite-Greenstone Terrane

    NASA Astrophysics Data System (ADS)

    François, C.; Philippot, P.; Rey, P.; Rubatto, D.

    2014-06-01

    Archean granitic domes and intervening volcano-sedimentary basins are commonly interpreted as the product of “sagduction”, a process involving the gravitational sinking of surficial greenstone cover sequences into narrow belts and the coeval exhumation of deeper granitic crust into broad domes. Alternatives to the sagduction model that can account for the regional dome and basin pattern include fold interferences and extensional metamorphic core complexes. In order to provide quantitative constraints on the pressure-temperature-time (P-T-t) evolution experienced by greenstone-granite pairs we investigate the Warrawoona greenstone belt and adjacent Mount Edgar granitoid dome the East Pilbara craton (Western Australia). We adopt a multidisciplinary approach that includes structural, metamorphic, geochronological and numerical investigation of the 3.5-3.2 Ga Mount Edgar high-grade metamorphic rocks. Garnet-bearing metasediments and metabasalts collected along the SW and SE rims of the Mount Edgar Dome show higher pressure but lower temperature of equilibration (9-11 kbar and 450-550 °C) than enclaves collected in the core of the dome (6-7 kbar and 650-750 °C). In situ oxygen isotope analysis and U-Pb dating of zircons from the enclave indicate a metasedimentary origin (?18O˜+13‰) for the protoliths and a metamorphic age of 3311.9±4.9 Ma. In addition, monazites included in garnet from the SW dome margin yield an age of 3443.4±4.5 Ma. These monazites suggest the existence of an older metamorphic cycle and imply a polymetamorphic evolution of the unit. The P-T-t data support fast, gravity-driven tectonics, wherein sedimentary rocks were buried to lower crustal conditions, metamorphosed and exhumed back to the surface during a cycle lasting only a few million years. Forward thermo-mechanical modeling confirms the P-T-t evolutions deduced from thermobarometry and geochronology. Our model shows a large range of possible apparent geothermal gradients during sagduction, including low apparent geothermal gradients that are similar to those proposed for Archean and modern subduction.

  3. Archean sedimentation and tectonics in southern Africa

    NASA Technical Reports Server (NTRS)

    Kidd, W. S. F.

    1984-01-01

    Sequences in the Barberton Mountain Land greenstone belt (southern Africa) were examined to determine the nature of the sedimentary rocks, their tectonic implications, and their bearing on the present large-scale structural condition of the belt. Also assessed was whether there was evidence for a significant component of shallow-water-deposited sedimentary rocks in the parent materials of the Limpopo belt. The nature of a largehigh strain zone on the southern margin of the central Limpopo belt was examined.

  4. Barberton drilling project - Buck Reef Chert core BARB3

    NASA Astrophysics Data System (ADS)

    Hofmann, Axel; Karykowski, Bartosz; Mason, Paul; Chunnet, Gordon; Arndt, Nick

    2013-04-01

    As part of the ICDP-sponsored Barberton drilling project a single drill core (BARB3) with a total length of 899 m was obtained from the c. 3.4 Ga old Buck Reef Chert (BRC). The BRC is an unusually thick (up to 350 m) sequence of predominantly black-and-white banded chert and banded ferruginous chert that are steeply dipping. It overlies a shallow intrusive to extrusive sequence of dacitic volcanic rocks of the Hooggenoeg Formation and is separated from ultramafic lapillistone of the Kromberg Formation by a >150 m thick ultramafic sill. Drilling commenced in the ultramafic sill at an angle of c. 45° and c. 200 m of serpentinized peridotite were intersected. The remaining c. 700 m of the core include a great variety of chert lithofacies and minor intrusive mafic to intermediate igneous rocks. The base of the BRC was not intersected. Geophysical logging was done up to a depth of 847 m and included acoustic televiewer, gamma ray, resistivity, magnetic field and caliper logs. Stratigraphic and geophysical logs will be presented that will form the basis of follow-up studies on the BARB3 core. Abundance of organic matter, sulphides and Fe-bearing carbonates in specific intervals or associated with specific facies of the chert succession reflect changes in the oceanic, environmental and/or hydrothermal conditions in a shallow marine early Archaean setting. Evaluating the different processes will require a combined sedimentological, mineralogical, and geochemical approach that will provide insights into the habitat of early life, geochemical cycles and marine/hydrothermal conditions.

  5. Age of the Mulcahy Lake intrusion, northwest Ontario, and implications for the evolution of greenstone-granite terrains

    NASA Technical Reports Server (NTRS)

    Morrison, D. A.; Bogard, D. D.; Phinney, W. C.; Davis, D. W.; Wooden, J. L.; Ashwal, L. D.; Maczuga, D. E.

    1985-01-01

    An investigation of zircon data from the Mulcahy Lake gabbro, a 63 sq km layered mafic intrusion in the Wabigoon subprovince of Ontario, which show that the gabbro crystallized at 2733.2 +1.0, -0.9 Ma, is considered. It is shown that the gabbro intrudes tholeiites of the Crow Lake-Savant Lake greenstone belt. Whole rock samples and mineral separates from the Mulcahy Lake intrusion are dated by Rb-Sr, Sm-Nd, and Ar-30-Ar-40 techniques. Disturbances in the system are revealed by the Rb-Sr data and an initial Sr ratio of 0.7007 for an age of 2733 Ma is indicated by samples with low Rb/Sr ratios. The age determined for the Sm-Nd data is 2744 + or 55 Ma with an epsilon Nd value of +2.6 + or - 1.2 which indicates a source region depleted in a light rare earth element. Primary hornblende is analyzed for Ar-40/Ar-39 and an age of 2703 + or - 20 is obtained. Some implications for the development of greenstone-granite belts are discussed.

  6. Geochemistry and mineralogy of Early Archean spherule beds, Baberton Mountain Land, South Africa: Evidence for origin by impact doubtful

    Microsoft Academic Search

    Christian Koeberl; Wolf Uwe Reimold; Rudolf H. Boer

    1993-01-01

    Spherule layers in the approximately 3.4 Ga Barberton Greenstone Belt, South Africa, have been interpreted as being the result of large asteroid or comet impacts on the early earth. This interpretation was based, among other arguments, on the enrichment of siderophile elements, especially the platinum group elements. We made a detailed mineralogical, petrological and geochemical study of spherule bed samples

  7. The oldest impact deposits on earth — First confirmation of an extraterrestrial component

    Microsoft Academic Search

    Alexander Shukolyukov; Frank T. Kyte; Gtinter W. Lugmair; Donald R. Lowe; Gary R. Byerly

    The chromium isotopic compositions of samples from an early Archean (3.22 Ga) spherule bed (S4) from the Barberton Greenstone Belt, South Africa, are distinct from that in background rocks and other terrestrial samples. This positively confirms the presence of an extraterrestrial component in this bed and supports hypotheses of an impact origin. The source of the extraterrestrial Cr is most

  8. Fluid chemistry of Archean seafloor hydrothermal vents: Implications for the composition of circa 3.2 Ga seawater

    Microsoft Academic Search

    Cornel E. J. de Ronde; Dominic M. der. Channer; Kevin Faure; Colin J. Bray; Edward T. C. Spooner

    1997-01-01

    Seafloor hydrothermal vents of mid-Archean age (ca. 3230 Ma) have been identified and mapped in the Barberton greenstone belt, South Africa and are known as the Ironstone Pods. Fluid inclusion homogenization temperature data, when combined with gas chromatographic data, provide a minimum calculated water depth for the pods of 982 m. Ironstone Pod hydrothermal fluid endmember concentrations (Mg = 0)

  9. Fluid chemistry of Archean seafloor hydrothermal vents: Implications for the composition of circa 3.2 Ga seawater

    Microsoft Academic Search

    Cornel E. J. De Ronde; Dominic M. de R. Channer; Kevin Faure; Colin J. Bray; Edward T. C. Spooner

    1997-01-01

    Seafloor hydrothermal vents of mid-Archean age (ca. 3230 Ma) have been identified and mapped in the Barberton greenstone belt, South Africa and are known as the Ironstone Pods. Fluid inclusion homogenization temperature data, when combined with gas chromatographic data, provide a minimum calculated water depth for the pods of 982 m.Ironstone Pod hydrothermal fluid endmember concentrations (Mg = 0) of

  10. Adding SOMLib capabilities to the Greenstone Digital Library System

    E-print Network

    Rauber,Andreas

    Adding SOMLib capabilities to the Greenstone Digital Library System Rudolf Mayer, Andreas Rauber. Many conventional digital library systems offer access to their collections only via full text or meta of a digital library by their content. In this paper, we present an integration of this system into the popular

  11. Metallogeny of precious and base metal mineralization in the Murchison Greenstone Belt, South Africa

    E-print Network

    Boyer, Edmond

    , located at the eastern end of the Antimony Line. Crystallization of a granodiorite in the Malati Pump mine and of the Baderoukwe granodiorite are dated at 2964 ± 7 Ma and 2970 ± 7 Ma, respectively (zircon U-Pb), while pyrite associated with gold mineralization yielded a Pb-Pb age of 2967 ± 48 Ma. Therefore, granodiorite emplacement

  12. Early Proterozoic (2.04 GA) Phoshorites of Pechenga Greenstone Belt and Their Origin

    NASA Technical Reports Server (NTRS)

    Rozanov, Alexei Yu.; Astafieva, Marina M.; Hoover, Richard B.

    2007-01-01

    No principal differences have been found between microfossils described from Cambrian and Phanerozoic and the 2000 Ma phosphorites. Numerous samples revealed diverse microbial microstructures interpreted as cyanobacterial mats consisting of filamentous (1-3 microns in diameter, 20 microns in length), coccoidal (0.8-1.0 microns) and ellipsoidal or rod-shaped microfossils (0.8 microns in diameter, around 2 microns in length) which morphologically resemble modern Microcoleus and Siphonophycus, Thiocapsa, and Rhabdoderma, respectively, reported from alkali ne or saline environment_ The sequence of the early Palaeoproterozoic events which point to a significant oxidation of the hydrosphere, including the formation of phosphorites and changes in the phosphorous cycle, mimics the sequence which was repeated at the Neoproterozoic-Cembrian transition, implying that oxidation of the terrestrial atmosphere-hydrosphere system experienced an irregular cyclic development.

  13. Radiation Belts

    NSDL National Science Digital Library

    Mendez, J.

    This website, authored and curated by David Stern, provides an outline of the motion of charged particles in the Earth's magnetic fields, and the Van Allen and outer radiation belts. It summarizes their discovery, their properties and their physics, as well as providing links to background materials and additional information. This is part of a large web site on the Exploration of the Earth's Magnetosphere. The page also includes a helpful timeline and glossary to help contextualize some of the information available. A Spanish translation is available.

  14. The geological record of life 3500 MA ago: Coping with the rigors of a young earth during late accretion

    Microsoft Academic Search

    Donald R. Lowe

    1989-01-01

    Thin cherty sedimentary layers within the volcanic portions of the 3,500 to 3,300 Ma-old Onverwacht and Fig Tree Groups, Barberton Greenstone belt, South Africa, and Warrawoona Group, eastern Pilbara Block, Western Australia, contain an abundant record of early Archean life. Five principal types of organic and probably biogenic remains and or structures can be identifed: stromatolites, stromatolite detritus, carbonaceous laminite

  15. Aluminum depletion in komatiites and garnet fractionation in the early Archean mantle - Hafnium isotopic constraints

    Microsoft Academic Search

    G. Gruau; C. Chauvel; N. T. Arndt; J. Cornichet

    1990-01-01

    Hafnium isotopic compositions were measured in Al-depleted and Al-enriched komatiites from the 3450-Ma-old Barberton greenstone belt, southern Afric. All samples have initial epsilon (Hf) values close to zero. Such values are at variance with the strongly negative or positive values that should be observed if these rocks came from old garnet-depleted or garnet-enriched layers, such as may have formed during

  16. Asteroid impact ejecta units overlain by iron-rich sediments in 3.5–2.4 Ga terrains, Pilbara and Kaapvaal cratons: Accidental or cause–effect relationships?

    Microsoft Academic Search

    Andrew Glikson

    2006-01-01

    The significance of temporal and spatial associations between asteroid\\/comet impact ejecta units and overlying iron-rich sediments, including banded iron-formation (BIF), jaspilite and ferruginous shale, observed in the Pilbara Craton, Western Australia and the Barberton Greenstone Belt (BGB), Kaapvaal Craton, South Africa, is considered. Such associations include (1) 3470.1±1.9 Ma impact spherule units and tsunami-type breccia overlain by jaspilite in the Antarctic

  17. Enriched and depleted arc basalts, with Mg-andesites and adakites: A potential paired arc-back-arc of the 2.6 Ga Hutti greenstone terrane, India

    NASA Astrophysics Data System (ADS)

    Manikyamba, C.; Kerrich, R.; Khanna, Tarun C.; Satyanarayanan, M.; Krishna, A. Keshav

    2009-03-01

    The ˜2.6 Ga Hutti greenstone belt is one of several Neoarchean greenstone terranes of the eastern Dharwar Craton. There are prevalent mafic volcanic flows with subordinate felsic volcanic units and siliciclastic sedimentary rocks. All lithologies show variable intensities of submarine hydrothermal alteration, polyphase deformation and greenschist to amphibolite grade metamorphism, yet pillow, cumulus, and other primary volcanic features are locally preserved. Well exposed interlayered metabasalts, Mg-andesites (MA), and felsic flows outcrop along an 11 km sector in the SE of the terrane. Based on combined petrographic and geochemical characteristics, two tholeiitic basalt populations have been identified within the metabasalts: (1) those with enriched LREE at 20-50 times chondrite, and (2) an depleted LREE population at 12-20 times chondrite. The former has fractionated LREE, where (La/Sm) N = 1.2-1.7, but flat HREE, and negative anomalies at Nb, P, and Ti relative to neighbouring REE. The latter has lower absolute abundances of compatible and incompatible elements, mildly fractionated LREE, smaller anomalies at Nb, P, and Ti, with (Gd/Yb) N = 1.1-1.6. Several samples have the "N-MORB" signature of LREE depletion coupled with positive Nb anomalies. On the Th/Yb vs. Nb/Yb discrimination diagram depleted basalts plot near the MORB field whereas enriched basalts overlap the backarc and arc fields, consistent with a paired arc-back-arc. Mg-andesites feature SiO 2 57-61 wt.%, multielement pattens similar to enriched basalts, coupled with Cr, Co, Ni contents greater than "normal" andesites. Felsic volcanic rocks are characterized by low Y, high (La/Yb) N, and Zr/Sm, but low Nb/Ta, with zero to positive Eu anomalies, thus conforming to most of the compositional criteria of Archean and Phanerozoic adakites. Similar associations of enriched and depleted arc basalts, with adakites, are known from Neoarchean greenstone terranes of the Superior Province. During intraoceanic subduction, slab dehydration-wedge melting generated arc basalts whereas slab melting-wedge hybridization, generated adakites and Mg-andesites.

  18. Evolution of the Archaean granite-greenstone terranes of the Eastern Goldfields, Western Australia: SHRIMP U?Pb zircon constraints

    Microsoft Academic Search

    D. R. Nelson

    1997-01-01

    Thirty-five high-precision SHRIMP U?Pb zircon dates (with an average 95% confidence error of ±6 Ma) have been obtained from the granite-greenstone terranes in the southern part of the Eastern Goldfields of Western Australia. These dates establish the timing of major deformation, metamorphism and granite intrusion events, and test inferred stratigraphic relationships within the greenstones. These new data reveal that felsic

  19. THE EFFECT OF IN SITU ALTERATION ON GOLD COMPOSITION AT NYARKAGWE, SUKUMALAND GREENSTONE BELT, NW-TANZANIA

    E-print Network

    and the flu ids themselves acted as lubricants for post quartz vein emplacement tectonics. Element transport networking in some parts of the quartz veins. A continuous compositional change of flu ids due

  20. Geochemical characters and tectonic evolution of the Chitradurga schist belt: An Archaean suture (?) of the Dharwar Craton, India

    NASA Astrophysics Data System (ADS)

    Naqvi, S. M.

    The Chitradurga schist belt extending for about 450 km in a NS direction and 2-50 km across, is one of the most prominent Archean (2.6 b.y.) tectonic features of the Indian Precambrian terrain, comprising about 2 to 10 km thick sequence of volcano sedimentary rocks. The basal unit of this belt is composed of an orthoquartzite-carbonate facies, unlike many other contemporary greentone belts of the Gondwana land which begin with a basal mafic-ultramafic sequence. Eighty percent of the belt is made up of detrital and chemogenic sediments, their succession commencing with a poorly preserved quartz pebble basal conglomerate and current bedded quartzites which, in turn, rest on tonalitic gneisses, the latter having been further remobilized with along the schist belt. Deposition of current bedded matue arenites indicte the existence of platformal conditions near the shore line. Polymictic graywacke conglomerates, graywackes, shales, phyllites, carbonates, BIFs (oxide, carbonate and sulfide) BMF's (Banded Maganese Formations) and cherts thus constitute the main sedimentary rocks of the belt. The polymicitic conglomerates contain debris of rocks of older greenstone sequences, as well as an abundant measure of folded quartzites, BIF's and gneissic fragments which represent earlier orogenies.

  1. Seat belt aorta

    Microsoft Academic Search

    P. S. Mohinder; Randhawa; James O. Menzoian

    1990-01-01

    This review of 11 cases of seat-belt associated blunt abdominal aortic trauma, includes nine cases reported in the literature and two new cases. Lap-type seat belts were the cause of this injury in eight of the 11 patients (73%). Clinical presentation was acute in 73% of the cases, with symptoms of acute arterial insufficiency, or an acute abdomen or neurologic

  2. Evaluation of early Archean volcaniclastic and volcanic flow rocks as possible sites for carbonaceous fossil microbes.

    PubMed

    Walsh, Maud M

    2004-01-01

    Sedimentary rocks have traditionally been the focus of the search for Archean microfossils; the Earth's oldest fossil bacteria are associated with carbonaceous matter in sedimentary cherts in greenstone belts in the eastern Pilbara block of Western Australia and Barberton greenstone belt of South Africa. Reports of possible fossils in a martian meteorite composed of igneous rock and the discovery of modern bacteria associated with basalts have stimulated a new look at Archean volcanic rocks as possible sites for fossil microbes. This study examines silicified volcaniclastic rocks, near-surface altered volcanic flow rocks, and associated stromatolite- like structures from the Archean Barberton greenstone belt to evaluate their potential for the preservation of carbonaceous fossils. Detrital carbonaceous particles are widely admixed with current-deposited debris. Carbonaceous matter is also present in altered volcanic flow rocks as sparse particles in silica veins that appear to be fed by overlying carbonaceous chert layers. Neither microfossils nor mat-like material was identified in the altered volcanic rocks or adjacent stromatolite-like structures. Ancient volcanic flow and volcaniclastic rocks are not promising sites for carbonaceous fossil preservation. PMID:15684724

  3. To Belt or Not To Belt?

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1999-01-01

    The National Highway Traffic Transportation Safety Administration (NHTSA) is in the midst of the first school-bus crash tests in more than 10 years. Its report is expected in June 2000, and those on both sides of the seat-belt debate are waiting to see what NHTSA will recommend on passenger restraints in large school buses. A sidebar lists sources…

  4. Precambrian Cratons and Fold-Belts in Brazil: Overview

    NASA Astrophysics Data System (ADS)

    Fuck, R.

    2008-05-01

    The main Precambrian terrains recognized in Brazil comprise the Amazonian, São Francisco and Rio de la Plata cratons, surrounded by Neoproterozoic Brasiliano fold belts, making up the Borborema, Mantiqueira and Tocantins provinces. The Amazonian craton comprises an Archean core, surrounded by Paleoproterozoic terrains (Maroni-Itacaiunas, Ventuari-Tapajós, Rio Negro-Juruena), which southwestwards give way to the Mesoproterozoic Rondoniano-San Ignacio and Sunsas belts, the latter thought to be related to the Grenville belt of North America. The São Francisco craton comprises several Archean blocks (Gavião, Serrinha, Jequié) amalgamated by the Paleoproterozoic high-grade Itabuna-Salvador-Curaçá orogen. The Rio de la Plata craton, largely covered by Phanerozoic strata, is made of Paleoproterozoic basement gneiss and several Paleoproterozoic greenstone belts. Other cratonic blocks are hidden below large Phanerozoic basins, like the Paranapanema and Parnaíba blocks below the Paraná and Parnaíba basins, respectively. Several smaller Archean/Paleoproterozoic blocks appear within the Brasiliano provinces: some were strongly reworked during the Neoproterozoic orogenic events (São José do Campestre, Pernambuco-Alagoas, Goiás, Guanhães, Juiz de Fora, Curitiba), others were only marginally affected (São Luiz, Rio Apa, Luís Alves). The Brasiliano provinces are the result of Neoproterozoic to early Paleozoic orogenic events within the framework of West Gondwana amalgamation. The Mantiqueira Province extends from eastern Brazil to southern Uruguay and includes the Araçuaí, Ribeira and Dom Feliciano fold belts, bordering the São Francisco, Paranapanema and Rio de la Plata cratons and surrounding the Luís Alves craton. The Tocantins province in central Brazil includes the Araguaia, Paraguay and Brasília fold belts, the former bordering the Amazonian craton, the second bordering both the southern Amazonian craton and the Rio Apa block, and the last established on the western border of the São Francisco craton and on the northeastern margin of the Paranapanema block. Deep seismic refraction and other geophysical and geological studies were able to discriminate several crust compartments within the Brasília belt, like the juvenile Goiás magmatic arc, the Archean/Paleoproterozoic Goiás massif, and the external belt zone, as distinguished from the São Francisco craton. The Borborema Province in northeast Brazil is a complex array of Neoproterozoic fold belts (Médio Coreaú, Seridó, Sergipana, Riacho do Pontal, Rio Preto) between the São Luiz and São Francisco cratons, partially covering different crustal blocks (NW Ceará, Ceará Central, Rio Grande do Norte, Pernambuco-Alagoas) separated by large crustal-scale, strike-slip lineaments (Transbrasiliano, Senador Pompeu, Orós, Porta Alegre, Patos, Pernambuco, etc.). Basement of the crustal blocks is mainly Paleoproterozoic in age, but may include Archean cores (São José do Campestre, Grangeiro, Troia). South of the Patos lineament, Mesoproterozoic gneiss, granite and supracrustal belts are recorded in the Transversal domain, in the Pernambuco-Alagoas massif and in the Sergipano and Riacho do Pontal fold belts. Geophysical studies (MT sounding, gravity, seismology, deep seismic refraction, etc.) are underway in order to understand crustal structure and evolution of the province.

  5. Radiation Belts and Trapped Particles

    NSDL National Science Digital Library

    This tutorial introduces students to Earth's radiation belts, also known as the Van Allen Belts after their discoverer. Topics include the structure of the radiation belts and the currents of particles trapped in Earth's magnetic fields, their properties, and where they come from. There is also a set of classroom activities for exploring radiation belts and solar storms and a set of illustrations and movies of the belts. Other materials include news items related to the radiation belts, recordings of 'space sounds' related to the influence of lightning on Earth's magnetic field, and a frequently-asked-questions feature.

  6. An Archean Geomagnetic Reversal in the Kaap Valley Pluton, South Africa

    PubMed

    Layer; Kroner; McWilliams

    1996-08-16

    The Kaap Valley pluton in South Africa is a tonalite intrusion associated with the Archean Barberton Greenstone Belt. Antipodal paleomagnetic directions determined from the central and marginal parts of the pluton record a geomagnetic reversal that occurred as the pluton cooled. The age of the reversal is constrained by an 40Ar/39Ar plateau age from hornblende at 3214 +/- 4 million years, making it the oldest known reversal. The data presented here suggest that Earth has had a reversing, perhaps dipolar, magnetic field since at least 3.2 billion years ago. PMID:8688075

  7. Aluminum depletion in komatiites and garnet fractionation in the early Archean mantle: Hafnium isotopic constraints

    SciTech Connect

    Gruau, G. (Max Planck Institut fuer Chemie, Mainz (West Germany) Universite de Rennes (France)); Chauvel, C.; Arndt, N.T. (Max Planck Institut fuer Chemie, Mainz (West Germany)); Cornichet, J. (Universite de Rennes (France))

    1990-11-01

    Hafnium isotopic compositions were measured in Al-depleted and Al-enriched komatiites from the 3,450 Ma old Barberton greenstone belt, southern Africa. All samples have initial {var epsilon}{sub Hf} values close to zero. Such values are at variance with the strongly negative or positive values that should be observed if these rocks came from old garnet-depleted or garnet-enriched layers, such as may have formed during the solidification of an ancient terrestrial magma ocean. The garnet fractionation observed in komatiites probably took place during the melting event.

  8. Rust Belt Rebounds

    NSDL National Science Digital Library

    1998-01-01

    This recent Census Brief (CENBR/98-7) looks at nonfarm business establishments, unemployment, crime, and new job generation in so-called "rust belt" metropolitan areas such as Detroit-Ann Arbor-Flint, MI and Cleveland-Akron, OH. The report notes an economic and demographic rebound, deemed a "statistical reversal of fortune," with some exceptions outside of the Midwest.

  9. Kuiper Belt Objects (Invited)

    NASA Astrophysics Data System (ADS)

    Tegler, S. C.; Romanishin, W.

    1999-09-01

    The Kuiper belt represents an exciting, new frontier in solar system research. About 200 Kuiper belt objects (KBOs) with diameters larger than 100 km are known to exist between 30 and 50 AU from the Sun. Surveys indicate that there may be as many as 100,000 KBOs larger than 100 km and perhaps billions of KBOs larger than 1 km between 30 and 50 AU. Although the total mass in these bodies is perhaps a few tenths of an Earth mass, accretion calculations indicate that the primordial Kuiper belt must have contained 10 to 30 Earth masses of material between 30 and 50 AU in order to explain the growth of large KBOs and the Pluto and Charon system in the 100 million years before the onset of the disruptive influence of Neptune. Once Neptune reached a fraction of its current mass, dynamical studies indicate that a combination of erosional collisions and mean motion and secular resonances sculpted the belt into its present day mass and structure. The influence of the resonances can be seen in the belt today as about one-third of the known KBOs are in a stable 2:3 mean motion resonance with Neptune, i.e. eccentric and inclined orbits, that approach or cross the orbit of Neptune, and semi-major axes, a, about 39.4 AU. Many KBOs with a > 42 AU are sufficiently far from Neptune that they are on stable, low inclination, low eccentricity, non-resonant orbits. A combination of resonances and disruptive collisions continue to deplete the Kuiper belt today as they inject KBOs or collision fragments inward into the solar system as Centaur objects and Jupiter family comets. Physical studies of KBOs are in their infancy. Perhaps one of the most surprising results is the observation that KBO colors and hence their surface compositions divide neatly into a grey and an extraordinarily red population. The red population suggests some surfaces are rich in complex carbon-bearing molecules. The colors exhibit no trend with resonant or non-resonant orbits or object size and suggest that something unexpected and important happened in the outer solar system. Visible and infrared spectra are available for only a few of the brightest KBOs and indicate the presence of frozen methane and water. Optical light curve studies suggest that the smallest KBOs are irregular in shape. Albedo measurements and searches for comae around KBOs are just beginning. Many fundamental questions remain unanswered about the Kuiper belt. For example, no KBO has been found beyond 50 AU. Does 50 AU represent an edge to the belt? On the other hand, is the region beyond 50 AU sufficiently far from the disruptive influence of Neptune that Pluto-sized or larger bodies await discovery?

  10. Metamorphic belts of Anatolia

    NASA Astrophysics Data System (ADS)

    Oberhänsli, Roland; Prouteau, Amaury; Candan, Osman; Bousquet, Romain

    2015-04-01

    Investigating metamorphic rocks from high-pressure/low-temperature (HP/LT) belts that formed during the closure of several oceanic branches, building up the present Anatolia continental micro-plate gives insight to the palaeogeography of the Neotethys Ocean in Anatolia. Two coherent HP/LT metamorphic belts, the Tav?anl? Zone (distal Gondwana margin) and the Ören-Afyon-Bolkarda? Zone (proximal Gondwana margin), parallel their non-metamorphosed equivalent (the Tauride Carbonate Platform) from the Aegean coast in NW Anatolia to southern Central Anatolia. P-T conditions and timing of metamorphism in the Ören-Afyon-Bolkarda? Zone (>70?-65 Ma; 0.8-1.2 GPa/330-420°C) contrast those published for the overlying Tav?anl? Zone (88-78 Ma; 2.4 GPa/500 °C). These belts trace the southern Neotethys suture connecting the Vardar suture in the Hellenides to the Inner Tauride suture along the southern border of the Kir?ehir Complex in Central Anatolia. Eastwards, these belts are capped by the Oligo-Miocene Sivas Basin. Another HP/LT metamorphic belt, in the Alanya and Bitlis regions, outlines the southern flank of the Tauride Carbonate Platform. In the Alanya Nappes, south of the Taurides, eclogites and blueschists yielded metamorphic ages around 82-80 Ma (zircon U-Pb and phengite Ar-Ar data). The Alanya-Bitlis HP belt testifies an additional suture not comparable to the northerly Tav?anl? and Ören-Afyon belts, thus implying an additional oceanic branch of the Neotethys. The most likely eastern lateral continuation of this HP belt is the Bitlis Massif, in SE Turkey. There, eclogites (1.9-2.4 GPa/480-540°C) occur within calc-arenitic meta-sediments and in gneisses of the metamorphic (Barrovian-type) basement. Zircon U-Pb ages revealed 84.4-82.4 Ma for peak metamorphism. Carpholite-bearing HP/LT metasediments representing the stratigraphic cover of the Bitlis Massif underwent 0.8-1.2 GPa/340-400°C at 79-74 Ma (Ar-Ar on white mica). These conditions compares to the Tav?anl?-Afyon realm. However the differences in time and P-T conditions (eclogite- vs. blueschist-facies units) in the Bitlis Massif indicate that the different metamorphic peak conditions were reached at different times in a single subduction zone. Exhumation from approx. 65 to 35 km depth occurred within <10 myr. The special relations between eclogite-blueschist are due to the fact that collision with the Arabian plate was and still is on going in the Bitlis area. The Bitlis HP rocks represent a subduction realm that separated the Bitlis-Pütürge(-Bistun?) continental block from the South-Armenian (Tauride?) block, further north. Post-Eocene blueschists south of the Bitlis Massif witness the separation of the Bitlis-Pütüre block from the Arabian plate, and the southward migration of the subduction zone from the Late Cretaceous to the Oligocene. Continuous convergence of Africa and Eurasia engendered the simultaneous consumption of several, separated branches of the Neotethys Ocean and amalgamation of different terranes. The rise of the Eastern Anatolia Plateau is related to this complex geodynamic setting. Reduced seismic velocities inferred from geophysical observations, which are interpreted as complete replacement of lithospheric- by asthenospheric mantle, can be explained by thermodynamic modelling as partial hydration of the lithospheric mantle wedge during protracted subduction. Hydrated lithospheric mantle is interpreted as result of the complex geodynamic setting in Anatolia with multiple simultaneous subduction zones.

  11. SLH Timing Belt Powertrain

    SciTech Connect

    Schneider, Abe

    2014-04-09

    The main goal of this proposal was to develop and test a novel powertrain solution for the SLH hydroEngine?, a low-cost, efficient low-head hydropower technology. Nearly two-thirds of U.S. renewable electricity is produced by hydropower (EIA 2010). According to the U.S. Department of Energy; this amount could be increased by 50% with small hydropower plants, often using already-existing dams (Hall 2004). There are more than 80,000 existing dams, and of these, less than 4% generate power (Blankinship 2009). In addition, there are over 800 irrigation districts in the U.S., many with multiple, non-power, low-head drops. These existing, non-power dams and irrigation drops could be retrofitted to produce distributed, baseload, renewable energy with appropriate technology. The problem is that most existing dams are low-head, or less than 30 feet in height (Ragon 2009). Only about 2% of the available low-head hydropower resource in the U.S. has been developed, leaving more than 70 GW of annual mean potential low-head capacity untapped (Hall 2004). Natel Energy, Inc. is developing a low-head hydropower turbine that operates efficiently at heads less than 6 meters and is cost-effective for deployment across multiple low-head structures. Because of the unique racetrack-like path taken by the prime-movers in the SLH, a flexible powertrain is required. Historically, the only viable technological solution was roller chain. Despite the having the ability to easily attach blades, roller chain is characterized by significant drawbacks, including high cost, wear, and vibration from chordal action. Advanced carbon-#12;fiber-reinforced timing belts have been recently developed which, coupled with a novel belt attachment system developed by Natel Energy, result in a large reduction in moving parts, reduced mass and cost, and elimination of chordal action for increased fatigue life. The work done in this project affirmatively addressed each of the following 3 major uncertainties concerning a timing-belt based hydroEngine ?powertrain: 1. Can a belt handle the high torques and power loads demanded by the SLH? (Yes.) 2. Can the SLH blades be mounted to belt with a connection that can withstand the loads encountered in operation? (Yes.) 3. Can the belt, with blade attachments, live through the required cyclic loading? (Yes.) The research adds to the general understanding of sustainable small hydropower systems by using innovative system testing to develop and demonstrate performance of a novel powertrain solution, enabling a new type of hydroelectric turbine to be commercially developed. The technical effectiveness of the methods investigated has been shown to be positive through an extensive design and testing process accommodating many constraints and goals, with a major emphasis on high cycle fatigue life. Economic feasibility of the innovations has been demonstrated through many iterations of design for manufacturability and cost reduction. The project is of benefit to the public because it has helped to develop a solution to a major problem -- despite the large available potential for new low-head hydropower, high capital costs and high levelized cost of electricity (LCOE) continue to be major barriers to project development. The hydroEngine? represents a significant innovation, leveraging novel fluid mechanics and mechanical configuration to allow lower-cost turbine manufacture and development of low head hydropower resources.

  12. Moving belt metal detector

    NASA Astrophysics Data System (ADS)

    Nelson, Carl V.; Mendat, Deborah P.; Huynh, Toan B.

    2006-05-01

    The Johns Hopkins University Applied Physics Laboratory (APL) has developed a prototype metal detection survey system that will increase the search speed of conventional technology while maintaining high sensitivity. Higher search speeds will reduce the time to clear roads of landmines and improvised explosive devices (IED) and to locate unexploded ordnance (UXO) at Base Realignment and Closure (BRAC) sites, thus reducing remediation costs. The new survey sensor system is called the moving belt metal detector (MBMD) and operates by both increasing sensor speed over the ground while maintaining adequate sensor dwell time over the target for good signal-to-noise ratio (SNR) and reducing motion-induced sensor noise. The MBMD uses an array of metal detection sensors mounted on a flexible belt similar to a tank track. The belt motion is synchronized with the forward survey speed so individual sensor elements remain stationary relative to the ground. A single pulsed transmitter coil is configured to provide a uniform magnetic field along the length of the receivers in ground contact. Individual time-domain electromagnetic induction (EMI) receivers are designed to sense a single time-gate measurement of the total metal content. Each sensor module consists of a receiver coil, amplifier, digitizing electronics and a low power UHF wireless transmitter. This paper presents the survey system design concepts and metal detection data from various targets at several survey speeds. Although the laboratory prototype is designed to demonstrate metal detection survey speeds up to 10 m/s, higher speeds are achievable with a larger sensor array. In addition, the concept can be adapted to work with other sensor technologies not previously considered for moving platforms.

  13. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...SURFACE WORK AREAS OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.406 Drive belts. (a) Drive belts...shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied...

  14. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...SURFACE WORK AREAS OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.406 Drive belts. (a) Drive belts...shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied...

  15. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...SURFACE WORK AREAS OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.406 Drive belts. (a) Drive belts...shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied...

  16. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...SURFACE WORK AREAS OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.406 Drive belts. (a) Drive belts...shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied...

  17. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...SURFACE WORK AREAS OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.406 Drive belts. (a) Drive belts...shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied...

  18. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...63 Safety belts. (a) There must be a safety belt, harness, or other restraining means for each occupant, unless the Administrator finds it unnecessary. If installed, the belt, harness, or other restraining means and its supporting...

  19. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...63 Safety belts. (a) There must be a safety belt, harness, or other restraining means for each occupant, unless the Administrator finds it unnecessary. If installed, the belt, harness, or other restraining means and its supporting...

  20. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...63 Safety belts. (a) There must be a safety belt, harness, or other restraining means for each occupant, unless the Administrator finds it unnecessary. If installed, the belt, harness, or other restraining means and its supporting...

  1. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...63 Safety belts. (a) There must be a safety belt, harness, or other restraining means for each occupant, unless the Administrator finds it unnecessary. If installed, the belt, harness, or other restraining means and its supporting...

  2. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...63 Safety belts. (a) There must be a safety belt, harness, or other restraining means for each occupant, unless the Administrator finds it unnecessary. If installed, the belt, harness, or other restraining means and its supporting...

  3. Number Conveyor Belt

    NSDL National Science Digital Library

    2012-01-01

    This activity for the interactive white board (free access with registration) allows a teacher to create an arithmetic sequence for students to watch being built as the sequence of numbers moves along a conveyor. Learners must determine the pattern being used so when the belt randomly stops, the missing number in the sequence can be dragged/ dropped into its place. The teacher sets the start number (0-19), the interval or common difference (1-10) and if the sequence will count up or down. This last option provides an opportunity to display patterns with integers.

  4. Paleoarchean trace fossils in altered volcanic glass

    PubMed Central

    Staudigel, Hubert; Furnes, Harald; DeWit, Maarten

    2015-01-01

    Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas. PMID:26038543

  5. Paleoarchean trace fossils in altered volcanic glass.

    PubMed

    Staudigel, Hubert; Furnes, Harald; DeWit, Maarten

    2015-06-01

    Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas. PMID:26038543

  6. Teaching Science: Seat Belt Science.

    ERIC Educational Resources Information Center

    Leyden, Michael B.

    1994-01-01

    Describes activities that will help students understand how car seat belts work, the limited reaction time available to passengers in an automobile accident, and the force of impact in a car collision. These activities will provide students with hands-on experiences that demonstrate the importance of always wearing seat belts while in an…

  7. Geography of the asteroid belt

    NASA Technical Reports Server (NTRS)

    Zellner, B. H.

    1978-01-01

    The CSM classification serves as the starting point on the geography of the asteroid belt. Raw data on asteroid types are corrected for observational biases (against dark objects, for instance) to derive the distribution of types throughout the belt. Recent work on family members indicates that dynamical families have a true physical relationship, presumably indicating common origin in the breakup of a parent asteroid.

  8. Belt conveyors for bulk materials. 6th ed.

    SciTech Connect

    NONE

    2007-07-01

    The 16 chapters are entitled: Belt conveyor general applications economics; Design considerations; Characteristics and conveyability of bulk materials; Capacities, belt widths and speeds; Belt conveyor idlers; Belt tension and power engineering; Belt selection; Pulleys and shafts; Curves; Steep angle conveying; Belt cleaners and accessories; Transfer points; Conveyor motor drives and controls; Operation, maintenance and safety; Belt takeups; and Emerging technologies. 6 apps.

  9. Archean sedimentary styles and early crustal evolution

    NASA Astrophysics Data System (ADS)

    Lowe, D. R.

    The distinctions between and implications of early and late Archean sedimentary styles are presented. Early Archean greenstone belts, such as the Barberton of South Africa and those in the eastern Pilbar Block of Australia are characterized by fresh or slightly reworked pyroclastic debris, orthochemical sediments such as carbonates, evaporites, and silica, and biogenic deposits including cherts and stromatolitic units. Terrigenous deposits are rare, and it is suggested that early Archean sediments were deposited on shallow simatic platforms, with little or no components derived from sialic sources. In contrast, late Archean greenstone belts in the Canadian Shield and the Yilgarn Block of Australia contain coarse terrigenous clastic rocks including conglomerate, sandstone, and shale derived largely from sialic basement. Deposition appears to have taken place in deepwater, tectonically unstable environments. These observations are interpreted to indicate that the early Archean greenstone belts formed as anorogenic, shallow water, simatic platforms, with little or no underlying or adjacent continental crust, an environment similar to modern oceanic islands formed over hot spots.

  10. Greenstone and diabase utilization in the stone age of western Norway: Technological and socio?cultural aspects of axe and adze production and distribution

    Microsoft Academic Search

    Asle Bruen Olsen; Sigmund Alsaker

    1984-01-01

    The subject of this article is the production and distribution of stone axes and adzes originating from two large Stone Age quarries in western Norway: the greenstone quarry on the small island of Hespriholmen, Bømlo kommune, Hordaland fylke, and the diabase quarry at Stakaneset, Flora kommune, Sogn og Fjordane Fylke. The identification of production sites and distributed products associated with

  11. Fluid evolution in the H 2O-CH 4-CO 2-NaCl system during emerald mineralization at Gravelotte, Murchison Greenstone Belt, Northeast Transvaal, South Africa

    NASA Astrophysics Data System (ADS)

    Nwe, Yin Yin; Morteani, Giulio

    1993-01-01

    Fluid evolution during emerald mineralization at the Gravelotte emerald mine has been studied by microthermometry and laser Raman microprobe spectrometry. The emeralds and associated phenakites occur on the flanks of a highly metasomatised albitite pegmatoid body and in the biotite schists at and near its contact. The fluids lie in the H 2O-CH 4-CO 2-NaCl system and four types of inclusions are characterised based on time of trapping and fluid contents. The earliest type 1 inclusions, found in phenakites and the emeralds which formed from them, are low salinity (<6 wt% NaCl) with up to 18 mol% CH 4. The carbonic phase contains over 93 mol% CH 4 and variable small amounts of CO 2, C 2H 6, N 2, and H 2S. The solvus crest for this system lies at ?400°C, closer to the H 2O end of the join. With time the fluids become less CH 4 rich and more saline. The type 2 fluids are highly variable in both CH 4-CO 2 contents and salinity, reflecting mixing of type 1 fluids with higher salinity brines. The late type 3 and 4 inclusions are CH 4-CO 2-free high salinity inclusions with up to 38 wt% NaCl. Trapping conditions for the type 1 fluids were around 450-500°C and 4 kb based on model isochores and geologic evidence. During the trapping of type 2 inclusions, fluid pressures probably fluctuated due to opening and resealing of fractures. Approximate P- T ranges of trapping for these and other later inclusions have been defined, minimum trapping temperatures for types 2, 3, and 4 being, respectively, 250, 150, and 240°C, and pressures in the range of 1-4 kb. Calculations of ƒ O 2 show an initial low ƒ O 2 between QFM and the synthetic graphite-CH 4 buffer for the type 1 fluids. This rises to above QFM in the later stages. Such low initial values are uncharacteristic of granitic pegmatite systems, and it is suggested that the phenakites formed in the post-magmatic stage of alkali metasomatism when the albitization took place. In the later stages, phenakite was converted to emerald as alumina activities in the system increased. Concomitantly higher salinity brines, at least some of which are probably related to regional metamorphism in the area, were trapped under higher ƒ O 2 conditions. Metasomatic exchange with the mafic host rocks also increased as evidenced by the incorporation of Cr in the late emeralds. The energy necessary for the continuous growth of the later emeralds was probably supplied by regional metamorphism.

  12. Fluid chemistry and evolution of hydrothermal fluids in an Archaean transcrustal fault zone network: The case of the Cadillac Tectonic Zone, Abitibi greenstone belt, Canada

    USGS Publications Warehouse

    Neumayr, P.; Hagemann, S.G.; Banks, D.A.; Yardley, B.W.D.; Couture, J.-F.; Landis, G.P.; Rye, R.

    2007-01-01

    Detailed fluid geochemistry studies on hydrothermal quartz veins from the Rouyn-Noranda and Val-d'Or areas along the transcrustal Cadillac Tectonic Zone (CTZ) indicate that unmineralized (with respect to gold) sections of the CTZ contained a distinct CO2-dominated, H2S-poor hydrothermal fluid. In contrast, both gold mineralized sections of the CTZ (e.g., at Orenada #2) and associated higher order shear zones have a H2O-CO2 ?? CH4-NaCl hydrothermal fluid. Their CO2/H2S ratios indicate H2S-rich compositions. The Br/Cl compositions in fluid inclusions trapped in these veins indicate that hydrothermal fluids have been equilibrated with the crust. Oxygen isotope ratios from hydrothermal quartz veins in the CTZ are consistently 2??? more enriched than those of associated higher order shear zones, which are interpreted to be a function of greater fluid/rock ratios in the CTZ and lower fluid/rock ratios, and more efficient equilibration of the hydrothermal fluid with the wall rock, in higher order shear zones. An implication from this study is that the lower metal endowment of the transcrustal CTZ, when compared with the higher metal endowment in higher order shear zones (ratio of about 1 : 1000), may be the result of the lack of significant amounts of H2O-H2S rich fluids in most of the CTZ. In contrast, gold mineralization in the higher order shear zones appear to be controlled by the high H2S activity of the aqueous fluids, because gold was likely transported in a bisulfide complex and was deposited during sulfidation reactions in the wall rock and phase separation in the quartz veins. ?? 2007 NRC Canada.

  13. Fluid evolution in the H 2 OCH 4 CO 2 NaCl system during emerald mineralization at Gravelotte, Murchison Greenstone Belt, Northeast Transvaal, South Africa

    Microsoft Academic Search

    Yin Yin Nwe; Giulio Morteani

    1993-01-01

    Fluid evolution during emerald mineralization at the Gravelotte emerald mine has been studied by microthermometry and laser Raman microprobe spectrometry. The emeralds and associated phenakites occur on the flanks of a highly metasomatised albitite pegmatoid body and in the biotite schists at and near its contact. The fluids lie in the H 2 O-CH 4 -CO 2 -NaCl system and

  14. Radial Basis Functional Link Nets Used as a Prospectivity Mapping Tool for Orogenic Gold Deposits Within the Central Lapland Greenstone Belt, Northern Fennoscandian Shield

    Microsoft Academic Search

    Vesa Nykänen

    2008-01-01

    Among the more popular spatial modeling techniques, artificial neural networks (ANN) are tools that can deal with non-linear\\u000a relationships, can classify unknown data into categories by using known examples for training, and can deal with uncertainty;\\u000a characteristics that provide new possibilities for data exploration. Radial basis functional link nets (RBFLN), a form of\\u000a ANN, are applied to generate a series

  15. Mantle heterogeneity and crustal recycling in Archean granite-greenstone belts - Evidence from Nd isotopes and trace elements in the Rainy Lake area, Superior Province, Ontario, Canada

    NASA Technical Reports Server (NTRS)

    Shirey, Steven B.; Hanson, Gilbert N.

    1986-01-01

    Crustal evolution in the Rainy Lake area, Ontario is studied in terms of geochemical characteristics. The Nd isotope data are examined for heterogeneity of the Archean mantle, and the Sm/Nd depletion of the mantle is analyzed. The Nd isotope systematics of individual rock suites is investigated in order to understand the difference between crust and mantle sources; the precursors and petrogenetic processes are discussed. The correlation between SiO2 content and Nd values is considered. Rapid recycling of crustal components, which were previously derived from depleted mantle sources, is suggested based on the similarity of the initial Nd isotopic composition for both mantle-derived and crustally-derived rocks.

  16. Composition and origin of fluids associated with lode gold deposits in a Mesoarchean greenstone belt (Warrawoona Syncline, Pilbara Craton, Western Australia) using synchrotron radiation X-ray fluorescence

    Microsoft Academic Search

    Nicolas Thébaud; Pascal Philippot; Patrice Rey; Jean Cauzid

    2006-01-01

    Microthermometry and Raman spectroscopy techniques are routinely use to constrain ore-fluids ?18O and molar proportions of anhydrous gas species (CO2, CH4, N2). However, these methods remain imprecise concerning the ore-fluids composition and source. Synchrotron radiation X-ray fluorescence allows access to major and trace element concentrations (Cl, Br and K, Ca, Fe, Cu, Zn, As, Rb, Sr) of single fluid inclusion.

  17. Composition and origin of fluids associated with lode gold deposits in a Mesoarchean greenstone belt (Warrawoona Syncline, Pilbara Craton, Western Australia) using synchrotron radiation X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Thébaud, Nicolas; Philippot, Pascal; Rey, Patrice; Cauzid, Jean

    2006-10-01

    Microthermometry and Raman spectroscopy techniques are routinely use to constrain ore-fluids ?18O and molar proportions of anhydrous gas species (CO2, CH4, N2). However, these methods remain imprecise concerning the ore-fluids composition and source. Synchrotron radiation X-ray fluorescence allows access to major and trace element concentrations (Cl, Br and K, Ca, Fe, Cu, Zn, As, Rb, Sr) of single fluid inclusion. In this paper, we present the results of the combination of these routine and newly developed techniques in order to document the fluids composition and source associated with a Mesoarchaean lode gold deposit (Warrawoona Syncline, Western Australia). Fluid inclusion analyses show that quartz veins preserved records of three fluid inclusion populations. Early fluids inclusions, related to quartz veins precipitation, are characterized by a moderate to high Br/Cl ratio relative to modern seawater, CO2 ± CH4 ± N2, low to moderate salinities and significant base metal (Fe, Cu, Zn) and metalloid (As) concentrations. Late fluid inclusions trapped in secondary aqueous fluid inclusions are divided into two populations with distinct compositions. The first population consists of moderately saline aqueous brines, with a Br/Cl ratio close to modern seawater and a low concentration of base metals and metalloids. The second population is a fluid of low to moderate salinity, with a low Br/Cl ratio relative to modern seawater and significant enrichment in Fe, Zn, Sr and Rb. These three fluid inclusion populations point to three contrasting sources: (1) a carbonic fluid of mixed metamorphic and magmatic origin associated with the gold-bearing quartz precipitation; (2) a secondary aqueous fluid with seawater affinity; and (3) a surface-derived secondary aqueous fluid modified through interaction with felsic lithologies, before being flushed into the syncline. Primary carbonic fluids present similar characteristics than those ascribed to Mesoarchaean lode gold deposits. This suggests similar mineralization processes for mid- and Mesoarchaean lode gold deposits despite contrasting fluid-rock interaction histories. However, in regard to the protracted history documented in the Warrawoona Syncline, we question the robustness of the epigenetic crustal continuum model, as ore-fluid characteristics equally support an epigenetic or a polyphased mineralization process.

  18. Foreland basins and fold belts

    SciTech Connect

    Macqueen, R.W.; Leckie, D.A. (Geological Survey of Canada, Inst. of Sedimentary and Petroleum Geology, Calgary, Alberta (Canada))

    1992-01-01

    The papers in this book describe six foreland basins and fold belts in terms of their regional setting, stratigraphy, tectonics, and structure, and their oil and gas systems. All of the basins show general similarities, but each differs significantly in detail from the others, posing something of a problem in terms of arriving at a 'typical' foreland basin and fold belt. Some are major hydrocarbon producers; others are not. The major characteristics of the six foreland basins and fold belts are summarized in Tables 1 through 5, which provide a convenient means of comparing and contrasting these basins and their hydrocarbon resources. The Western Canada foreland basin and fold belt serves as the type example for several reasons. These include: its setting and clear relationship to a major orogene of Mesozoic-Cenozoic age; the fact that it is uncomplicated by later overprinting, segmentation, or cover rocks unlike the Ouachita, Eastern Venezuela, and U.S. Rocky Mountain foreland basins and fold belts); the fact that there is a large volume of publicly available data on the basin and an active exploration and research community; and the fact that it has reasonable oil and gas reserves in a well-defined stratigraphic framework.

  19. Satellite Feature Identification: Conveyor Belts

    NSDL National Science Digital Library

    COMET

    2014-03-18

    Conveyor belts highlight important atmospheric processes that can be advantageous for making forecasts. They can be used for identifying general temperature patterns, defining the extent of cloud cover, predicting moisture return, evaluating stability, forecasting wind gusts, pinpointing cyclogenesis, and understanding the three-dimensional structure of the atmosphere. For short-term forecasts, they can even augment NWP showing the three-dimensional structure and portraying the same information as equivalent or wet-bulb potential temperature and potential vorticity surfaces. Conveyor belts make representing the total wind easier than using isobaric surfaces which only cut through the processes giving limited, two-dimensional views of the total wind. In this lesson, learn to identify conveyor belts using water vapour imagery. You'll be able to understand the structure of the conveyor belt's isentropic surfaces from the water vapour imagery and use that knowledge to enhance your forecasting. Further analysis will allow you to break your conveyor belts into branches for even more forecasting ability. It is highly encouraged that students review the "Deformation Zone Analysis" and "Inferring Three Dimensions from Water Vapour imagery" lessons before attempting this lesson.

  20. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 false Safety belts. 27.1413 Section...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  1. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 2010-01-01 false Safety belts. 27.1413 Section...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  2. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2011-01-01 false Safety belts. 27.1413 Section...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  3. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 false Safety belts. 27.1413 Section...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  4. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 false Safety belts. 27.1413 Section...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety...

  5. 1 The Main Asteroid Belt Carolyn Crow: NASA's Dawn Mission The Main Asteroid Belt

    E-print Network

    Waliser, Duane E.

    1 The Main Asteroid Belt Carolyn Crow: NASA's Dawn Mission The Main Asteroid Belt Written to the main asteroid belt to visit two of the largest protoplanets, Vesta and Ceres. Using sunlight, a mere accomplished by a spacecraft before. What compelled astronomers to send Dawn to the asteroid belt and what does

  6. Fishbone Model for Belt Object Deformation

    Microsoft Academic Search

    Hidefumi Wakamatsu; Eiji Arai; Shinichi Hirai

    2007-01-01

    A modeling method for representing belt object deformation is proposed. Deformation of belt objects such as film circuit boards or flexible circuit boards must be estimated for automatic manipulation and assembly. In this paper, we assume that deformation of an inextensible belt object can be described by the shape of its central axis in a longitudinal direction called \\

  7. Pregnancy: Should I Use a Seat Belt?

    MedlinePLUS

    ... injury or death in the event of a car crash. You should wear a seat belt no matter where you sit in the car. How should I wear my seat belt? The ... belts keep you from being thrown from the car during an accident. The shoulder strap also keeps ...

  8. Timing of multiple hydrothermal events in the iron oxide-copper-gold deposits of the Southern Copper Belt, Carajás Province, Brazil

    NASA Astrophysics Data System (ADS)

    Moreto, Carolina P. N.; Monteiro, Lena V. S.; Xavier, Roberto P.; Creaser, Robert A.; DuFrane, S. Andrew; Melo, Gustavo H. C.; Delinardo da Silva, Marco A.; Tassinari, Colombo C. G.; Sato, Kei

    2015-06-01

    The Southern Copper Belt, Carajás Province, Brazil, hosts several iron oxide-copper-gold (IOCG) deposits, including Sossego, Cristalino, Alvo 118, Bacuri, Bacaba, Castanha, and Visconde. Mapping and U-Pb sensitive high-resolution ion microprobe (SHRIMP) IIe zircon geochronology allowed the characterization of the host rocks, situated within regional WNW-ESE shear zones. They encompass Mesoarchean (3.08-2.85 Ga) TTG orthogneiss, granites, and remains of greenstone belts, Neoarchean (ca. 2.74 Ga) granite, shallow-emplaced porphyries, and granophyric granite coeval with gabbro, and Paleoproterozoic (1.88 Ga) porphyry dykes. Extensive hydrothermal zones include albite-scapolite, biotite-scapolite-tourmaline-magnetite alteration, and proximal potassium feldspar, chlorite-epidote and chalcopyrite formation. U-Pb laser ablation multicollector inductively coupled mass spectrometry (LA-MC-ICP-MS) analysis of ore-related monazite and Re-Os NTIMS analysis of molybdenite suggest multiple Neoarchean (2.76 and 2.72-2.68 Ga) and Paleoproterozoic (2.06 Ga) hydrothermal events at the Bacaba and Bacuri deposits. These results, combined with available geochronological data from the literature, indicate recurrence of hydrothermal systems in the Southern Copper Belt, including 1.90-1.88-Ga ore formation in the Sossego-Curral ore bodies and the Alvo 118 deposit. Although early hydrothermal evolution at 2.76 Ga points to fluid migration coeval with the Carajás Basin formation, the main episode of IOCG genesis (2.72-2.68 Ga) is related to basin inversion coupled with Neoarchean (ca. 2.7 Ga) felsic magmatism. The data suggest that the IOCG deposits in the Southern Copper Belt and those in the Northern Copper Belt (2.57-Ga Salobo and Igarapé Bahia-Alemão deposits) do not share a common metallogenic evolution. Therefore, the association of all IOCG deposits of the Carajás Province with a single extensive hydrothermal system is precluded.

  9. Radiation Belt Analysis and Modeling

    Microsoft Academic Search

    J. N. Bass; U. Dasgupta; C. A. Hein; J. M. Griffin; D. S. Reynolds

    1995-01-01

    Efforts have been conducted in modeling of radiation belts, and cosmic radiation, principally in connection with the CRRES mission. Statistical studies of solar particle events have been conducted in a search for predictors of the occurrence of geomagnetic storms. Certain spectral and temporal properties of protons and electrons were found to correlate with the occurrence of storms. Comparative studies of

  10. Seat Belt Sign and Its Significance

    PubMed Central

    Agrawal, Amit; Inamadar, Praveenkumar Ishwarappa; Subrahmanyam, Bhattara Vishweswar

    2013-01-01

    Safety belts are the most important safety system in motor vehicles and when worn intend to prevent serious injuries. However, in unusual circumstances (high velocity motor vehicle collisions) these safety measures (seat belts) can be the source and cause of serious injuries. The seat belt syndrome was first described as early by Garrett and Braunste in but the term “seat belt sign” was discussed by Doersch and Dozier. Medical personnel's involved in emergency care of trauma patients should be aware of seat belt sign and there should a higher index of suspicion to rule out underlying organ injuries. PMID:24479100

  11. The Virtual Radiation Belt Observatory

    NASA Astrophysics Data System (ADS)

    Weigel, R. S.; O'Brien, T. P.; Friedel, R. H.; Green, J. C.; Zhizhin, M.; Mishin, D. Y.

    2010-12-01

    ViRBO (Virtual Radiation Belt Observatory) is one of the domain-specific virtual observatories funded under the NASA Heliophysics Data Environment (HPDE) program that began development in 2006. In this work, we report on the search, display, and data access functionality of ViRBO along with plans for interaction with upcoming missions, including Radiation Belt Storms Probes (RBSP). We also describe the relationship between the services and data provided by ViRBO and the general architecture of the HPDE and the plan articulated in the 2010 Senior Review of Data Centers. The lessons learned in the development of ViRBO include issues related to (1) creating a user base given the limits of the types of activities a virtual observatory are charged with supporting and (2) dealing with limitations on existing software and standards when developing data services.

  12. Liquid belt radiator design study

    NASA Technical Reports Server (NTRS)

    Teagan, W. P.; Fitzgerald, K. F.

    1986-01-01

    The Liquid Belt Radiator (LBR) is an advanced concept developed to meet the needs of anticipated future space missions. A previous study documented the advantages of this concept as a lightweight, easily deployable alternative to present day space heat rejection systems. The technical efforts associated with this study concentrate on refining the concept of the LBR as well as examining the issues of belt dynamics and potential application of the LBR to intermediate and high temperature heat rejection applications. A low temperature point design developed in previous work is updated assuming the use of diffusion pump oil, Santovac-6, as the heat transfer media. Additional analytical and design effort is directed toward determining the impact of interface heat exchanger, fluid bath sealing, and belt drive mechanism designs on system performance and mass. The updated design supports the earlier result by indicating a significant reduction in system specific system mass as compared to heat pipe or pumped fluid radiator concepts currently under consideration (1.3 kg/sq m versus 5 kg/sq m).

  13. Current Understanding of Radiation Belt Acceleration, Transport and Loss

    Microsoft Academic Search

    T. P. O'Brien; J. E. Mazur

    2008-01-01

    This invited talk will review the major acceleration, transport, and loss processes that govern the topology and dynamics of the Earth's radiation belts. The belts are typically divided into an inner belt and an outer belt, with a slot of comparatively low flux intensity in between. The hallmark of the inner belt is intense energetic proton flux, co-located with a

  14. China belting up or down? Seat belt wearing trends in Nanjing and Zhoushan

    Microsoft Academic Search

    Virginia Routley; Joan Ozanne-Smith; Dan Li; Min Yu; Jianyue Wang; Junhe Zhang; Zhendong Tong; Ming Wu; Peihua Wang; Yu Qin

    2008-01-01

    National seat belt wearing legislation became effective in China May 2004 and associated provincial and city regulations followed. Despite rapid motorisation seat belt studies in China have been scarce. Patterns and trends in urban seat belt wearing were observed for all driver, front and rear seating positions over the years 2005–2007 in two eastern cities Nanjing (Jiangsu Province) and Zhoushan

  15. Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China)

    E-print Network

    Paris-Sud XI, Université de

    Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics recognized in western Inner Mongolia (China), including, from south to north: North China Craton (NCC), Southern Orogenic Belt (SOB), Hunshandake Block (HB), Northern Orogenic Belt (NOB), South Mongolia

  16. Effect of enhanced seat belt reminders on driver fatality risk

    Microsoft Academic Search

    Charles M. Farmer; JoAnn K. Wells

    2010-01-01

    ObjectiveEnhanced seat belt reminders in automobiles have been shown to increase belt use rates by approximately 3 percentage points. The objective of this study was to estimate the effect of enhanced seat belt reminders on driver fatality risk.

  17. Observations of the outer belt

    NASA Astrophysics Data System (ADS)

    Lagerkvist, C.-. I.; Moroz, L.; Karlsson, O.; Nathues, A.; Erikson, A.; Lahulla, F.; Dahlgren, M.; Davidsson, B.

    The outer belt consist of three major groups, the Cybeles, the Hildas and the Trojans. Taxonomic classification of the asteroids reveal a dependence with size. The largest bodies are C types followed by P types and D types. A possible explanation for this is an alternation of the surfaces over time leading to a reduced spectral slope. The D types is mostly collisional fragments and thus have the youngest and reddest surfaces. Although the Trojans, consisting of the two subgroups L_4 and L_5, is the most numerous group it is the least observed one.

  18. Seat belt use in cars with air bags.

    PubMed Central

    Williams, A F; Wells, J K; Lund, A K

    1990-01-01

    Seat belt use was observed in 1,628 cars with air bags and manual belts and 34,223 cars with manual seat belts only. Sixty-six percent of drivers in cars with air bags wore seat belts compared to 63 percent of drivers in cars with manual belts only. The study found no evidence for the speculation that drivers with air bags will reduce their seat belt use because they believe an air bag alone provides sufficient protection. PMID:2240346

  19. Seat Belts on School Buses: Some Considerations.

    ERIC Educational Resources Information Center

    Soule, David

    1982-01-01

    A representative of the National Highway Traffic Safety Administration weighs advantages and discusses issues associated with installing seat belts in school buses. Federal regulations and research findings are considered. A list of guideline questions for school districts planning to install seat belts is included. (PP)

  20. A BOOSTER SEAT positions the seat belt

    E-print Network

    and chest to restrain the child safely in a crash. It should not rest on the stomach area or across the neck the lap belt must lie snugly across the upper thighs, not the stomach. The shoulder belt should lie snug

  1. DESIGN AND OPERATION OF BELT FILTER PRESSES

    EPA Science Inventory

    Because early models of belt filter presses (developed from technology associated with the manufacture of paper) performed poorly, improved design and operation procedures for these presses were studied. Belt filter presses form part of a sludge dewatering system, and in terms of...

  2. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 1 2011-07-01 2011-07-01 false Safety belts. 4.15 Section 4.15 Parks, Forests...SERVICE, DEPARTMENT OF THE INTERIOR VEHICLES AND TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger...

  3. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 1 2013-07-01 2013-07-01 false Safety belts. 4.15 Section 4.15 Parks, Forests...SERVICE, DEPARTMENT OF THE INTERIOR VEHICLES AND TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger...

  4. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 1 2014-07-01 2014-07-01 false Safety belts. 4.15 Section 4.15 Parks, Forests...SERVICE, DEPARTMENT OF THE INTERIOR VEHICLES AND TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger...

  5. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 1 2012-07-01 2012-07-01 false Safety belts. 4.15 Section 4.15 Parks, Forests...SERVICE, DEPARTMENT OF THE INTERIOR VEHICLES AND TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger...

  6. Effects of Obesity on Seat Belt Fit

    Microsoft Academic Search

    Matthew P. Reed; Sheila M. Ebert-Hamilton; Jonathan D. Rupp

    2012-01-01

    Introduction Obesity has been shown to increase the risks of some types of injury in crashes. One way in which obesity may increase injury risk is by changing the routing of the belt relative to the underlying skeletal structures.Methods Belt fit was measured in a laboratory study of 54 men and women, 48 percent of whom were obese, defined by

  7. Focus on Seat Belt Use in China

    Microsoft Academic Search

    Virginia Routley; Joan Ozanne-Smith; Min Yu; Jianyue Wang; Ming Wu; Junhe Zhang; Yu Qin; Ming Zhao

    2010-01-01

    Objective: To explain low seat belt use prevalence results of observation and interview surveys in Nanjing, Jiangsu Province, and Zhoushan, Zhejiang Province, and to extend knowledge on associated seat belt use determinants.Method: Ten focus groups comprising professional, owner, and taxi drivers; passengers; van drivers (Nanjing); or police (Zhoushan) were conducted to capture a range of experiences, attitudes, and opinions.Results: There

  8. International survey of seat belt use exemptions

    Microsoft Academic Search

    H Weiss; H Sirin; J A Levine; E Sauber

    2006-01-01

    Background: Substantial evidence of seatbelt efficacy has been shown by several studies, and it is widely recommended that motor vehicle occupants use properly fitted seat belts. However, some (but a heretofore unknown number of) countries with national seat belt laws permit various exemptions which may lower use rates. The aim of this study was to survey the variety of exemptions

  9. Parameters affecting seat belt use in Greece.

    PubMed

    Yannis, G; Laiou, A; Vardaki, S; Papadimitriou, E; Dragomanovits, A; Kanellaidis, G

    2011-09-01

    The objective of this research is the exploration of seat belt use in Greece and particularly the identification of the parameters affecting seat belt use in Greece. A national field survey was conducted for the analytical recording of seat belt use. A binary logistic regression model was developed, and the impact of each parameter on seat belt use in Greece was quantified. Parameters included in the model concern characteristics of car occupants (gender, age and position in the car), the type of the car and the type of the road network. The data collection revealed that in Greece, the non-use of seat belt on the urban road network was higher than on the national and rural road network and young and older men use seat belts the least. The developed model showed that travelling on a national road is negative for not wearing the seat belt. Finally, the variable with the highest impact on not wearing a seat belt is being a passenger on the back seats. PMID:21452095

  10. Petrology and structure of greenstone blocks encased in mud-matrix melange of the Franciscan complex near San Simeon, California

    SciTech Connect

    Davidsen, R.K.; Cloos, M.

    1985-01-01

    Greenstones comprise about 20% of all mappable (>1 m) blocks encased in blueschist-block-bearing mud-matrix melange exposed in a 10 km-length of sea cliffs near San Simeon. Field and petrographic analysis of 25 blocks show they vary from finely crystalline (<1 mm) locally porphyritic or amygdaloidal, volcanics to coarsely crystalline (1 to 5 mm) diabase. Some are in contact with bedded chert and two have relict pillows. However, most blocks are intensely deformed. Pinch-and-swell and boundinage are recognized on scales from cm to about 10 m. Distortion was accommodated by cataclasis to an aggregate of pieces from mm to m across. Generally, m-sized blocks are pervasively cataclastic whereas larger blocks are crosscut by cataclastic zones that emanate from pervasively cataclastic margins or necked regions of boudins. Discontinuous, cm-thick veins and cavities that are lined by quartz and clacite and rarely, laumontite, prehnite and aragonite locally crosscut all other structures. Relict igneous textures show the primary minerals are plagioclase and clinopyroxene. Abundant secondary minerals, particularly in cataclastic zones, are albite, chlorite, pumpellyite (some have high Al), and calcite. The metamorphic parageneses indicate relatively minor greenschist-facies, sea-floor-type alterations under static conditions followed by lower-temperature alterations synchronous with cataclasis and the development of boudinage. If the blocks are fragments of disrupted ophiolites, only the uppermost section of the suite are present within the mud-matrix melange near San Simeon. The simplest explanation for their crystallization, metamorphism and incorporation into the melange is that they are fragments of seamounts dismembered during subduction.

  11. Geological and geochemical record of 3400-million-year-old terrestrial meteorite impacts

    NASA Technical Reports Server (NTRS)

    Lowe, Donald R.; Byerly, Gary R.; Asaro, Frank; Kyte, Frank T.

    1989-01-01

    Beds of sand-sized spherules in the 3400-million-year-old Fig Tree Group, Barberton Greenstone belt, South Africa, formed by the fall of quenched liquid silicate droplets into a range of shallow- to deep-water depositional environments. The regional extent of the layers, their compositional complexity, and lack of included volcanic debris suggest that they are not products of volcanic activity. The layers are greatly enriched in iridium and other platinum group elements in roughly chondritic proportions. Geochemical modeling based on immobile element abundances suggests that the original average spherule composition can be approximated by a mixture of fractionated tholeiitic basalt, komatiite, and CI carbonaceous chondrite. The spherules are thought to be the products of large meteorite impacts on the Archean earth.

  12. More evidence on the effectiveness of seat belt laws

    Microsoft Academic Search

    Christopher Garbacz

    1992-01-01

    A state cross-sectional model of traffic fatalities estimates the effectiveness of seat belt laws. Seat belt laws have no statistically significant effect on total or occupant fatalities. However, the results suggest that seat belt laws lead to increased non-occupant deaths possibly as a result of more dangerous driving. In an indirect fashion, the zero effect of seat belt laws on

  13. Increasing Automobile Seat Belt Use: An Intervention Emphasizing Risk Susceptibility

    Microsoft Academic Search

    Neil D. Weinstein; Paul Dallas Grubb; James S. Vautier

    1986-01-01

    A seat belt promotion program was based on the previous finding (Weinstein, 1984) that many people fail to take their seat belt use into account when thinking about their risk of being injured in an automobile accident. The goal of the program was to increase belt use by making the link between belt use and personal risk more salient. The

  14. Plains tectonism on Venus - The deformation belts of Lavinia Planitia

    NASA Technical Reports Server (NTRS)

    Squyres, Steven W.; Jankowski, David G.; Simons, Mark; Solomon, Sean C.; Hager, Bradford H.; Mcgill, George E.

    1992-01-01

    The belts of the Lavinia Planitia region of Venus are discussed in detail with reference to high-resolution radar images from the Magellan spacecraft. Two types of deformation belts are identified: ridge belts and fracture belts. Ridge belts are composed of parallel ridges, each a few hundred meters in elevation, that are interpreted as folds. Typical fold spacings are 5-10 km. Fracture belts are dominated by intense faulting, with faults in some instances paired to form narrow grabens. The formation of ridge and fracture belts is explored using simple models.

  15. The geological record of life 3500 MA ago: Coping with the rigors of a young earth during late accretion

    NASA Astrophysics Data System (ADS)

    Lowe, Donald R.

    1989-03-01

    Thin cherty sedimentary layers within the volcanic portions of the 3,500 to 3,300 Ma-old Onverwacht and Fig Tree Groups, Barberton Greenstone belt, South Africa, and Warrawoona Group, eastern Pilbara Block, Western Australia, contain an abundant record of early Archean life. Five principal types of organic and probably biogenic remains and or structures can be identifed: stromatolites, stromatolite detritus, carbonaceous laminite or flat stromalite, carbonaceous detrital particles, and microfossils. Early Archean stromatolites were reported from both the Barberton and eastern Pilbara greenstone belts. Systematic studies are lacking, but two main morphological types of stromatolites appear to be represented by these occurrences. Morphology of the stromalites is described. Preserved early Archean stromatolites and carbonaceous matter appear to reflect communities of photosynthetic cyanobacteria inhabiting shallow, probably marine environments developed over the surfaces of low-relief, rapidly subsiding, simatic volcanic platforms. The overall environmental and tectonic conditions were those that probably prevailed at Earth's surface since the simatic crust and oceans formed sometime before 3,800 Ma. Recent studies also suggest that these early Archean sequences contain layers of debris formed by large-body impacts on early Earth. If so, then these early bacterial communities had developed strategies for coping with the disruptive effects of possibly globe-encircling high-temperature impact vapor clouds, dust blankets, and impact-generated tsunamis. It is probable that these early Archean biogenic materials represent organic communities that evolved long before the beginning of the preserved geological record and were well adapted to the rigors of life on a young, volcanically active Earth during late bombardment. These conditions may have had parallels on Mars during its early evolution.

  16. The Compositional Structure of the Asteroid Belt

    E-print Network

    DeMeo, Francesca E; Walsh, Kevin J; Chapman, Clark R; Binzel, Richard P

    2015-01-01

    The past decade has brought major improvements in large-scale asteroid discovery and characterization with over half a million known asteroids and over 100,000 with some measurement of physical characterization. This explosion of data has allowed us to create a new global picture of the Main Asteroid Belt. Put in context with meteorite measurements and dynamical models, a new and more complete picture of Solar System evolution has emerged. The question has changed from "What was the original compositional gradient of the Asteroid Belt?" to "What was the original compositional gradient of small bodies across the entire Solar System?" No longer is the leading theory that two belts of planetesimals are primordial, but instead those belts were formed and sculpted through evolutionary processes after Solar System formation. This article reviews the advancements on the fronts of asteroid compositional characterization, meteorite measurements, and dynamical theories in the context of the heliocentric distribution of...

  17. Dynamical evolution of the asteroid belt

    NASA Astrophysics Data System (ADS)

    Morbidelli, A.; Walsh, K.; O'Brien, D.; Minton, D.; Bottke, W.

    2014-07-01

    We discusses the properties of the asteroid belt that dynamical evolution models should explain, i.e. mass deficit, orbital excitation, partial mixing of taxonomic types, the short cumulative collisional age of the asteroid belt (10 Gy; Bottke et al., 2005), and the rapid decay of the Ar-Ar shock ages for HEDs 4.5 Gy ago. We start by discussing the early dynamical sculpting of the asteroid belt, reviewing first the canonical model of Wetherill (1992), then the more recent Grand Tack Scenario (Walsh et al., 2011). In the second part of the talk, we describe the late evolution of the asteroid belt, affected by the dynamical instability that brought the giant planets to their current orbits about 4.1 Gy ago. The role of asteroids in the so-called Late Heavy Bombardment of the terrestrial planets will also be discussed.

  18. Seat Belt Use in 2012 - Overall Results

    MedlinePLUS

    ... shoulder belts observed between the hours of 7 a.m. and 6 p.m. 3 The statistical confidence ... sampled roadways, who observe passenger vehicles between 7 a.m. and 6 p.m. Observations are made either ...

  19. A study of binary Kuiper Belt objects

    E-print Network

    Kern, Susan Diane

    2006-01-01

    About 105 bodies larger than 100km in diameter (Jewitt 1998) reside in the Kuiper Belt, beyond the orbit of Neptune. Since 1992 observational surveys have discovered over one thousand of these objects, believed to be fossil ...

  20. Earth's radiation belts. Environmental research papers

    SciTech Connect

    Spjeldvik, W.N.; Rothwell, P.L.

    1983-09-20

    This report develops radiation belt transport theory from physical principles and compares the results with experimental data. It also provides an easy reference to the present empirical radiation flux models with some simple application techniques given. Specialized topics include shell-splitting, effects of wave-particle interactions, the ring current, geosynchronous environment, nuclear detonations and radiation effects. Heavy ions are specifically highlighted as a significant component of the radiation belts.

  1. A photometric survey of outer belt asteroids

    NASA Technical Reports Server (NTRS)

    Dimartino, M.; Gonano-Beurer, M.; Mottola, Stefano; Neukum, G.

    1992-01-01

    Since 1989, we have been conducting a research program devoted to the study of the Trojans and outer belt asteroids (Hilda and Cybele groups), in order to characterize their rotational properties and shapes. As an outcome of several observational campaigns, we determined rotational periods and lightcurve amplitudes for 23 distant asteroids, using both CCD and photoelectric photometry. In this paper, we compare the rotational properties of main belt asteroids and Trojans, based on the preliminary results of this survey.

  2. Decay rate of the second radiation belt.

    PubMed

    Badhwar, G D; Robbins, D E

    1996-01-01

    Variations in the Earth's trapped (Van Allen) belts produced by solar flare particle events are not well understood. Few observations of increases in particle populations have been reported. This is particularly true for effects in low Earth orbit, where manned spaceflights are conducted. This paper reports the existence of a second proton belt and it's subsequent decay as measured by a tissue-equivalent proportional counter and a particle spectrometer on five Space Shuttle flights covering an eighteen-month period. The creation of this second belt is attributed to the injection of particles from a solar particle event which occurred at 2246 UT, March 22, 1991. Comparisons with observations onboard the Russian Mir space station and other unmanned satellites are made. Shuttle measurements and data from other spacecraft are used to determine that the e-folding time of the peak of the second proton belt. It was ten months. Proton populations in the second belt returned to values of quiescent times within eighteen months. The increase in absorbed dose attributed to protons in the second belt was approximately 20%. Passive dosimeter measurements were in good agreement with this value. PMID:11540362

  3. Oil generation in overthrust belts

    SciTech Connect

    Angevine, C.L.; Turcotte, D.L.

    1983-02-01

    The burial of immature sediments beneath a thrust sheet may result in sufficient heating to generate hydrocarbons. The authors present a model for the thermally activated generation of oil from kerogen and the subsequent destruction of the oil through cracking. Using this oil generation model in conjunction with a model applicable to the thermal evolution of overthrust belts, the evolution is studied of oil in sediments beneath a thrust sheet composed of sedimentary rocks. Oil generation may begin soon after emplacement of the thrust sheet. Beneath thick thrust sheets (>8 km), all oil in the sedimentary section may be destroyed less than 5 m.y. after thrusting. The authors results to the timing of oil generation in the sedimentary section beneath the Absaroka thrust plate in the Fossil syncline of western Wyoming. Calculations indicate that the Paleozoic and a part of the Mesozoic section were thermally mature prior to emplacement of the Absaroka plate. The remaining part of Mesozoic sediments matured only after thrusting. The results are in agreement with Warner's 1980 observations that oil being produced from reservoirs in the Absaroka plate was generated in the underthrust Mesozoic section.

  4. Sm-Nd age and isotopic systematics of the bimodal suite, ancient gneiss complex, Swaziland

    USGS Publications Warehouse

    Carlson, R.W.; Hunter, D.R.; Barker, F.

    1983-01-01

    Studies of the development and stabilization of the Archaean crust often focus on the relative temporal relationships between the metamorphosed basaltic to ultramafic volcanic units (greenstone belts) and the sialic gneiss terrains that make up the oldest sections of the terrestrial crust. At the heart of this interest are the questions of the processes responsible for crust formation in the Archaean and whether or not the various units of an Archaean crustal section represent new additions to the crust from the mantle or are products of the reprocessing of even older crustal materials. One area where this controversy has been particularly pronounced is the Archaean crustal section of south-west Africa1-6. The oldest rocks in the Kaapvaal craton consist of the Onverwacht Group of mafic to ultramafic metavolcanics of the Barberton greenstone belt and a grey-gneiss complex termed the ancient gneiss complex (AGC) of Swaziland. We report here the results of a whole-rock Sm-Nd isotopic study of the AGC and the implications these data may have for crustal evolution in the Kaapvaal craton. ?? 1983 Nature Publishing Group.

  5. Thoracic response and injury with belt, driver side airbag, and force limited belt restraint systems

    Microsoft Academic Search

    J. R. Crandall; C. R. Bass; W. D. Pikey; H. J. Miller; J. Sikorski; M. Wilkins

    1996-01-01

    The performance of belt, airbag, and force limited belt restraint systems for the driver were compared using frontal sled tests. Nine human cadaver and six dummy sled tests were conducted at 56 km\\/h using a test buck representing a mid-size vehicle. Subject instrumentation included upper and lower chestbands to measure local thoracic deformations and sternal and spinal accelerometers to record

  6. Injuries to Children Restrained in 2- and 3- Point Belts

    PubMed Central

    Gotschall, Catherine S.; Better, Allison I.; Bulas, Dorothy; Eichelberger, Martin R.; Bents, Frances; Warner, Mike

    1998-01-01

    Injury risks to children restrained in 2-point belts have been well described. “Seat belt syndrome,” associated with the use of 2-point belts, includes contusion of the abdominal wall, fracture of the lumbar spine, and intra-abdominal injury. Using crash reconstruction methodologies and prospectively collected clinical data, we compared injury patterns by restraint type among a sample of 98 belted children. There were no significant differences in injury severity or hospital charges by belt type. There was no difference in the risk of AIS ? 2 injury to the head, neck, chest, abdominal contents or extremities by belt type. Children restrained in 3-point belts exhibit a similar pattern of injury to those in 2-point belts, however 3-point belts appear to be protective for lumbar fracture.

  7. Asteroid Belt Constraints on Giant Planets Evolution

    NASA Astrophysics Data System (ADS)

    Morbidelli, Alessandro; Brasser, R.; Tsiganis, K.; Gomes, R.; Levison, H.

    2009-09-01

    We investigate the dynamical evolution of the asteroid belt during the planetesimal-driven migration of the giant planets. We assume that giant planet migration happened after the primordial depletion/excitation of the asteroid belt, which occurred during terrestrial planet formation. This is a requirement of models that link giant planet migration to the origin of the Late Heavy Bombardment. During the migration of Jupiter and Saturn the secular resonances nu6 and nu16 sweep through the asteroid belt. These secular resonances cause large-amplitude responses in the eccentricities and inclinations of the asteroids if the amplitude of the g6 and s6 modes in Jupiter are similar to the current ones. The final structure of the asteroid belt depends sensitively on the migration speed of Jupiter and Saturn. Our numerical simulations show the current orbital distribution of the asteroid belt can be reproduced if the e-folding time for the migration is shorter than 1 Myr. This is much shorter than traditional results on planetesimal-driven migration; even in the Nice model, which has the fastest possible migration because the entire planetesimal disc is destabilised at once, the shortest measured time is approximately 5 Myr. As a remedy to this problem we propose a 'jumping Jupiter' scenario, which is a subset of the admissible solutions of the Nice model, in which encounters between an ice giant and Jupiter, without ejection of the former, cause the latter to migrate away from Saturn much faster than caused solely by encounters with planetesimals. The jumping Jupiter scenario leads to the secular resonances quickly sweeping through most of the asteroid belt, thereby only depleting the inner belt.

  8. Fatality risk reduction from safety belt use.

    PubMed

    Evans, L

    1987-07-01

    This paper presents an overview of recent estimations of safety belt effectiveness obtained using a new technique--the double-pair comparison method. By effectiveness is meant the reduction, expressed as per cent, in fatalities to a presently unbelted population that would result if all of its members were to use belts, but not otherwise change their driving behavior. The double-pair comparison method is presented more simply, with less mathematical detail and rigor, than in earlier descriptions of it. The method is applied to determine the effectiveness of three-point lap/shoulder belts in preventing fatalities to drivers and right front passengers in passenger cars of model year 1974 or later, averaged over the distribution of crashes which occur in U.S. traffic. The method is then applied to investigate the dependence of effectiveness on a variety of vehicular, accident, roadway, and environmental factors. It is reported that if all presently unbelted drivers and right front passengers were to use the provided lap/shoulder belts, but not otherwise change their behavior, fatalities to this group would decline by (43 +/- 3)%. Safety belt effectiveness for drivers is higher in single-car crashes than in multiple-vehicle crashes, but does not depend much on a variety of other vehicle factors (for example, car size), accident factors (travel speed), roadway factors (posted speed limit), and environmental factors (light versus dark). PMID:3612846

  9. IDENTIFYING COLLISIONAL FAMILIES IN THE KUIPER BELT

    SciTech Connect

    Marcus, Robert A.; Ragozzine, Darin; Murray-Clay, Ruth A.; Holman, Matthew J., E-mail: rmarcus@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2011-05-20

    The identification and characterization of numerous collisional families-clusters of bodies with a common collisional origin-in the asteroid belt has added greatly to the understanding of asteroid belt formation and evolution. More recent study has also led to an appreciation of physical processes that had previously been neglected (e.g., the Yarkovsky effect). Collisions have certainly played an important role in the evolution of the Kuiper Belt as well, though only one collisional family has been identified in that region to date, around the dwarf planet Haumea. In this paper, we combine insights into collisional families from numerical simulations with the current observational constraints on the dynamical structure of the Kuiper Belt to investigate the ideal sizes and locations for identifying collisional families. We find that larger progenitors (r {approx} 500 km) result in more easily identifiable families, given the difficulty in identifying fragments of smaller progenitors in magnitude-limited surveys, despite their larger spread and less frequent occurrence. However, even these families do not stand out well from the background. Identifying families as statistical overdensities is much easier than characterizing families by distinguishing individual members from interlopers. Such identification seems promising, provided the background population is well known. In either case, families will also be much easier to study where the background population is small, i.e., at high inclinations. Overall, our results indicate that entirely different techniques for identifying families will be needed for the Kuiper Belt, and we provide some suggestions.

  10. Specific Entropy and Radiation-Belt Electrons

    NASA Astrophysics Data System (ADS)

    Borovsky, J. E.; Cayton, T. E.; Denton, M. H.

    2011-12-01

    Specific entropy is a quantity commonly used for fluid behavior. It is shown for single-particle motion in a magnetic mirror that the specific entropy of a particle population is related to the number density of first and second adiabatic invariants per unit magnetic flux. The specific entropy is measured for two populations: the outer electron radiation belt at geosynchronous orbit and the energetic-electron population in the magnetotail. The two specific entropies are similar, arguing that the tail and geosynchronous populations are the same. This sameness implies that either (A) the tail electrons are the source population for the radiation belt or (B) that the tail electrons are leaked from the radiation belt. Examination of the temporal behaviors of the two populations will argue for case B.

  11. Distribution of Dust from Kuiper Belt Objects

    NASA Technical Reports Server (NTRS)

    Gorkavyi, Nick N.; Ozernoy, Leonid; Taidakova, Tanya; Mather, John C.; Fisher, Richard (Technical Monitor)

    2000-01-01

    Using an efficient computational approach, we have reconstructed the structure of the dust cloud in the Solar system between 0.5 and 100 AU produced by the Kuiper belt objects. Our simulations offer a 3-D physical model of the 'kuiperoidal' dust cloud based on the distribution of 280 dust particle trajectories produced by 100 known Kuiper belt objects; the resulting 3-D grid consists of 1.9 x 10' cells containing 1.2 x 10" particle positions. The following processes that influence the dust particle dynamics are taken into account: 1) gravitational scattering on the eight planets (neglecting Pluto); 2) planetary resonances; 3) radiation pressure; and 4) the Poynting-Robertson (P-R) and solar wind drags. We find the dust distribution highly non-uniform: there is a minimum in the kuiperoidal dust between Mars and Jupiter, after which both the column and number densities of kuiperoidal dust sharply increase with heliocentric distance between 5 and 10 AU, and then form a plateau between 10 and 50 AU. Between 25 and 45 AU, there is an appreciable concentration of kuiperoidal dust in the form of a broad belt of mostly resonant particles associated with Neptune. In fact, each giant planet possesses its own circumsolar dust belt consisting of both resonant and gravitationally scattered particles. As with the cometary belts simulated in our related papers, we reveal a rich and sophisticated resonant structure of the dust belts containing families of resonant peaks and gaps. An important result is that both the column and number dust density are more or less flat between 10 and 50 AU, which might explain the surprising data obtained by Pioneers 10 & 11 and Voyager that the dust number density remains approximately distance-independent in this region. The simulated kuiperoidal dust, in addition to asteroidal and cometary dust, might represent a third possible source of the zodiacal light in the Solar system.

  12. 29. Elevator no. 3: top floor, conveyor belt rollers for ...

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

    29. Elevator no. 3: top floor, conveyor belt rollers for belt to gangway (in background) connecting with elevator no. 2, facing northwest - Washburn Crosby Company Elevators No. 2 & 3, 900 & 1000 Second Avenue, South, Minneapolis, Hennepin County, MN

  13. 14 CFR 29.1413 - Safety belts: passenger warning device.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 false Safety belts: passenger warning device...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 29.1413 Safety belts: passenger warning...

  14. 14 CFR 29.1413 - Safety belts: passenger warning device.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 false Safety belts: passenger warning device...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 29.1413 Safety belts: passenger warning...

  15. 14 CFR 29.1413 - Safety belts: passenger warning device.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 false Safety belts: passenger warning device...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 29.1413 Safety belts: passenger warning...

  16. 14 CFR 29.1413 - Safety belts: passenger warning device.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 2010-01-01 false Safety belts: passenger warning device...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 29.1413 Safety belts: passenger warning...

  17. 14 CFR 29.1413 - Safety belts: passenger warning device.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2011-01-01 false Safety belts: passenger warning device...DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS...CATEGORY ROTORCRAFT Equipment Safety Equipment § 29.1413 Safety belts: passenger warning...

  18. A shell model for tyre belt vibrations

    NASA Astrophysics Data System (ADS)

    Lecomte, C.; Graham, W. R.; Dale, M.

    2010-05-01

    We present a new formulation for the prediction of tyre belt vibrations in the frequency range 0-500 Hz. Our representation includes the effects of belt width, curvature and anisotropy, and also explicitly models the tyre sidewalls. Many of the associated numerical parameters are fixed by physical considerations; the remainder require empirical input. A systematic and general approach to this problem is developed, and illustrated for the specific example of a Goodyear Wrangler tyre. The resulting predictions for the radial response to radial forcing show good correspondence with experiment up to 300 Hz, and satisfactory agreement up to 1 kHz.

  19. The Mesoproterozoic Irumide belt of Zambia

    NASA Astrophysics Data System (ADS)

    De Waele, B.; Kampunzu, A. B.; Mapani, B. S. E.; Tembo, F.

    2006-09-01

    The Mesoproterozoic Irumide belt is a northeast-trending structural province stretching from central Zambia to the Zambia-Tanzania border and northern Malawi. Mesoproterozoic and Neoproterozoic transcurrent shear zones within reactivated parts of the Palaeoproterozoic Ubendian belt define its northeastern limit. The northwestern margin is defined by the largely undeformed basement lithologies of the Bangweulu block. An intensely folded and sheared zone at the southeastern margin of the Mporokoso Group sedimentary depocentre on the Bangweulu block, interpreted to have developed above a thrust at the basement-cover interface, indicates that far-field effects of the Irumide Orogen also affected the southeastern part of the Bangweulu block sedimentary cover. To the west and southwest, Irumide and basement lithologies were reworked by the Damara-Lufilian-Zambezi Orogen within the Neoproterozoic Zambezi and Lufilian belts. The Choma-Kalomo block, previously regarded as the southwesterly continuation of the Irumide belt, is a distinct Mesoproterozoic province, while a succession of structurally juxtaposed tectonic terranes in eastern Zambia record a deformation event related to the Irumide Orogen. The lithological units identified in the Irumide belt include: (1) limited Neoarchaean rocks emplaced between 2.73 and 2.61 Ga and representing the oldest rocks in the Bangweulu block; (2) ca. 2.05-1.85 Ga volcano-plutonic complexes and gneisses representing the most important components in the Bangweulu block; (3) an extensive quartzite-metapelite succession with minor carbonate forming the Muva Supergroup, and deposited at ca. 1.85 Ga; (4) granitoids emplaced between 1.65 and 1.55 Ga; (5) a minor suite of anorogenic plutons (nepheline syenite and biotite granite) restricted to the far northeastern Irumide belt and emplaced between 1.36 and 1.33 Ga; (6) voluminous syn- to post-kinematic Irumide granitoids emplaced between 1.05 and 0.95 Ga. Crustal shortening and thickening in the Irumide belt are shown by northwestward-directed thrusts and related folds and metamorphic parageneses recording a clockwise medium-pressure/medium-temperature P- T- t path. Metamorphic grades range from greenschist facies in the foreland to the northwest to upper amphibolite facies in the southeast, with local granulites. Peak metamorphism is diachronous across the belt and bracketed between 1.05 in the southeast and 1.02 Ga in the northwest.

  20. Radiation Belt Environment model: Application to space weather nowcasting

    Microsoft Academic Search

    Mei-Ching Fok; Richard B. Horne; Nigel P. Meredith; Sarah A. Glauert

    2008-01-01

    (1) A data-driven physical model of the energetic electrons in the Earth's radiation belts, called the Radiation Belt Environment (RBE) model, has been developed to understand Earth's radiation belt dynamics and to predict the radiation conditions found there. This model calculates radiation belt electron fluxes from 10 keV to 6 MeV in the inner magnetosphere. It takes into account the

  1. Radiation Belt Environment model: Application to space weather nowcasting

    Microsoft Academic Search

    Mei-Ching Fok; Richard B. Horne; Nigel P. Meredith; Sarah A. Glauert

    2008-01-01

    A data-driven physical model of the energetic electrons in the Earth's radiation belts, called the Radiation Belt Environment (RBE) model, has been developed to understand Earth's radiation belt dynamics and to predict the radiation conditions found there. This model calculates radiation belt electron fluxes from 10 keV to 6 MeV in the inner magnetosphere. It takes into account the realistic,

  2. Techniques for applying belt dressing. Technical progress report

    Microsoft Academic Search

    Doyak

    1977-01-01

    In response to the growing number of accidents involved in applying belt dressing to increase friction coefficient, the Bureau of Mines with the assistance of the Mining Enforcement and Safety Administration has been seeking a safer method for applying belt dressing to machinery requiring belt drive. Existing procedures consist of aerosol-can and swab-type applications; both methods have proved hazardous. Between

  3. The state of knowledge concerning the Kuiper belt

    NASA Technical Reports Server (NTRS)

    Levison, Harold F.

    1992-01-01

    The arguments for and against the idea that most short-period comets originate in the Kuiper belt are discussed. Observational constraints on the distribution of mass in the Kuiper belt are reviewed as well as a model of the physical conditions that now exist. Finally, predictions from this model about the detectability of the Kuiper belt are compared to optical surveys.

  4. New Horizons mission to Pluto and the Kuiper Belt

    Microsoft Academic Search

    Andrew Cheng

    2008-01-01

    New Horizons is the first mission to the Pluto system and the Kuiper Belt [1,2]. There are currently thought to be about 1000 dwarf planets in the Kuiper Belt which may preserve essential characteristics of the planetesimals from which the giant planets originally accreted. Pluto is the brightest member of the Kuiper Belt and the first discovered (in 1930). Pluto's

  5. Seat belts and trauma: Clinical clues for the surgeon

    Microsoft Academic Search

    Jeanette M. Dolezal; Paul R. G. Cunningham

    1999-01-01

    Since their introduction over 30 years ago, seat belts have reduced the overall mortality associated with motor vehicle accidents by as much as 50%. The position and adjustment of the seat belt appear to play an important role in preventing injury. The lap portion of the belt should be kept low on the abdomen at the level of the anterior

  6. ENHANCED SEAT BELT REMINDER SYSTEMS FOR TEENAGE DRIVERS AND PASSENGERS

    Microsoft Academic Search

    Neil Lerner; Jeremiah Singer; Mark Freedman

    Summary: Failure to use a seat belt is a significant highway safety concern for teenagers. The current Federally-required seat belt reminder system is limited in its effectiveness, and many automobile manufacturers are now providing enhanced seat belt reminder (ESBR) systems. Current systems are designed for the general driving public and their design must represent a trade-off between effectiveness in promoting

  7. Colors of Kuiper Belt objects : the relationship between KBO colors and Kuiper Belt plane inclination

    E-print Network

    Kane, Julia Frances

    2006-01-01

    A large population of small, icy bodies orbits the sun just beyond Neptune, known as the Kuiper Belt. These objects, thought to be the progenitors of short period comets, could provide a sample of primordial material in ...

  8. Measurements of the Jovian radiation belts

    Microsoft Academic Search

    R. W. Fillius; C. E. McIlwain

    1974-01-01

    The University of California at San Diego trapped radiation detector measured proton and electron fluxes, angular distributions, and energy spectra throughout the Pioneer 10 flyby of Jupiter last December. Here the instrumentation and calibrations are described, and good values for particle fluxes in the inner and outer regions are presented. The major features of the Jovian radiation belts are described,

  9. Trapped radiation belts of Saturn - First look

    Microsoft Academic Search

    W. Fillius; W. H. Ip; C. E. McIlwain

    1980-01-01

    Data on the magnetosphere of Saturn obtained with the trapped radiation detector package on board the Pioneer 11 spacecraft is reported. Radiation belt profiles determined by the trapped radiation detectors on Pioneer 10 and 11 indicate that Saturn's magnetosphere is intermediate in size between those of the earth and Jupiter, with particle intensities similar to those of the earth. The

  10. The importance of exploring the asteroid belt.

    PubMed

    Papagiannis, M D

    1983-01-01

    Following life's innate tendency to expand into every available space, technological civilizations will inevitably colonize the entire galaxy establishing space habitats around all its well-behaved stars. The most reasonable place in our solar system to test this possibility is the asteroid belt, which is an ideal source of raw materials for space colonies. PMID:11541562

  11. Radiation Belts Throughout the Solar System

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.

    2008-12-01

    The several preceding decades of deep space missions have demonstrated that the generation of planetary radiation belts is a universal phenomenon. All strongly magnetized planets show well developed radiation regions, specifically Earth, Jupiter, Saturn, Uranus, and Neptune. The similarities occur despite the tremendous differences between the planets in size, levels of magnetization, external environments, and most importantly, in the fundamental processes that power them. Some planets like Jupiter are powered overwhelmingly by planetary rotation, much like astrophysical pulsars, whereas others, like Earth and probably Uranus, are powered externally by the interplanetary environment. Uranus is a particularly interesting case in that despite the peculiarities engendered by its ecliptic equatorial spin axis orientation, its magnetosphere shows dynamical behavior similar to that of Earth as well as radiation belt populations and associated wave emissions that are perhaps more intense than expected based on Earth-derived theories. Here I review the similarities and differences between the radiation regions of radiation belts throughout the solar system. I discuss the value of the comparative approach to radiation belt physics as one that allows critical factors to be evaluated in environments that are divorced from the special complex conditions that prevail in any one environment, such as those at Earth.

  12. School Buses & Seat Belts: A Discussion.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau.

    Safety belts are not installed in school buses for several reasons. School buses are constructed differently from automobiles in terms of (1) the locations of doors and instrument panels relative to passengers, (2) outer construction, (3) seat design and padding, and (4) visibility on the road. Under current regulations, bus seats are constructed…

  13. 5, 1072310745, 2005 Antarctic NAT belt

    E-print Network

    Paris-Sud XI, Université de

    Sounding (MIPAS) reveal the formation of a belt of polar strato- spheric clouds (PSCs) of nitric acid nitric acid containing particles (likely nitric acid trihydrate, NAT) that, via sedimentation, are now generally believed to be the major cause of denitrification. However, the nucleation processes of nitric

  14. Reference Governors for Controlled Belt Restraint Systems

    Microsoft Academic Search

    E. P. van der Laan; H. J. C. Luijten; W. P. M. H. Heemels; F. E. Veldpaus; M. Steinbuch

    2009-01-01

    This paper presents a novel control strategy for real-time controlled restraint systems. Today's restraint systems typically include a number of airbags, and a three-point seat belt with load limiter and pretensioner. In the class of real- time controlled restraint systems, the restraint actuator settings are continuously manipulated during the crash. The control strategy developed here is based on reference management,

  15. Reference governors for controlled belt restraint systems

    Microsoft Academic Search

    E. P. van der Laan; H. J. C. Luijten; W. P. M. Heemels; F. E. Veldpaus; M. Steinbuch

    2008-01-01

    This paper presents a novel control strategy for real-time controlled restraint systems. Todaypsilas restraint systems typically include a number of airbags, and a three-point seat belt with load limiter and pretensioner. In the class of realtime controlled restraint systems, the restraint actuator settings are continuously manipulated during the crash. The control strategy developed here is based on reference management, in

  16. Research on an Active Seat Belt System

    NASA Astrophysics Data System (ADS)

    Kawashima, Takeshi

    In a car crash, permanent injury can be avoided if deformation of an occupant's rib cage is maintained within the allowable value. In order to realize this condition, the occupant's seat belt tension must be instantaneously adjusted by a feedback control system. In this study, a seat belt tension control system based on the active shock control system is proposed. The semi-active control law used is derived from the sliding mode control method. One advantage of this proposed system is that it does not require a large power actuator because the seat belt tension is controlled by a brake mechanism. The effectiveness is confirmed by numerical simulation using general parameters of a human thorax and a passenger car in a collision scenario with a wall at a velocity of 100 km/h. The feasibility is then confirmed with a control experiment using a scale model of about 1/10 scale. The relative displacement of the thorax model approaches the allowable value smoothly along the control reference and settles near this value. Thus, the proposed seat belt tension control system design is established.

  17. VERO cells harbor a poly-ADP-ribose belt partnering their epithelial adhesion belt.

    PubMed

    Lafon-Hughes, Laura; Vilchez Larrea, Salomé C; Kun, Alejandra; Fernández Villamil, Silvia H

    2014-01-01

    Poly-ADP-ribose (PAR) is a polymer of up to 400 ADP-ribose units synthesized by poly-ADP-ribose-polymerases (PARPs) and degraded by poly-ADP-ribose-glycohydrolase (PARG). Nuclear PAR modulates chromatin compaction, affecting nuclear functions (gene expression, DNA repair). Diverse defined PARP cytoplasmic allocation patterns contrast with the yet still imprecise PAR distribution and still unclear functions. Based on previous evidence from other models, we hypothesized that PAR could be present in epithelial cells where cadherin-based adherens junctions are linked with the actin cytoskeleton (constituting the adhesion belt). In the present work, we have examined through immunofluorescence and confocal microscopy, the subcellular localization of PAR in an epithelial monkey kidney cell line (VERO). PAR was distinguished colocalizing with actin and vinculin in the epithelial belt, a location that has not been previously reported. Actin filaments disruption with cytochalasin D was paralleled by PAR belt disruption. Conversely, PARP inhibitors 3-aminobenzamide, PJ34 or XAV 939, affected PAR belt synthesis, actin distribution, cell shape and adhesion. Extracellular calcium chelation displayed similar effects. Our results demonstrate the existence of PAR in a novel subcellular localization. An initial interpretation of all the available evidence points towards TNKS-1 as the most probable PAR belt architect, although TNKS-2 involvement cannot be discarded. Forthcoming research will test this hypothesis as well as explore the existence of the PAR belt in other epithelial cells and deepen into its functional implications. PMID:25332845

  18. VERO cells harbor a poly-ADP-ribose belt partnering their epithelial adhesion belt

    PubMed Central

    Vilchez Larrea, Salomé C.; Kun, Alejandra

    2014-01-01

    Poly-ADP-ribose (PAR) is a polymer of up to 400 ADP-ribose units synthesized by poly-ADP-ribose-polymerases (PARPs) and degraded by poly-ADP-ribose-glycohydrolase (PARG). Nuclear PAR modulates chromatin compaction, affecting nuclear functions (gene expression, DNA repair). Diverse defined PARP cytoplasmic allocation patterns contrast with the yet still imprecise PAR distribution and still unclear functions. Based on previous evidence from other models, we hypothesized that PAR could be present in epithelial cells where cadherin-based adherens junctions are linked with the actin cytoskeleton (constituting the adhesion belt). In the present work, we have examined through immunofluorescence and confocal microscopy, the subcellular localization of PAR in an epithelial monkey kidney cell line (VERO). PAR was distinguished colocalizing with actin and vinculin in the epithelial belt, a location that has not been previously reported. Actin filaments disruption with cytochalasin D was paralleled by PAR belt disruption. Conversely, PARP inhibitors 3-aminobenzamide, PJ34 or XAV 939, affected PAR belt synthesis, actin distribution, cell shape and adhesion. Extracellular calcium chelation displayed similar effects. Our results demonstrate the existence of PAR in a novel subcellular localization. An initial interpretation of all the available evidence points towards TNKS-1 as the most probable PAR belt architect, although TNKS-2 involvement cannot be discarded. Forthcoming research will test this hypothesis as well as explore the existence of the PAR belt in other epithelial cells and deepen into its functional implications. PMID:25332845

  19. A deep survey of the Kuiper belt

    NASA Astrophysics Data System (ADS)

    Allen, Rhiannon Lynne

    The Kuiper belt, the population of small icy planetesimals orbiting the Sun beyond Neptune, offers an exciting new avenue for studying the formation and evolution of the Solar System. Over 500 Kuiper belt objects (KBOs) have been detected in the decade since the first KBO was discovered. Almost all of these have been discovered within 50 AU of the Sun, despite surveys sensitive enough to detect objects beyond 60 AU. This lack of distant KBOs contradicts the current model of the Kuiper belt, which predicts a dynamically cold and primordially dense population of KBOs beyond 50 AU. We have conducted a deep survey (R ˜ 25) for KBOs over a total of 2.3 deg2. In order to reach these faint limiting magnitudes for moving objects, we have developed software to rapidly shift and add a series of images at all potential KBO motion vectors. R = 25 is faint enough to detect KBOs of diameter D ? 200 km at a distance of 60 AU. Our survey discovered 34 objects; none of these objects, however, is beyond 53 AU. The first group of fields observed in this survey, with the deepest limiting magnitudes, find the mean volume density of D > 160 km KBOs in the 55 65 AU region is (at the >95% confidence level) lower than the mean density in the 30 50 AU region, and at most ? of the mean density from 40 50 AU, if the distant Kuiper belt is of similar vertical dispersion as the classical KBOs. One theory proposed to explain the observed absence of KBOs beyond 50 AU suggests the outer Kuiper belt is in an extremely cold, primordial dynamical state, visible only as a very thin disk which could have slipped between previous deep survey fields. The second stage of our survey was designed to search the most likely locations for this thin disk. We find that we can exclude the existence of a distant disk thinner than ? = 1°.75 , inclined by i ? 1° to the invariable plane and containing more than 1.2 times as many D > 185 km KBOs between 50 and 60 AU as the observed inner Kuiper belt at the 95% CL.

  20. Persistence of Salmonella on egg conveyor belts is dependent on the belt type but not on the rdar morphotype.

    PubMed

    Stocki, S L; Annett, C B; Sibley, C D; McLaws, M; Checkley, S L; Singh, N; Surette, M G; White, A P

    2007-11-01

    Commercial caged layer flocks in Alberta, Canada, are commonly monitored for Salmonella enterica serovar Enteritidis (SE) and S. enterica serovar Typhimurium (ST) by environmental sampling. In one recent case, a SE strain isolated from the egg conveyor belt was a source of persistent infection for the flock. This study was undertaken to examine Salmonella colonization on egg conveyor belts and to determine whether the rdar morphotype, a conserved physiology associated with aggregation and long-term survival, contributed to persistence. Four woven belts constructed of natural or nonnatural fibers and a 1-piece belt made of vinyl were tested with rdar-positive ST and SE strains and a rdar-negative ST DeltaagfD reference strain. The type of egg belt was the most important factor influencing Salmonella colonization and persistence. The vinyl belt, with the least surface area available for colonization, had the fewest Salmonella remaining after washing and disinfection, whereas the hemp-plastic belt, with the greatest surface area, had the most Salmonella remaining. Real-time gene expression indicated that the rdar morphotype was involved in colonizing the egg belt pieces; however, it was not essential for persistence. In addition, rdar-positive and rdar-negative strains were equally similarly to disinfection on the egg belt pieces. The results indicate that Salmonella can persist on a variety of egg belts by mechanisms other than the rdar morphotype, and that using egg conveyer belts with reduced surface area for bacterial colonization can lessen contamination problems. PMID:17954588

  1. Geological Processes on Kuiper Belt Objects

    E-print Network

    Shumway, John

    Naval Observatory M = 1.52 x 1021 kg, R = 603 km, = 1.65 g cm-3 Synthetic map by Marc Buie Charon #12;What is the Kuiper Belt? Stern et al. (2005) HST Nix & Hydra Charon: diameter 603 km orbits in 6.3872 days = 1 Charon orbit Nix: diameter 50-140 km orbits in 24.856 days = 3.89 4 Charon orbits Hydra

  2. Compositional structure of the asteroid belt

    Microsoft Academic Search

    J. Gradie; E. Tedesco

    1982-01-01

    A variety of observations, mainly albedos derived from 10 and 20 micron radiometry and eight-filter broadband spectrophotometry, were used to show that the asteroid belt is highly structured in composition. The bias-corrected distribution from 1.8 to 5.2 A.U. of the previously defined compositional types C,S,E,R, and M, plus type D and the newly described types F and P, are reported

  3. Early Archaean collapse basins, a habitat for early bacterial life.

    NASA Astrophysics Data System (ADS)

    Nijman, W.

    For a better definition of the sedimentary environment in which early life may have flourished during the early Archaean, understanding of the basin geometry in terms of shape, depth, and fill is a prerequisite. The basin fill is the easiest to approach, namely from the well exposed, low-grade metamorphic 3.4 - 3.5 Ga rock successions in the greenstone belts of the east Pilbara (Coppin Gap Greenstone Belt and North Pole Dome) in West Australia and of the Barberton Greenstone Belt (Buck Ridge volcano-sedimentary complex) in South Africa. They consist of mafic to ultramafic volcanic rocks, largely pillow basalts, with distinct intercalations of intermediate to felsic intrusive and volcanic rocks and of silicious sediments. The, partly volcaniclastic, silicious sediments of the Buck Ridge and North Pole volcano-sedimentary complexes form a regressive-transgressive sequence. They were deposited close to base level, and experienced occasional emersion. Both North Pole Chert and the chert of the Kittys Gap volcano-sedimentary complex in the Coppin Gap Greenstone Belt preserve the flat-and-channel architecture of a shallow tidal environment. Thickness and facies distribution appear to be genetically linked to systems, i.e. arrays, of syn-depositionally active, extensional faults. Structures at the rear, front and bottoms of these fault arrays, and the fault vergence from the basin margin towards the centre characterize the basins as due to surficial crustal collapse. Observations in the Pilbara craton point to a non-linear plan view and persistence for the basin-defining fault patterns over up to 50 Ma, during which several of these fault arrays became superposed. The faults linked high-crustal level felsic intrusions within the overall mafic rock suite via porphyry pipes, black chert veins and inferred hydrothermal circulations with the overlying felsic lavas, and more importantly, with the cherty sediments. Where such veins surfaced, high-energy breccias, and in the case of the North Pole Chert huge barite growths, are juxtaposed with the otherwise generally low-energy sediments. Such localities are interpreted as sites of hydrothermal vents. Within this large-scale geological context, many environments on the micro-scale were habitable for life, such as hydrothermal vents and their vicinities, volcanic rock surfaces, subsurface sediments and sediment surfaces. These early collapse basins, hosting this bacterial life, are only partially comparable to Earthly analogues. A resemblance with Venus' coronae and the chaos terranes on Mars is suggested. This study forms part of an international project on Earth's Earliest Sedimentary Basins, supported by the Dutch Foundation Dr. Schürmannfonds. 2

  4. Radiation Belt Loss at the Magnetopause

    NASA Astrophysics Data System (ADS)

    Onsager, T. G.; Green, J. C.; Singer, H. J.; Reeves, G. D.; Bourdarie, S.

    2005-12-01

    A critical factor controlling the dynamics of the outer electron radiation belt is the abrupt electron loss from the magnetosphere that frequently occurs. Although the major loss mechanisms are known to be transport out across the magnetopause and precipitation into the atmosphere, it is not known quantitatively how effective either of these mechanisms is under any set of circumstances. It is thought that a compression of the magnetopause should cause a reduction of the electron fluxes at the larger L shells, but it is not known what the magnitude of the flux reduction should be. In this study, we investigate the depletion of radiation belt electron flux associated with the compression of the magnetopause to inside geosynchronous orbit. Multiple geosynchronous satellites are used to determine the local-time dependence of the flux dropouts. A clear local-time dependence is observed as the flux decreases during the earthward compression of the magnetopause and during the recovery of the flux as the magnetopause expands back outward. Surprisingly, the flux recovers immediately to levels moderately below the original flux levels with the relaxation of the magnetopause to outside geosynchronous orbit. These results are used to quantify the loss of radiation belt electrons due to the inward motion of the magnetopause and the subsequent recovery.

  5. The Size Distribution of Kuiper Belt Objects

    E-print Network

    Scott J. Kenyon; Benjamin C. Bromley

    2004-06-24

    We describe analytical and numerical collisional evolution calculations for the size distribution of icy bodies in the Kuiper Belt. For a wide range of bulk properties, initial masses, and orbital parameters, our results yield power-law cumulative size distributions, N_C propto r^{-q}, with q_L = 3.5 for large bodies with radii of 10-100 km, and q_s = 2.5-3 for small bodies with radii lesss than 0.1-1 km. The transition between the two power laws occurs at a break radius of 1-30 km. The break radius is more sensitive to the initial mass in the Kuiper Belt and the amount of stirring by Neptune than the bulk properties of individual Kuiper Belt objects (KBOs). Comparisons with observations indicate that most models can explain the observed sky surface density of KBOs for red magnitudes, R = 22-27. For R 28, the model surface density is sensitive to the amount of stirring by Neptune, suggesting that the size distribution of icy planets in the outer solar system provides independent constraints on the formation of Neptune.

  6. CHAOTIC DIFFUSION OF RESONANT KUIPER BELT OBJECTS

    SciTech Connect

    Tiscareno, Matthew S. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Malhotra, Renu [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)], E-mail: matthewt@astro.cornell.edu

    2009-09-15

    We carried out extensive numerical orbit integrations to probe the long-term chaotic dynamics of the two strongest mean-motion resonances of Neptune in the Kuiper Belt, the 3:2 (Plutinos) and 2:1 (Twotinos). Our primary results include a computation of the relative volumes of phase space characterized by large- and small-resonance libration amplitudes, and maps of resonance stability measured by mean chaotic diffusion rate. We find that Neptune's 2:1 resonance has weaker overall long-term stability than the 3:2-only {approx}15% of Twotinos are projected to survive for 4 Gyr, compared to {approx}27% of Plutinos, based on an extrapolation from our 1-Gyr integrations. We find that Pluto has only a modest effect, causing a {approx}4% decrease in the Plutino population that survives to 4 Gyr. Given current observational estimates, and assuming an initial distribution of particles proportional to the local phase-space volume in the resonance, we conclude that the primordial populations of Plutinos and Twotinos formerly made up more than half the population of the classical and resonant Kuiper Belt. We also conclude that Twotinos were originally nearly as numerous as Plutinos; this is consistent with predictions from early models of smooth giant planet migration and resonance sweeping of the Kuiper Belt and provides a useful constraint for more detailed models.

  7. Compositional variations in the Mesoarchean chromites of the Nuggihalli schist belt, Western Dharwar Craton (India): potential parental melts and implications for tectonic setting

    NASA Astrophysics Data System (ADS)

    Mukherjee, Ria; Mondal, Sisir K.; Rosing, Minik T.; Frei, Robert

    2010-12-01

    The chromite deposits in the Archean Nuggihalli schist belt are part of a layered ultramafic-mafic sequence within the Western Dharwar Craton of the Indian shield. The 3.1-Ga ultramafic-mafic units occur as sill-like intrusions within the volcano-sedimentary sequences of the Nuggihalli greenstone belt that are surrounded by the tonalite-trondhjemite-granodiorite (TTG) suite of rocks. The entire succession is exposed in the Tagdur mining district. The succession has been divided into the lower and the upper ultramafic units, separated by a middle gabbro unit. The ultramafic units comprise of deformed massive chromitite bodies that are hosted within chromite-bearing serpentinites. The chromitite bodies occur in the form of pods and elongated lenses (~60-500 m by ~15 m). Detailed electron microprobe studies reveal intense compositional variability of the chromite grains in silicate-rich chromitite (~50% modal chromite) and serpentinite (~2% modal chromite) throughout the entire ultramafic sequence. However, the primary composition of chromite is preserved in the massive chromitites (~60-75% modal chromite) from the Byrapur and the Bhaktarhalli mining district of the Nuggihalli schist belt. These are characterized by high Cr-ratios (Cr/(Cr + Al) = 0.78-0.86) and moderate Mg-ratios (Mg/(Mg + Fe2+) = 0.38-0.58). The compositional variability occurs due to sub-solidus re-equilibration in the accessory chromite in the serpentinite (Mg-ratio = 0.01-0.38; Cr-ratio = 0.02-0.99) and in silicate-rich chromitite (Mg-ratio = 0.06-0.48; Cr-ratio = 0.60-0.99). In the massive chromitites, the sub-solidus re-equilibration for chromite is less or absent. However, the re-equilibration is prominent in the co-existing interstitial and included olivine (Fo96-98) and pyroxene grains (Mg-numbers = 97-99). Compositional variability on the scale of a single chromite grain occurs in the form of zoning, and it is common in the accessory chromite grains in serpentinite and in the altered grains in chromitite. In the zoned grains, the composition of the core is modified and the rim is ferritchromit. In general, ferritchromit occurs as irregular patches along the grain boundaries and fractures of the zoned grains. In this case, ferritchromit formation is not very extensive. This indicates a secondary low temperature hydrothermal origin of ferritchromit during serpentinization. In some occurrences, the ferritchromit rim is very well developed, and only a small relict core appears to remain in the chromite grain. However, complete alteration of the chromite grains to ferritchromit without any remnant core is also present. The regular, well-developed and continuous occurrence of ferritchromit rims around the chromite grain boundaries, the complete alteration of the chromite grains and the modification of the core composition indicate the alteration in the Nuggihalli schist belt to be intense, pervasive and affected by later low-grade metamorphism. The primary composition of chromite has been used to compute the nature of the parental melt. The parental melt calculations indicate derivation from a high-Mg komatiitic basalt that is similar to the composition of the komatiitic rocks reported from the greenstone sequences of the Western Dharwar Craton. Tectonic discrimination diagrams using the primary composition of chromites indicate a supra-subduction zone setting (SSZ) for the Archean chromitites of Nuggihalli and derivation from a boninitic magma. The composition of the komatiitic basalts resembles those of boninites that occur in subduction zones and back-arc rift settings. Formation of the massive chromitites in Nuggihalli may be due to magma mixing process involving hydrous high-Mg magmas or may be related to intrusions of chromite crystal laden magma; however, there is little scope to test these models because the host rocks are highly altered, serpentinized and deformed. The present configurations of the chromitite bodies are related to the multistage deformation processes that are common in Archean greenstone belts.

  8. Radiation Belts of Antiparticles in Planetary Magnetospheres

    NASA Astrophysics Data System (ADS)

    Pugacheva, G. I.; Gusev, A. A.; Jayanthi, U. B.; Martin, I. M.; Spjeldvik, W. N.

    2007-05-01

    The Earth's radiation belts could be populated, besides with electrons and protons, also by antiparticles, such as positrons (Basilova et al., 1982) and antiprotons (pbar). Positrons are born in the decay of pions that are directly produced in nuclear reactions of trapped relativistic inner zone protons with the residual atmosphere at altitudes in the range of about 500 to 3000 km over the Earth's surface. Antiprotons are born by high energy (E > 6 GeV) cosmic rays in p+p - p+p+p+ pbar and in p+p - p+p+n+nbar reactions. The trapping and storage of these charged anti-particles in the magnetosphere result in radiation belts similar to the classical Van Allen belts of protons and electrons. We describe the mathematical techniques used for numerical simulation of the trapped positron and antiproton belt fluxes. The pion and antiproton yields were simulated on the basis of the Russian nuclear reaction computer code MSDM, a Multy Stage Dynamical Model, Monte Carlo code, (i.e., Dementyev and Sobolevsky, 1999). For estimates of positron flux there we have accounted for ionisation, bremsstrahlung, and synchrotron energy losses. The resulting numerical estimates show that the positron flux with energy >100 MeV trapped into the radiation belt at L=1.2 is of the order ~1000 m-2 s-1 sr-1, and that it is very sensitive to the shape of the trapped proton spectrum. This confined positron flux is found to be greater than that albedo, not trapped, mixed electron/positron flux of about 50 m-2 s-1 sr-1 produced by CR in the same region at the top of the geomagnetic field line at L=1.2. As we show in report, this albedo flux also consists mostly of positrons. The trapped antiproton fluxes produced by CR in the Earth's upper rarified atmosphere were calculated in the energy range from 10 MeV to several GeV. In the simulations we included a mathematic consideration of the radial diffusion process, both an inner and an outer antiproton source, losses of particles due to ionization process, annihilation, and nuclear interactions with the ambient matter. We have found that the Earth's antiproton belt possesses about 6-60 times larger antiproton fluxes compared to the galactic fluxes in interplanetary space during minimum and maximum solar activity at all energies in confinement zone. The radiation belt antiproton fluxes are spread into a wider L-shell range than its generation location around L=1.2. This is due to diffusion processes, and it demonstrates that radial diffusion as a relatively significant process for antimatter, even in the inner magnetosphere. Antimatter accumulated in the magnetospheres of solar system bodies may be of significance for space travel. It could be used as a propulsion for space missions to the outer planets and beyond. Antimatter has an energy density more than ten orders of magnitude higher than the best chemical propellants currently used in rocket systems. References: Basilova, R. N., A.A. Gusev, G.I. Pugacheva , Geom. and Aeronom. V. 22, p. 671-673, 1982.Chen, J., T. Dementyev, A.V., Sobolevsky, N.M. Radiation Measurements, 30, 553, 1999.

  9. Car safety belts: a study of two models adapted for people with arthritis.

    PubMed

    Arie, E

    1986-05-01

    People with arthritis find car seat belts difficult to use. Sixteen arthritic patients and 19 healthy volunteers completed a comparative study of one standard inertia-reel belt and two adapted inertia-reel belts with reduced retraction forces. Those with arthritis were strong enough to use the standard belt but both adapted belts had features making them easier to use. PMID:3708235

  10. Jupiters radiation belts and their effects on spacecraft

    NASA Technical Reports Server (NTRS)

    Parker, R. H.; Divita, E. L.; Gigas, G.

    1974-01-01

    The effects of electron and proton radiation on spacecraft which will operate in the trapped radiation belts of the planet Jupiter are described, and the techniques and results of the testing and simulation used in the radiation effects program are discussed. Available data from the Pioneer 10 encounter of Jupiter are compared with pre-encounter models of the Jupiter radiation belts. The implications that the measured Jovian radiation belts have for future missions are considered.

  11. State of the art in radiation belt research

    NASA Astrophysics Data System (ADS)

    Summers, Danny; Mann, Ian R.; Baker, Daniel N.

    2011-12-01

    AGU Chapman Conference on Dynamics of the Earth's Radiation Belts and Inner Magnetosphere; St. John's, Newfoundland and Labrador, Canada, 17-22 July 2011 Earth's radiation belts were discovered by James Van Allen and colleagues in 1958 using data from the Explorer I satellite. Since then, the Van Allen belts have been under extensive theoretical and experimental investigation. Because highly energetic (relativistic) electrons generated in the outer radiation zone during geomagnetically disturbed times can damage orbiting satellites, Earth's radiation belts are regarded as a serious space weather hazard. The emerging science of space weather has fueled a resurgence of interest in radiation belt physics in the past 10 years. This will culminate in 2012 with the launch of NASA's Radiation Belt Storm Probes (RBSP) twin satellite mission, which will make in situ measurements of the radiation belts. Shortly after 2012 are also planned launches of the Japanese Energization and Radiation in Geospace (ERG) satellite and the Russian mission RESONANCE, both designed to probe Earth's radiation belts. Thus, 2012-2013 promises to be an exciting and pivotal period in radiation belt science.

  12. The Discovery and Early History of the Earth's Radiation Belts

    NSDL National Science Digital Library

    Stern, David P. (David Peter), 1931-

    The first of 6 linked web pages, authored and curated by David P. Stern, on how the inner radiation belt was discovered in 1958 by Van Allen, on the type of instrument used (Geiger counter), on the belt's explanation based on neutron albedo, on radiation belts created by nuclear bombs and on the discovery of the outer belt. Nonmathematical and short; a longer exposition (with references) is in file bh2_1.html of the same collection. A Spanish translation for all of these resources is available.

  13. COLORS OF INNER DISK CLASSICAL KUIPER BELT OBJECTS

    SciTech Connect

    Romanishin, W. [Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Tegler, S. C. [Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ 86011 (United States); Consolmagno, G. J., E-mail: wromanishin@ou.ed, E-mail: Stephen.Tegler@nau.ed, E-mail: gjc@specola.v [Vatican Observatory, Specola Vaticana, V-00120 (Vatican City State, Holy See)

    2010-07-15

    We present new optical broadband colors, obtained with the Keck 1 and Vatican Advanced Technology telescopes, for six objects in the inner classical Kuiper Belt. Objects in the inner classical Kuiper Belt are of interest as they may represent the surviving members of the primordial Kuiper Belt that formed interior to the current position of the 3:2 resonance with Neptune, the current position of the plutinos, or, alternatively, they may be objects formed at a different heliocentric distance that were then moved to their present locations. The six new colors, combined with four previously published, show that the ten inner belt objects with known colors form a neutral clump and a reddish clump in B-R color. Nonparametric statistical tests show no significant difference between the B-R color distribution of the inner disk objects compared to the color distributions of Centaurs, plutinos, or scattered disk objects. However, the B-R color distribution of the inner classical Kuiper Belt Objects does differ significantly from the distribution of colors in the cold (low inclination) main classical Kuiper Belt. The cold main classical objects are predominately red, while the inner classical belt objects are a mixture of neutral and red. The color difference may reveal the existence of a gradient in the composition and/or surface processing history in the primordial Kuiper Belt, or indicate that the inner disk objects are not dynamically analogous to the cold main classical belt objects.

  14. Three-dimensional modeling of the radiation belts using the Versatile Electron Radiation Belt (VERB) code

    Microsoft Academic Search

    D. A. Subbotin; Y. Y. Shprits

    2009-01-01

    Relativistic electrons are hazardous for satellites and humans in space. In this study, we present a detailed description of the Versatile Electron Radiation Belt (VERB) code. The computationally efficient methods described in this report make the VERB code a useful tool for space weather forecasting and nowcasting of the relativistic electron environment. The computational efficiency of the code makes it

  15. Anatomy of an intracratonic fold belt: Examples from the southwestern Palmyride fold belt in central Syria

    SciTech Connect

    Chaimov, T.A.; Barazangi, M.; Best, J.A. (Cornell Univ., Ithaca, NY (United States)); Al-Saad, D.; Sawaf, T.; Gebran, A. (Syrian Petroleum Co., Damascus (Syria))

    1991-03-01

    The Palmyride fold belt, a 400 {times} 100 km, NE-trending, transpressive belt in central Syria, represents the late Mesozoic and Cenozoic inversion of a linear intracratonic basin. The southwestern Palmyrides are characterized by short wavelength (2-5 km) folds separated by small intermontane basins. To elucidate the subsurface structure, a three-dimensional model, based mainly on about 450 km of two-dimensional seismic reflection data, was generated using a LandMark{reg sign} graphics workstation. The new model includes many features not identified in outcrop. Short, NW-trending transcurrent, or transfer, faults link the short, en echelon NE-trending thrust faults and blind thrusts of the Palmyrides. Varying structural styles are observed within the southwestern part of the belt. In one instance the structure of Mesozoic and Cenozoic rocks mimics that in deeper Paleozoic rocks; elsewhere, a strong discordance between Paleozoic and Mesozoic rocks appears to be related to the development of a regional detachment in Triassic rocks at about 4 km depth. Shortening the southwestern palmyrides totals about 20-25 km, based on palinspastic restoration of a balanced cross section across the belt. Seismic stratigraphy constrains the timing of at least three distinct episodes of Palmyride shortening: Late Cretaceous, middle Eocene, and Miocene to present. All three episodes were penecontemporaneous with specific tectonic events along the northern Arabian plate boundaries.

  16. The Overthrust Belt of Western North America

    SciTech Connect

    Verrall, P.

    1993-02-01

    The Overthrust Belt extends for 5000 mi (8000 km) from the Brooks Range in Alaska to the Sierra Madre Oriental in Mexico. It consists of northeastward vergent thrust and fold structures involving late Precambrian to early Tertiary sedimentary section. These sediments represent deposition off the western rift margin, formed in late Precambrian time, of the North American Precambrian craton. The northeastward thrusting continued throughout the Mesozoic as a response to the convergence of the East Pacific Plate with the North American Plate. This convergence resulted in subduction beneath the North American Plate except at the northwest end (the Brooks Range) where the result was obduction. Convergence ceased when the west edge of the East Pacific Plate reached the subduction zone. The sedimentary section involved in the Thrust Belt contains good Devonian to Cretaceous hydrocarbon source rocks, and Ordovician to traps related to the thrusting (simple thrust sheets, imbricate thrust sheets, folded thrust sheets, step anticlines, footwall cutoffs, footwall anticlines, etc.). Field methods involved in exploration for hydrocarbons include field geological mapping, remote sensing (aerial photography and Landsat imagery), various seismic refraction and seismic reflection techniques (including modern detailed three dimension surveys) and potential field methods such as gravity and magnetic surveying. Studies of the field data include paleontology, source rock and hydrocarbon migration studies, structural and stratigraphic analyses, and the processing of geophysical data. This work has succeeded in two major areas: the Western Canadian Rocky Mountain Foothills, a major gas province producing mainly from Paleozoic reservoirs; and the Wyoming-Idaho-Utah portion of the thrust belt, also a major gas producer from Paleozoic reservoirs and, in addition, a major oil producer from the Jurassic Nugget Sandstone.

  17. 14 CFR 29.785 - Seats, berths, litters, safety belts, and harnesses.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Seats, berths, litters, safety belts, and harnesses. 29.785 Section 29.785 Aeronautics...Seats, berths, litters, safety belts, and harnesses. (a) Each seat, safety belt, harness, and adjacent part of the...

  18. 14 CFR 27.785 - Seats, berths, litters, safety belts, and harnesses.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Seats, berths, litters, safety belts, and harnesses. 27.785 Section 27.785 Aeronautics...Seats, berths, litters, safety belts, and harnesses. (a) Each seat, safety belt, harness, and adjacent part of the...

  19. 14 CFR 27.785 - Seats, berths, litters, safety belts, and harnesses.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Seats, berths, litters, safety belts, and harnesses. 27.785 Section 27.785 Aeronautics...Seats, berths, litters, safety belts, and harnesses. (a) Each seat, safety belt, harness, and adjacent part of the...

  20. 14 CFR 29.785 - Seats, berths, litters, safety belts, and harnesses.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Seats, berths, litters, safety belts, and harnesses. 29.785 Section 29.785 Aeronautics...Seats, berths, litters, safety belts, and harnesses. (a) Each seat, safety belt, harness, and adjacent part of the...

  1. 14 CFR 29.785 - Seats, berths, litters, safety belts, and harnesses.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Seats, berths, litters, safety belts, and harnesses. 29.785 Section 29.785 Aeronautics...Seats, berths, litters, safety belts, and harnesses. (a) Each seat, safety belt, harness, and adjacent part of the...

  2. 14 CFR 27.785 - Seats, berths, litters, safety belts, and harnesses.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Seats, berths, litters, safety belts, and harnesses. 27.785 Section 27.785 Aeronautics...Seats, berths, litters, safety belts, and harnesses. (a) Each seat, safety belt, harness, and adjacent part of the...

  3. 14 CFR 27.785 - Seats, berths, litters, safety belts, and harnesses.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Seats, berths, litters, safety belts, and harnesses. 27.785 Section 27.785 Aeronautics...Seats, berths, litters, safety belts, and harnesses. (a) Each seat, safety belt, harness, and adjacent part of the...

  4. Aircraft radial-belted tire evaluation

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Stubbs, Sandy M.; Davis, Pamela A.

    1990-01-01

    An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.

  5. Water activities in the Kerala Khondalite Belt

    NASA Technical Reports Server (NTRS)

    Chacko, Thomas; Kumar, G. R. Ravindra; Peterson, J. W.

    1988-01-01

    The author and colleagues presented their determinations of water activities in various granulite-facies rocks of the Kerala Khondalite Belt. Using mineral equilibria, thermodynamic data, and assumed geopressure-geotemperature conditions of 5.5 kbar and 750 C, they calculated uniformly low a(H2O) values of about 0.27 over a large geographic region. They suggested that these conditions were produced by the presence of abundant CO2-rich fluids, derived either from deeper levels or from metamorphic reactions involving graphite.

  6. Inner main belt asteroids in Slivan states?

    NASA Astrophysics Data System (ADS)

    Vraštil, J.; Vokrouhlický, D.

    2015-07-01

    Context. The spin state of ten asteroids in the Koronis family has previously been determined. Surprisingly, all four asteroids with prograde rotation were shown to have spin axes nearly parallel in the inertial space. All asteroids with retrograde rotation had large obliquities and rotation periods that were either short or long. The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect has been demonstrated to be able to explain all these peculiar facts. In particular, the effect causes the spin axes of the prograde rotators to be captured in a secular spin-orbit resonance known as Cassini state 2, a configuration dubbed "Slivan state". Aims: It has been proposed based on an analysis of a sample of asteroids in the Flora family that Slivan states might also exist in this region of the main belt. This is surprising because convergence of the proper frequency s and the planetary frequency s6 was assumed to prevent Slivan states in this zone. We therefore investigated the possibility of a long-term stable capture in the Slivan state in the inner part of the main belt and among the asteroids previously observed. Methods: We used the swift integrator to determine the orbital evolution of selected asteroids in the inner part of the main belt. We also implemented our own secular spin propagator into the swift code to efficiently analyze their spin evolution. Results: Our experiments show that the previously suggested Slivan states of the Flora-region asteroids are marginally stable for only a small range of the flattening parameter ?. Either the observed spins are close to the Slivan state by chance, or additional dynamical effects that were so far not taken into account change their evolution. We find that only the asteroids with very low-inclination orbits (lower than ?4°, for instance) could follow a similar evolution path as the Koronis members and be captured in their spin state into the Slivan state. A greater number of asteroids in the inner main-belt Massalia family, which are at a slightly larger heliocentric distance and at lower inclination orbits than in the Flora region, may have their spin in the Slivan state.

  7. Effects of driver characteristics on seat belt fit.

    PubMed

    Reed, Matthew P; Ebert, Sheila M; Hallman, Jason J

    2013-11-01

    A laboratory study of posture and belt fit was conducted with 46 men and 51 women, 61% of whom were age 60 years or older and 32% age 70 years or older. In addition, 28% of the 97 participants were obese, defined as body mass index ? 30 kg/m^2. A mockup of a passenger vehicle driver's station was created and five belt anchorage configurations were produced by moving the buckle, outboard-upper (D-ring), and outboard-lower anchorages. An investigator recorded the three-dimensional locations of landmarks on the belt and the participant's body using a coordinate measurement machine. The location of the belt with respect to the underlying skeletal structures was analyzed, along with the length of belt webbing. Using linear regression models, an increase in age from 20 to 80 years resulted in the lap belt positioned 18 mm further forward relative to the pelvis, 26 mm greater lap belt webbing length, and 19 mm greater shoulder belt length. An increase in stature of 350 mm (approximately the range from 5th-percentile female to 95th-percentile male in the U.S. population) was associated with the lap belt 14 mm further forward relative to the pelvis, the shoulder belt 37 mm more outboard relative to the body centerline, and 38 mm less shoulder belt webbing length. Among the driver factors considered, body mass index had the greatest effects. An increase of BMI in 20 kg/m^2, which spans approximately the central 90% of U.S. adults, was associated with the lap belt being placed 102 mm further forward and 94 mm higher, relative to the pelvis, and increases in lap and shoulder belt webbing length of 276 and 258 mm, respectively. Gender did not have important effects on the analyzed belt fit measures after taking into account stature and body mass index. These results offer important considerations for future crash safety assessments and suggest that further research is needed to consider belt fit for older and obese occupants. PMID:24435726

  8. On the excitation of the primordial small body belts

    NASA Astrophysics Data System (ADS)

    Petit, J.-M.; Morbidelli, A.; Valsecchi, G.

    1998-12-01

    The existence of the asteroid belt and of the Edgeworth-Kuiper belt, both dynamically excited and with a total mass that is only a small fraction of the original one, is very intriguing and may provide several clues for understanding the forming phases of our Solar System. The existence and the main properties of the belts of small bodies should be considered as observational constraints to discriminate among ``good'' and ``bad'' scenarios of Solar System's primordial evolution. For example, the median eccentricity of the asteroid belt is about 0.15, while its median inclination is 5.9(deg) . The present total mass is estimated to be of order 5 x 10(-4}M_{oplus ) , namely 10(2) --10(3) times smaller than its primordial mass. The Edgeworth-Kuiper belt seems to have similar characteristics.. We introduce a new method for estimating the excitation of a swarm of small bodies due to gravitational interaction with large planetesimals scattered by a giant planet. We show that a few Neptune-scattered planetesimals of one to two Earth masses could have excited the eccentricities and inclinations of the vast majority of bodies in the primordial Edgeworth-Kuiper belt. This could result in sculpting the belt to its currently observed structure and in depleting most of its primordial mass by: (i) injecting most of the bodies from the stable into the unstable regions in the inner belt; (ii) enhancing the role of mutual catastrophic collisions in the outer belt. The same mechanism involving Jupiter scattered planetesimals of about one Earth mass can excite the outer asteroid belt, hence depleting it of most of its primordial mass by increasing the eccentricities above the critical value 0.05. However this fails to excite the inner belt except in a few rare cases where the planetesimals can be decoupled from Jupiter by mutual gravitational perturbations.

  9. Pattern of seat belt wearing in Nanjing, China

    PubMed Central

    Routley, V; Ozanne?Smith, J; Li, D; Hu, X; Wang, P; Qin, Y

    2007-01-01

    Objective To describe the patterns of seat belt wearing in Nanjing, China for drivers, front seat passengers, and rear occupants of motor vehicles. Design Roadside observational study. Setting Four sites in central and northern Nanjing during daylight hours over 1 week in April 2005. Subjects Drivers and passengers of 17?147 cars, taxis, goods vans, and pickups, which traveled in the inside traffic lane. Main outcome measures Percentage seat belt wearing for each of seating position, age/sex, time of day, vehicle type, day of week. Results The rate of seat belt wearing was significantly higher in drivers (67.3%, 95% CI 66.6 to 68.0) than front seat passengers (18.9%, 95% CI, 18.0 to 19.8). It was negligible for second front seat passengers (2.6%, 95% CI 0.3 to 4.9) and rear seat passengers (0.5%, 95% CI 0.3 to 0.7). Belt tampering, such that protection would be reduced in the event of a crash, was observed for 18.5% of taxi drivers. Drivers were most likely to wear seat belts in cars and vans and at a city roundabout; front seat passengers were most likely to wear seat belts in non?taxi vehicles, during the evening rush hour, if the driver was wearing a belt, and on the local north road. Drivers were least likely to wear a belt in the early morning, in pickups and taxis, on Tuesday (or the following week), and on the local north road; front seat passengers were least likely to wear a belt in taxis and if the driver was not wearing a belt. Conclusions Rates of seat belt wearing by passengers were low despite national legislation and provincial regulations coming into effect several months before the survey. Combined education and enforcement are necessary accompaniments to legislation. PMID:18056315

  10. Late Archean greenstone tectonics: Evidence for thermal and thrust-loading lithospheric subsidence from stratigraphic sections in the Slave Province, Canada

    NASA Technical Reports Server (NTRS)

    Kidd, W. S. F.; Kusky, T. M.; Bradley, D. C.

    1988-01-01

    How late Archean tectonics could be seen to have operated in the Slave Province is illustrated. Lithospheric thinning and stretching, with the formation of rifted margins (to continental or island arc fragments), and lithospheric flexural loading of the kind familiar in arcs and mountain belts could be discerned.

  11. Modulation of forelimb and hindlimb muscle activity during quadrupedal tied-belt and split-belt locomotion in intact cats.

    PubMed

    Frigon, A; Thibaudier, Y; Hurteau, M-F

    2015-04-01

    The modulation of the neural output to forelimb and hindlimb muscles when the left and right sides step at different speeds from one another in quadrupeds was assessed by obtaining electromyography (EMG) in seven intact adult cats during split-belt locomotion. To determine if changes in EMG during split-belt locomotion were modulated according to the speed of the belt the limb was stepping on, values were compared to those obtained during tied-belt locomotion (equal left-right speeds) at matched speeds. Cats were chronically implanted for EMG, which was obtained from six muscles: biceps brachii, triceps brachii, flexor carpi ulnaris, sartorius, vastus lateralis and medial gastrocnemius. During tied-belt locomotion, cats stepped from 0.4 to 1.0m/s in 0.1m/s increments whereas during split-belt locomotion, cats stepped with left-right speed differences of 0.1 to 0.4m/s in 0.1m/s increments. During tied-belt locomotion, EMG burst durations and mean EMG amplitudes of all muscles respectively decreased and increased with increasing speed. During split-belt locomotion, there was a clear differential modulation of the EMG patterns between flexors and extensors and between the slow and fast sides. Changes in the EMG pattern of some muscles could be explained by the speed of the belt the limb was stepping on, while in other muscles there were clear dissociations from tied-belt values at matched speeds. Therefore, results show that EMG patterns during split-belt locomotion are modulated to meet task requirements partly via signals related to the stepping speed of the homonymous limb and from the other limbs. PMID:25644423

  12. CORN BELT PLAIN RIVER AND STREAMS PROJECT - 3 BIOCRITERIA PRODUCTS

    EPA Science Inventory

    This effort resulted in eight products, as follows: 1) Development of Index of Biotic Integrity Expectations for the Ecoregions of Indiana I. Central Corn Belt Plain; 2) Ibid. II. Huron-Erie Lake Plain; 3) Ibid III. Northern Indiana Till Plain; 4) Ibid .IV.Eastern Corn Belt Plain...

  13. Prioritizing Safety with Seat Belts: The Unanswered Question.

    ERIC Educational Resources Information Center

    Farrell, Elaine

    1987-01-01

    Reviews conflicting federal and state developments (including liability lawsuits) involving seat belt installation on school buses. The National Highway Traffic Safety Administration and the National Transportation Safety Board differ on this issue, and several states are considering seat belt legislation or crashworthiness studies. Hints are…

  14. The Harang discontinuity in auroral belt ionospheric currents.

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1972-01-01

    Discussion of the nature of a discontinuity in the ionospheric current of the auroral belt whose existence was suggested by Harang in 1946. Convection characteristics, time variability, and current continuity in the auroral belt are considered in a context of observations and arguments supporting the reality of Harang's discontinuity.

  15. Industrial back belts and low back pain: Mechanisms and outcomes

    Microsoft Academic Search

    Bruce A. Barron; Michael Feuerstein

    1994-01-01

    The recent increased utilization of industrial back belts as personal protective equipment in the workplace has generated considerable controversy among occupational health and safety professionals in the United States. The purpose of this article is to review the literature regarding proposed mechanisms of action of these devices and studies related to outcome of belt utilization in the prevention of low

  16. An Evaluation of the Seat Belt Education Campaign.

    ERIC Educational Resources Information Center

    Rochon, James

    A seat belt education campaign conducted in Canada to dispel myths surrounding seat belts and promote a better understanding of their functions was evaluated. Two telephone surveys, each comprised of 4,000 respondents, were conducted. The first was done immediately before the campaign and the second immediately succeeding the campaign. Also, a…

  17. Loss Prevention through Safety Belt Use: A Handbook for Managers.

    ERIC Educational Resources Information Center

    National Highway Traffic Safety Administration (DOT), Washington, DC.

    This handbook is designed to help managers address safety belt usage issues through a cost-effective and direct approach--establishing an employee safety belt program. The handbook offers a hands-on guide for conducting the program and provides for implementation at all levels. The handbook contains cost information, a program overview, policy and…

  18. New horizons: a Pluto-Kuiper belt mission

    Microsoft Academic Search

    A. Stern; A. Cheng

    2002-01-01

    New Horizons is the mission that NASA has selected to explore the Pluto-Charon binary planet system and other objects in the Kuiper Belt. The mission plan calls for a launch in January 2006 with an arrival at Pluto-Charon as early as 2015, and for a flyby of one or more Kuiper Belt objects by 2021.. The spacecraft will carry four

  19. Anorthosite belts, continental drift, and the anorthosite event

    USGS Publications Warehouse

    Herz, N.

    1969-01-01

    Most anorthosites lie in two principal belts when plotted on a predrift continental reconstruction. Anorthosite ages in the belts cluster around 1300 ?? 200 million years and range from 1100 to 1700 million years. This suggests that anorthosites are the product of a unique cataclysmic event or a thermal event that was normal only during the earth's early history.

  20. Anorthosite belts, continental drift, and the anorthosite event.

    PubMed

    Herz, N

    1969-05-23

    Most anorthosites lie in two principal belts when plotted on a predrift continental reconstruction. Anorthosite ages in the belts cluster around 1300 +/- 200 million years and range from 1100 to 1700 million years. This suggests that anorthosites are the product of a unique cataclysmic event or a thermal event that was normal only during the earth's early history. PMID:17775597

  1. Anorthosite Belts, Continental Drift, and the Anorthosite Event

    Microsoft Academic Search

    Norman Herz

    1969-01-01

    Most anorthosites lie in two principal belts when plotted on a predrift continental reconstruction. Anorthosite ages in the belts cluster around 1300 ± 200 million years and range from 1100 to 1700 million years. This suggests that anorthosites are the product of a unique cataclysmic event or a thermal event that was normal only during the earth's early history.

  2. The fossilized size distribution of the main asteroid belt

    Microsoft Academic Search

    William F. Bottke; Daniel D. Durda; D. Nesvorn'y; Robert Jedicke; Alessandro Morbidelli; D. Vokrouhlick'y; Hal Levison

    2005-01-01

    Planet formation models suggest the primordial main belt experienced a short but intense period of collisional evolution shortly after the formation of planetary embryos. This period is believed to have lasted until Jupiter reached its full size, when dynamical processes (e.g., sweeping resonances, excitation via planetary embryos) ejected most planetesimals from the main belt zone. The few planetesimals left behind

  3. Effectiveness of Automatic Shoulder Belt Systems in Motor Vehicle Crashes

    Microsoft Academic Search

    Frederick P. Rivara; Thomas D. Koepsell; David C. Grossman; Charles Mock

    2000-01-01

    Context Approximately 10 million cars with automatic shoulder belt systems are cur- rently in use in the United States. However, reports on the effectiveness of such re- straints have yielded conflicting results. Objective To determine the effectiveness of automatic shoulder belt systems in re- ducing the risk of injury and death among front-seat passenger vehicle occupants. Design, Setting, and Subjects

  4. Modeling and Simulation of the Effect of Reversible Belt Pretensioners

    Microsoft Academic Search

    C. Kurutas; K. Elsaber; D. Schramm; M. Hiller

    2006-01-01

    The general task of a belt pretensioner is to reduce the slack in the seatbelt-system. While pretensioning the seat-belt is tightened to help to reduce seatbelt slack prior to occupant movement. In combination with other safety components like airbags this helps to reduce the potential for injuries to an occupant. A specific type of pretensioner is incorporated in the so

  5. VIR, the imaging spectrometer for the asteroid belt exploration

    Microsoft Academic Search

    M. C. De Sanctis; A. Coradini; E. Ammannito; M. T. Capria; S. Fonte

    2009-01-01

    We describe the journey Dawn mission to the asteroid belt. The objective of Dawn is to explore backward in time via its observations of the primitive bodies, Vesta and Ceres. Dawn is the ninth mission in NASA's Discovery Program and is the first interplanetary mission that will orbit two solar system bodies: the massive main belt asteroid Vesta and the

  6. Failure of plastic press release buttons in automobile seat belts

    Microsoft Academic Search

    Russell F. Dunn; Richard H. McSwain; Terry Mills; Brian Malone

    2005-01-01

    In the late 1980s and early 1990s Honda, Nissan, Mitsubishi, Mazda, Suzuki, Subaru, Isuzu and Daihatsu and other automobile manufacturers modified their restraint system seat belt buckle assemblies in several models of vehicles. These automobile manufacturers incorporated plastic seat belt buckle assemblies manufactured by Takata Corporation as the 52 and A7 model series [National Highway Transportation Safety Administration (NHTSA), 1997,

  7. Concurrent paediatric seat belt injuries of the abdomen and spine

    Microsoft Academic Search

    G. A. Hoy; W. G. Cole

    1992-01-01

    Between 1981 and 1989, 541 children were admitted with abdominal injuries sustained as passengers in motor vehicle accidents. Twenty-nine of them had seat belt injuries of the abdomen. From 1981 to 1984, 1 child was admitted each year with such injuries and 21% of the abdominal injuries were due to seat belts. The number of cases had increased to 8

  8. Policy Implications From an Evaluation of Seat Belt Use Regulation

    Microsoft Academic Search

    Anand Desai; Min-Bong You

    1992-01-01

    The mandatory seat belt law is among the most recent of a long list of highway and vehicle safety regulations aimed at reducing the risk of injury in motor vehicle accidents. In this article the effects of this law on seat belt use, on the number of accidents, and on the number of fatal and severe injuries on rural interstate

  9. Seat Belt Injuries of the Breast: Findingson Mammographyand Sonography

    Microsoft Academic Search

    Pamela J. DiPiro; Jack E. Meyer; Thomas H. Fnenna; Christine M. Denison

    OBJECTIVE. The purpose of this study was to determine the mammographic and sonographic findings of injuries of the breast caused by seat belts in automobile acci- dents. The imaging findings of such injuries must be differentiated from those of car- cinoma, so that inappropriate treatment is avoided. MATERIALS AND METHODS. Five patients who had breast injuries caused by seat belts

  10. 33 CFR 142.42 - Safety belts and lifelines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...is a hazard of falling 10 or more feet shall wear a safety belt or harness secured by a lanyard to a lifeline, drop line, or fixed anchorage. (b) Each safety belt, harness, lanyard, lifeline, and drop line must meet the...

  11. 33 CFR 142.42 - Safety belts and lifelines.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...is a hazard of falling 10 or more feet shall wear a safety belt or harness secured by a lanyard to a lifeline, drop line, or fixed anchorage. (b) Each safety belt, harness, lanyard, lifeline, and drop line must meet the...

  12. 33 CFR 142.42 - Safety belts and lifelines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...is a hazard of falling 10 or more feet shall wear a safety belt or harness secured by a lanyard to a lifeline, drop line, or fixed anchorage. (b) Each safety belt, harness, lanyard, lifeline, and drop line must meet the...

  13. 33 CFR 142.42 - Safety belts and lifelines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...is a hazard of falling 10 or more feet shall wear a safety belt or harness secured by a lanyard to a lifeline, drop line, or fixed anchorage. (b) Each safety belt, harness, lanyard, lifeline, and drop line must meet the...

  14. 33 CFR 142.42 - Safety belts and lifelines.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...is a hazard of falling 10 or more feet shall wear a safety belt or harness secured by a lanyard to a lifeline, drop line, or fixed anchorage. (b) Each safety belt, harness, lanyard, lifeline, and drop line must meet the...

  15. WATER ICE IN THE KUIPER BELT

    SciTech Connect

    Brown, M. E.; Fraser, W. C. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Schaller, E. L., E-mail: mbrown@caltech.edu [NASA Dryden Aircraft Operations Facility, Palmdale, CA 93550 (United States)

    2012-06-15

    We examine a large collection of low-resolution near-infrared spectra of Kuiper Belt objects (KBOs) and centaurs in an attempt to understand the presence of water ice in the Kuiper Belt. We find that water ice on the surface of these objects occurs in three separate manners: (1) Haumea family members uniquely show surfaces of nearly pure water ice, presumably a consequence of the fragmentation of the icy mantle of a larger differentiated proto-Haumea; (2) large objects with absolute magnitudes of H < 3 (and a limited number to H = 4.5) have surface coverings of water ice-perhaps mixed with ammonia-that appears to be related to possibly ancient cryovolcanism on these large objects; and (3) smaller KBOs and centaurs which are neither Haumea family members nor cold-classical KBOs appear to divide into two families (which we refer to as 'neutral' and 'red'), each of which is a mixture of a common nearly neutral component and either a slightly red or very red component that also includes water ice. A model suggesting that the difference between neutral and red objects due to formation in an early compact solar system either inside or outside, respectively, of the {approx}20 AU methanol evaporation line is supported by the observation that methanol is only detected on the reddest objects, which are those which would be expected to have the most of the methanol containing mixture.

  16. The origin of Jupiter's outer radiation belt

    NASA Astrophysics Data System (ADS)

    Woodfield, Emma; Horne, Richard; Glauert, Sarah; Menietti, John; Shprits, Yuri

    2014-05-01

    The intense inner radiation belt at Jupiter (>50 MeV at 1.5 RJ) is the result of adiabatic transport of electrons from further away from the planet; however, a seed population of high energy electrons is still required at between 6 and 10 RJ with energies that exceed 1 MeV. Here we test the hypothesis that the seed population outside the orbit of the moon Io could be formed from a very soft energy spectrum due to particle injection processes, and acceleration via whistler mode chorus waves. Using particle data as an initial condition at an energy of 20 keV, we use the BAS radiation belt model to calculate the change in the electron energy spectrum between 6.5 and 15 RJ due to whistler mode chorus waves. Simulations show that the resulting energy spectrum lies very close to the empirical Galileo Interim Radiation Electron model (GIRE) spectrum at Jupiter after less than one day at 100 keV and less than 10 days at 1 MeV, suggesting that the seed population could indeed be formed by wave-particle interactions. The results are insensitive to the softness of the initial energy spectrum but do critically depend on the value of the flux at the minimum energy boundary. Simulations for wave acceleration and radial diffusion together show that the resulting spectrum remains close to the GIRE spectrum but the radial profile of phase space density is smoothed.

  17. Seat belt utilisation and awareness in UAE.

    PubMed

    Bendak, S; Al-Saleh, K

    2013-01-01

    Seat belts (SBs) are effective devices for reducing injury risk due to traffic accidents. Seat belt wearing was made compulsory in the United Arab Emirates (UAE) in January 1999 for drivers and front seat passengers (FSPs). No comprehensive study has ever assessed SB wearing rates across the country. Also, little is known on drivers' awareness of the importance of wearing seatbelts and how human factors affect wearing habits. This study aims to determine SB wearing rates for drivers and FSPs in UAE through an observational field study. It also aims to investigate perceptions and behaviour of drivers on this issue as well as human factors that affect wearing rate through a randomly distributed questionnaire. The results of the field study show that the overall SB wearing rate across the country was 61% for drivers and 43.4% for FSPs and that there were significant differences between the seven emirates that constitute the country. The questionnaire results show that age, education level, gender, marital status and nationality of drivers affect wearing habits and perceptions. Future implications in terms of improving traffic safety awareness are discussed. PMID:23163241

  18. a Wave Model for a Pneumatic Tyre Belt

    NASA Astrophysics Data System (ADS)

    PINNINGTON, R. J.; BRISCOE, A. R.

    2002-06-01

    A one-dimensional wave equation of an infinite flattened tyre belt is generated. The belt vibration is controlled by bending, tension, shear and the sidewall stiffness. The dispersion relations for two waves in the belt are calculated and used to find both the input impedance and attenuation on a tyre belt of infinite extent. Tension and the sidewall controls the deformation and stiffness below 100Hz. Waves propagate around the belt above this frequency. The wave speeds due to bending and shear were predicted and measured. The model presented here should be valid for the prediction of tyre response above about 400 Hz when for a car tyre the modal behaviour is observed to cease. In this high-frequency region, the tyre at the input appears to be of infinite extent.

  19. Neptune's eccentricity and the nature of the kuiper belt

    PubMed

    Ward; Hahn

    1998-06-26

    The small eccentricity of Neptune may be a direct consequence of apsidal wave interaction with the trans-Neptune population of debris called the Kuiper belt. The Kuiper belt is subject to resonant perturbations from Neptune, so that the transport of angular momentum by density waves can result in orbital evolution of Neptune as well as changes in the structure of the Kuiper belt. In particular, for a belt eroded out to the vicinity of Neptune's 2:1 resonance at about 48 astronomical units, Neptune's eccentricity can damp to its current value over the age of the solar system if the belt contains slightly more than an earth mass of material out to about 75 astronomical units. PMID:9641913

  20. The Palaeoproterozoic Ubendian shear belt in Tanzania: geochronology and structure

    NASA Astrophysics Data System (ADS)

    Lenoir, J. L.; Liégeois, J.-P.; Theunissen, K.; Klerkx, J.

    1994-10-01

    The Ubendian belt is a linear, NW-SE trending orogenic belt in western Tanzania. It is part of a larger Palaeoproterozoic orogen, developed around the west and south-western margin of the Archaean Tanzanian craton. The Ubendian Belt has experienced several periods of reactivation since the Palaeoproterozoic, acting as a zone of displacement during successive orogenic and rift-forming events. The Ubendian Belt is characterized by an early deformation and granulite-facies metamorphism, isotopically dated at 2100-2025 Ma, and marked by an E-W to ESE-WNW trending foliation. This phase also affected the adjacent Usagaran (and Bangweulu?) Belt and is interpreted as a product of collisional orogeny along the SW margin of the Tanzanian, and possibly Congo, cratons. A second phase of deformation, apparently restricted to the Ubendian Belt, is characterized by large, NW-SE trending, dextral shear zones. This phase is responsible for the creation of the eight crustal blocks developed throughout the belt and overprints much of the earlier deformation fabric. This second deformation phase is terminated by late- to post-kinematic calc-alkaline granitic batholiths ( ca 1860 Ma). A phase of tectonic reactivation occurred locally at ca 1725 Ma. Notable by its absence, is any evidence of Kibaran isotopic ages in the Ubendian Belt. Major Kibaran orogenic belts occur to the north (Burundi) and south (Zambia) of the Ubendian Belt, although they are apparently not isotopically recorded within it. A third phase of deformation is characterized by Neoproterozoic ( ca 750 Ma) reactivations of the Ubendian shear zones. This deformation is marked by the development of sinistral, brittle-ductile shear zones, displaying retrograde metamorphic mineral assemblages, and intruded by alkaline plutons. These late shear zones were the preferential locus for the brittle rift faults of the western branch of the East African Rift.

  1. Late orogenic extension in mountain belts: Insights from the basin and range and the late paleozoic Variscan belt

    Microsoft Academic Search

    Jacques Malavieille

    1993-01-01

    From two examples of orogenic domains, some general mechanisms significant of late orogenic tectonic processes in mountain belts are characterized. The Basin and Range province and the Variscan belt in the French Massif Central have both suffered important compressional orogenic crustal thickening, and the results of late orogenic processes can be observed in the field. Both areas are covered by

  2. The Ocean-Atmosphere Hydrothermohaline Conveyor Belt

    NASA Astrophysics Data System (ADS)

    Döös, Kristofer; Kjellsson, Joakim; Zika, Jan; Laliberté, Frédéric; Brodeau, Laurent

    2015-04-01

    The ocean thermohaline circulation is linked to the hydrothermal circulation of the atmosphere. The ocean thermohaline circulation is expressed in potential temperature-salinity space and comprises a tropical upper-ocean circulation, a global conveyor belt cell and an Antarctic Bottom Water cell. The atmospheric hydrothermal circulation in a potential temperature-specific humidity space unifies the tropical Hadley and Walker cells as well as the midlatitude eddies into a single, global circulation. Superimposed, these thermohaline and hydrothermal stream functions reveal the possibility of a close connection between some parts of the water and air mass conversions. The exchange of heat and fresh water through the sea surface (precipiation-evaporation) and incoming solar radiation act to make near-surface air warm and moist while making surface water warmer and saltier as both air and water travel towards the Equator. In the tropics, air masses can undergo moist convection releasing latent heat by forming precipitation, thus acting to make warm surface water fresher. We propose that the Clausius-Clapeyron relationship for moist near-surface air acts like a lower bound for the atmospheric hydrothermal cell and an upper bound for the ocean thermohaline Conveyor-Belt cell. The analysis is made by combining and merging the overturning circulation of the ocean and atmosphere by relating the salinity of the ocean to the humidity of the atmosphere, where we set the heat and freshwater transports equal in the two stream functions By using simulations integrated with our Climate-Earth system model EC-Earth, we intend to produce the "hydrothermohaline" stream function of the coupled ocean-atmosphere overturning circulation in one single picture. We explore how the oceanic thermohaline Conveyor Belt can be linked to the global atmospheric hydrothermal circulation and if the water and air mass conversions in humidity-temperature-salinity space can be related and linked to each other along a "line" corresponding to the Clausius-Clapeyron relationship. A geographical description of how and where this occurs together with this new hydrothermohaline stream function will be searched for. The net heat and freshwater transport of the ocean and atmosphere can aslo be calculated from the thermohaline and hydrothermal stream functions. The heat transport across isohumes in the atmosphere and isohalines in the ocean as well as the freshwater transport across isotherms in both the atmosphere and ocean are computed. The maximum heat transport is about 16 PW in the atmosphere, while that of the ocean is just about 1 PW. The freshwater transport across isotherms in the atmosphere and ocean are shown to be tightly connected with a net maximum freshwater transport of 4 SV in the atmosphere and 2 Sv in the ocean.

  3. Studying the Saturn Inner Radiation Belt

    NASA Astrophysics Data System (ADS)

    Kotova, A.; Roussos, E.; Krupp, N.; Dandouras, I.

    2013-09-01

    In 2004 the MIMI/INCA detector onboard the Cassini spacecraft measured the significant flux of the energetic neutral atoms (ENA) coming from the area between the D-ring and the Saturn's atmosphere, what brought up the idea of the possible existence of the innermost radiation belt in this narrow gap. In the present study we estimate the possible sources for this radiation belt, assuming the two main processes: the double charge exchange of the ENAs, coming from the middle magnetosphere, what can bring the keV ions to the region of our interest, and the interaction of the Galactic Cosmic Rays (GCR) with the Saturn's atmosphere and rings, which due to CRAND process can produce the keV-MeV ions or electrons in the region. Both of these possible sources are possible to evaluate using the charged particle tracer. In our group we developed such charged particle tracer, which works in all different modes (Newton-Lorentz full equation of motion, guiding center or bounce averaged approximations), and allows using the different magnetic field models (from simple dipole magnetic field till complex realistic magnetic field model like Khurana model of Saturn's magnetosphere) for both forward and backward tracing simulations. This charged particle tracer was validated using the comparison of the simulation results and observations during several flybys of Cassini by icy moons of Saturn. Using the particle tracer we can calculate the access of GCRs to the atmosphere and rings of the planet and evaluate the filtering of the GCR spectrum that hits the atmosphere from the direction of the Saturn's main rings. Also we can investigate different non-dipolar effects which possible can change the Stroemer cutoff rigidities of GCRs, especially for the high-latitude atmosphere, which maps magnetically in the outer magnetosphere. We can also estimate the production of secondaries as well (and also from the multiple impacts of these secondaries on the rings or atmosphere) and evaluate the energy spectrum of neutrons, the decay of which leads to the production of final CRAND elements in the inner Saturnian radiation belts. Using this complex simulation we are going to predict the fluxes of energetic ions and electrons, which particle detector MIMI/LEMMS onboard the Cassini can measure during the so-called "proximal" orbits in 2017, when the Cassini spacecraft will pass directly through this diverse and enigmatic region extremely close to the planet.

  4. Plains tectonism on Venus: The deformation belts of Lavinia Planitia

    NASA Technical Reports Server (NTRS)

    Squyres, Steven W.; Jankowski, David G.; Simons, Mark; Solomon, Sean C.; Hager, Bradford H.; Mcgill, George E.

    1993-01-01

    High-resolution radar images from the Magellan spacecraft have revealed the first details of the morphology of the Lavinia Planitia region of Venus. A number of geologic units can be distinguished, including volcanic plains units with a range of ages. Transecting these plains over much of the Lavinia region are two types of generally orthogonal features that we interpret to be compressional wrinkle ridges and extensional grooves. The dominant tectonic features of Lavinia are broad elevated belts of intense deformation that transect the plains with complex geometry. They are many tens to a few hundred kilometers wide, as much as 1000 km long, and elevated hundreds of meters above the surrounding plains. Two classes of deformation belts are seen in the Lavinia region. 'Ridge belts' are composed of parallel ridges, each a few hundred meters in elevation, that we interpret to be folds. Typical fold spacings are 5-10 km. 'Fracture belts' are dominated instead by intense faulting, with faults in some instances paired to form narrow grabens. There is also some evidence for modest amounts of horizontal shear distributed across both ridge and fracture belts. Crosscutting relationships among the belts show there to be a range in belt ages. In western Lavinia, in particular, many ridge and fracture belts appear to bear a relationship to the much smaller wrinkle ridges and grooves on the surrounding plains: ridge morphology tends to dominate belts that lie more nearly parallel to local plains wrinkle ridges, and fracture morphology tends to dominate belts that lie more nearly parallel to local plains grooves. We use simple models to explore the formation of ridge and fracture belts. We show that convective motions in the mantle can couple to the crust to cause horizontal stresses of a magnitude sufficient to induce the formation of deformation belts like those observed in Lavinia. We also use the small-scale wavelengths of deformation observed within individual ridge belts to place an approximate lower limit on the venusian thermal gradient in the Lavinia region at the time of deformation.

  5. What Drives the Global Conveyer Belt?

    NSDL National Science Digital Library

    In this laboratory activity, students observe what happens when a fluid of one density is placed in a fluid of a different density. The fluids are salt water and fresh water, cold water and warm water. They generalize their results to describe what occurs in the world's oceans to drive the global conveyor belt pattern of ocean currents. There is an option to conduct an investigation taking quantitative measurements, which requires an immersible thermometer and a heat source. Assessment suggestions are included. The investigation is found in the teacher's guide accompanying the textbook, Climate Change, part of Global System Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

  6. Measuring and modeling twilight's Belt of Venus.

    PubMed

    Lee, Raymond L

    2015-02-01

    The Belt of Venus (or antitwilight arch) is a reddish band often seen above the antisolar horizon during clear civil twilights, and immediately beneath it is the bluish-gray earth's shadow (or dark segment) cast on the atmosphere. Although both skylight phenomena have prompted decades of scientific research, surprisingly few measurements exist of their spectral, colorimetric, and photometric structure. Hyperspectral imaging of several clear twilights supplies these missing radiometric details and reveals some common spectral features of the antisolar sky at twilight: (1) color differences between the dark segment and the sunlit sky above the antitwilight arch are small or nil; (2) antisolar color and luminance extremes usually occur at different elevation angles; and (3) the two twilight phenomena are most vivid for modest aerosol optical depths. A second-order scattering model that includes extinction by aerosols and ozone provides some preliminary radiative transfer explanations of these twilight features' color and brightness. PMID:25967826

  7. Subsurface Meridional Circulation in the Active Belts

    E-print Network

    I. Gonzalez Hernandez; S. Kholikov; F. Hill; R. Howe; R. Komm

    2008-08-26

    Temporal variations of the subsurface meridional flow with the solar cycle have been reported by several authors. The measurements are typically averaged over periods of time during which surface magnetic activity existed in the regions were the velocities are calculated. The present work examines the possible contamination of these measurements due to the extra velocity fields associated with active regions plus the uncertainties in the data obtained where strong magnetic fields are present. We perform a systematic analysis of more than five years of GONG data and compare meridional flows obtained by ring-diagram analysis before and after removing the areas of strong magnetic field. The overall trend of increased amplitude of the meridional flow towards solar minimum remains after removal of large areas associated with surface activity. We also find residual circulation toward the active belts that persist even after the removal of the surface magnetic activity, suggesting the existence of a global pattern or longitudinally-located organized flows.

  8. INCLINATION MIXING IN THE CLASSICAL KUIPER BELT

    SciTech Connect

    Volk, Kathryn; Malhotra, Renu, E-mail: kvolk@lpl.arizona.edu [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

    2011-07-20

    We investigate the long-term evolution of the inclinations of the known classical and resonant Kuiper Belt objects (KBOs). This is partially motivated by the observed bimodal inclination distribution and by the putative physical differences between the low- and high-inclination populations. We find that some classical KBOs undergo large changes in inclination over gigayear timescales, which means that a current member of the low-inclination population may have been in the high-inclination population in the past, and vice versa. The dynamical mechanisms responsible for the time variability of inclinations are predominantly distant encounters with Neptune and chaotic diffusion near the boundaries of mean motion resonances. We reassess the correlations between inclination and physical properties including inclination time variability. We find that the size-inclination and color-inclination correlations are less statistically significant than previously reported (mostly due to the increased size of the data set since previous works with some contribution from inclination variability). The time variability of inclinations does not change the previous finding that binary classical KBOs have lower inclinations than non-binary objects. Our study of resonant objects in the classical Kuiper Belt region includes objects in the 3:2, 7:4, 2:1, and eight higher-order mean motion resonances. We find that these objects (some of which were previously classified as non-resonant) undergo larger changes in inclination compared to the non-resonant population, indicating that their current inclinations are not generally representative of their original inclinations. They are also less stable on gigayear timescales.

  9. A Comprehensive Simulation Method for Examining Radiation Belt Dynamics

    NASA Astrophysics Data System (ADS)

    Elkington, S. R.; Chan, A. A.; Zheng, L.

    2013-12-01

    The particles comprising the Van Allen radiation belts are affected by a variety of electromagnetic and electrostatic waves present in the magnetosphere. For example, the Van Allen Probes mission has recently uncovered evidence for heating in the radiation belts as a result of local kHz wave-particle interactions, violating the cyclotron invariant. Similarly, global variations at mHz frequencies commensurate with the particle drift frequency can lead to effective transport, heating, and loss within the radiation belts as a result of changes to the third adiabatic invariant. The wide variety of waves occurring over this disparate frequency range presents a fundamental challenge in constructing dynamic models of the radiation belts. In this effort we present results from a new method for tracking the global dynamics of the radiation belts. Here we examine a well-observed flux dropout and subsequent acceleration event occurring on 20 September 2007. We use 3d magnetohydrodynamic (MHD) simulations of the solar wind/magnetospheric interaction to track particles in a bounce-averaged formalism, combined with stochastic differential equation (SDE) simulations of local wave-particle interactions, to provide a comprehensive model of the radiation belts encompassing both large-scale transport and local heating and loss within the radiation belts.

  10. The Use of Orbital Tethers to Remediate Geomagnetic Radiation Belts

    NASA Astrophysics Data System (ADS)

    Hudoba de Badyn, Mathias; Marchand, Richard; Sydora, Richard

    2014-10-01

    The Van Allen radiation belts pose a hazard to spacecraft and astronauts, and similar radiation belts around other planets pose a hazard to interplanetary probes. We discuss a method of remediating these radiation belts proposed by Hoyt, Minor and Cash where a long, charged tether is placed in orbit inside a radiation belt. The electric field of the tether adiabatically scatters the belt particles into a pitch angle loss cone due to absorption of the particles in the atmosphere. We present a test particle calculation which computes the scattered pitch angle of belt particles as a function of initial pitch angle and gyrophase for different particle energies. We then use the moments of the resulting histogram of scattered angle versus initial pitch angle to compute the number density of the belt as a function of time using a Fokker-Planck diffusion model. Finally, we use the characteristic timescales of scattering for particles of different energies to discuss the feasibility of using such a system of tethers as a long and short-term remediation solution.

  11. The Fossilized Size Distribution of the Main Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Durda, D.; Nesvorny, D.; Jedicke, R.; Morbidelli, A.

    2004-05-01

    The main asteroid belt evolved into its current state via two processes: dynamical depletion and collisional evolution. During the planet formation epoch, the primordial main belt (PMB) contained several Earth masses of material, enough to allow the asteroids to accrete on relatively short timescales (e.g., Weidenschilling 1977). The present-day main belt, however, only contains 5e-4 Earth masses of material (Petit et al. 2002). To explain this mass loss, we suggest the PMB evolved in the following manner: Planetesimals and planetary embryos accreted (and differentiated) in the PMB during the first few Myr of the solar system. Gravitational perturbations from these embryos dynamically stirred the main belt, enough to initiate fragmentation. When Jupiter reached its full size, some 10 Myr after the solar system's birth, its perturbations, together with those of the embryos, dynamically depleted the main belt region of > 99% of its bodies. Much of this material was sent to high (e,i) orbits, where it continued to pummel the surviving main belt bodies at high impact velocities for more than 100 Myr. While some differentiated bodies in the PMB were disrupted, most were instead scattered; only small fragments from this population remain. This period of comminution and dynamical evolution in the PMB created, among other things, the main belt's wavy size-frequency distribution, such that it can be considered a "fossil" from this violent early epoch. From this time forward, however, relatively little collisional evolution has taken place in the main belt, consistent with the surprising paucity of prominent asteroid families. We will show that the constraints provided by asteroid families and the shape of the main belt size distribution are essential to obtaining a unique solution from our model's initial conditions. We also use our model results to solve for the asteroid disruption scaling law Q*D, a critical function needed in all planet formation codes that include fragmentation between rocky planetesimals.

  12. Radiation Belt Storm Probes: Resolving Fundamental Physics with Practical Consequences

    NASA Technical Reports Server (NTRS)

    Ukhorskiy, Aleksandr Y.; Mauk, Barry H.; Fox, Nicola J.; Sibeck, David G.; Grebowsky, Joseph M.

    2011-01-01

    The fundamental processes that energize, transport, and cause the loss of charged particles operate throughout the universe at locations as diverse as magnetized planets, the solar wind, our Sun, and other stars. The same processes operate within our immediate environment, the Earth's radiation belts. The Radiation Belt Storm Probes (RBSP) mission will provide coordinated two-spacecraft observations to obtain understanding of these fundamental processes controlling the dynamic variability of the near-Earth radiation environment. In this paper we discuss some of the profound mysteries of the radiation belt physics that will be addressed by RBSP and briefly describe the mission and its goals.

  13. Dynamic models for ridge belt formation on Venus

    NASA Technical Reports Server (NTRS)

    Simons, Mark; Solomon, Sean C.; Hager, Bradford H.

    1991-01-01

    The hypothesis is tested that the lithospheric shortening expressed by the ridge belts is the result of convective downwelling beneath the lowland planitia. Dynamical models are developed for the interaction of mantle convection with the crust and the models are compared to the characteristics of the ridge belts in Lavinia Planitia. The models support the hypothesis that convective stresses can produce the broad topographic depression of lowlands on Venus and can lead to the formation of ridge belts on either side of the topographic low.

  14. Kuiper Belt Objects Along the Pluto-Express Path

    NASA Technical Reports Server (NTRS)

    Jewitt, David (Principal Investigator)

    1997-01-01

    The science objective of this work is to identify objects in the Kuiper Belt which will, in the 5 years following Pluto encounter, be close to the flight path of NASA's Pluto Express. Our hope is that we will find a Kuiper Belt object or objects close enough that a spacecraft flyby will be possible. If we find a suitable object, the science yield of Pluto Express will be substantially enhanced. The density of objects in the Kuiper Belt is such that we are reasonably likely to find an object close enough to the flight path that on-board gas thrusters can effect a close encounter.

  15. Tectonic framework of disturbed belt of west-central Montana

    SciTech Connect

    Woodward, L.A.

    1981-02-01

    The Disturbed Belt of west-central Montana consists of a zone of Laramide convex-eastward thrusts and fold that include the major Eldorado-Lombard overthrust that has brought Precambrian rocks of the Belt Supergroup eastward over Paleozoic and Mesozoic strata. Most of the Disturbed Belt is east of and structurally below the Eldorado-Lombard overthrust. Deformed rocks range in age from middle Precambrian to early Tertiary. Tectonic features are described that play an important role in hydrocarbon exploration in the area. (JMT)

  16. The variable extension of Saturn's electron radiation belts

    NASA Astrophysics Data System (ADS)

    Roussos, E.; Krupp, N.; Paranicas, C.; Carbary, J. F.; Kollmann, P.; Krimigis, S. M.; Mitchell, D. G.

    2014-12-01

    Contrary to the permanent MeV ion belts which are relatively stable in intensity over both short and long time scales and are modulated by a single Galactic Cosmic Ray driven source, the electron belts of Saturn appear to be much more complex in both structure and temporal evolution. In order to understand the responses of this system to the different factors that may control it (internal or external/solar sources) we study its long-term, temporal evolution. We achieve that by tracking the equatorial distance of the belts' outer boundary, using MIMI/LEMMS energetic charged particle observations over a period of more than 7 years. This boundary is defined at the distance that a selected count rate level is measured in a LEMMS channel that has the properties of an omnidirectional, integral energy detector. Simulated solar wind moments, energetic neutral atom (ENA) observations and solar irradiance data are used to support the analysis. In many cases, correlations of the different datasets are weak, suggesting that the electron belts are modulated in time scales that are much shorter than the sampling of the electron belt boundary (typically every 10-30 days). Still, we find several cases of persistent, long term and strong perturbations in the system that appear to have corresponding disturbances in the extension of the electron belts, even on such long time scales. From the analysis of those intervals we believe that we have established a solid link with the planetary ring current as the primary source of the electron belts of Saturn. This is concluded mostly on the basis of an extended ring current decay in 2011 (inferred through ENA observations), coinciding with a similar, unusual drop in the electron belt extension (and intensity). This means that the electron belts should reflect also the modulation of the ring current. We suggest that possible sources of long term modulation are both the solar UV irradiance of the Saturnian thermosphere and the solar wind. The former appears to acquire large values and exhibit significant changes during the period of the electron belt/ring current decay, while an approximate 2-week periodicity (characteristic for the case of two solar wind streams per solar rotation) appears in the electron belts in the form of recurrent expansions or intensifications. The latter finding indicates that external forcing by the solar wind can have a considerable impact on the planet's electron belts, contrary to the expectations that Saturn's magnetospheric dynamics are rotationally dominated and internally driven.

  17. Optical sensor for velocity and slip measurement of automobile belt drives

    Microsoft Academic Search

    Christian Berger

    2002-01-01

    To investigate and optimize the operational behavior of automobile belt drives, it is important to detect unfavorable operating conditions, such as excessive slippage. To measure slippage, the speed of the belt is compared to the peripheral velocities of pulleys in the belt drive. The velocity of the belt is obtained by a contactless optical sensor, whose signals are processed employing

  18. 77 FR 30885 - Clarification of Prior Interpretations of the Seat Belt and Seating Requirements for General...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ...belt, if the pertinent information is available, the pilot...belt is approved and rated for such use; and the...commenters that this information cannot always be obtained...belt, if the pertinent information is available, the PIC...belt is approved and rated for such use;...

  19. Seat belt use among rear passengers: validity of self-reported versus observational measures

    Microsoft Academic Search

    Francesco Zambon; Ugo Fedeli; Maria Marchesan; Elena Schievano; Antonio Ferro; Paolo Spolaore

    2008-01-01

    BACKGROUND: The effects of seat belt laws and public education campaigns on seat belt use are assessed on the basis of observational or self-reported data on seat belt use. Previous studies focusing on front seat occupants have shown that self-reports indicate a greater seat belt usage than observational findings. Whether this over-reporting in self reports applies to rear seat belt

  20. 30 CFR 57.15005 - Safety belts and lines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Safety belts and lines. 57.15005 Section 57.15005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH...

  1. 30 CFR 57.15005 - Safety belts and lines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Safety belts and lines. 57.15005 Section 57.15005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH...

  2. 30 CFR 56.15005 - Safety belts and lines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Safety belts and lines. 56.15005 Section 56.15005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH...

  3. 30 CFR 56.15005 - Safety belts and lines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Safety belts and lines. 56.15005 Section 56.15005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH...

  4. 2. Left to right: coke ovens, wharf with belt conveyor, ...

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

    2. Left to right: coke ovens, wharf with belt conveyor, coal bunker, coke stack, brick quencher, gas holder, view framed by bracing for overhead conveyor. Looking south/southeast - Rouge Steel Company, 3001 Miller Road, Dearborn, Wayne County, MI

  5. 65. Modular bed storage unit, safety belt at left center, ...

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

    65. Modular bed storage unit, safety belt at left center, north side - Ellsworth Air Force Base, Delta Flight, Launch Control Facility, County Road CS23A, North of Exit 127, Interior, Jackson County, SD

  6. 56. Rock Belt Line, Transfer Building, date unknown Historic Photograph, ...

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

    56. Rock Belt Line, Transfer Building, date unknown Historic Photograph, Photographer Unknown; Collection of William Everett, Jr.(Wilkes-Barre, PA), photocopy by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

  7. Physical effects of collisions in the Kuiper belt

    E-print Network

    Zoe M. Leinhardt; Sarah T. Stewart; Peter H. Schultz

    2007-05-27

    Collisions are a major modification process over the history of the Kuiper Belt. Recent work illuminates the complex array of possible outcomes of individual collisions onto porous, volatile bodies. The cumulative effects of such collisions on the surface features, composition, and internal structure of Kuiper Belt Objects are not yet known. In this chapter, we present the current state of knowledge of the physics of cratering and disruptive collisions in KBO analog materials. We summarize the evidence for a rich collisional history in the Kuiper Belt and present the range possible physical modifications on individual objects. The question of how well present day bodies represent primordial planetesimals can be addressed through future studies of the coupled physical and collisional evolution of Kuiper Belt Objects.

  8. Teenage Years in the "Stroke Belt" Drive up Risk

    MedlinePLUS

    Teenage Years in the “Stroke Belt” Drive up Risk Follow NINDSnews For release: Thursday, May 16, 2013 ... Disorders and Stroke (NINDS), people who spent their teenage years (ages 13-18) living in the Stroke ...

  9. 2. DETAIL OF CONVEYOR BELT PATH AND CATWALK, NORTHEAST VIEW. ...

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

    2. DETAIL OF CONVEYOR BELT PATH AND CATWALK, NORTHEAST VIEW. - Vanadium Corporation of America (VCA) Naturita Mill, Grinding Rod Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  10. 5. DETAIL OF ROD MILL BASE AND CONVEYOR BELT SUPPORT, ...

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

    5. DETAIL OF ROD MILL BASE AND CONVEYOR BELT SUPPORT, EAST VIEW. - Vanadium Corporation of America (VCA) Naturita Mill, Grinding Rod Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  11. Bunkhouse basement interior showing storage area and a conveyor belt ...

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

    Bunkhouse basement interior showing storage area and a conveyor belt (circa 1936) used to unload dry goods into the basement through an opening on the east side of the bunkhouse. - Sespe Ranch, Bunkhouse, 2896 Telegraph Road, Fillmore, Ventura County, CA

  12. The IRBEM library -- open source tools for radiation belt modeling

    NASA Astrophysics Data System (ADS)

    O'Brien, P. P.; Bourdarie, S.

    2012-12-01

    The COSPAR Panel on Radiation Belt Models sponsors an open-source library of software routines for radiation belt modeling, the International Radiation Belt Models (IRBEM) library (irbem.sf.net). Descended from the ONERA-DESP library, the IRBEM library contains primarily Fortran routines for magnetic field model evaluation and tracing, coordinate transforms, orbit propagation, radiation models, and neutral atmosphere models. The library can be accessed from several popular languages via a dynamic linked library (DLL) interface. Extra capabilities that have not been integrated into the library are provided for computing particle diffusion coefficients, training and evaluating neural networks, evaluating instrument response functions, inverting particle measurements from data channels to flux spectra, fast nearest-neighbors look-ups, and sharing structured data between high level languages. The IRBEM library continues to grow to meet the changing needs of radiation belt researchers.

  13. Visualization of Radiation Belts from REPT Data - Duration: 69 seconds.

    NASA Video Gallery

    This visualization, created using actual data from the Relativistic Electron-Proton Telescopes (REPT) on NASAâ??s Van Allen Probes, clearly shows the emergence of new third belt and second slot reg...

  14. 161. BLACKSMITH SHOP, OVERHEAD SHAFT. BELT ON LEFT CONNECTS TO ...

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

    161. BLACKSMITH SHOP, OVERHEAD SHAFT. BELT ON LEFT CONNECTS TO SHAFTS WHICH RUN POWER PRESS AND HYDRAULIC TIRE SETTER. - Gruber Wagon Works, Pennsylvania Route 183 & State Hill Road at Red Bridge Park, Bernville, Berks County, PA

  15. 108. BASEMENT, DRIVE SHAFT BENEATH ORIGINAL SHOP OF 1883. BELT ...

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

    108. BASEMENT, DRIVE SHAFT BENEATH ORIGINAL SHOP OF 1883. BELT AT RIGHT CONNECTS TO MAIN DRIVE SHAFT. - Gruber Wagon Works, Pennsylvania Route 183 & State Hill Road at Red Bridge Park, Bernville, Berks County, PA

  16. 1. Shown in the electric motor which powered the belts ...

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

    1. Shown in the electric motor which powered the belts and drive shafts. This power system drove the tumblers which cleaned chain in building #7. - American Chain & Cable Company, East Princess Street (400 Block), York, York County, PA

  17. Unbiased Inclination Distributions for Objects in the Kuiper Belt

    E-print Network

    Gulbis, Amanda A. S.

    Using data from the Deep Ecliptic Survey (DES), we investigate the inclination distributions of objects in the Kuiper Belt. We present a derivation for observational bias removal and use this procedure to generate unbiased ...

  18. Looking southeast at the conveyor belt and tripper feeding the ...

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

    Looking southeast at the conveyor belt and tripper feeding the coal storage hoppers. - Wheeling-Pittsburgh Steel Corporation, Allenport Works, Boiler House, Route 88 on West bank of Monongahela River, Allenport, Washington County, PA

  19. Looking southeast at the conveyor belt and tripper feeding the ...

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

    Looking southeast at the conveyor belt and tripper feeding the coal storage hoppers at the top of the boilers. - Wheeling-Pittsburgh Steel Corporation, Allenport Works, Boiler House, Route 88 on West bank of Monongahela River, Allenport, Washington County, PA

  20. Looking southeast at the conveyor belt feeding the coal storage ...

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

    Looking southeast at the conveyor belt feeding the coal storage hoppers at the top of the boilers. - Wheeling-Pittsburgh Steel Corporation, Allenport Works, Boiler House, Route 88 on West bank of Monongahela River, Allenport, Washington County, PA

  1. VIEW NORTH, SOUTH ELEVATION OF (FROM LEFT) ECCENTRIC HOUSE, BELT ...

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

    VIEW NORTH, SOUTH ELEVATION OF (FROM LEFT) ECCENTRIC HOUSE, BELT SHED, AND ENGINE HOUSE, NOTE EXHAUST LOWER RIGHT OF ENGINE HOUSE. - Golden Oil Company, Lot 410 Lease, Sheffield Field, Donaldson, Warren County, PA

  2. VIEW SOUTH, NORTH ELEVATION OF (FROM LEFT) ENGINE HOUSE, BELT ...

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

    VIEW SOUTH, NORTH ELEVATION OF (FROM LEFT) ENGINE HOUSE, BELT SHED, ECCENTRIC HOUSE, NOTE ROD LINES EXITING ECCENTRIC HOUSE. - Golden Oil Company, Lot 410 Lease, Sheffield Field, Donaldson, Warren County, PA

  3. 30 CFR 75.1108 - Approved conveyor belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Fire Protection Fire Suppression Devices and Fire-Resistant Hydraulic Fluids on Underground Equipment § 75.1108 Approved conveyor belts. (a) Until December 31, 2009 conveyor...

  4. "Abomination"--life as a Bible belt gay.

    PubMed

    Barton, Bernadette

    2010-01-01

    Drawing on observation, autoethnography, and audio-taped interviews, this article explores the religious backgrounds and experiences of Bible Belt gays. In the Bible Belt, Christianity is not confined to Sunday worship. Christian crosses, messages, paraphernalia, music, news, and attitudes permeate everyday settings. Consequently, Christian fundamentalist dogma about homosexuality-that homosexuals are bad, diseased, perverse, sinful, other, and inferior-is cumulatively bolstered within a variety of other social institutions and environments in the Bible Belt. Of the 46 lesbians and gay men interviewed for this study (age 18-74 years), most describe living through spirit-crushing experiences of isolation, abuse, and self-loathing. This article argues that the geographic region of the Bible Belt intersects with religious-based homophobia. Informants explained that negative social attitudes about homosexuality caused a range of harmful consequences in their lives including the fear of going to hell, depression, low self-esteem, and feelings of worthlessness. PMID:20391006

  5. 46 CFR 169.825 - Wearing of safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Operations § 169.825 Wearing of safety belts. The master of each vessel shall ensure that each person wears an approved safety harness when aloft or working topside in heavy weather. Tests, Drills, and...

  6. 13. VIEW OF SWEEP ARMDRIVE MECHANISM AND BELT CHAIN FROM ...

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

    13. VIEW OF SWEEP ARM-DRIVE MECHANISM AND BELT CHAIN FROM MOOR, LOOKING EAST - Mystic River Drawbridge No. 7, Spanning Mystic River at Boston & Maine Railroad Eastern Route, Somerville, Middlesex County, MA

  7. Trio of Neptunes and their Belt

    NASA Astrophysics Data System (ADS)

    2006-05-01

    Using the ultra-precise HARPS spectrograph on ESO's 3.6-m telescope at La Silla (Chile), a team of European astronomers have discovered that a nearby star is host to three Neptune-mass planets. The innermost planet is most probably rocky, while the outermost is the first known Neptune-mass planet to reside in the habitable zone. This unique system is likely further enriched by an asteroid belt. ESO PR Photo 18a/06 ESO PR Photo 18a/06 Planetary System Around HD 69830 (Artist's Impression) "For the first time, we have discovered a planetary system composed of several Neptune-mass planets", said Christophe Lovis, from the Geneva Observatory and lead-author of the paper presenting the results [1]. During more than two years, the astronomers carefully studied HD 69830, a rather inconspicuous nearby star slightly less massive than the Sun. Located 41 light-years away towards the constellation of Puppis (the Stern), it is, with a visual magnitude of 5.95, just visible with the unaided eye. The astronomers' precise radial-velocity measurements [2] allowed them to discover the presence of three tiny companions orbiting their parent star in 8.67, 31.6 and 197 days. "Only ESO's HARPS instrument installed at the La Silla Observatory, Chile, made it possible to uncover these planets", said Michel Mayor, also from Geneva Observatory, and HARPS Principal Investigator. "Without any doubt, it is presently the world's most precise planet-hunting machine" [3]. ESO PR Photo 18d/06 ESO PR Photo 18d/06 Phase Folded Measurements of HD 69830 The detected velocity variations are between 2 and 3 metres per second, corresponding to about 9 km/h! That's the speed of a person walking briskly. Such tiny signals could not have been distinguished from 'simple noise' by most of today's available spectrographs. The newly found planets have minimum masses between 10 and 18 times the mass of the Earth. Extensive theoretical simulations favour an essentially rocky composition for the inner planet, and a rocky/gas structure for the middle one. The outer planet has probably accreted some ice during its formation, and is likely to be made of a rocky/icy core surrounded by a quite massive envelope. Further calculations have also shown that the system is in a dynamically stable configuration. ESO PR Photo 18e/06 ESO PR Photo 18e/06 Formation Process of the Planetary System The outer planet also appears to be located near the inner edge of the habitable zone, where liquid water can exist at the surface of rocky/icy bodies. Although this planet is probably not Earth-like due to its heavy mass, its discovery opens the way to exciting perspectives. "This alone makes this system already exceptional", said Willy Benz, from Bern University, and co-author. "But the recent discovery by the Spitzer Space Telescope that the star most likely hosts an asteroid belt is adding the cherry to the cake." With three roughly equal-mass planets, one being in the habitable zone, and an asteroid belt, this planetary system shares many properties with our own solar system. "The planetary system around HD 69830 clearly represents a Rosetta stone in our understanding of how planets form", said Michel Mayor. "No doubt it will help us better understand the huge diversity we have observed since the first extra-solar planet was found 11 years ago." High resolution images and their captions are available on this page. Video footage and animations are also available on this page.

  8. Meningococcal carriage in the African meningitis belt

    PubMed Central

    2013-01-01

    A meningococcal serogroup A polysaccharide/tetanus toxoid conjugate vaccine (PsA-TT) (MenAfriVac#x2122;) is being deployed in countries of the African meningitis belt. Experience with other polysaccharide/protein conjugate vaccines has shown that an important part of their success has been their ability to prevent the acquisition of pharyngeal carriage and hence to stop transmission and induce herd immunity. If PsA-TT is to achieve the goal of preventing epidemics, it must be able to prevent the acquisition of pharyngeal carriage as well as invasive meningococcal disease and whether PsA-TT can prevent pharyngeal carriage needs to be determined. To address this issue, a consortium (the African Meningococcal Carriage (MenAfriCar) consortium) was established in 2009 to investigate the pattern of meningococcal carriage in countries of the African meningitis belt prior to and after the introduction of PsA-TT. This article describes how the consortium was established, its objectives and the standardised field and laboratory methods that were used to achieve these objectives. The experience of the MenAfriCar consortium will help in planning future studies on the epidemiology of meningococcal carriage in countries of the African meningitis belt and elsewhere. Un vaccin conjugué contenant un polysaccharide du sérogroupe A méningococcique et une anatoxine du tétanos (PsA-TT) (MenAfriVac™) est en cours de déploiement dans les pays de la ceinture africaine de la méningite. L’ expérience avec d’ autres vaccins conjugués polysaccharide/protéine a montré qu’ une partie importante de leur succès a été leur capacité à empêcher l’ acquisition du portage pharyngé et donc à arrêter la transmission et à induire une immunité de group. Si PsA-TT doit d’ atteindre l’ objectif de prévenir les épidémies, il devrait être en mesure d’ empêcher l’ acquisition du portage pharyngé ainsi que la méningococcie invasive et le fait que PsA-TT puisse empêcher le portage pharyngé devrait être déterminé. Pour résoudre ce problème, le consortium MenAfriCar (Consortium Africain du Portage Méningococcique) a été établi en 2009 pour étudier le mode de portage du méningocoque dans les pays de la ceinture africaine de la méningite avant et après l’ introduction de PsA-TT. Cet article décrit comment le consortium a été établi, ses objectifs et les méthodes de laboratoire et de terrain standardisées qui ont été utilisées pour atteindre ces objectifs. L’ expérience du consortium MenAfriCar aidera à planifier les futures études sur l’ épidémiologie du portage du méningocoque dans les pays de la ceinture africaine de la méningite et d’ ailleurs. Se está utilizando una vacuna meningocócica conjugada (MenAfriVac™) de polisacárido del serogrupo A / tétano toxoide (PsA-TT) en países del cinturón Africano de meningitis. Las experiencias obtenidas con otras vacunas conjugadas polisacárido/proteína han demostrado que una parte importante de su éxito se debe a su habilidad para prevenir la colonización faríngea de los portadores, acabando por lo tanto con la transmisión, y a la de inducir la protección de rebaño. Si PsA-TT ha de cumplir el objetivo de prevenir epidemias, debe ser capaz de prevenir el estado de portador faríngeo, al igual que la enfermedad invasiva por meningococo, y para ello es necesario determinar si la PsA-TT puede prevenir la colonización faríngea. Con el fin de abordar esta cuestión se estableció un consorcio africano en el 2009 - el MenAfriCar (African Meningococcal Carriage Consortium) – para investigar los patrones del estado de portador de meningococo en paí

  9. Equatorial irregularity belt and its movement during a magnetic storm

    NASA Technical Reports Server (NTRS)

    Vats, H. O.; Chandra, H.; Deshpande, M. R.; Rastogi, R. G.; Murthy, B. S.; Janve, A. V.; Rai, R. K.; Singh, M.; Gurm, H. S.; Jain, A. R.

    1978-01-01

    Evidence for an equatorial irregularity belt and its movement during a magnetic storm has been obtained from Faraday rotation measurements at a chain of 140-MHz radio beacons receiving from the ATS-6 satellite. The stations covered a latitude region from the magnetic equator to the 45 deg N dip on the Indian subcontinent. An irregularity belt extending from the magnetic equator to about 27 deg N latitude was observed during the main phase of the magnetic storm of 10 January, 1976.

  10. Exploring fold and thrust belts in Google Earth

    NSDL National Science Digital Library

    Jack Loveless

    Google Earth enhances traditional geologic maps by allowing the viewer to explore three-dimensional map patterns and the interaction between structure and topography in dictating those map patterns. This activity overlays 4, 7.5' USGS quadrangles on Google Earth terrain and imagery data and encourages students to investigate common features of fold-and-thrust belts. Keywords: Google Earth, fold-and-thrust belt, visualization

  11. Kuiper Belt Objects Along the Pluto Express Path

    NASA Technical Reports Server (NTRS)

    Jewitt, David

    1999-01-01

    The objective of this proposal was to mount a ground-based search for Kuiper Belt objects near the trajectory of the NASA Pluto Express spacecraft. The high density of Kuiper Belt objects established from work on Mauna Kea makes it probable that one or more bodies can be visited by Pluto Express after its encounter with Pluto. The work was funded during its first year through NASA HQ. The second year was funded through Goddard. The third year was never funded.

  12. Small Main-Belt Asteroid Spectroscopic Survey: Initial Results

    Microsoft Academic Search

    Shui Xu; Richard P. Binzel; Thomas H. Burbine; Schelte J. Bus

    1995-01-01

    The spectral characterization of small asteroids is important for understanding the evolution of their compositional and mineralogical properties. We report the results of a CCD spectroscopic survey of small main-belt asteroids which we call the Small Main-belt Asteroid Spectroscopic Survey (SMASS). Spectra of 316 asteroids were obtained, with wavelength coverage ranging from 4000 to 10000 Å (0.4 to 1 ?m).

  13. “Abomination”—Life as a Bible Belt Gay

    Microsoft Academic Search

    Bernadette Barton

    2010-01-01

    Drawing on observation, autoethnography, and audio-taped interviews, this article explores the religious backgrounds and experiences of Bible Belt gays. In the Bible Belt, Christianity is not confined to Sunday worship. Christian crosses, messages, paraphernalia, music, news, and attitudes permeate everyday settings. Consequently, Christian fundamentalist dogma about homosexuality—that homosexuals are bad, diseased, perverse, sinful, other, and inferior—is cumulatively bolstered within a

  14. Injuries to belted older children in motor vehicle crashes

    Microsoft Academic Search

    J. Felipe García-España; Dennis R. Durbin

    2008-01-01

    ContextThe American Academy of Pediatrics and the National Highway Traffic Safety Administration currently recommend that, unless they are under 57in. in height, 8–12-year-old children use seat belts and all should ride in the rear seats of vehicles. These recommendations assume that the vehicle seat belt should provide adequate protection for these older children in the event of a crash.

  15. A Multi-Disciplinary Approach to Seat Belt Issues

    Microsoft Academic Search

    Stephen J. Werber

    1980-01-01

    To fully appreciate the life-saving and injury-reduction capacity of seat belt restraint systems, it is necessary to examine several non-legal topics which have direct bearing on what the law should reflect. In addition, these topics could prove to have practical application for the attorney attempting to establish the necessity for judicial acceptance of the seat belt defense. These areas include:

  16. Extending the core paradox posed by an early dynamo

    NASA Astrophysics Data System (ADS)

    Tarduno, J. A.; Cottrell, R. D.

    2014-12-01

    New, higher values of core thermal conductivity, together with the reliance of any early geodynamo on thermal convection, represent a paradox (Olson, 2013). These factors suggest either early Earth lacked an internally-generated magnetic field or novel mechanisms for driving an early dynamo. The oldest record of past field strength from in situ igneous rocks comes from 3.4 to 3.45 Ga dacites of the Barberton and Nondweni Greenstone belts of South Africa. These analyses, based on single silicate crystals containing magnetic inclusions with ideal recording characteristics, indicate a field strength within 50 to 70% of the present-day field (Tarduno et al., 2010). Much older igneous rocks are generally not viable as paleomagnetic recorders because of their high metamorphic state (amphibolite grade or higher). Here we discuss extending Earth's magnetic field history further back in time using Archean and Hadean zircons hosting magnetic inclusions that are now found in younger sedimentary units of low metamorphic grade. Thellier-Coe paleointensity data passing reliability checks from zircons of the Jack Hills belt (Western Australia) suggest the presence of a magnetic field at 3.55 Ga, thereby extending the core paradox by 100 million years. We will discuss our continuing efforts to test for the presence/absence of a dynamo field between 3.55 Ga and 4.2 Ga.

  17. Records of geomagnetism, climate, and tectonics across a Paleoarchean erosion surface

    NASA Astrophysics Data System (ADS)

    Bradley, Kyle; Weiss, Benjamin P.; Buick, Roger

    2015-06-01

    Paleomagnetism has provided key constraints on the evolution of Earth's climate, geomagnetic field, and continental geography through Phanerozoic and Proterozoic time. Extending these constraints into the Archean eon has been particularly challenging due to the paucity of the ancient rock record. Here we report paleomagnetic measurements on the NASA Astrobiology Drilling Project (ABDP)-8 core drilled through one of the world's least deformed and least metamorphosed Paleoarchean [3200-3600 million year old (Ma)] rock successions located in the East Strelley Belt of the eastern Pilbara Craton, Australia. Our results show that the ?3350 Ma Euro Basalt preserves a shallow magnetic inclination that appears to have formed as a result of early seafloor hydrothermal alteration, suggesting that the evaporitic carbonate platform of the conformably underlying Strelley Pool Formation was deposited in a near-equatorial location. This is consistent with (although does not require) late Paleoarchean climatic zoning, low orbital obliquity, and a geocentric axial dipole (GAD) field geometry similar to that of the Phanerozoic. The Euro Basalt paleopole overlaps with previously published Paleoarchean poles from the East Pilbara craton and with time-equivalent poles reported from the Barberton Greenstone Belt of the Kaapvaal craton, supporting the existence of a Paleoarchean Vaalbara continental aggregation.

  18. Reassessing the biogenicity of Earth’s oldest trace fossil with implications for biosignatures in the search for early life

    PubMed Central

    Grosch, Eugene G.; McLoughlin, Nicola

    2014-01-01

    Microtextures in metavolcanic pillow lavas from the Barberton greenstone belt of South Africa have been argued to represent Earth’s oldest trace fossil, preserving evidence for microbial life in the Paleoarchean subseafloor. In this study we present new in situ U–Pb age, metamorphic, and morphological data on these titanite microtextures from fresh drill cores intercepting the type locality. A filamentous microtexture representing a candidate biosignature yields a U–Pb titanite age of 2.819 ± 0.2 Ga. In the same drill core hornfelsic-textured titanite discovered adjacent to a local mafic sill records an indistinguishable U–Pb age of 2.913 ± 0.31 Ga, overlapping with the estimated age of intrusion. Quantitative microscale compositional mapping, combined with chlorite thermodynamic modeling, reveals that the titanite filaments are best developed in relatively low-temperature microdomains of the chlorite matrix. We find that the microtextures exhibit a morphological continuum that bears no similarity to candidate biotextures found in the modern oceanic crust. These new findings indicate that the titanite formed during late Archean ca. 2.9 Ga thermal contact metamorphism and not in an early ca. 3.45 Ga subseafloor environment. We therefore question the syngenicity and biogenicity of these purported trace fossils. It is argued herein that the titanite microtextures are more likely abiotic porphyroblasts of thermal contact metamorphic origin that record late-stage retrograde cooling in the pillow lava country rock. A full characterization of low-temperature metamorphic events and alternative biosignatures in greenstone belt pillow lavas is thus required before candidate traces of life can be confirmed in Archean subseafloor environments. PMID:24912193

  19. The Walker Lane Belt in northeastern California

    SciTech Connect

    Grose, T.L.T. (Colorado School of Mines, Golden, CO (United States). Dept. of Geology and Geological Engineering)

    1993-04-01

    The Walker Lane Belt (WLB) has been suspected to significantly project NW-ward into NE CA from the Pyramid Lake-Honey Lake area which has been generally regarded as its northwestern terminus. Within the WLB, most of the exposed rocks are Miocene to Late Quaternary (10--0.1 Ma) volcanics, mainly andesitic, but significantly rhyolitic and basaltic. The Hayden Hill Au mine within a Mid-Miocene NNW-SSE volcanotectonic depression and the Quaternary NE-SW Eagle lake volcanotectonic depression are confined within the WLB. Most of the faults are high-angle normal and right normal, W-dipping, NW- to N-trending, and locally left-stepping en echelon, and 2 to 18 km long. Dip slip varies from 10 to 200 m. Strike slip across the entire zone seems impossible to determine, but probably is less than 20 km since Mid-Miocene. Many faults localize volcanic vents, though most do not appear to. Tectonic tilt of beds within fault blocks is less than 10[degree]. Fault activity and volcanism both continued at a slow rate from Mid-Miocene to Late Quaternary. The WLB in NE CA is a transitional boundary between the Sierra Nevada-Cascade arc on the southwest and the Basin and Range-Modoc Plateau on the northeast.

  20. Spectroscopy of Kuiper Belt Objects and Centaurs

    NASA Astrophysics Data System (ADS)

    de Bergh, C.; Barucci, A.; Doressoundiram, A.; Dotto, E.

    Due to their faintness, only a small fraction of the Kuiper Belt Objects (KBOs) and Centaurs discovered so far have been studied by spectroscopy. The spectra acquired have revealed a large variety of spectral shapes. Very few of them present absorptions. Only water ice (for a few Centaurs and KBOs) and methane (for the KBO 50000 Quaoar) have been identified unambiguously at the surface of these primitive bodies. Some weak features are found in the near infrared (for the KBO 26375 (1999DE9)) as well as in the visible (for the KBOs 47932 (2000 GN171), 38628 Huya, and 2003 AZ84) that are tentatively assigned to the presence of hydrated silicates. Other features (a narrow one due to methanol ice - or ice of a similar compound -, and a broad one that could be due to olivine) appear only in spectra of the Centaur 5145 Pholus. A few objects have heterogeneous surfaces revealed by differences in spectra recorded for different rotational phases. We will review the spectroscopic investigations and modelling attempts made so far, and see what can be deduced from them. We will then evaluate the needs for additional spectral data and laboratory data to optimize the scientific return of the observations that have been carried out. Some concluding remarks on object selections for future spectroscopic investigations and target selections for space exploration will be made.

  1. Trapped radiation belts of Saturn - First look

    NASA Technical Reports Server (NTRS)

    Fillius, W.; Ip, W. H.; Mcilwain, C. E.

    1980-01-01

    Data on the magnetosphere of Saturn obtained with the trapped radiation detector package on board the Pioneer 11 spacecraft is reported. Radiation belt profiles determined by the trapped radiation detectors on Pioneer 10 and 11 indicate that Saturn's magnetosphere is intermediate in size between those of the earth and Jupiter, with particle intensities similar to those of the earth. The outer region of the Saturn magnetosphere is found to contain particles of lower energy than the outer region, being strongly influenced by the time-varying solar wind. The moons and rings of Saturn are observed to be effective absorbers of trapped particles, confirming the discoveries of the F ring, the Pioneer ring division and the moon 1979 S 2. Particle diffusion rates are used to estimate a cross-sectional area of greater than 7 x 10 to the 13th sq cm and an opacity greater than 0.00001 for the F ring. It is suggested that cosmic-ray albedo neutron decay be studied as a possible source of energetic particles in the inner magnetosphere of Saturn.

  2. Radiation Belt Electron Dynamics: Modeling Atmospheric Losses

    NASA Technical Reports Server (NTRS)

    Selesnick, R. S.

    2003-01-01

    The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .

  3. Seat Belts Pay Off. The Use of Economic Incentives and Public Education to Increase Seat Belt Use in a Community. Final Report.

    ERIC Educational Resources Information Center

    Campbell, B. J.; And Others

    A six-month campaign to increase seat belt use in Chapel Hill and Carrboro, North Carolina centered around the idea of giving out economic incentives for seat belt wearing. The approach was to stop vehicles at random and give all belted vehicle occupants a small prize and a chance for a large cash prize. Precampaign activities involve collecting…

  4. Nd and Sr isotopic constraints on the source of Alleghanian granites in the Raleigh metamorphic belt and Eastern slate belt, southern Appalachians, U.S.A

    Microsoft Academic Search

    David G. Coler; Scott D. Samson; J. Alexander Speer

    1997-01-01

    Pennsylvanian-Permian granites that intrude the Raleigh metamorphic belt and the Eastern slate belt of the southern Appalachian orogen account for ? 40% of the total volume of granite produced during the Alleghanian orogeny. We report major- and trace-element concentrations and initial Nd and Sr isotopic compositions from 31 samples of Allegahanian granites that intrude these belts to further constrain the

  5. The effects of seat belts on injury severity of front and rear seat occupants in the same frontal crash

    Microsoft Academic Search

    Donald F. Huelke; Charles P. Compton

    1995-01-01

    Data on passenger cars in frontal crashes were reviewed using NASS 1980–1991. Only crashes with one or more rear seat passengers were included. Combinations (pairs) were made based on restraint use: lap-shoulder belts in the front seat (or no belts worn) and lap belts, (or belts worn) in the rear seat. Passive belts or child restrained occupants were not included.

  6. Electrospun nanofiber belts made from high performance copolyimide

    NASA Astrophysics Data System (ADS)

    Chen, Shuiliang; Hu, Ping; Greiner, Andreas; Cheng, Chuyun; Cheng, Haofang; Chen, Fangfang; Hou, Haoqing

    2008-01-01

    Electrospun nanofibers based on copolyimides were made, aiming at finding a promising method for improving the mechanical properties of electrospun polyimide nanofibers. The copolyimide had a backbone consisting of 3,3',4,4'-biphenyl-tetracarboxylic dianhydride (BPDA), biphenylamide (BPA) and 4,4'-oxydianiline (ODA) residues. The structure and composition of the copolyimide was controlled by the ratio of rigid BPA and flexible ODA moieties. The electrospun copolyimide nanofibers were collected in the form of a belt using a rotating disc with a rim of 8 mm width. Scanning electron microscopy (SEM), infrared (IR) spectroscopy, x-ray scattering and tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were used to characterize the nanofiber belts. The nanofibers had a diameter range from 80 to 300 nm and were well aligned in the belts. The thermal stability of the nanofiber belts was over 460 °C. The tensile test showed that the copolyimide nanofiber belts had much better mechanical properties than either of the flexible and rigid homo-polyimide (homo-PI) nanofiber belts. The tensile strength, modulus and elongation to break of the copolyimide nanofiber belt with BPA/ODA ratio of 40/60 are respectively 1.1 ± 0.1 GPa, 6.2 ± 0.7 GPa and 20.8 ± 1.2%, compared to 459 ± 36 MPa, 2.1 ± 0.3 GPa and 41.3 ± 2.2% for BPDA/ODA homo-PI as well as 384 ± 18 MPa, 11.5 ± 0.6 GPa and 3.9 ± 0.1% for BPDA/BPA homo-PI. The important feature is that the electrospun polymer nanofibers can be made very strong by using copolyimides as spinning materials.

  7. Electrospun nanofiber belts made from high performance copolyimide.

    PubMed

    Chen, Shuiliang; Hu, Ping; Greiner, Andreas; Cheng, Chuyun; Cheng, Haofang; Chen, Fangfang; Hou, Haoqing

    2008-01-01

    Electrospun nanofibers based on copolyimides were made, aiming at finding a promising method for improving the mechanical properties of electrospun polyimide nanofibers. The copolyimide had a backbone consisting of 3,3',4,4'-biphenyl-tetracarboxylic dianhydride (BPDA), biphenylamide (BPA) and 4,4'-oxydianiline (ODA) residues. The structure and composition of the copolyimide was controlled by the ratio of rigid BPA and flexible ODA moieties. The electrospun copolyimide nanofibers were collected in the form of a belt using a rotating disc with a rim of 8 mm width. Scanning electron microscopy (SEM), infrared (IR) spectroscopy, x-ray scattering and tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were used to characterize the nanofiber belts. The nanofibers had a diameter range from 80 to 300 nm and were well aligned in the belts. The thermal stability of the nanofiber belts was over 460?°C. The tensile test showed that the copolyimide nanofiber belts had much better mechanical properties than either of the flexible and rigid homo-polyimide (homo-PI) nanofiber belts. The tensile strength, modulus and elongation to break of the copolyimide nanofiber belt with BPA/ODA ratio of 40/60 are respectively 1.1 ± 0.1 GPa, 6.2 ± 0.7 GPa and 20.8 ± 1.2%, compared to 459 ± 36 MPa, 2.1 ± 0.3 GPa and 41.3 ± 2.2% for BPDA/ODA homo-PI as well as 384 ± 18 MPa, 11.5 ± 0.6 GPa and 3.9 ± 0.1% for BPDA/BPA homo-PI. The important feature is that the electrospun polymer nanofibers can be made very strong by using copolyimides as spinning materials. PMID:21730539

  8. Super-Comet or Big Asteroid Belt?

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Figure 1: Spectrograph of HD 69830

    This graph of data from NASA's Spitzer Space Telescope demonstrates that the dust around a nearby star called HD 69830 (upper line) has a very similar composition to that of Comet Hale-Bopp. Spitzer spotted large amounts of this dust in the inner portion of the HD 69830 system.

    The bumps and dips seen in these data, or spectra, represent the 'fingerprints' of various minerals. Spectra are created when an instrument called a spectrograph spreads light out into its basic parts, like a prism turning sunlight into a rainbow. These particular spectra reveal the presence of the silicate mineral called olivine, and more specifically, a type of olivine called forsterite, which is pictured in the inset box. Forsterite is a bright-green gem found on Earth, on the 'Green Sand Beach' of Hawaii among other places; and in space, in comets and asteroids.

    Because the dust around HD 69830 has a very similar make-up to that of Comet Hale-Bopp, astronomers speculate that it might be coming from a giant comet nearly the size of Pluto. Such a comet may have been knocked into the inner solar system of HD 69830, where it is now leaving in its wake a trail of evaporated dust.

    Nonetheless, astronomers say the odds that Spitzer has caught a 'super-comet' spiraling in toward its star - an unusual and relatively short-lived event - are slim. Instead, they favor the theory that the observed dust is actually the result of asteroids banging together in a massive asteroid belt.

    The data of HD 69830's dust were taken by Spitzer's infrared spectrograph. The data of Comet Hale-Bopp were taken by the European Space Agency's Infrared Observatory Satellite. The picture of forsterite comes courtesy of Dr. George Rossman, California Institute of Technology, Pasadena.

  9. The Fossilized Size Distribution of the Main Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Durda, D.; Nesvorny, D.; Jedicke, R.; Morbidelli, A.

    2003-05-01

    At present, we do not understand how the main asteroid belt evolved into its current state. During the planet formation epoch, the primordial main belt (PMB) contained several Earth masses of material, enough to allow the asteroids to accrete on relatively short timescales (e.g., Weidenschilling 1977). The present-day main belt, however, only contains 5e-4 Earth masses of material (Petit et al. 2002). Constraints on this evolution come from (i) the observed fragments of differentiated asteroids, (ii) meteorites collected from numerous differentiated parent bodies, (iii) the presence of ˜ 10 prominent asteroid families, (iv) the "wavy" size-frequency distribution of the main belt, which has been shown to be a by-product of substantial collisional evolution (e.g., Durda et al. 1997), and (v) the still-intact crust of (4) Vesta. To explain the contradictions in the above constraints, we suggest the PMB evolved in this fashion: Planetesimals and planetary embryos accreted (and differentiated) in the PMB during the first few Myr of the solar system. Gravitational perturbations from these embryos dynamically stirred the main belt, enough to initiate fragmentation. When Jupiter reached its full size, some 10 Myr after the solar system's birth, its perturbations, together with those of the embryos, dynamically depleted the main belt region of ˜ 99% of its bodies. Much of this material was sent to high (e,i) orbits, where it continued to pummel the surviving main belt bodies at high impact velocities for more than 100 Myr. While some differentiated bodies in the PMB were disrupted, most were instead scattered; only small fragments from this population remain. This period of comminution and dynamical evolution in the PMB created, among other things, the main belt's wavy size distribution, such that it can be considered a "fossil" from this violent early epoch. From this time forward, however, relatively little collisional evolution has taken place in the main belt, consistent with the surprising paucity of prominent asteroid families. Preliminary modeling results of this scenario and implications will be presented.

  10. The fossilized size distribution of the main asteroid belt

    NASA Astrophysics Data System (ADS)

    Bottke, William F.; Durda, Daniel D.; Nesvorný, David; Jedicke, Robert; Morbidelli, Alessandro; Vokrouhlický, David; Levison, Hal

    2005-05-01

    Planet formation models suggest the primordial main belt experienced a short but intense period of collisional evolution shortly after the formation of planetary embryos. This period is believed to have lasted until Jupiter reached its full size, when dynamical processes (e.g., sweeping resonances, excitation via planetary embryos) ejected most planetesimals from the main belt zone. The few planetesimals left behind continued to undergo comminution at a reduced rate until the present day. We investigated how this scenario affects the main belt size distribution over Solar System history using a collisional evolution model (CoEM) that accounts for these events. CoEM does not explicitly include results from dynamical models, but instead treats the unknown size of the primordial main belt and the nature/timing of its dynamical depletion using innovative but approximate methods. Model constraints were provided by the observed size frequency distribution of the asteroid belt, the observed population of asteroid families, the cratered surface of differentiated Asteroid (4) Vesta, and the relatively constant crater production rate of the Earth and Moon over the last 3 Gyr. Using CoEM, we solved for both the shape of the initial main belt size distribution after accretion and the asteroid disruption scaling law QD?. In contrast to previous efforts, we find our derived QD? function is very similar to results produced by numerical hydrocode simulations of asteroid impacts. Our best fit results suggest the asteroid belt experienced as much comminution over its early history as it has since it reached its low-mass state approximately 3.9-4.5 Ga. These results suggest the main belt's wavy-shaped size-frequency distribution is a "fossil" from this violent early epoch. We find that most diameter D?120 km asteroids are primordial, with their physical properties likely determined during the accretion epoch. Conversely, most smaller asteroids are byproducts of fragmentation events. The observed changes in the asteroid spin rate and lightcurve distributions near D˜100-120 km are likely to be a byproduct of this difference. Estimates based on our results imply the primordial main belt population (in the form of D<1000 km bodies) was 150-250 times larger than it is today, in agreement with recent dynamical simulations.

  11. Fall Protection Characteristics of Safety Belts and Human Impact Tolerance.

    PubMed

    Hino, Yasumichi; Ohdo, Katsutoshi; Takahashi, Hiroki

    2014-08-23

    Many fatal accidents due to falls from heights have occurred at construction sites not only in Japan but also in other countries. This study aims to determine the fall prevention performance of two types of safety belts: a body belt(1)), which has been used for more than 40?yr in the Japanese construction industry as a general type of safety equipment for fall accident prevention, and a full harness(2, 3)), which has been used in many other countries. To determine human tolerance for impact trauma, this study discusses features of safety belts with reference(4-9)) to relevant studies in the medical science, automobile crash safety, and aircrew safety. For this purpose, simple drop tests were carried out in a virtual workplace to measure impact load, head acceleration, and posture in the experiments, the Hybrid-III pedestrian model(10)) was used as a human dummy. Hybrid-III is typically employed in official automobile crash tests (New Car Assessment Program: NCAP) and is currently recognized as a model that faithfully reproduces dynamic responses. Experimental results shows that safety performance strongly depends on both the variety of safety belts used and the shock absorbers attached onto lanyards. These findings indicate that fall prevention equipment, such as safety belts, lanyards, and shock absorbers, must be improved to reduce impact injuries to the human head and body during falls. PMID:25152087

  12. Basal Murphy belt and Chilhowee Group -- Sequence stratigraphic comparison

    SciTech Connect

    Aylor, J.G. Jr. (Florida State Univ., Tallahassee, FL (United States). Dept. of Geology)

    1994-03-01

    The lower Murphy belt in the central western Blue Ridge is interpreted to be correlative to the Early Cambrian Chilhowee Group of the westernmost Blue Ridge and Appalachian fold and thrust belt. Basal Murphy belt depositional sequence stratigraphy represents a second-order, type-2 transgressive systems tract initiated with deposition of lowstand turbidites of the Dean Formation. These transgressive deposits of the Nantahala and Brasstown Formations are interpreted as middle to outer continental shelf deposits. Cyclic and stacked third-order regressive, coarsening upwards sequences of the Nantahala Formation display an overall increase in feldspar content stratigraphically upsection. These transgressive siliciclastic deposits are interpreted to be conformably overlain by a carbonate highstand systems tract of the Murphy Marble. Palinspastic reconstruction indicates that the Nantahala and Brasstown Formations possibly represent a basinward extension of up to 3 km thick siliciclastic wedge. The wedge tapers to the southwest along the strike of the Murphy belt at 10[degree] and thins northwestward to 2 km in the Tennessee depocenter where it is represented by the Chilhowee Group. The Murphy belt basin is believed to represent a transitional rift-to-drift facies deposited on the lower plate of the southern Blue Ridge rift zone.

  13. JOVIAN EARLY BOMBARDMENT: PLANETESIMAL EROSION IN THE INNER ASTEROID BELT

    SciTech Connect

    Turrini, D.; Coradini, A.; Magni, G., E-mail: diego.turrini@ifsi-roma.inaf.it [Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, Via Fosso del Cavaliere 100, 00133, Rome (Italy)

    2012-05-01

    The asteroid belt is an open window on the history of the solar system, as it preserves records of both its formation process and its secular evolution. The progenitors of the present-day asteroids formed in the Solar Nebula almost contemporary to the giant planets. The actual process producing the first generation of asteroids is uncertain, strongly depending on the physical characteristics of the Solar Nebula, and the different scenarios produce very diverse initial size-frequency distributions (SFDs). In this work, we investigate the implications of the formation of Jupiter, plausibly the first giant planet to form, on the evolution of the primordial asteroid belt. The formation of Jupiter triggered a short but intense period of primordial bombardment, previously unaccounted for, which caused an early phase of enhanced collisional evolution in the asteroid belt. Our results indicate that this Jovian Early Bombardment caused the erosion or the disruption of bodies smaller than a threshold size, which strongly depends on the SFD of the primordial planetesimals. If the asteroid belt was dominated by planetesimals less than 100 km in diameter, the primordial bombardment would have caused the erosion of bodies smaller than 200 km in diameter. If the asteroid belt was instead dominated by larger planetesimals, the bombardment would have resulted in the destruction of bodies as big as 500 km.

  14. The role of EMIC waves in radiation belt dynamics

    NASA Astrophysics Data System (ADS)

    Usanova, Maria; Drozdov, Alexander; Mann, Ian; Orlova, Ksenia; Shprits, Yuri; Ergun, Robert

    2015-04-01

    Electromagnetic ion cyclotron (EMIC) waves are believed to be important for influencing the dynamics of relativistic electrons in the outer radiation belt through a Doppler shifted cyclotron resonance, including changes in electron pitch-angle distributions and electron scattering loss into the atmosphere. Theory predicts that regions of enhanced cold dense plasma density embedded in relatively low background magnetic field (such as the outer plasmasphere or plasmaspheric plumes) should aid EMIC wave growth. Also, enhanced plasma density lowers the energy threshold for electrons that can resonantly interact with EMIC waves down to less than 1 MeV and can be potentially important for loss of radiation belt electrons. However, so far there has been limited direct experimental evidence supporting this hypothesis. Our recent observations on the Van Allen Probes in conjunction with numerical modeling of electron pitch-angle distributions showed that EMIC waves do interact with radiation belt electrons, however this interaction is limited to very energetic (~ several MeV) particles and does not affect the core distribution. Up to this point, the relative importance of EMIC waves in the dynamics of the radiation belts remains unresolved and their properties, especially in the inner magnetosphere need further experimental and theoretical examination. In this talk, we will focus on these Van Allen Probes results and will address outstanding questions related to EMIC wave role in relativistic electron loss in the outer radiation belt.

  15. Fall protection characteristics of safety belts and human impact tolerance.

    PubMed

    Hino, Yasumichi; Ohdo, Katsutoshi; Takahashi, Hiroki

    2014-01-01

    Many fatal accidents due to falls from heights have occurred at construction sites not only in Japan but also in other countries. This study aims to determine the fall prevention performance of two types of safety belts: a body belt, which has been used for more than 40?yr in the Japanese construction industry as a general type of safety equipment for fall accident prevention, and a full harness, which has been used in many other countries. To determine human tolerance for impact trauma, this study discusses features of safety belts with reference to relevant studies in the medical science, automobile crash safety, and aircrew safety. For this purpose, simple drop tests were carried out in a virtual workplace to measure impact load, head acceleration, and posture in the experiments, the Hybrid-III pedestrian model was used as a human dummy. Hybrid-III is typically employed in official automobile crash tests (New Car Assessment Program: NCAP) and is currently recognized as a model that faithfully reproduces dynamic responses. Experimental results shows that safety performance strongly depends on both the variety of safety belts used and the shock absorbers attached onto lanyards. These findings indicate that fall prevention equipment, such as safety belts, lanyards, and shock absorbers, must be improved to reduce impact injuries to the human head and body during falls. PMID:25345426

  16. A Search for 23rd Magnitude Kuiper Belt Comets

    NASA Technical Reports Server (NTRS)

    Luu, Jane

    1997-01-01

    The goal of the project was to identify a statistically significant sample of large (200 km-sized) Kuiper Belt Objects (KBOs), by covering 10 sq. degrees of the sky to a red limiting magnitude m(sub R) = 23. This work differs from, but builds on, previous surveys of the outer solar system in that it will cover a large area to a limiting magnitude that is deep enough to guarantee positive results. The proposed work should provide us with a significant number of 200 km-size KBOs (approx. 20 are expected) for subsequent studies. Such a sample is crucial if we are to investigate the statistical properties of the Belt and its members. It was modified the original research strategy to accommodate unanticipated problems such as the urgent need for follow-up observations,the original goal was still reached: we have substantially increased the number of Kuiper Belt Objects brighter than 23rd mag.

  17. Two new basaltic asteroids in the Outer Main Belt

    E-print Network

    Duffard, R

    2007-01-01

    The identification of other basaltic objects in the asteroid belt is mandatory to explain the diversity in the collection of basaltic meteorites. This diversity requires more than one differentiated parent body, a fact that is consistent with the diversity of differentiated parent bodies implied by the iron meteorites. Based on a list of previously identified candidate basaltic (V-type) asteroids, two asteroids in the outer main belt, (7472) Kumakiri and (10537) 1991 RY16, were spectroscopically observed during an observational run in Calar Alto Observatory, Spain. We confirm the V-type character of these two asteroids that, together with (1459) Magnya, become the only known traces of basaltic found in the outer main belt up to now. We also demonstrate that the searching for candidate V-type asteroids using a photometric survey, like the Sloan Digital Sky Survey, produces reliable results.

  18. Exploring the collisional evolution of the asteroid belt

    NASA Astrophysics Data System (ADS)

    Bottke, W.; Broz, M.; O'Brien, D.; Campo Bagatin, A.; Morbidelli, A.

    2014-07-01

    The asteroid belt is a remnant of planet-formation processes. By modeling its collisional and dynamical history, and linking the results to constraints, we can probe how the planets and small bodies formed and evolved. Some key model constraints are: (i) The wavy shape of the main-belt size distribution (SFD), with inflection points near 100-km, 10--20-km, 1 to a few km, and ˜0.1-km diameter; (ii) The number of asteroid families created by the catastrophic breakup of large asteroid bodies over the last ˜ 4 Gy, with the number of disrupted D > 100 km bodies as small as ˜20 or as large as 60; (iii) the flux of small asteroids derived from the main belt that have struck the Moon over the last 3.5 Ga --- crater SFDs on lunar terrains with known ages suggest the D < 0.1 km projectile population has not varied appreciably over this interval; (iv) Vesta has an intact basaltic crust with two very large basins, but only two, on its surface. Fits to these parameters allow us to predict the shape of the initial main-belt SFD after accretion and the approximate asteroid disruption scaling law, with the latter consistent with numerical hydrocode simulations. Overall, we find that the asteroid belt probably experienced the equivalent of ˜6--10 Gy of comminution over its history. This value may seem strange, considering the solar system is only 4.56 Gy old. One way to interpret it is that the main belt once had more mass that was eliminated by early dynamical processes between 4--4.56 Ga. This would allow for more early grinding, and it would suggest the main belt's wavy-shaped SFD is a ''fossil'' from a more violent early epoch. Simulations suggest that most D > 100 km bodies have been significantly battered, but only a fraction have been catastrophically disrupted. Conversely, most small asteroids today are byproducts of fragmentation events. These results are consistent with growing evidence that most of the prominent meteorite classes were produced by young asteroid families. The big question is how to use what we know to determine the main belt's original size and state. This work is ongoing, but dynamical models hint at many possibilities, including both the late arrival and late removal of material from the main belt. In addition, no model has yet properly accounted for the bombardment of the primordial main belt by leftover planetesimals in the terrestrial planet region. It is also possible to use additional constraints, such as the apparent paucity of Vesta-like or V-type objects in the outer main belt, to argue that the primordial main belt at best only 3--4 its current mass at its start. In our talk, we will review what is known, what has been predicted, and some intriguing directions for the future.

  19. The Size Frequency Distribution of Small Main-Belt Asteroids

    NASA Technical Reports Server (NTRS)

    Burt, Brian J.; Trilling, David E.; Hines, Dean C.; Stapelfeldt, Karl R.; Rebull, Luisa M.; Fuentes, Cesar I.; Hulsebus, Alan

    2012-01-01

    The asteroid size distribution informs us about the formation and composition of the Solar System. We build on our previous work in which we harvest serendipitously observed data of the Taurus region and measure the brightness and size distributions of Main-belt asteroids. This is accomplished with the highly sensitive MIPS 24 micron channel. We expect to catalog 104 asteroids, giving us a statistically significant data set. Results from this investigation will allow us to characterize the total population of small, Main-belt asteroids. Here we will present new results on the completeness of our study; on the presence of size distribution variations with inclination and radial distance in the belt; and early result on other archival fields.

  20. Relativistic surfatron process for Landau resonant electrons in radiation belts

    NASA Astrophysics Data System (ADS)

    Osmane, A.; Hamza, A. M.

    2014-01-01

    Recent theoretical studies of the nonlinear wave-particle interactions for relativistic particles have shown that Landau resonant orbits could be efficiently accelerated along the mean background magnetic field for propagation angles ? in close proximity to a critical propagation ?c associated with a Hopf-Hopf bifurcation condition. In this report, we extend previous studies to reach greater modeling capacities for the study of electrons in radiation belts by including longitudinal wave effects and inhomogeneous magnetic fields. We find that even though both effects can limit the surfatron acceleration of electrons in radiation belts, gains in energy of the order of 100 keV, taking place on one tenth of a millisecond, are sufficiently strong for the mechanism to be relevant to radiation belt dynamics.

  1. The Living with a Star Radiation Belt Storm Probes

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.; Mauk, B. H.; Grebowsky, J. M.; Fox, N. J.

    2007-01-01

    The goal of NASA's Living With a Star Radiation Belt Storm Probe mission is to understand, ideally to the point of predictability, how populations of relativistic electrons and ions in space form or change in response to the variable inputs of energy from the Sun. The investigations selected for this 2-spacecraft mission scheduled for launch in early 2012 address this task by making extensive observations of the plasma waves, thermal, ring current, and relativistic particle populations, and DC electric and magnetic fields within the Earth's inner and outer radiation belts. We first describe the current mission concept within the scope of NASA's strategic plan and the Vision for Exploration, and then consider how its observations will be used to define and quantify the processes that accelerate, transport, and remove particles in the Earth's radiation belts.

  2. Global storm time depletion of the outer electron belt

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, A. Y.; Sitnov, M. I.; Millan, R. M.; Kress, B. T.; Fennell, J. F.; Claudepierre, S. G.; Barnes, R. J.

    2015-04-01

    The outer radiation belt consists of relativistic (>0.5 MeV) electrons trapped on closed trajectories around Earth where the magnetic field is nearly dipolar. During increased geomagnetic activity, electron intensities in the belt can vary by orders of magnitude at different spatial and temporal scales. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the main-phase depletions: adiabatic inflation of electron drift orbits caused by the ring current growth, electron loss into the atmosphere, and electron escape through the magnetopause boundary. In this paper we investigate the relative importance of the adiabatic effect and magnetopause loss to the rapid depletion of the outer belt observed at the Van Allen Probes spacecraft during the main phase of 17 March 2013 storm. The intensities of >1 MeV electrons were depleted by more than an order of magnitude over the entire radial extent of the belt in less than 6 h after the sudden storm commencement. For the analysis we used three-dimensional test particle simulations of global evolution of the outer belt in the Tsyganenko-Sitnov (TS07D) magnetic field model with an inductive electric field. Comparison of the simulation results with electron measurements from the Magnetic Electron Ion Spectrometer experiment shows that magnetopause loss accounts for most of the observed depletion at L>5, while at lower L shells the depletion is adiabatic. Both magnetopause loss and the adiabatic effect are controlled by the change in global configuration of the magnetic field due to storm time development of the ring current; a simulation of electron evolution without a ring current produces a much weaker depletion.

  3. Response of radiation belt simulations to different radial diffusion coefficients

    NASA Astrophysics Data System (ADS)

    Drozdov, A.; Shprits, Y.; Subbotin, D.; Kellerman, A. C.

    2013-12-01

    Resonant interactions between Ultra Low Frequency (ULF) waves and relativistic electrons may violate the third adiabatic invariant of motion, which produces radial diffusion in the electron radiation belts. This process plays an important role in the formation and structure of the outer electron radiation belt and is important for electron acceleration and losses in that region. Two parameterizations of the resonant wave-particle interaction of electrons with ULF waves in the magnetosphere by Brautigam and Albert [2000] and Ozeke et al. [2012] are evaluated using the Versatile Electron Radiation Belt (VERB) diffusion code to estimate their relative effect on the radiation belt simulation. The period of investigation includes quiet time and storm time geomagnetic activity and is compared to data based on satellite observations. Our calculations take into account wave-particle interactions represented by radial diffusion transport, local acceleration, losses due to pitch-angle diffusion, and mixed diffusion. We show that the results of the 3D diffusion simulations depend on the assumed parametrization of waves. The differences between the simulations and potential missing physical mechanisms are discussed. References Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999JA900344 Ozeke, L. G., I. R. Mann, K. R. Murphy, I. J. Rae, D. K. Milling, S. R. Elkington, A. A. Chan, and H. J. Singer (2012), ULF wave derived radiation belt radial diffusion coefficients, J. Geophys. Res., 117, A04222, doi:10.1029/2011JA017463.

  4. Ultra-fast Electrons Explain Third Radiation Belt - Duration: 44 seconds.

    NASA Video Gallery

    In September 2012, NASA's Van Allen Probes observed the radiation belts around Earth had settled into a new configuration, separating into three belts instead of two. Scientists think the unusual p...

  5. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Seats, safety belts, and shoulder harnesses. 121.311 Section 121.311 ...Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane...213 (49 CFR 571.213)), vest- and harness-type child restraint systems,...

  6. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Seats, safety belts, and shoulder harnesses. 121.311 Section 121.311 ...Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane...213 (49 CFR 571.213)), vest- and harness-type child restraint systems,...

  7. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Seats, safety belts, and shoulder harnesses. 121.311 Section 121.311 ...Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane...213 (49 CFR 571.213)), vest- and harness-type child restraint systems,...

  8. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Seats, safety belts, and shoulder harnesses. 121.311 Section 121.311 ...Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane...213 (49 CFR 571.213)), vest- and harness-type child restraint systems,...

  9. Mission Overview for the Radiation Belt Storm Probes Mission

    NASA Astrophysics Data System (ADS)

    Stratton, J. M.; Harvey, R. J.; Heyler, G. A.

    2013-11-01

    Provided here is an overview of Radiation Belt Storm Probes (RBSP) mission design. The driving mission and science requirements are presented, and the unique engineering challenges of operating in Earth's radiation belts are discussed in detail. The implementation of both the space and ground segments are presented, including a discussion of the challenges inherent with operating multiple observatories concurrently and working with a distributed network of science operation centers. An overview of the launch vehicle and the overall mission design will be presented, and the plan for space weather data broadcast will be introduced.

  10. Structural evolution of the Kolar Schist Belt, South India

    NASA Technical Reports Server (NTRS)

    Mukhopahyay, Dilip K.

    1988-01-01

    The structural evolution of the Kolar Schist Belt was discussed. Evidence was described from structures in the ferrigenous quartzite within the schist belt for two periods of nearly coaxial isoclinal folding attributable to E-W compression. This folding was followed by collapse of the F sub 1/F sub 2 folds, forming open F sub 3 folds with NNE-SSW axes. Finally, a period of N-S shortening caused a broad warping of the earlier N-S trending fold axes. There is evidence within the gneisses for shearing produced by similar, nearly E-W compression.

  11. How Montana's deepest hole cut Mississippian carbonates underneath Precambrian belt

    SciTech Connect

    Peterson, C.H.; Nims, R.C. (Unocal Corp., Los Angeles, CA (US))

    1992-08-03

    This paper discusses the Unocal i-B30 Federal Canyon Creek well drilled in the Montana thrust belt about 27 miles northwest of Helena to test Mississippian carbonates in a seismic structure in the footwall of the Eldorado thrust. The well penetrated more than 12,000 ft of thrusted Precambrian belt metasedimentary rocks before encountering a faulted and fractured footwall section of Cretaceous through Mississippian shales, sandstones, and carbonates. The 1-B30 well demonstrated that a more complex duplex structure was present under the Eldorado thrust and that the Madison was deeper than anticipated with a true vertical depth of 16,688 ft.

  12. A Spectroscopically Unique Main Belt Asteroid: 10537 (1991 RY16)

    E-print Network

    Nicholas A. Moskovitz; Samuel Lawrence; Robert Jedicke; Mark Willman; Nader Haghighipour; Schelte J. Bus; Eric Gaidos

    2008-06-13

    We present visible and near-infrared reflectance spectra and interpreted surface mineralogy for asteroid 10537 (1991 RY16). The spectrum of this object is without precedent amongst the Main Belt asteroids. A unique absorption band centered at 0.63 microns could be attributed to one of several mineralogies. Pronounced 1- and 2-micron absorption bands suggest that the composition of 10537 is a mixture of pyroxenes and olivine and that it originated from a parent body that was partially or fully differentiated. The closest available analog is the large Main Belt asteroid 349 Dembowska but 10537 may be an isolated fragment from a completely eroded parent body.

  13. Gold mineralization models for the Virginia gold-pyrite belt, U. S. A

    Microsoft Academic Search

    1985-01-01

    The Virginia gold-pyrite belt is a 30 by 215 km zone extending through the Virginia Piedmont. This belt occurs within metasedimentary and metavolcanic rocks of the central Virginia volcanic-plutonic belt. Rock units have mineral assemblages ranging from lower greenschist to middle amphibolite facies. Within the gold-pyrite belt, gold occurrences are distributed irregularly into clusters controlled by lithostratigraphic features. Clusters may

  14. Energy spectrum and charge composition of a new, long-lived, unstable electron radiation belt

    Microsoft Academic Search

    A. M. Galper; S. V. Koldashov; V. V. Mikhailov; S. A. Voronov; L. V. Maslennikov; N. I. Shvetz

    1999-01-01

    An experimental study of a long-lived unstable electron belt created on March 24, 1991 is presented. The new belt occupied the slot region between the inner and outer radiation belts. Electrons, positrons, and protons with 20-200 MeV\\/c momenta were measured with the Mariya-2 magnetic time-of-flight spectrometer-telescope on board the orbital station Mir. The unstable belt turned out to consist solely

  15. Improved design of VSS controller for a linear belt-driven servomechanism

    Microsoft Academic Search

    A. Hace; K. Jezernik; A. Sabanovic

    2005-01-01

    This paper proposes a new control algorithm for a linear belt-driven servomechanism. The elasticity of the belt and large nonlinear friction along with large variation of parameters limit the applicability of the belt driven servosystems. Design of simple control that can guarantee stable, vibration-free operation for large variation of load is needed to extend application of such a linear stage.

  16. 23 CFR Appendix D to Part 1240 - Determination of National Average Seat Belt Use Rate

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...1240.11 or § 1240.12 of this part, as applicable, along with information on seat belt use rates from the FARS, and an algorithm relating FARS seat belt use rates to observed seat belt use rates (see Appendix 1, note). This procedure will...

  17. The Dynamical Structure of the Kuiper Belt and its Primordial Origin

    E-print Network

    A. Morbidelli; H. F. Levison; R. Gomes

    2007-03-21

    This chapter discusses the dynamical properties of the Kuiper belt population. Then, it focuses on the characteristics of the Kuiper belt that cannot be explained by its evolution in the framework of the current solar system. We review models of primordial solar system evolution that have been proposed to reproduce the Kuiper belt features, outlining advantages and problems of each of them.

  18. The effect of polyesterurethane belt surface roughness on Listeria monocytogenes biofilm formation and its cleaning efficiency

    Microsoft Academic Search

    Yuphakhun Chaturongkasumrit; Hajime Takahashi; Suwimon Keeratipibul; Takashi Kuda; Bon Kimura

    2011-01-01

    Contamination of surfaces in direct contact with food in the processing line is the major cause of finished product cross-contamination, especially conveyor belt surfaces that transfer food products. Polyesterurethane (PSU) is one of the materials widely used in conveyor belt systems; therefore, the objective of this study was to examine the effect of PSU conveyor belt surface roughness on the

  19. Two contrasting paleozoic magmatic belts in northern Inner Mongolia, China: petrogenesis and tectonic implications

    Microsoft Academic Search

    Bin Chen; Bor-ming Jahn; S Wilde; Bei Xu

    2000-01-01

    The Solonker zone, extending from Solonker to Sonidzuoqi and Xilinhot in northern Inner Mongolia, China, has been considered as the suture between the Manchurides and Altaids. Two magmatic belts have been recognized along the suture zone: an older, variably deformed arc-related magmatic belt represented by the Baolidao magma suite, and a younger, collisional granite belt, represented by the Halatu plutons.

  20. From Cars to CartsIncreasing Safety Belt Usage in Shopping Carts

    Microsoft Academic Search

    Joseph R. Ferrari; Charles H. Baldwin

    1989-01-01

    A modified reversal\\/ multiple-baseline design across three supermarkets was used to examine the effectiveness of behavioral interventions in increasing the frequency of safety belt usage in shopping carts. Following low baseline rates, safety belt usage increased significantly during a prompt plus personal contact condition at Stores 1 and 2. Safety belt usage then decreased, but remained above baseline levels, in

  1. NEPTUNE'S MIGRATION INTO A STIRRED-UP KUIPER BELT: A DETAILED COMPARISON OF SIMULATIONS TO OBSERVATIONS

    E-print Network

    Hahn, Joseph M.

    NEPTUNE'S MIGRATION INTO A STIRRED-UP KUIPER BELT: A DETAILED COMPARISON OF SIMULATIONS the consequences of Neptune's outward migration into the Kuiper Belt, with the simulated end states being compared and coworkers, who showed that Neptune's migration into a previously stirred- up Kuiper Belt can account

  2. Seat Belts in School Buses: Analyzing the Literature and Using the Results.

    ERIC Educational Resources Information Center

    Splaine, Pam; Frankel, Steven M.

    1987-01-01

    This literature review addresses three specific safety issues: installing seat belts in new buses, retrofitting existing buses with seat belts, and comparing seat belts with other safety features. While inconclusive evidence is provided concerning the first issue, studies do suggest retiring older buses and possibly equipping buses that meet PL…

  3. Thermo-mechanical structure beneath the young orogenic belt of Taiwan

    E-print Network

    Ma, Kuo-Fong

    Central Range (ECR), Neogene to Paleogene slate belts in the Backbone Range (BR), and the Hsueshan RangeThermo-mechanical structure beneath the young orogenic belt of Taiwan Kuo-Fong Ma*, Teh-Ru Alex Abstract We investigate the thermo-mechanical properties beneath the young orogenic belt of Taiwan

  4. Basal thrust contact of the accreted Carolina Slate belt volcanic arc, southern Appalachian piedmont

    Microsoft Academic Search

    E. F. Stoddard; A. S. Jr. Wylie; D. E. Blake

    1985-01-01

    Fossil evidence indicates that the Carolina Slate belt, interpreted as a late Precambrian to early Paleozoic volcanic arc, is a terrane exotic to North America (Secor et al., 1983). Petrographic and isotopic evidence (Farrar, 1983) suggests that the Raleigh belt, located between the Western and Eastern Carolina Slate belts, is at least partly Grenville basement and has affinity to North

  5. Seat Belt and Child Seat Use in Lipetskaya Oblast, Russia: Frequencies, Attitudes, and Perceptions

    Microsoft Academic Search

    Sai Ma; Nhan Tran; Vladimir E. Klyavin; Francesco Zambon; Kristin W. Hatcher; Adnan A. Hyder

    2012-01-01

    Objective: Despite the importance of understanding seat belt use patterns among drivers and passengers for the purpose of direct interventions or monitoring improvements, no study has described wearing rates for all seat positions in Russia. This study describes observed seat belt use and knowledge, attitudes, and perceptions of seat belt use in Lipetskaya Oblast, Russia.Methods: An observational study on the

  6. Assessment of the static fit of automobile lap-belt systems on front-seat passengers

    Microsoft Academic Search

    R. P. WELLS; R. W. NORMAN; P. BISHOP; D. A. RANNEY

    1986-01-01

    While automobile seat belts are recognized as reducing injury in frontal collisions, the lap belt can cause injury to the abdominal contents during impact. A lap belt which is malpositioned, i.e., above the anterior superior iliac spines (ASIS) of the pelvis before impact, is suggested as a causative factor in many of these injuries. A questionnaire was completed by 198

  7. Long-term Benefits of Prompts to Use Safety Belts among Drivers Exiting Senior Communities

    Microsoft Academic Search

    CORY D. COX; BRIAN S. COX; Daniel J Cox

    2005-01-01

    Senior drivers are vulnerable to automobile crashes and subsequent injury and death. Safety belts reduce health risks associated with auto crashes. Therefore, it is important to encourage senior drivers to wear safety belts while driving. Using a repeated baseline design (AAB), we previously reported that motivating signs boosted safety belt usage by drivers exiting senior communities from baseline (72% and

  8. Plate tectonic model for the Carboniferous evolution of the New England Fold Belt

    Microsoft Academic Search

    C. G. Murray; C. L. Fergusson; P. G. Flood; W. G. Whitaker; R. J. Korsch

    1987-01-01

    The New England Fold Belt forms the easternmost, youngest part of the Tasman Fold Belt System. For much of Late Palaeozoic time, it was a convergent plate margin at the edge of the Australian continent. At present, the New England Fold Belt is separated into the Yarrol Province in the north and the New England Province in the south by

  9. 23 CFR Appendix A to Part 1340 - State Seat Belt Use Survey Reporting Form

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false State Seat Belt Use Survey Reporting Form A Appendix A to Part...UNIFORM CRITERIA FOR STATE OBSERVATIONAL SURVEYS OF SEAT BELT USE Pt. 1340, App. A...A to Part 1340—State Seat Belt Use Survey Reporting Form PART A: To be...

  10. 23 CFR Appendix A to Part 1340 - State Seat Belt Use Survey Reporting Form

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false State Seat Belt Use Survey Reporting Form A Appendix A to Part...UNIFORM CRITERIA FOR STATE OBSERVATIONAL SURVEYS OF SEAT BELT USE Pt. 1340, App. A...A to Part 1340—State Seat Belt Use Survey Reporting Form PART A: To be...

  11. 23 CFR Appendix A to Part 1340 - State Seat Belt Use Survey Reporting Form

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false State Seat Belt Use Survey Reporting Form A Appendix A to Part...UNIFORM CRITERIA FOR STATE OBSERVATIONAL SURVEYS OF SEAT BELT USE Pt. 1340, App. A...A to Part 1340—State Seat Belt Use Survey Reporting Form PART A: To be...

  12. The Behemoth Has a Thick Belt

    NASA Astrophysics Data System (ADS)

    2008-05-01

    Talk about a diet! By resolving, for the first time, features of an individual star in a neighbouring galaxy, ESO's VLT has allowed astronomers to determine that it weighs almost half of what was previously thought, thereby solving the mystery of its existence. The behemoth star is found to be surrounded by a massive and thick torus of gas and dust, and is most likely experiencing unstable, violent mass loss. dusty torus around WOH G64 ESO PR Photo 15/08 The Torus around WOH G64 Artist's Impression WOH G64 is a red supergiant star almost 2 000 times as large as our Sun and is located 163 000 light-years away in the Large Magellanic Cloud, one of the Milky Way's satellite galaxies. "Previous estimates gave an initial mass of 40 times the mass of the Sun to WOH G64. But this was a real problem as it was way too cold, compared to what theoretical models predict for such a massive star. Its existence couldn't be explained," says Keiichi Ohnaka, who led the work on this object. New observations, made with ESO's Very Large Telescope Interferometer, conclude that the gas and dust around the star is arranged in a thick ring, rather than a spherical shell, and the star is thus less hidden than had been assumed. This implies that the object is in fact half as luminous as previously thought, and thus, less massive. The astronomers infer that the star started its life with a mass of 25 solar masses. For such a star, the observed temperature is closer to what one would expect. "Still, the characteristics of the star mean that it may be experiencing a very unstable phase accompanied by heavy mass loss," says co-author Markus Wittkowski from ESO. "We estimate that the belt of gas and dust that surrounds it contains between 3 and 9 solar masses, which means that the star has already lost between one tenth and a third of its initial mass." To reach this conclusion, the team of astronomers used the MIDI instrument to combine the light collected by three pairs of 8.2-m Unit Telescopes of the VLT. This is the first time that MIDI has been used to study an individual star outside our Galaxy. The observations allowed the astronomers to clearly resolve the star. Comparisons with models led them to conclude that the star is surrounded by a gigantic, thick torus, expanding from about 15 stellar radii (or 120 times the distance between the Earth and the Sun - 120 AU!) to more than 250 stellar radii (or 30 000 AU!). "Everything is huge about this system. The star itself is so big that it would fill almost all the space between the Sun and the orbit of Saturn," says Ohnaka. "And the torus that surrounds it is perhaps a light-year across! Still, because it is so far away, only the power of interferometry with the VLT could give us a glimpse on this object. "

  13. Shape, size and multiplicity of main-belt asteroids

    Microsoft Academic Search

    F. Marchis; M. Kaasalainen; E. F. Y. Hom; J. Berthier; J. Enriquez; D. Hestroffer; D. Le Mignant; I. de Pater

    2006-01-01

    This paper presents results from a high spatial resolution survey of 33 main-belt asteroids with diameters >40 km using the Keck II Adaptive Optics (AO) facility. Five of these (45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra) were confirmed to have satellite. Assuming the same albedo as the primary, these moonlets are relatively small (?5% of the primary

  14. CFD MODELLING OF THE STEEL BELT SINTERING PROCESS

    Microsoft Academic Search

    J. Keihäs; P. Mäkelä; J. Ollila; L. Hekkala

    The Outokumpu Steel Belt Sintering (SBS) Technology is used for manufacturing chromite pellets that are charged into a smelting furnace for ferrochromium production. One of the main elements in successful fur- nace operation is the control of gas flows inside the furnace, giving improved temperature distribution in the bed during the process. Computational Fluid Dynamics (CFD) gives excellent opportunities for

  15. DIFFUSION OF PROTONS IN THE OUTER RADIATION BELT

    Microsoft Academic Search

    M. P. Nakada; G. D. Mead

    1965-01-01

    The diffusion of protons in the outer radiation belt due to violation of the third adiabatic invariant has been examined. The particular mechanism studied is one in which variations in the intensity of the solar wind produce magnetic disturbances causing motion of particles between L shells. A Fokker-Planck diffusion equation is used with terms describing Coulomb energy degradation and charge-exchange

  16. Collisional and dynamic evolution of dust from the asteroid belt

    NASA Technical Reports Server (NTRS)

    Gustafson, Bo A. S.; Gruen, Eberhard; Dermott, Stanley F.; Durda, Daniel D.

    1992-01-01

    The size and spatial distribution of collisional debris from main belt asteroids is modeled over a 10 million year period. The model dust and meteoroid particles spiral toward the Sun under the action of Poynting-Robertson drag and grind down as they collide with a static background of field particles.

  17. THE LIFETIME OF ICE ON MAIN BELT ASTEROIDS Norbert Schorghofer

    E-print Network

    Schörghofer, Norbert

    introduce the concept of a ``buried snow line,'' where the loss of ice is sufficiently slow over the age for ice to survive over the age of the solar system exist for all of the main asteroid belt pointed out that on extinct comets, ice may be accessible within 10 m of the surface. Later, Fanale

  18. Smoking, Sociodemographic Determinants, and Stress in the Alabama Black Belt

    ERIC Educational Resources Information Center

    Shuaib, Faisal; Foushee, H. R.; Ehiri, John; Bagchi, Suparna; Baumann, Angela; Kohler, Connie

    2011-01-01

    Purpose: In the Alabama Black Belt, poverty is high, and the educational level is low. Studies have found increased tobacco use among individuals exposed to high levels of stress. Few studies have been conducted in this region to measure smoking status, its sociodemographic determinants, and how smoking status relates to stressful environmental…

  19. Modeling and analysis of belt conveyor using bond graph approach

    Microsoft Academic Search

    Kuo-Hsiung Tseng; Ruey-Fong Chang; Juei-Long Chiu; Te-Wei Shen

    2011-01-01

    By combining a Bond Graph model (BGs model) and a SEBD simulation model developed by MATLAB\\/Simulink software, this study explores the dynamic characteristics of a DC motor when driving a belt conveyor. This study first constructs a BGs model for a DC motor in order to determine the causality relationship between the circuit diagram model of a DC motor and

  20. 47. Northwest Side of Breaker, Rock Belt Line (foreground), date ...

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

    47. Northwest Side of Breaker, Rock Belt Line (foreground), date unknown Historic Photograph, Photograher Unknown; Collection of William Everett, Jr. (Wilkes-Barre, PA), photocopy by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

  1. Impact of the New Zealand Seat Belt Law

    Microsoft Academic Search

    Christopher Garbacz

    1991-01-01

    Offsetting consumer behavior may have reduced the effectiveness of a mandatory seat belt law in reducing fatalities in New Zealand. It appears that the favorable effect on automobile occupants may be offset partially, or in some models perhaps completely, by deaths among cyclists and pedestrians that may be caused by more dangerous driving by drivers who feel safer. Furthermore, the

  2. Evidence for a planetary system sculpting Fomalhaut's dust belt

    NASA Astrophysics Data System (ADS)

    Kalas, Paul

    2005-10-01

    The Sun and at least 15% of stars are surrounded by dust disks that are collisionally replenished by asteroids and comets. Disk structure can be directly tied to the dynamical influence of more massive bodies such as planets. For example, planetary perturbations maintain a ~30 AU radius inner edge to our Kuiper Belt and offset the centre of our zodiacal dust disk ~0.01 AU away from the Sun. Here we discuss the first optical detection of reflected light from dust grains surrounding the nearby star Fomalhaut (HD 216956). We find a belt of material between 133 and 158 AU radius that has a center position offset ~15 AU from the stellar position, and with a sharp inner edge. Given Fomalhaut's proximity to the Sun (7.7 pc), these images represent the closest and highest angular resolution view of an extrasolar analog to our Kuiper Belt. We interpret the center of symmetry offset and the sharp inner edge of Fomalhaut's belt as evidence for planet-mass objects orbiting the star.

  3. New Horizons: NASA's Pluto-Kuiper Belt Mission

    Microsoft Academic Search

    H. A. Weaver; S. A. Stern

    2008-01-01

    The New Horizons (NH) mission was selected by NASA in November 2001 to conduct the first in situ reconnaissance of Pluto and the Kuiper belt. The NH spacecraft was launched on January 19, 2006, received a gravity assist from Jupiter during closest approach on February 28, 2007, and is currently heading for a flyby encounter with the Pluto system. NH

  4. Pioneer Anomaly? Gravitational Pull due to the Kuiper Belt

    Microsoft Academic Search

    José A. de Diego; Darío Núñez; Jesús Zavala

    2006-01-01

    In this work, we study the gravitational influence of the material extending from Uranus orbit to the Kuiper belt and beyond on objects moving within these regions. We conclude that a density distribution given by rho (r)=(1)\\/(r)\\\\ (for\\\\ r >= 20\\\\ AU) generates a constant acceleration towards the Sun on those objects, which, with the proper amount of mass, accounts

  5. The edge of the Kuiper belt: the Planet X scenario

    Microsoft Academic Search

    M. D. Melita; I. P. Williams; Simon J. Collander-Brown; Alan Fitzsimmons

    2004-01-01

    Our goal is to determine whether or not the observed sudden termination of the Edgeworth-Kuiper belt can be the result of perturbations from a hypothetical planet. We investigate the effects that such an object would produce on the primordial orbital distribution if the trans-neptunian objects, for a range of masses and orbital parameters of the hypothetical planet. In this numerical

  6. The edge of the Kuiper belt: the Planet X scenario

    Microsoft Academic Search

    M. D. Melita; I. P. Williams; Simon J. Collander-Brown; Alan Fitzsimmons

    2004-01-01

    Our goal is to determine whether or not the observed sudden termination of the Edgeworth–Kuiper belt can be the result of perturbations from a hypothetical planet. We investigate the effects that such an object would produce on the primordial orbital distribution if the trans-neptunian objects, for a range of masses and orbital parameters of the hypothetical planet. In this numerical

  7. DISC BRAKE SYSTEM (CENTER), INCLUDING BELT DRIVE TO SECONDARY GENERAL ...

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

    DISC BRAKE SYSTEM (CENTER), INCLUDING BELT DRIVE TO SECONDARY GENERAL MOTORS ENGINE (LEFT)AND FERREL REDUCTION GEAR CONNECTION TO ALLIS-CHALMERS DIESEL ENGINE (RIGHT), LOOKING NORTH. NOTE TORQUE CONVERTER (TOP) AND THROTTLE (BELOW) LINES CONNECTING TO PRIMARY ENGINE. - Mad River Glen, Single Chair Ski Lift, 62 Mad River Glen Resort Road, Fayston, Washington County, VT

  8. Pluto, the Kuiper Belt, and the Trans-Neptunian Objects

    E-print Network

    Walter, Frederick M.

    Pluto, the Kuiper Belt, and the Trans-Neptunian Objects #12;Recap ­ Origin, & Rabinowitz · Radius ~ 1163 km ­ About as large as Pluto · P ~ 560 years sub-divisions: ­ Plu3nos: same orbit as Pluto (a 2:3 resonance with Neptune

  9. On enigmatic properties of the main belt asteroids

    Microsoft Academic Search

    G. Kochemasov

    2006-01-01

    Two properties of the main belt asteroids still bother planetologists: why they are mainly of an oblong shape and why the larger bodies rotate faster than the smaller ones. According to the excepted impact theory constantly produced fragments should be rather more or less of equal dimensions. Larger bodies are more difficult to make rotating by hits than the smaller

  10. 14 CFR 125.211 - Seat and safety belts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...PERSONS ON BOARD SUCH AIRCRAFT Instrument and...211 Seat and safety belts. (a...Federal motor vehicle safety standards”; and...MOTOR VEHICLES AND AIRCRAFT” in red lettering...Federal Motor Vehicle Safety Standard No. 213...approved for use in aircraft; and...

  11. 14 CFR 125.211 - Seat and safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...PERSONS ON BOARD SUCH AIRCRAFT Instrument and...211 Seat and safety belts. (a...Federal motor vehicle safety standards”; and...MOTOR VEHICLES AND AIRCRAFT” in red lettering...Federal Motor Vehicle Safety Standard No. 213...approved for use in aircraft; and...

  12. 14 CFR 125.211 - Seat and safety belts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...PERSONS ON BOARD SUCH AIRCRAFT Instrument and...211 Seat and safety belts. (a...Federal motor vehicle safety standards”; and...MOTOR VEHICLES AND AIRCRAFT” in red lettering...Federal Motor Vehicle Safety Standard No. 213...approved for use in aircraft; and...

  13. 14 CFR 125.211 - Seat and safety belts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...PERSONS ON BOARD SUCH AIRCRAFT Instrument and...211 Seat and safety belts. (a...Federal motor vehicle safety standards”; and...MOTOR VEHICLES AND AIRCRAFT” in red lettering...Federal Motor Vehicle Safety Standard No. 213...approved for use in aircraft; and...

  14. Interior of secondary building, first floor, ceilingmounted drive belt wheels, ...

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

    Interior of secondary building, first floor, ceiling-mounted drive belt wheels, bevel gears and open pigment conveyor (center). Desk with paint labels below, vaulted brick ceiling above. - Tarr and Wonson Paint Factory, End of Horton Street, Gloucester, Essex County, MA

  15. Poludnista Dorsa, Venus: History and context of a deformation belt

    E-print Network

    Hansen, Vicki

    Poludnista Dorsa, Venus: History and context of a deformation belt D. A. Young and V. L. Hansen lowlands comprise 80% of Venus's surface, and thus developing a geological understating of resurfacing and tectonism is critical for our understanding of Venus' evolution. In this paper, global, regional, and local

  16. A Population of Comets in the Main Asteroid Belt

    Microsoft Academic Search

    Henry H. Hsieh; David Jewitt

    2006-01-01

    Comets are icy bodies that sublimate and become active when close to the Sun. They are believed to originate in two cold reservoirs beyond the orbit of Neptune: the Kuiper Belt (equilibrium temperatures of ~40 kelvin) and the Oort Cloud (~10 kelvin). We present optical data showing the existence of a population of comets originating in a third reservoir: the

  17. Dynamical lifetimes of objects injected into asteroid belt resonances

    Microsoft Academic Search

    B. J. Gladman; Fabbio Migliorini; Alessandro Morbidelli; Vincenzo Zappala; Patrick Michel; Alberto Cellino; Christiane Froeschle; H. F. Levison; Mark Bailey; Martin Duncan

    1997-01-01

    Numerical simulations of particles placed in orbital resonances in the main asteroid belt show that the typical dynamical lifetimes of objects that could become near-Earth asteroids or meteorites are only a few million years, with the majority destroyed by being transferred to Jupiter-crossing orbits or being driven into the sun. Particles that fortu- itously migrate to the terrestrial planet region

  18. The Distribution of Basaltic Asteroids in the Main Belt

    E-print Network

    Nicholas A. Moskovitz; Robert Jedicke; Eric Gaidos; Mark Willman; David Nesvorny; Ronald Fevig; Zeljko Ivezic

    2008-07-24

    We present the observational results of a survey designed to target and detect asteroids whose colors are similar to those of Vesta family members and thus may be considered as candidates for having a basaltic composition. Fifty basaltic candidates were selected with orbital elements that lie outside of the Vesta dynamical family. Optical and near-infrared spectra were used to assign a taxonomic type to 11 of the 50 candidates. Ten of these were spectroscopically confirmed as V-type asteroids, suggesting that most of the candidates are basaltic and can be used to constrain the distribution of basaltic material in the Main Belt. Using our catalog of V-type candidates and the success rate of the survey, we calculate unbiased size-frequency and semi-major axis distributions of V-type asteroids. These distributions, in addition to an estimate for the total mass of basaltic material, suggest that Vesta was the predominant contributor to the basaltic asteroid inventory of the Main Belt, however scattered planetesimals from the inner Solar System (a asteroid 15 Eunomia, which may be derived from a differentiated parent body in the middle Main Belt (2.5 asteroidal evidence for a large number of previously undiscovered basaltic asteroids, which agrees with previous theories suggesting that basaltic fragments from the ~100 differentiated parent bodies represented in meteorite collections have been "battered to bits" [Burbine, T.H., Meibom, A., Binzel, R.P., 1996. Mantle material in the Main Belt: Battered to bits? Met. & Planet. Sci. 31, 607].

  19. Stratigraphy and sedimentation in the Mediterranean Ridge diapiric belt

    Microsoft Academic Search

    M. B. Cita; E. Erba; R. Lucchi; M. Pott; R. van der Meer; L. Nieto

    1996-01-01

    Two basic sediment types are recorded in the Mediterranean Ridge diapiric belt: the host sediment and the mud breccia. The host sediment consists of hemipelagic marl as dominant lithology, associated with sapropels and tephras as minor isochronous lithologies. A high resolution stratigraphy, which allows much more detailed and precise correlations than those based on biostratigraphy (essentially calcareous nannofossils) is applicable

  20. The Philippine Mobile Belt: a complex plate boundary

    NASA Astrophysics Data System (ADS)

    Rangin, Claude

    The Philippine archipelago is regarded as the product of the Late Cenozoic oblique collision of the Philippine Plate with the thinned margin of Eurasia. The Philippine Mobile Belt is presented, mainly composed by the Philippine arc, a Paleogene volcanic arc belonging to the Philippine Sea Plate and crustal fragments belonging to the Eurasian Plate. Kinematic and geological data are presented for this collision history.

  1. 3-D orbital evolution model of outer asteroid belt

    NASA Technical Reports Server (NTRS)

    Solovaya, Nina A.; Gerasimov, Igor A.; Pittich, Eduard M.

    1992-01-01

    The evolution of minor planets in the outer part of the asteroid belt is considered. In the framework of the semi-averaged elliptic restricted three-dimensional three-body model, the boundary of regions of the Hill's stability is found. As was shown in our work, the Jacobian integral exists.

  2. BMM SEPARATION SCREEN PERMITS SAND TO PASS TO BELT CONVEYORS ...

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

    BMM SEPARATION SCREEN PERMITS SAND TO PASS TO BELT CONVEYORS BELOW THAT TRANSPORT THE SAND BACK TO STORAGE AND RECONDITIONING BINS WHILE CASTINGS ARE TRANSPORTED ON ADDITIONAL VIBRATING CONVEYORS TO DEGATING AREAS. - Southern Ductile Casting Company, Shaking, Degating & Sand Systems, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  3. What kinds of people do not use seat belts?

    PubMed Central

    Helsing, K J; Comstock, G W

    1977-01-01

    In the course of a Community Mental Health Epidemiology study conducted in Washington County, Maryland between December, 1971 and July, 1974, interviews were conducted with randomly selected adults in a weekly systematic sampling of households. In a subsequent re-interview of 1009 respondents who had family cars with seat belts, nearly 47 per cent said they did not use them. Non-use of seat belts was significantly higher among females and among persons with less than high school education or low income. Non-use of seat belts was also higher among those who felt that their station in life as measured by the Cantril ladder was unsatisfactory, who felt powerless to change at least some aspects of their lives, and who were infrequent church attenders. Significant associations were also found with infrequency of two other preventive health behaviors, dental checkups and Pap tests. Among young adults the tendency seemed to be for marriage to increase the non-use of seat belts among females but to decrease non-use among males. Images FIGURE 1. FIGURE 2 FIGURE 3 PMID:911016

  4. Earthquakes, geodesy, and the structure of mountain belts

    NASA Astrophysics Data System (ADS)

    Allen, Mark; Walters, Richard; Nissen, Ed

    2015-04-01

    Most terrestrial mountain belts are the topographic expression of thrust faulting and folding, which are how the continents deform in compression. Fold-and-thrust belts are therefore a global phenomenon, in existence since at least the onset of plate tectonics. They are typically described as wedge-shaped zones of deformation, overlying a basal low-angle thrust fault (?10o dip). Here we use earthquake focal mechanisms and geodetic data from active continental fold-and-thrust belts worldwide, to test these concepts. We find that widespread, seismogenic, low-angle thrusting at the base of a wedge occurs only in the Himalayas, New Guinea, Talesh and far-eastern Zagros, which are plausibly underthrust by strong plates. In other ranges there is no focal mechanism evidence for a basal low-angle thrust, and well-constrained hypocentre depths are typically <20 km. Available geodetic data show that active deformation is focussed on a single, low-angle thrust in the Himalayas and New Guinea, but distributed in other ranges for which there are sufficient observations. We suggest that the more common style of deformation approximates to pure shear, with a brittle lid overlying the rest of the plate, where ductile or plastic deformation predominates. Interpretations of both active and ancient mountain belts will need re-evaluation in the light of these results.

  5. The Belt Theory of Discipline and Delinquency. Critical Issues Presentation.

    ERIC Educational Resources Information Center

    Welsh, Ralph S.

    Parental discipline appears to play a major role in the development of delinquent and aggressive behavior. The belt theory predicts that parents who have used corporal punishment are likely to produce children who exhibit delinquent behavior. A striking factor is that all delinquent youths see corporal punishment as necessary in child rearing and…

  6. Pioneer Anomaly and the Kuiper Belt mass distribution

    E-print Network

    O. Bertolami; P. Vieira

    2006-06-18

    Pioneer 10 and 11 were the first probes sent to study the outer planets of the Solar System and Pioneer 10 was the first spacecraft to leave the Solar System. Besides their already epic journeys, Pioneer 10 and 11 spacecraft were subjected to an unaccounted effect interpreted as a constant acceleration toward the Sun, the so-called Pioneer anomaly. One of the possibilities put forward for explaining the Pioneer anomaly is the gravitational acceleration of the Kuiper Belt. In this work we examine this hypothesis for various models for the Kuiper Belt mass distribution. We find that the gravitational effect due to the Kuiper Belt cannot account for the Pioneer anomaly. Furthermore, we have also studied the hypothesis that drag forces can explain the the Pioneer anomaly; however we conclude that the density required for producing the Pioneer anomaly is many orders of magnitude greater than those of interplanetary and interstellar dust. Our conclusions suggest that only through a mission, the Pioneer anomaly can be confirmed and further investigated. If a mission with these aims is ever sent to space, it turns out, on account of our results, that it will be also a quite interesting probe to study the mass distribution of the Kuiper Belt.

  7. REGIONALIZATION OF THE WESTERN CORN BELT PLAINS ECOREGION

    EPA Science Inventory

    As part of a larger effort to study the fate and transport of agrichemicals in the midwestern United States, the U.S. Environmental Protection Agency commissioned a study of spatial variability within the Western Corn Belt Plains ecoregion. he objective of this study was to syste...

  8. SeatBelt Use and Related Behaviors Among Young Adults

    Microsoft Academic Search

    Dorothy J. Begg; John D. Langley

    2000-01-01

    Seat-belt use among young adults was examined to identify factors associated with nonuse. This research was part of the Dunedin Multidisciplinary Health and Development Study, which is a study of the health, development, and behavior of a birth cohort of young New Zealanders (n = 1037). At age 21 years, 948 (93%) members of this cohort were administered a face-to-face

  9. NEP for a Kuiper Belt Object Rendezvous Mission

    Microsoft Academic Search

    MICHAEL G. HOUTS; ROGER X. LENARD; RONALD J. LIPINSKI; BRUCE PATTON; DAVID I. POSTON; STEVEN A. WRIGHT

    1999-01-01

    Kuiper Belt Objects (KBOs) are a recently-discovered set of solar system bodies which lie at about the orbit of Pluto (40 AU) out to about 100 astronomical units (AU). There are estimated to be about 100,000 KBOS with a diameter greater than 100 km. KBOS are postulated to be composed of the pristine material which formed our solar system and

  10. NEP for a Kuiper Belt Object rendezvous mission

    Microsoft Academic Search

    Ronald J. Lipinski; Roger X. Lenard; Steven A. Wright; Michael G. Houts; Bruce Patton; David I. Poston

    2000-01-01

    Kuiper Belt Objects (KBOs) are a recently-discovered set of solar system bodies which lie at about the orbit of Pluto (40 AU) out to about 100 astronomical units (AU). There are estimated to be about 100,000 KBOs with a diameter greater than 100 km. KBOs are postulated to be composed of the pristine material which formed our solar system and

  11. Camelina: A Potential Winter Crop for the Northern Corn Belt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Camelina (Camelina sativa L.) may offer a low-input oilseed alternative for biodiesel and other vegetable oil applications. Little is known about its agronomic potential or the winter survivability of winter cultivars in the northern Corn Belt. A study was initiated in west central Minnesota to eval...

  12. Shaping mobile belts by small-scale convection.

    PubMed

    Faccenna, Claudio; Becker, Thorsten W

    2010-06-01

    Mobile belts are long-lived deformation zones composed of an ensemble of crustal fragments, distributed over hundreds of kilometres inside continental convergent margins. The Mediterranean represents a remarkable example of this tectonic setting: the region hosts a diffuse boundary between the Nubia and Eurasia plates comprised of a mosaic of microplates that move and deform independently from the overall plate convergence. Surface expressions of Mediterranean tectonics include deep, subsiding backarc basins, intraplate plateaux and uplifting orogenic belts. Although the kinematics of the area are now fairly well defined, the dynamical origins of many of these active features are controversial and usually attributed to crustal and lithospheric interactions. However, the effects of mantle convection, well established for continental interiors, should be particularly relevant in a mobile belt, and modelling may constrain important parameters such as slab coherence and lithospheric strength. Here we compute global mantle flow on the basis of recent, high-resolution seismic tomography to investigate the role of buoyancy-driven and plate-motion-induced mantle circulation for the Mediterranean. We show that mantle flow provides an explanation for much of the observed dynamic topography and microplate motion in the region. More generally, vigorous small-scale convection in the uppermost mantle may also underpin other complex mobile belts such as the North American Cordillera or the Himalayan-Tibetan collision zone. PMID:20520711

  13. Global Storm-Time Depletion of the Outer Electron Belt

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, A. Y.; Sitnov, M. I.; Millan, R. M.; Kress, B. T.; Fennell, J. F.

    2014-12-01

    The outer radiation belt consists of relativistic (?0.5 MeV) electrons trapped on closed trajectories around Earth where its magnetic field is nearly dipolar. During increased geomagnetic activity electron intensities in the belt can vary by orders of magnitude at different spatial and temporal scale. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the depletions: fully adiabatic inflation of electron drift orbits caused the ring current growth, electron loss into the atmosphere due to pitch-angle scattering by plasma waves (e.g., EMIC and whistler waves), and electron escape through the magnetopause boundary. In this paper we investigate the relative importance of the magnetopause losses to the rapid depletion of the outer belt observed at the Van Allen Probes spacecraft during the main phase of March 17, 2013 storm. The intensities of > 1 MeV electrons were depleted by more that an order of magnitude over the entire radial extent of the belt in less than 6 hours after the sudden storm commencement. For the analysis we used three-dimensional test-particle simulations of global evolution of the outer belt in the Tsyganenko-Sitnov (TS07D) magnetic field model with the inductive electric field. The comparison of the simulation results with electron measurements from the MagEIS experiment shows that the magnetopause losses in the model accounts for most of the observed depletion. The individual electron motion the process is non-adiabatic; the third invariant is violated by global variations of the inner magnetospheric fields caused by the magnetopause compressions and the buildup of ring current, while the second invariant is violated at drift orbit bifurcations. The analysis shows that the observed deep depletion of radiation belt intensities is enabled by the change in the global configuration of magnetic field due to storm-time development of the ring current; a simulation of electron evolution without a ring current produces a much weaker depletion.

  14. Paired Magmatic-Metallogenic Belts in Myanmar - an Andean Analogue?

    NASA Astrophysics Data System (ADS)

    Gardiner, Nicholas; Robb, Laurence; Searle, Michael; Morley, Christopher

    2015-04-01

    Myanmar (Burma) is richly endowed in precious and base metals, having one of the most diverse collections of natural resources in SE Asia. Its geological history is dominated by the staged closing of Tethys and the suturing of Gondwana-derived continental fragments onto the South China craton during the Mesozoic-Cenozoic. The country is located at a crucial geologic juncture where the main convergent Tethyan collision zone swings south around the Namche Barwa Eastern Himalayan syntaxis. However, despite recent work, the geological and geodynamic history of Myanmar remains enigmatic. Plate margin processes, magmatism, metasomatism and the genesis of mineral deposits are intricately linked, and there has long been recognized a relationship between the distribution of certain mineral deposit types, and the tectonic settings which favour their genesis. A better knowledge of the regional tectonic evolution of a potential exploration jurisdiction is therefore crucial to understanding its minerals prospectivity. This strong association between tectonics and mineralization can equally be applied in reverse. By mapping out the spatial, and temporal, distribution of presumed co-genetic mineral deposits, coupled with an understanding of their collective metallogenetic origin, a better appreciation of the tectonic evolution of a terrane may be elucidated. Identification and categorization of metallotects within a geodynamically-evolving terrane thus provides a complimentary tool to other methodologies (e.g. geochemical, geochronological, structural, geophysical, stratigraphical), for determining the tectonic history and inferred geodynamic setting of that terrane through time. Myanmar is one such study area where this approach can be undertaken. Here are found two near-parallel magmatic belts, which together contain a significant proportion of that country's mineral wealth of tin, tungsten, copper, gold and silver. Although only a few 100 km's apart, these belts exhibit a contrasting minerals endowment. The Mogok-Mandalay-Mergui (MMM) Belt hosts crustal-melt S-type granites with significant tin-tungsten mineralization, and contains the historically major tungsten deposit of Mawchi. The Wuntho-Popa Arc comprises I-type granites and granodiorites with porphyry-type copper-gold and epithermal gold mineralization, and includes the world-class Monywa copper mine. Recent U-Pb radiometric age dating has shown the potential for the two belts to be both active from the Late Cretaceous to Eocene. The spatial juxtaposition of these two sub-parallel belts, the implication of contemporary magmatism, and their distinct but consistent metallogenic endowment bears strong similarities to the metallogenic belts of the South American Cordillera. Here we investigate whether they together represent the magmatic and metallogenic expression of an Andean-type setting in Myanmar during the subduction of Neo-Tethys. In this analogue the Wuntho-Popa Arc represents a proximal I-type magmatic belt sited immediately above the eastwards-verging Neo-Tethys subduction zone. Exhibiting porphyry-type copper-gold and epithermal gold mineralization, this would therefore be the Myanmar equivalent of the Andean coastal copper belts. Conversely, the parallel MMM Belt, comprised of more distal crustal-melt S-type tin granites, would have an analogue in the Bolivian tin belt.

  15. Radiation belt electron precipitation fluxes associated with lightning

    NASA Astrophysics Data System (ADS)

    Clilverd, M. A.; Rodger, C. J.; Nunn, D.

    2004-12-01

    In this study we consider the dependence of precipitation fluxes arising from whistler-induced radiation belt losses on the strength of the associated lightning's return stroke current. As a result of this work, it will be possible to use lightning activity data sets to estimate globally induced precipitation flux rates and thus determine the lightning-induced effect on the radiation belts more accurately. Four study days were selected, during which a high proportion of the lightning activity occurring near the east coast of North America produced observable Trimpi effects on VLF transmitter signals propagating in the region of the Antarctic Peninsula (˜L = 2-2.5). The lack of lightning in Antarctica gives this location a unique advantage for this study. The functional dependence of the relative scattered field amplitude with the return stroke peak current of the lightning discharge suggests that during these events diffusion conditions are occurring near the precipitating radiation belt particles loss cone due to strong whistler wave fields, probably caused by ducted signals. The range of observed Trimpi scatter amplitude of -10 to -35 dB was produced by precipitation bursts with energy fluxes estimated to range over 6.5-0.4 × 10-3 ergs cm-2 s-1. The largest fluxes were found to be driven by lightning currents of about 250 kA, while the smallest detectable fluxes relate to lightning currents of 70 kA. Although 3 of the 4 study days showed a high degree of consistency between the levels of lightning return stroke peak current required to produce any given perturbation scatter amplitude value, conditions were significantly different on 23 April 1994. On this day, observed Trimpi signatures were 6-7 dB greater for any given lightning intensity than on the other study days. These events are consistent with a significantly harder radiation belt precipitation spectra, probably caused by geomagnetic storm-time acceleration processes of radiation belt electrons.

  16. Effects of Emic Waves on the Outer Electron Radiation Belt.

    NASA Astrophysics Data System (ADS)

    Horne, R. B.; Kersten, T.; Glauert, S.; Meredith, N. P.; Fraser, B. J.; Grew, R. S.

    2014-12-01

    Over the last few years there has been substantial progress to incorporate wave-particle interactions into global simulation models of the radiation belts. Models of plasmaspheric hiss and whistler mode chorus make a huge impact on the variability of the relativistic electron flux. Electromagnetic Ion Cyclotron (EMIC) waves also cause electron loss from the radiation belts but their effectiveness has not been fully quantified. Here we present the results of simulations using a new chorus diffusion matrix and demonstrate that in principle the outer electron radiation belt can be formed by wave acceleration from a soft electron spectrum. We also describe a new model for EMIC waves. Wave data derived from the fluxgate magnetometer on CRRES was used to define the power spectrum as a function of geomagnetic activity, L* and magnetic local time for Hydrogen and Helium band waves. We show that wave power depends on activity as measured by AE and Kp. Using an assumed ion composition, and previously defined plasma density models the PADIE code was used to calculate bounce and drift averaged diffusion rates for EMIC waves and incorporated into the BAS Radiation Belt Model together with whistler mode chorus, plasmaspheric hiss and radial diffusion. Thus the model can be driven by a time sequence of Kp with appropriate boundary conditions. By simulating a 100 day period in 1990 we show that the model can produce electron flux up to energies of several MeV. When EMIC waves are included they cause a significant reduction in the electron flux for energies greater than 2 MeV but only for pitch angles lower than about 60 degrees. The simulations show that the distribution of electrons left behind in space looks like a pancake distribution at MeV energies. We show that EMIC waves cannot remove electrons at all pitch angles even at 30 MeV and are therefore unlikely to set an upper energy limit to the outer radiation belt.

  17. Abdominal Injuries in Belt-Positioning Booster Seats

    PubMed Central

    Arbogast, Kristy B.; Ghati, Yoganand

    2009-01-01

    Previous studies have demonstrated that booster seats reduce the risk of abdominal injuries by improving the fit of the seat belt on young children and encouraging better posture and compatibility with the vehicle seat. Recently, several studies have reported cases of abdominal injuries in booster seated children questioning the protective effects of these restraints. The objective of this study was to examine cases of abdominal injuries in booster seated children through parametric modeling to gain a thorough understanding of the injury causation scenarios. The Partners for Child Passenger Safety and CIREN in-depth crash investigation databases were queried to identify children in belt-positioning booster seats with abdominal injuries. The injury causation scenarios for these injuries were delineated using the CIREN Biotab method. The cases were modeled, using MADYMO with variations in key parameters, to determine the ranges of loads and loading rates for the abdomen and thorax. A parametric study was completed examining the influence of pretensioners and load limiters on the injury metrics obtained. Query of the two databases revealed three cases involving abdominal injuries to booster seated children. Children in two of the cases sustained a thoracic injury (AIS 3/AIS 4) in addition to their abdominal injuries (AIS 2) and review of these cases pointed to the role of shoulder belt loading in the injury causation. Modeling of these cases revealed chest compressions and accelerations of 30–53 mm and 41–89 g, respectively and abdominal deflection and velocity of 7.0–13.3 mm and 1.2–2.2 m/s, respectively. Parametric study suggested that coupling shoulder belt load limiting and lap belt buckle pretensioning resulted in improved chest and abdominal metrics while reducing head excursion, indicating that these technologies may provide injury reduction potential to pediatric rear seat occupants. PMID:20184845

  18. MAIN-BELT COMET P/2008 R1 (GARRADD)

    SciTech Connect

    Jewitt, David; Yang Bin; Haghighipour, Nader [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)], E-mail: jewitt@ifa.hawaii.edu, E-mail: yangbin@ifa.hawaii.edu, E-mail: nader@ifa.hawaii.edu

    2009-05-15

    We present a study of the newly discovered main-belt comet P/2008 R1 (Garradd), an object with the dynamical characteristics of an asteroid and the physical characteristics of a comet. Photometry sets a limit to the effective radius of the nucleus at r{sub e} < 0.7 km (red geometric albedo 0.05 assumed). The coma shows a secular fading in our data caused by the escape of dust particles from the near-nucleus environment. The optical reflection spectrum is a nearly neutral continuum devoid of gaseous emission lines, from which we derive a limit to the cyanide (CN) radical production rate of Q {sub CN}< 1.4 x 10{sup 23} s{sup -1} and infer a mass-loss rate <1.5 kg s{sup -1} at the time of our observations. Unlike the first-reported main-belt comets, P/2008 R1 is not dynamically stable. The nearby 8:3 mean-motion resonance with Jupiter induces dynamical instability on timescales 20-30 Myr. Hence, we conclude that P/2008 R1 has recently arrived from a more stable source elsewhere. The high Tisserand parameter of the orbit (in fact, with T{sub J} = 3.216 it is the highest of any comet) points to a source in the asteroid belt itself, instead of in the Kuiper belt (putative source of the Jupiter family comets). We infer that P/2008 R1 is an icy body from the outer asteroid belt in which sublimation has been triggered by rising temperatures resulting from a decreasing perihelion distance.

  19. MICROWAVE EMISSION FROM THE EDGEWORTH-KUIPER BELT AND THE ASTEROID BELT CONSTRAINED FROM THE WILKINSON MICROWAVE ANISOTROPY PROBE

    SciTech Connect

    Ichikawa, Kazuhide; Fukugita, Masataka [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan)

    2011-08-01

    Objects in the Edgeworth-Kuiper Belt and the main asteroid belt should emit microwaves that may give rise to extra anisotropy signals in the multipole of the cosmic microwave background (CMB) experiment. Constraints are derived from the absence of positive detection of such anisotropies for l {approx}< 50, meaning the total mass of Edgeworth-Kuiper Belt objects is smaller than 0.2 M{sub +}. This limit is consistent with the mass extrapolated from the observable population with the size of a {approx}> 15 km, assuming that the small-object population follows the power law in size dN/da {approx} a{sup -q} with the canonical index expected for collisional equilibrium, q {approx_equal} 3.5, with which 23% of the mass is ascribed to objects smaller than are observationally accessible down to grains. A similar argument applied to the main asteroid belt indicates that the grain population should not increase more quickly than q {approx_equal} 3.6 toward smaller radii, if the grain population follows the power law that continues to observed asteroids with larger radii. Both cases are at or only slightly above the limit that can be physically significant, implying the importance of further tightening the CMB anisotropy limit, which may be attained with observation at higher radio frequencies.

  20. Intrusive rocks and plutonic belts of southeastern Alaska, U.S.A.

    USGS Publications Warehouse

    Brew, David A.; Morrell, Robert P.

    1983-01-01

    About 30 percent of the 175,000-km2 area of southeastern Alaska is underlain by intrusive igneous rocks. Compilation of available information on the distribution, composition, and ages of these rocks indicates the presence of six major and six minor plutonic belts. From west to east, the major belts are: the Fairweather-Baranof belt of early to mid-Tertiary granodiorite; the Muir-Chichagof belt of mid-Cretaceous tonalite and granodiorite; the Admiralty-Revillagigedo belt of porphyritic granodiorite, quartz diorite, and diorite of probable Cretaceous age; the Klukwan-Duke belt of concentrically zoned or Alaskan-type ultramafic-mafic plutons of mid-Cretaceous age within the Admiralty-Revillagigedo belt; the Coast Plutonic Complex sill belt of tonalite of unknown, but perhaps mid-Cretaceous, age; and the Coast Plutonic Complex belt I of early to mid-Tertiary granodiorite and quartz monzonite. The minor belts are distributed as follows: the Glacier Bay belt of Cretaceous and(or) Tertiary granodiorite, tonalite, and quartz diorite lies within the Fair-weather-Baranof belt; layered gabbro complexes of inferred mid-Tertiary age lie within and are probably related to the Fairweather-Baranof belt; the Chilkat-Chichagof belt of Jurassic granodiorite and tonalite lies within the Muir-Chichagof belt; the Sitkoh Bay alkaline, the Kendrick Bay pyroxenite to quartz monzonite, and the Annette and Cape Fox trondhjemite plutons, all interpreted to be of Ordovician(?) age, together form the crude southern southeastern Alaska belt within the Muir-Chichagof belt; the Kuiu-Etolin mid-Tertiary belt of volcanic and plutonic rocks extends from the Muir-Chichagof belt eastward into the Admiralty-Revillagigedo belt; and the Behm Canal belt of mid- to late Tertiary granite lies within and next to Coast Plutonic Complex belt II. In addition, scattered mafic-ultramafic bodies occur within the Fairweather-Baranof, Muir-Chichagof, and Coast Plutonic Complex belts I and II. Palinspastic reconstruction of 200 km of right-lateral movement on the Chatham Strait fault does not significantly change the pattern of the major belts but does bring parts of the minor mid-Tertiary and Ordovician(?) belts closer together. The major belts are related to the stratigraphic-tectonic terranes of Berg, Jones, and Coney (1978) as follows: the Fairweather-Baranof belt is largely in the Chugach, Wrangell (Wrangellia), and Alexander terranes; the Muir-Chichagof belt is in the Alexander and Wrangell terranes; the Admiralty-Revillagigedo belt is in the Gravina and Taku terranes; the Klukwan-Duke belt is in the Gravina, Taku, and Alexander terranes; the Coast Plutonic Complex sill belt is probably between the Taku and Tracy Arm terranes; and the Coast Plutonic Complex belts I and II are in the Tracy Arm and Stikine terranes. Significant metallic-mineral deposits are spatially related to certain of these belts, and some deposits may be genetically related. Gold, copper, and molybdenum occurrences may be related to granodiorites of the Fairweather-Baranof belt. Magmatic copper-nickel deposits occur in the layered gabbro within that belt. The Juneau gold belt, which contains gold, silver, copper, lead, and zinc occurrences, parallels and lies close to the Coast Plutonic Complex sill belt; iron deposits occur in the Klukwan-Duke belt; and porphyry molybdenum deposits occur in the Behm Canal belt. The Muir-Chichagof belt of mid-Cretaceous age and the Admiralty-Revillagigedo belt of probable Cretaceous age are currently interpreted as possible magmatic arcs associated with subduction events. In general, the other belts of intrusive rocks are spatially related to structural discontinuities, but genetic relations, if any, are not yet known. The Coast Plutonic Complex sill belt is probably related to a post-Triassic, pre-early Tertiary suture zone that nearly corresponds to the boundary between the Tracy Arm and Taku terranes. The boundary between the Admiralty-Revillagigedo and Muir-Chichagof belts coincides nearly with the Seymour Canal-Clarence Strait lineament and also is probably a

  1. Controls on accretion of flysch and mélange belts at convergent margins: Evidence from the Chugach Bay thrust and Iceworm mélange, Chugach accretionary wedge, Alaska

    NASA Astrophysics Data System (ADS)

    Kusky, Timothy M.; Bradley, Dwight C.; Haeussler, Peter J.; Karl, Sue

    1997-12-01

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

  2. A single-subject approach to evaluating vehicle safety belt reminders: Back to basics

    PubMed Central

    Berry, Thomas D.; Geller, E. Scott

    1991-01-01

    A single-subject ABA reversal design was applied to evaluate the effectiveness of a limited 8-s safety belt reminder system and two modified reminder systems (a delayed and second reminder) to increase the safety belt use of 13 drivers. The research was conducted with a specially equipped research vehicle that permitted the manipulation of different safety belt reminder stimuli and the unobtrusive recording of a driver's belt use. For 2 subjects, the limited 8-s reminder increased safety belt use. For another 2 subjects, the second reminder markedly increased belt use. Some subjects were uninfluenced by the reminder systems presented; others always buckled up during both baseline and intervention conditions. The approach and results are discussed with regard to the application of behavior analysis methodologies (e.g., cumulative records) and principles (e.g., schedules of reinforcement) to advance the utility and investigation of safety belt reminder systems. PMID:16795740

  3. Turbulent-boundary-layer development on a moving ground belt of rough texture

    NASA Technical Reports Server (NTRS)

    Roper, A. T.; Gentry, G. L., Jr.

    1972-01-01

    The equations presented can be used to predict the shape factor and the ratio of the momentum thickness to the relative momentum thickness with reasonable accuracy for a moving ground belt provided that the stationary quantities are known and the two following basic approximations are valid: (1) Shape factor based upon velocity relative to the ground belt is nearly independent of the ratio of belt velocity to free-stream velocity. (2) The ratio of moving-belt momentum thickness to stationary-belt momentum thickness is independent of the coordinate measured in the streamwise direction. In addition, the integral quantities, momentum thickness and displacement thickness, can be predicted for the moving ground belt by using an empirically determined polynomial whose coefficients will change with different belt roughnesses.

  4. Numerical modeling of water spray suppression of conveyor belt fires in a large-scale tunnel

    PubMed Central

    Yuan, Liming; Smith, Alex C.

    2015-01-01

    Conveyor belt fires in an underground mine pose a serious life threat to miners. Water sprinkler systems are usually used to extinguish underground conveyor belt fires, but because of the complex interaction between conveyor belt fires and mine ventilation airflow, more effective engineering designs are needed for the installation of water sprinkler systems. A computational fluid dynamics (CFD) model was developed to simulate the interaction between the ventilation airflow, the belt flame spread, and the water spray system in a mine entry. The CFD model was calibrated using test results from a large-scale conveyor belt fire suppression experiment. Simulations were conducted using the calibrated CFD model to investigate the effects of sprinkler location, water flow rate, and sprinkler activation temperature on the suppression of conveyor belt fires. The sprinkler location and the activation temperature were found to have a major effect on the suppression of the belt fire, while the water flow rate had a minor effect. PMID:26190905

  5. UPb and Sm-Nd geochronology of the neoproterozoic granitic-gneissic Dom Feliciano belt, Southern Brazil

    Microsoft Academic Search

    Marly Babinski; Farid Chemale; W. R. Van Schmus; Leo Afrâneo Hartmann; Luiz Carlos Da Silva

    1997-01-01

    The Brasiliano Cycle in southern Brazil and Uruguay is represented by three major NE-SW trending geotectonic units: the Vila Nova belt, Tijucas belt and Dom Feliciano belt. The Vila Nova belt is located in western part of Rio Grande do Sul State; its evolution took place between 900 and 700 Ma and it corresponds to one of the few areas

  6. 23 CFR 1240.12 - Determination of State seat belt use rate for calendar year 1998 and beyond.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Determination of State seat belt use rate for calendar year 1998 and beyond. 1240.12 ...Determination of State seat belt use rate for calendar year 1998 and beyond. (a) State seat belt use survey. (1) Beginning in calendar year 1998, State seat belt use...

  7. 23 CFR 1240.12 - Determination of State seat belt use rate for calendar year 1998 and beyond.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Determination of State seat belt use rate for calendar year 1998 and beyond. 1240.12 ...Determination of State seat belt use rate for calendar year 1998 and beyond. (a) State seat belt use survey. (1) Beginning in calendar year 1998, State seat belt use...

  8. 23 CFR 1240.12 - Determination of State seat belt use rate for calendar year 1998 and beyond.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Determination of State seat belt use rate for calendar year 1998 and beyond. 1240.12 ...Determination of State seat belt use rate for calendar year 1998 and beyond. (a) State seat belt use survey. (1) Beginning in calendar year 1998, State seat belt use...

  9. 23 CFR 1240.12 - Determination of State seat belt use rate for calendar year 1998 and beyond.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Determination of State seat belt use rate for calendar year 1998 and beyond. 1240.12 ...Determination of State seat belt use rate for calendar year 1998 and beyond. (a) State seat belt use survey. (1) Beginning in calendar year 1998, State seat belt use...

  10. 23 CFR 1240.12 - Determination of State seat belt use rate for calendar year 1998 and beyond.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Determination of State seat belt use rate for calendar year 1998 and beyond. 1240.12 ...Determination of State seat belt use rate for calendar year 1998 and beyond. (a) State seat belt use survey. (1) Beginning in calendar year 1998, State seat belt use...

  11. Evolution of a reworked orogenic zone: The boundary between the delamerian and lachlan fold belts, southeastern Australia

    Microsoft Academic Search

    J. Mc L. Miller; D. Phillips; C. J. L. Wilson; L. J. Dugdale

    2005-01-01

    Ar\\/Ar age data from the boundary between the Delamerian and Lachlan Fold Belts identify the Moornambool Metamorphic Complex as a Cambrian metamorphic belt in the western Stawell Zone of the Palaeozoic Tasmanide System of southeastern Australia. A reworked orogenic zone exists between the Lachlan and Delamerian Fold Belts that contains the eastern section of the Cambrian Delamerian Fold Belt and

  12. Geology and gold–molybdenum porphyry mineralisation of the Archean Taschereau–Launay plutons, Abitibi, Quebec

    Microsoft Academic Search

    Michel Jébrak; Pierre Doucet

    2002-01-01

    Porphyry gold deposits constitute a new challenge for mineral exploration in Archean greenstone belts, yet the relationships between intrusive rocks and mineralisation remain poorly understood. The Messegay gold occurrence is situated in the Taschereau–Launay plutonic complex of the Northern Volcanic Zone of the Abitibi greenstone belt. The Taschereau intrusion (2718±2 Ma) represents a complex network of sills composed of tonalite

  13. Field evidence of Eros-scale asteroids and impact-forcing of Precambrian geodynamic episodes, Kaapvaal (South Africa) and Pilbara (Western Australia) Cratons

    NASA Astrophysics Data System (ADS)

    Glikson, Andrew Y.

    2008-03-01

    The role of asteroid and comet impacts as triggers of mantle-crust processes poses one of the fundamental questions in Earth science. I present direct field evidence for close associations between impact ejecta/fallout units, major unconformities and lithostratigraphic boundaries in Archaean and early Proterozoic terrains, including abrupt changes in the composition of volcanic and sedimentary assemblages across stratigraphic impact boundaries, with implications for the nature and composition of their provenance terrains. As originally observed by D.R. Lowe and G.R. Byerly, in the Barberton Greenstone Belt, eastern Kaapvaal Craton, South Africa, 3.26-3.24 Ga asteroid mega-impact units are closely associated with the abrupt break between an underlying simatic mafic-ultramafic volcanic crust and an overlying association of turbidites, banded iron formations, felsic tuff and conglomerates of continental affinities. Contemporaneous stratigraphic relationships are identified in the Pilbara Craton, Western Australia. Evidence for enrichment of seawater in ferrous iron in the wake of major asteroid impacts reflects emergence of new source terrains, likely dominated by mafic compositions, attributed to impact-triggered oceanic volcanic activity. Relationships between impact and volcanic activity are supported by the onset of major mafic dyke systems associated with ~ 2.48 Ga and possibly the 2.56 Ga mega-impact events.

  14. Abiological origin of described stromatolites older than 3.2 Ga

    NASA Technical Reports Server (NTRS)

    Lowe, D. R.

    1994-01-01

    The three well-documented occurrences of three-dimensional stromatolites older than 3.2 Ga meet most criteria for biogenicity except the presence of fossil bacteria. However, they also show features more consistent with nonbiological origins. Small conical structures in the Strelley Pool chert in the upper part of the Warrawoona Group (3.5-3.2 Ga), Western Australia, lack the structure typical of stromatolites and probably formed mainly through evaporitc precipitation. A domal structure from the North Pole chert, Warrawoona Group, formed by soft-sediment deformation or originally flat layers. Laminated chert containing domal and pseudocolumnar structures in the Onverwacht Group (3.5-3.3 Ga), Barberton Greenstone Belt, South Africa, extends downward into veins and cavities, where it formed through inorganic precipitation. Although bacterial communities were widespread on Earth prior to 3.2 Ga, these particular three-dimensional structures are probably abiotic in origin and do not provide information on the paleobiology or paleoecology of early organisms. The paucity of Archean stromatolites older than 3.2 Ga probably reflects the paucity of known and possibly extant carbonate deposits of this age.

  15. Multiple zircon growth within early Archaean tonalitic gneiss from the Ancient Gneiss Complex, Swaziland

    NASA Astrophysics Data System (ADS)

    Compston, W.; Kröner, A.

    1988-01-01

    U sbnd Pb age determinations by ion microprobe reveal multiple episodes of zircon growth and recrystallization within a single sample of tonalitic gneiss from the Ancient Gneiss Complex. The oldest episode at3644 ± 4Ma(2?) produced the dominant type of zircon, characteristically purplish-brown and massive in texture; this probably constitutes unaltered zircon precipitated from the original magma. Recrystallization accompanied (and obscured) by early Pb loss took place within the oldest grains at3504 ± 6Ma and3433 ± 8Ma. Whole new grains grew at these times also. We interpret the post-3644 Ma growth as due to episodic deformational and metamorphic events that transformed the tonalite pluton into foliated banded gneiss. In addition, many grains are visibly overgrown by two layers of younger zircon of different colour and texture, dated at2986 ± 20Ma and2867 ± 30Ma. Euhedral, finely-zoned whole grains having the 2986 Ma age are present also, evidently contributed by very thin felsic veins associated with the nearby Lochiel granite. The age of3644 ± 4Ma combined with precise zircon U sbnd Pb dating of volcanics from the Onverwacht Group reported elsewhere demonstrates that at least part of the Ancient Gneiss Complex is older than the Barberton Greenstone Belt.

  16. Three-dimensional modeling of the radiation belts using the Versatile Electron Radiation Belt (VERB) code

    NASA Astrophysics Data System (ADS)

    Subbotin, D. A.; Shprits, Y. Y.

    2009-10-01

    Relativistic electrons are hazardous for satellites and humans in space. In this study, we present a detailed description of the Versatile Electron Radiation Belt (VERB) code. The computationally efficient methods described in this report make the VERB code a useful tool for space weather forecasting and nowcasting of the relativistic electron environment. The computational efficiency of the code makes it also appropriate for future use with data assimilation tools to specify the state of the radiation environment and correct imperfect models. We also present several skill scores which can be used to quantify the state of the relativistic electron environment. Our numerical approach is based on the use of two grids: one for radial diffusion and the other for energy and pitch angle diffusion. In this paper, we describe the initial and boundary conditions, the grids and time step used for our simulations, and the tests we conduct to verify the validity of our numerical approaches. Specifically, we perform simulations with time steps ranging from 0.01 to 4 h and number of grid points ranging from 7 to 76 for each of the variables. We compare the results obtained using various spatial resolutions and time steps, giving the relative solution errors for each of the performed simulations on the basis of the developed set of skill scores. The choice of a 0.1 h time step with a grid resolution of 19 × 19 × 19 points was found to be optimal. We compare the block and split methods, showing that the split method is much faster than the block method and sufficiently accurate for time steps of half an hour or less. Additionally, we present an approximate method that simplifies simulation by using only one grid and compare it to the more accurate two-grid method.

  17. Water Ice on Kuiper Belt Object 1996 TO66

    NASA Technical Reports Server (NTRS)

    Brown, R. H.; Cruikshank, D. P.; Pendleton, Y.

    1999-01-01

    The 1.40-2.40 micron spectrum of Kuiper Belt object (KBO) 1996 TO66 was measured at the Keck Observatory in September 1998. It's spectrum shows the strong absorptions near 1.5 and 2.0 micron characteristic of water ice--the first such detection on a Kuiper Belt object. The depth of the absorption bands and the continuum reflectance of 1996 TO66 also suggest the presence of a black to slightly blue-colored, spectrally featureless particulate material as a minority component mixed with the water ice. In addition, there is evidence that the intensity of the water bands in the spectrum of 1996 TO66 vary with rotational phase suggesting that it has a "patchy" surface.

  18. Daytime Sky Brightness Modeling of Haleakala along the GEO Belt

    NASA Astrophysics Data System (ADS)

    Jim, K.,; Gibson, B.; Pier, E.

    2012-09-01

    We model the brightness of the daytime sky along the GEO belt, as seen from Haleakala, from 0.3 to 5 microns using MODTRAN. A model near summer solstice and near vernal equinox will illustrate how the sky brightness changes with season. Our goal is to determine the sky background radiance and transmission as a function of wavelength for imaging applications during the daytime. The sky brightness varies throughout a modeled day, and this is shown using a set of look angles toward the geosynchronous belt. We compare our results using radiosonde and real weather data recorded at the summit on two dates, one near the vernal equinox and one near the summer solstice.

  19. Geophysical ore guides along the Colorado mineral belt

    USGS Publications Warehouse

    Case, James E.

    1967-01-01

    A 40-50-mgal gravity low trends northeast along the Colorado mineral belt between Monarch Pass and Breckenridge, Colorado. The low is probably caused by a silicic Tertiary batholith of lower density than adjacent Precambrian crystalline rocks. Many major mining districts associated with silicic Tertiary intrusives are near the axis of the low. Positive and negative aeromagnetic anomalies are present over the larger silicic Tertiary intrusive bodies. A good correlation exists between the magnetic lows and zones of altered, mineralized porphyry. Apparently, original magnetite in the silicic porphyries has been altered to relatively nonmagnetic pyrite or iron oxides. The regional gravity low aids in defining the limits of the mineral belt, and the magnetic lows over the porphyries indicate specific alteration zones and the possibility of associated mineral deposits.

  20. Reducing the consequences of reactor accidents with a green belt

    SciTech Connect

    Gupta, V.K.; Kapoor, R.K.

    1985-08-01

    Considerable attention is being paid to reducing the consequences of low-probability accidents in nuclear power plants. A scheme based on the pollution absorption properties of trees is proposed to reduce early and continued mortalities among the general public due to an accident in a nuclear power plant. The consequences of a hypothetical case in which a large, cold, ground-level release of radionuclides into the atmosphere takes place have been analyzed in the absence and in the presence of a green belt (rows of trees). The results show that in the presence of a suitably designed green belt around a nuclear power plant, the consequences in terms of early and continued mortality as well as an interdiction area, involving relocation of population and supply of food stuff from an uncontaminated region, can be reduced by orders of magnitude. This could also help in substantially reducing the magnitude of emergency preparedness in the public domain.

  1. The Kuiper Belt and the Solar System's Comet Disk

    NASA Astrophysics Data System (ADS)

    Gladman, Brett

    2005-01-01

    Our planetary system is embedded in a small-body disk of asteroids and comets, vestigial remnants of the original planetesimal population that formed the planets. Once formed, those planets dispersed most of the remaining small bodies. Outside of Neptune, this process has left our Kuiper belt and built the Oort cloud, as well as emplacing comets into several other identifiable structures. The orbits in these structures indicate that our outer solar system's comet disk was shaped by a variety of different physical processes, which teach us about how the giant planets formed. Recent work has shown that the scattered disk is the most likely source of short-period comets. Moreover, a growing body of evidence indicates that the sculpting of the Kuiper belt region may have involved large-scale planetary migration, the presence of other rogue planetary objects in the disk, and/or the close passage of other stars in the Sun's birth cluster.

  2. Post-workshop models of Jupiter's radiation belts

    NASA Technical Reports Server (NTRS)

    Divine, N.

    1972-01-01

    Models for the charged particle populations of Jupiter's trapped radiation belts were derived at the Jupiter Radiation Belt Workshop on the basis of several assumptions which represented a consensus of opinion. It was possible to improve the models on the basis of work performed after the workshop concluded. These improvements affect the models in two ways. The effects of special relativity on the particle energy and flux dependences in the magnetosphere were included in a derivation based on L-shell diffusion with conservation of the magnetic moment. Quantitative conclusions are available for the limit which ion cyclotron instability places on the proton population. A set of models which incorporates these developments in a way consistent with the original workshop assumptions and conclusions is described.

  3. A Stratospheric Balloon Array for Radiation Belt Studies

    NASA Astrophysics Data System (ADS)

    Millan, Robyn

    The Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) is an Antarctic balloon investigation designed to study electron losses from Earth's radiation belts. Two BARREL balloon campaigns were carried out from Antarctic Research Stations SANAE IV and Halley VI in January-February 2013 and 2014. During each campaign, a total of 20 small (~20 kg) balloon payloads were hand-launched on 300,000 cubic foot balloons to an altitude of 38 km to maintain an array of 5-8 payloads distributed in magnetic latitude and local time. Each balloon carried a NaI scintillator to measure the bremsstrahlung X-rays produced by precipitating relativistic electrons as they collide with neutrals in Earth’s atmosphere, and a DC magnetometer. We present a summary of BARREL build-up and operations. BARREL successfully demonstrated the feasibility of maintaining a stratospheric balloon array as an observing platform.

  4. MOLECULAR, CELLULAR, AND DEVELOPMENTAL BIOLOGY Persistence of Salmonella on Egg Conveyor Belts Is Dependent on the Belt Type but Not on the rdar Morphotype

    Microsoft Academic Search

    S. L. Stocki; C. B. Annett; C. D. Sibley; M. McLaws; S. L. Checkley; N. Singh; M. G. Surette; A. P. White

    Commercial caged layer flocks in Alberta, Canada, are commonly monitored for Salmonella enterica serovar Enteritidis (SE) and S. enterica serovar Typhimu- rium (ST) by environmental sampling. In one recent case, a SE strain isolated from the egg conveyor belt was a source of persistent infection for the flock. This study was undertaken to examine Salmonella colonization on egg conveyor belts

  5. Patterns of Injury in Belted and Unbelted Individuals Presenting to a Trauma Center After Motor Vehicle Crash: Seat Belt Syndrome Revisited

    Microsoft Academic Search

    Robert S Porter; Ning Zhao

    1998-01-01

    Study Objective: Investigators have described a “seat belt syndrome” consisting variously of injuries to the lumbar or cervical spine, abdominal contents, or all 3. In this study we sought to identify these and any other patterns of injury associated with seat belt use in patients who presented to a trauma center after a motor vehicle crash. Methods: The charts of

  6. Radiation belt electron dynamics driven by large-amplitude whistlers

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Tel'nikhin, A. A.; Kronberg, T. K.

    2013-10-01

    Acceleration of radiation belt electrons driven by oblique large-amplitude whistler waves is studied. We show analytically and numerically that this is a stochastic process; the intensity of which depends on the wave power modified by Bessel functions. The type of this dependence is determined by the character of the nonlinear interaction due to coupling between action and phase. The results show that physically significant quantities have a relatively weak dependence on the wave power.

  7. Calderas of the Central Sector of the Mexican Volcanic Belt

    Microsoft Academic Search

    G. J. Aguirre-Diaz

    2001-01-01

    The central sector of the Mexican Volcanic Belt (MVB) (-99 to -103, Long W) has the largest number of calderas so far identified in this province. The calderas (with their age range in Ma, and distance to the Middle America Trench in km, in parenthesis) are: Amazcala (7-6, 480), Apaseo (7-6, 440), Huichapan (5-4, 420), Agustinos (5-4, 400), Amealco (5-4,

  8. Seat Belt-Related Chondrosternal Disruption With Lung Herniation

    Microsoft Academic Search

    David Rice; Naveen Bikkasani; Raphael Espada; Kenneth Mattox; Matthew Wall

    eat belt-related injuries have been well characterized and predominately involve the intraabdominal or- gans. Significant injury to the chest wall, cervical vascu- lature, and intrathoracic structures is infrequent, how- ever. We report a case of severe chest wall injury with resulting lung herniation after a motor vehicle accident in which the driver was restrained. A 54-year-old 270-lb male was a

  9. Injury causation scenarios in belt-restrained nearside child occupants.

    PubMed

    Maltese, Matthew R; Locey, Caitlin M; Jermakian, Jessica S; Nance, Michael L; Arbogast, Kristy B

    2007-10-01

    Successful development of side impact safety systems for rear row child occupants requires an understanding of injury causation and mitigation. However, data to guide the design of such safety systems for seat belt-restrained occupants is limited to injury risk assessments. Thus, we sought to elucidate Injury Causation Scenarios (ICS's) in children restrained by seat belts in nearside impacts. Included in the study were 4 to 15 year old children, involved in a side impact, seated on the nearside in the rear rows, restrained by a seat belt alone (no booster seats or side airbags) and who received an AIS 2+ injury. A Contact Point Map summarized the vehicle components that contribute to the injuries. The majority of head and face contacts points were found horizontally within the rear half of the window, and vertically from the window sill to the center of the window, and were a result of contact with both interior structures and structures on the crash partner. The most prevalent intracranial injuries included cerebral contusions, diffuse axonal injury (DAI), and subdural or subarachnoid hematoma/hemorrhage. The most common cause of torso and abdominal injury was contact with the side interior structure, and injuries included spleen lacerations or ruptures, liver lacerations and contusions, lung contusions, rib fractures, and clavicle fractures. Protuberances on the door interior, such as the armrest, were the most common source of abdominal injury in this dataset. These data provide important guidance for the development of rear row safety systems for belt-restrained children with no side airbags in nearside crashes. PMID:18278602

  10. Granite ascent in convergent orogenic belts: Testing a model

    Microsoft Academic Search

    Gary S. Solar; Rachel A. Pressley; Michael Brown; Robert D. Tucker

    1998-01-01

    The common spatial relationship in convergent orogenic belts between a crustal-scale shear-zone system, high-grade metamorphic rocks, and granites suggests a feedback relation between crustal anatexis and contractional deformation that helps granite extraction and focuses granite ascent. Such a feedback relation has been proposed for ascent of Early Devonian granites in west-central Maine. This interpretation requires that deformation, metamorphism, and plutonism

  11. Jurassic sedimentary basins in the Central Asian orogenic belt

    SciTech Connect

    Bebeshev, I.I. [Geological Institute, Moscow (Russian Federation)

    1995-05-01

    The principal stages of development of Jurassic sedimentary basins (from their origin to the end of their existence) in the Central Asian orogenic belt are considered. The interrelations of the basins with the surrounding paleorises are investigated. Paleogeographic maps are compiled representing the evolution of paleolandscapes and revealing their interrelations in space and time for each stage. Areas with the highest prospects for coal are found.

  12. A theoretical model of the inner proton radiation belt

    Microsoft Academic Search

    R. S. Selesnick; M. D. Looper; R. A. Mewaldt

    2007-01-01

    A theoretical calculation provides inner radiation belt proton intensities as a function of time and of the three adiabatic invariants, M, K, and L, in the kinetic energy range from ?10 MeV to ?4 GeV and the L range from 1.1 to 2.4. Long residence times for trapped protons of up to several thousand years require similarly long input time

  13. Artificial Depletion of the Relativistic Electrons in the Radiation Belt

    Microsoft Academic Search

    P. Song; B. Reinisch; G. Sales; V. Paznukhov; X. Huang; G. Ginet; J. Albert

    2003-01-01

    The lifetime of relativistic electrons in the inner radiation belt is very long, posing persistent harm to space systems, especially to low-earth orbit satellites. We propose to use a space-borne transmitter that radiates VLF waves to reduce the lifetime of these electrons via pitch angle diffusion. The transmitter can be located in a low-altitude high-inclination orbit flying through the feet

  14. Cosmic Ray Mantle Visibility on Kuiper Belt Objects

    NASA Technical Reports Server (NTRS)

    Cooper, John F.; Hill, Matt E.; Richardson, J. D.; Sturner, S. J.

    2006-01-01

    Optically red objects constitute the dynamically cold, old component of the Classical Kuiper Belt (40 - 47 AU) with heliocentric orbits of low eccentricity and inclination. The red colors likely arise from primordial mixed ices processed by irradiation to meters in surface depth over the past four billion years, since the time of giant planet migration and Kuiper Belt stirring, at relatively moderate dosages of 60 gigarads provided by galactic cosmic ray protons and heavier ions. The red cosmic ray mantle is uniformly visible on the cold classical objects beneath a minimally thin eroded layer of more neutrally colored material arising from cumulative effects of heliospheric particle irradiation. The radiation fluxes are lowest in the middle heliospheric region containing the Classical Kuiper Belt and increase from there both towards and away from the Sun. Despite increasing irradiation at various times of solar system history from increases in solar and interstellar ion fluxes, the red object region has apparently never reached sufficiently high dosage levels to neutralize in color the red mantle material. Erosion processes, including plasma sputtering and micrometeroid impacts, act continuously to reduce thickness of the upper neutral crust and expose the cosmic ray mantle. A deeper layer at tens of meters and more may consist of relatively unprocessed ices that can erupt to the surface by larger impacts or cryovolcanism and account for brighter surfaces of larger objects such as 2003 UB313. Surface colors among the Kuiper Belt and other icy objects of the outer solar system are then a function, assuming uniform primordial composition, of relative thickness for the three layers and of the resurfacing age dependent on the orbital and impact history of each object.

  15. Effective Conveyer Belt Inspection for Improved Mining Productivity

    SciTech Connect

    David LaRose

    2006-11-14

    This document details progress on the project ''Effective Conveyor Belt Inspection for Improved Mining Productivity'' during the period from May 15, 2006 to November 14, 2006. Progress during this period includes significant advances in development of a Smart Camera based prototype system for on-site mechanical splice detection, and continued deployment of both the mechanical splice detection system and the vulcanized splice detection system in area coal mines.

  16. Seat-belt injuries to the supra-aortic trunks.

    PubMed

    Illuminati, G; Caliò, F G; Bertagni, A; Forte, A; Gallinaro, L; Montesano, G

    1997-01-01

    Five seat-belt related injuries to the supra-aortic and cervical vessels occurring in four patients are reported. All patients but one were symptomatic, none presented with stroke, and in one case arterial lesion was revealed by delayed onset of symptoms. Outcome of surgical treatment was overall good. Systematic search of such injuries and surgical repair of those without major neurological signs might be advisable. PMID:9558771

  17. The gold-silver Okhotsk-Chukotka volcanic belt

    Microsoft Academic Search

    A. A. Sidorov; A. V. Volkov; V. F. Belyi; V. Yu. Alekseev; E. E. Kolova

    2009-01-01

    The Okhotsk-Chukotka volcanic belt (OChVB) formed over 25 Ma from the middle Albian to the Cenomanian at the boundary of the\\u000a continental Verkhoyansk-Chukotka and the Koryak-Kamchatka collages of terranes as a special tectonic unit of the Earth?s crust\\u000a composed of subaerial volcanic rocks extending for 3000 km. In regard to the oceanic margin, the inner, outer, and flank zones\\u000a of

  18. Solar System evolution from compositional mapping of the asteroid belt.

    PubMed

    DeMeo, F E; Carry, B

    2014-01-30

    Advances in the discovery and characterization of asteroids over the past decade have revealed an unanticipated underlying structure that points to a dramatic early history of the inner Solar System. The asteroids in the main asteroid belt have been discovered to be more compositionally diverse with size and distance from the Sun than had previously been known. This implies substantial mixing through processes such as planetary migration and the subsequent dynamical processes. PMID:24476886

  19. Developments in Australian longwall belt conveyors: Electronic controls

    SciTech Connect

    Elliott, M. [Australian Conveyor Engineering Pty Ltd., Gosford, New South Wales (Australia)

    1993-12-31

    The retreating longwall maingate conveyor belt presents unique design complexity based on an ever changing geometry. Equipment has been developed which provides automatic adoption to the changing conveyor characteristics through PLC based, adaptive control algorithms. These groups of adaptive conveyor systems reduces the skill demands on operators and allows improved performance from the conveyor system over changing conditions. Two such devices are presented and the mechanics, method of achieving environment feedback, and adaptive strategy is explained.

  20. Viscoelastic Response of the Thorax under Dynamic Belt Loading

    Microsoft Academic Search

    R. S. Salzar; C. R. Bass; D. Lessley; J. R. Crandall; R. W. Kent; J. R. Bolton

    2009-01-01

    Objective: Three postmortem human surrogates (PMHS) were positioned and rigidly mounted through the spine to a tabletop test fixture for the purpose of characterizing thoracic response to diagonal belt loading with well-defined boundary conditions.Methods: These PMHS were mounted to a stationary apparatus that supported the spine and shoulders in a configuration comparable to that seen in a 48 km\\/h automobile

  1. Community action in Alabama's Black Belt Timber-Dependent communities

    Microsoft Academic Search

    Andrew A. Zekeri

    1996-01-01

    The current decline in the economic well-being of the residents of the Alabama's Black Belt communities is well documented. High poverty rates, limited job growth, falling real per capita income, and increased out-migration are signs of current economic problems. With the resurgence of interest in promulgating self-help and community action mechanism at the local, state, and national levels, the purpose

  2. Failure of automobile seat belts caused by polymer degradation

    Microsoft Academic Search

    J. M. Henshaw; V. Wood; A. C. Hall

    1999-01-01

    This paper analyzes the failure of a particular brand of automobile seat belts. The failures described were part of what nearly became the most expensive and widespread automobile recall in U.S. history, affecting about 8.8 x 106 vehicles and with a potential total cost of U.S. $109 . The failures were caused by the degradation and fracture of the seat

  3. A photoelectric lightcurve survey of small main belt asteroids

    NASA Technical Reports Server (NTRS)

    Binzel, R. P.; Mulholland, J. D.

    1983-01-01

    A survey to obtain photoelectric lightcurves of small main-belt asteroids was conducted from November 1981 to April 1982 using the 0.91- and 2.1-m telescopes at the University of Texas McDonald Observatory. A total of 18 main-belt asteroids having estimated dimaters under 30 km were observed with over half of these being smaller than 15 km. Rotational periods were determined or estimated from multiple nights of observation for nearly all of these yielding a sample of 17 small main-belt asteroids which is believed to be free of observational selection effects. All but two of these objects were investigated for very short periods in the range of 1 min to 2 hr using power spectrum analysis of a continuous set of integrations. No evidence for such short periods was seen in this sample. Rotationally averaged B(1,0) magnitudes were determined for most of the surveyed asteroids, allowing diameter estimates to be made. Imposing the suspected selection effects of photogaphic photometry on the results of this survey gives excellent agreement with the results from that technique. This shows that the inability of photographic photometry to obtain results for many asteroids is indeed due to the rotational parameter of those asteroids.

  4. An Experimental Concept for Probing Nonlinear Radiation Belt Physics

    NASA Astrophysics Data System (ADS)

    Amatucci, Bill; Ganguli, Guru; Crabtree, Chris; Mithaiwala, Manish; Siefring, Carl; Tejero, Erik

    2014-10-01

    The SMART sounding rocket is designed to probe the nonlinear response of a known ionospheric stimulus. High-speed neutral barium atoms generated by a shaped charge explosion perpendicular to the magnetic field in the ionosphere form a ring velocity distribution of photo-ionized Ba+ that will generate lower hybrid waves. Induced nonlinear scattering of lower hybrid waves into whistler/magnetosonic waves has been theoretically predicted, confirmed by simulations, and observed in the lab. The effects of nonlinear scattering on wave evolution and whistler escape to the radiation belts have been studied and observable signatures quantified. The fraction of the neutral atom kinetic energy converted into waves is estimated at 10-12%. SMART will carry a Ba release module and an instrumented daughter section with vector wave magnetic and electric field sensors, Langmuir probes and energetic particle detectors to determine wave spectra in the source region and detect precipitated particles. The Van Allen Probes can detect the propagation of the scattered whistlers and their effects in the radiation belts. By measuring the radiation belt whistler energy density, SMART will confirm the nonlinear scattering process and the connection to weak turbulence. Supported by the Naval Research Laboratory Base Funds.

  5. Resonant and Secular Families of the Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Chiang, E. I.; Lovering, J. R.; Millis, R. L.; Buie, M. W.; Wasserman, L. H.; Meech, K. J.

    2003-06-01

    We review ongoing efforts to identify occupants of mean-motion resonances (MMRs) and collisional families in the Edgeworth-Kuiper belt. Direct integrations of trajectories of Kuiper belt objects (KBOs) reveal the 1:1 (Trojan), 5:4, 4:3, 3:2 (Plutino), 5:3, 7:4, 9:5, 2:1 (Twotino), and 5:2 MMRs to be inhabited. Apart from the Trojan, resonant KBOs typically have large orbital eccentricities and inclinations. The observed pattern of resonance occupation is consistent with resonant capture and adiabatic excitation by a migratory Neptune; however, the dynamically cold initial conditions prior to resonance sweeping that are typically assumed by migration simulations are probably inadequate. Given the dynamically hot residents of the 5:2 MMR and the substantial inclinations observed in all exterior MMRs, a fraction of the primordial belt was likely dynamically pre-heated prior to resonance sweeping. A pre-heated population may have arisen as Neptune gravitationally scattered objects into trans-Neptunian space. The spatial distribution of Twotinos offers a unique diagnostic of Neptune's migration history. The Neptunian Trojan population may rival the Jovian Trojan population, and the former's existence is argued to rule out violent orbital histories for Neptune. Finally, lowest-order secular theory is applied to several hundred non-resonant KBOs with well-measured orbits to update proposals of collisional families. No convincing family is detected.

  6. Search for Active Main-Belt Asteroids: The SAMBA Project

    NASA Astrophysics Data System (ADS)

    Hsieh, H. H.; Jewitt, D.

    2005-08-01

    We are conducting a deep optical survey of selected main-belt asteroids in search of comet-like behavior (comae or dust trails) like that observed for apparent Themis-family asteroid 7968 Elst-Pizarro (also 133P/Elst-Pizarro, hereafter EP). The surprising find of comet-like dust emission by EP (Hsieh, Jewitt, and Fernández, 2004, AJ 127, 2997) can be explained if (1) EP is a comet that has somehow evolved onto an asteroidal orbit, perhaps via the influence of cometary outgassing, or (2) EP is a native member of the asteroid belt on which preserved ice has recently become exposed. If EP is indeed an icy asteroid and not a lost comet, we would not expect uniqueness. A search for objects exhibiting comet-like behavior in the main belt, particularly among the Themis family among which EP itself resides, could reveal other icy bodies. We will present preliminary results (including activity level limits) for over 100 Themis family asteroids imaged as part of just such a search that we are currently conducting using telescopes on Mauna Kea and Cerro Tololo.

  7. Electron losses from the radiation belts caused by EMIC waves

    NASA Astrophysics Data System (ADS)

    Kersten, Tobias; Horne, Richard B.; Glauert, Sarah A.; Meredith, Nigel P.; Fraser, Brian J.; Grew, Russell S.

    2014-11-01

    Electromagnetic Ion Cyclotron (EMIC) waves cause electron loss in the radiation belts by resonating with high-energy electrons at energies greater than about 500 keV. However, their effectiveness has not been fully quantified. Here we determine the effectiveness of EMIC waves by using wave data from the fluxgate magnetometer on CRRES to calculate bounce-averaged pitch angle and energy diffusion rates for L*=3.5-7 for five levels of Kp between 12 and 18 MLT. To determine the electron loss, EMIC diffusion rates were included in the British Antarctic Survey Radiation Belt Model together with whistler mode chorus, plasmaspheric hiss, and radial diffusion. By simulating a 100 day period in 1990, we show that EMIC waves caused a significant reduction in the electron flux for energies greater than 2 MeV but only for pitch angles lower than about 60°. The simulations show that the distribution of electrons left behind in space looks like a pancake distribution. Since EMIC waves cannot remove electrons at all pitch angles even at 30 MeV, our results suggest that EMIC waves are unlikely to set an upper limit on the energy of the flux of radiation belt electrons.

  8. Discovery of Faint Kuiper Belt Objects with the MOSIAC Cameras

    NASA Astrophysics Data System (ADS)

    Millis, Robert L.; Buie, Marc W.; Wagner, R. Mark; Elliot, James L.

    2000-02-01

    Astronomers today are poised at the edge of a new frontier. With the discovery of the Kuiper Belt has come the realization that the Solar System beyond Neptune is not effectively empty, but rather contains tens of thousands of intriguing orbiting bodies. Only about 200 or these Kuiper Belt Objects (KBOs) have been discovered at this writing. Yet they promise fundamental insights into the physical and dynamical processes which sculpted the outer regions of the solar system. To understand the Kuiper Belt, we must probe its radial extent, discover the distribution of objects with ecliptic longitude and latitude, learn the size distribution of the KBOs, and establish the orbits of these bodies - both to reveal the relevant dynamical processes and to facilitate physical studies with large-aperture telescopes on the ground and in space. These scientific objectives can be accomplished only through a carefully planned, wide ranging reconnaissance. Here we propose to continue our highly successful program at KPNO and to extend it into the Southern Hemisphere using the newly commissioned Mosaic Camera on the Blanco Telescope.

  9. The population size distribution of the Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Trilling, D. E.

    2002-09-01

    The physical properties of Kuiper Belt Objects are determined by both the accretional and erosional histories of the Kuiper Belt. These two physical processes produce different slopes in the distribution of KBO sizes. We have used the orbital elements and magnitudes for the 219 designated/numbered KBOs discovered in the large-scale, relatively uniform Deep Ecliptic Survey (Millis et al.) to determine a population size distribution for a subset of the Kuiper Belt. This population size distribution is relatively free from biases that are unavoidable when data from more than one observing program are combined, although biases are still present in this data set. The observed population size distribution obeys a power law with a slope of -4 for bodies with radii 350 km > r > 150 km. This slope is consistent with that expected from KBO accretion models. The very largest KBOs (e.g., 28978 Ixion, radius around 600 km) do not obey the population size distribution power law; this behavior is reminiscent of signatures of oligarchic growth. An upcoming HST program (Bernstein et al.) will determine the population size distribution down to 20-40 km bodies. This HST program will test for a break in slope to a collisionally evolved, erosional KBO population (with a predicted slope of -3.5) at smaller sizes. This work is supported by grants from the AAS and from STScI.

  10. OORT-Cloud and Kuiper-Belt Comets

    NASA Technical Reports Server (NTRS)

    Whipple, Fred L.

    1998-01-01

    This paper follows the broadly accepted theory that Oort-Cloud Comets originated in the Solar Nebula in the general region where the major planets, Jupiter and Saturn, were formed while the Kuiper-Belt Comets originated farther out where the temperatures were lower. The Oort-Cloud Comets are identified orbitally by long periods and random inclinations and, including the Halley-type comets, comets with a Tisserand Criterion less than 2.0. Kuiper-Belt comets are identified by short periods, usually much less than 200 years, and small inclinations to the ecliptic. Here two criteria for comet activity are found to separate the two classes of comets. These quantities NG1 and NG2, were intended to measure theoretical nongravitaional effects on comet orbits. They are only, mildly successful in correlations with observed cases of measured non-gravitational forces. But, in fact, their variations with perihelion distance separate the two classes of comets. The results are consistent with the theory that the activity or intrinsic brightness of Oort-Cloud Comets fall off faster with increasing perihelion distance that does the intrinsic brightness of short-period Kuiper-Belt Comets.

  11. Unraveling the drivers of the storm time radiation belt response

    NASA Astrophysics Data System (ADS)

    Kilpua, E. K. J.; Hietala, H.; Turner, D. L.; Koskinen, H. E. J.; Pulkkinen, T. I.; Rodriguez, J. V.; Reeves, G. D.; Claudepierre, S. G.; Spence, H. E.

    2015-05-01

    We present a new framework to study the time evolution and dynamics of the outer Van Allen belt electron fluxes. The framework is entirely based on the large-scale solar wind storm drivers and their substructures. The Van Allen Probe observations, revealing the electron flux behavior throughout the outer belt, are combined with continuous, long-term (over 1.5 solar cycles) geosynchronous orbit data set from GOES and solar wind measurements A superposed epoch analysis, where we normalize the timescales for each substructure (sheath, ejecta, and interface region) allows us to avoid smearing effects and to distinguish the electron flux evolution during various driver structures. We show that the radiation belt response is not random: The electron flux variations are determined by the combined effect of the structured solar wind driver and prestorm electron flux levels. In particular, we find that loss mechanisms dominate during stream interface regions, coronal mass ejection (CME) ejecta, and sheaths while enhancements occur during fast streams trailing the stream interface or the CME.

  12. Digital field trip to the Central Nevada Thrust Belt

    SciTech Connect

    Chamberlain, A.K. (Cedar Strat Corp., Hiko, NV (United States)); Hook, S.C. (Texaco E P Technology Department, Houston, TX (United States)); Frost, K.R. (Texaco Exploration and Production, Inc., Houston, TX (United States))

    1996-01-01

    Hydrocarbon exploration in the Central Nevada Thrust Belt is still in its infancy. However, this thrust belt contains all the elements necessary for hydrocarbon accumulations: thick, organically-rich shales; reefs, regional unconformities, karst surfaces, porous sandstones, and extensive and pervasive fractures; anticlines tens of miles long by miles wide; thrust faults that juxtapose potential source and reservoir rocks; and oil seeps. Along a fairway from Las Vegas to Elko, for example, thick Mississippian shales contain 4-6% total organic carbon and are oil-prone and thermally mature. This presentation from a laptop computer and LCD projector is a multimedia version of our October 12-14, 1995 field trip to document the hydrocarbon potential of the thrust belt in Clark, Lincoln, and Nye Counties. Outcrop images were recorded by a digital camera that has a resolution equivalent to a 14 inch computer screen; these images were then downloaded to the computer. All of the images were processed digitally on location to enhance picture quality and color contrast. Many were annotated on location with our observations, measurements, and interpretations. These field annotations are supplemented in this presentation by laboratory analyses. The presentation includes full-color, annotated outcrop images, sounds, and animations. The results show the viability of the new, inexpensive digital cameras to geologic field work in which a multimedia report, ready for presentation to management, can be generated in the field.

  13. Digital field trip to the Central Nevada Thrust Belt

    SciTech Connect

    Chamberlain, A.K. [Cedar Strat Corp., Hiko, NV (United States); Hook, S.C. [Texaco E& P Technology Department, Houston, TX (United States); Frost, K.R. [Texaco Exploration and Production, Inc., Houston, TX (United States)

    1996-12-31

    Hydrocarbon exploration in the Central Nevada Thrust Belt is still in its infancy. However, this thrust belt contains all the elements necessary for hydrocarbon accumulations: thick, organically-rich shales; reefs, regional unconformities, karst surfaces, porous sandstones, and extensive and pervasive fractures; anticlines tens of miles long by miles wide; thrust faults that juxtapose potential source and reservoir rocks; and oil seeps. Along a fairway from Las Vegas to Elko, for example, thick Mississippian shales contain 4-6% total organic carbon and are oil-prone and thermally mature. This presentation from a laptop computer and LCD projector is a multimedia version of our October 12-14, 1995 field trip to document the hydrocarbon potential of the thrust belt in Clark, Lincoln, and Nye Counties. Outcrop images were recorded by a digital camera that has a resolution equivalent to a 14 inch computer screen; these images were then downloaded to the computer. All of the images were processed digitally on location to enhance picture quality and color contrast. Many were annotated on location with our observations, measurements, and interpretations. These field annotations are supplemented in this presentation by laboratory analyses. The presentation includes full-color, annotated outcrop images, sounds, and animations. The results show the viability of the new, inexpensive digital cameras to geologic field work in which a multimedia report, ready for presentation to management, can be generated in the field.

  14. The Origin and Evolution of the Asteroid Main Belt

    E-print Network

    Philip R. Bidstrup; Henning Haack; Anja C. Andersen; Rene Michelsen; John Leif Jorgensen

    2005-11-11

    Using a fully autonomous spacecraft - Bering - we propose to detect and study sub-km asteroids from an orbit within the asteroid Main Belt. The main purpose of the proposed Bering mission is to detect a statistically significant sample of an expected population of approximately 10^(10) main belt asteroids in the size range 1 m to 1 km. These asteroids are too faint to be observed using Earth-based telescopes. Sub-km asteroids can be detected from spacecraft at close range but due to the high relative velocities and the long communication times this requires a fully autonomous spacecraft. Using theoretical estimates of the distribution and abundance of sub-km asteroids we find that the Bering mission would detect approximately 6 new sub-km asteroids per day. With an expected lifetime for the mission of a few years we expect to detect and study several thousand sub-km asteroids. Results from the Bering mission would allow us to: 1) Provide further links between groups of meteorites and their parent asteroids. 2) Constrain the cratering rate at planetary surfaces and thus allow significantly improved cratering ages for terrains on Mars and other planets. 3) Constrain processes that transfer small asteroids from orbits in the main belt to the inner Solar System.

  15. Early Earth tectonics: A high-resolution 3D numerical modelling approach

    NASA Astrophysics Data System (ADS)

    Fischer, Ria; Gerya, Taras

    2015-04-01

    Early Earth had a higher amount of remaining radiogenic elements as well as a higher amount of leftover primordial heat. Both contributed to the increased temperature in the Earth's interior and it is mainly this increased mantle potential temperature ?Tp that controls the dynamics of the crust and upper mantle and the style of Early Earth tectonics. We conduct 3D petrological-thermomechanical numerical modelling experiments of the crust and upper mantle under Early Earth conditions using a plume tectonics model setup. For varying crustal structures and an increased mantle potential temperature ?Tp, a hot lower thermal boundary layer is used to introduce spontaneously developing mantle plumes. The model is able to self-sufficiently form depleted mantle lithosphere after repeated melt removal. New crust can be produced in the form of volcanics and/or plutonics. To simulate differentiation the newly formed crust can have a range in composition from basaltic to granitic depending on its source rock. For a major increase in the mantle temperature, presumably corresponding to an Archean mantle (?Tp = 200 - 300K compared to present day conditions), models show large amounts of subcrustal decompression melting and consequently large amounts of volcanics, which in turn influence the dynamics. Mantle and crust are convecting separately. Dome-shaped felsic plutons can be observed in the crust. Between these domes elongated belts of downwelling basalt and sediments are formed. Both crust and lithosphere thickness are regulated by thermo-chemical instabilities assisted by lower crust eclogitization: linear or cylindrical drips originating at the crust or lithosphere bottom or delamination of lower crust or lithosphere. Very similar examples of dome and belt structures are still preserved in Archean cratons. One example is the Kaapvaal craton is South Africa where the elongated shape of the Barberton Greenstone Belt, mainly built from mafic rocks and sediments, is surrounded by multiple plutons of both felsic and mafic composition. Another striking example is the Pilbara craton in northwest Australia which shows a very similar distribution of mafic greenstone belts and felsic domes.

  16. Geochemistry and U–Pb zircon ages of plutonic rocks from the Algodões granite-greenstone terrane, Troia Massif, northern Borborema Province, Brazil: Implications for Paleoproterozoic subduction-accretion processes

    NASA Astrophysics Data System (ADS)

    Costa, Felipe Grandjean da; Palheta, Edney Smith de Moraes; Rodrigues, Joseneusa Brilhante; Gomes, Iaponira Paiva; Vasconcelos, Antonio Maurilio

    2015-04-01

    The Algodões metavolcano-sedimentary sequence is located at the northern margin of the Archean/Paleoproterozoic Troia Massif, northern Borborema Province (NE Brazil). It represents a well-preserved Paleoproterozoic greenstone-like sequence affected by two major plutonic events. The early plutonism, represented by the Cipó orthogneisses, mainly comprises biotite-bearing metatonalites, which share similar geochemical signatures with Archean tonalite-trondjhemite-granodiorite (TTG). For these rocks, we report U-Pb (LA-ICPMS) zircon ages of 2189 ± 14 Ma and 2180 ± 15 Ma. A subsequent plutonic magmatism occurred at ?2150-2130 Ma and is mainly represented by hornblende-bearing dioritic to tonalitic orthogneisses of the Madalena Suite and São José da Macaoca Complex. Geochemical data indicate that these dioritic/tonalitic orthogneisses have adakitic characteristics and strongly suggest mantle-related magmas. A (sensu stricto) granite plutonism (Serra da Palha orthogneisses) also intruded the Algodões sequence and yielded U-Pb (LA-ICPMS) zircon age of 2150 ± 16 Ma. These granitic orthogneisses show high-K content, A-type characteristics and probably derived from partial melting of a crustal (tonalitic) source. We suggest that the early ?2190-2160 Ma TTG plutons probably developed in intra-oceanic arc setting, whereas the following ?2150-2130 Ma adakitic plutons and A-type granitic magmatism developed in response to arc-continent collision.

  17. "Inner electron" radiation belt: problems of model creation

    NASA Astrophysics Data System (ADS)

    Temnyi, V.

    The contents of intensive fluxes of trapped electrons J_e with energies E_e>40 keV in center of the inner terrestrial radiation belt is remains uncertain in model Vette AE-8, 1991. It is explained by methodical difficulties of discrete measurements of electrons by narrow-angle spectrometers with background from omnidirectional penetrating protons with energies E_p>40 MeV and electrons with E_e>1 MeV after STARFISH burst. The results of integral measurements of trapped electrons by 2 groups: Krassovsky V.I. on III Soviet satellite (May 1958) and J. Van Allen on EXPLORER-IV (July-August 1958) and on INJUN-1 (1961) heave given a performances concerning electron energy fluxes I_e(E_e>20 keV) ˜ (20-100) erg cm-2 c-1 into inner radiation belt. Improved integral measurements of electrons by Krassovsky group on satellites KOSMOS-3,-5 and ELECTRON-1,-3 (1962-1964) allow to determine the distributions of their intensities in the whole inner belt. They can add the central part of inner belt of AE-8 model (see report Bolunova et al., COSPAR-1965, publ. in SPACE RESEARCH VI, 1967, p. 649-661). From these data a maximum of trapped electrons J_e(E_e>40 keV)=2\\cdot10^9 cm-2 c-1 is placed on L=1,6, B/B_0=1. Intensities up to 2\\cdot10^7 cm-2 c-1 are determined only by coordinates (L, B). For smaller intensities become essential dependence from longitude along a drift shell. So, in the center of the inner radiation belt the energy fluxes I_e(E_e>40 keV) reach 500 erg cm-2 c-1 and density n_e=0,2 cm-3 while for trapped protons I_p(E_p>40 MeV) is less than 3 erg cm-2 c-1 and n_p< 5\\cdot10-6 cm-3. It forces to search a more powerful sources trapped electron than beta-decay of neutrons albedo of cosmic rays.

  18. Study of coal mine belt conveyor state on-line monitoring system of based on DTS

    NASA Astrophysics Data System (ADS)

    Wei, Yubin; Wu, Wenming; Liu, Tongyu; Sun, Yajun

    2013-09-01

    Coal mine belt transport system is the most important transportation system, directly determines the normal operation of coal mine production safety, so it is necessary to secure real-time online monitoring of running status. Based on distributed optical fiber temperature measurement technology, developed a coal mine belt conveyor running state online monitoring system, achieved to monitor the Real-time temperature of mainly electromechanical device and all the belt line. Field data analysis showed that coal mine belt conveyor state on-line monitoring system of based on DTS can real-time accurately monitor the temperature and belt conveyor running state, to guarantee the coal belt conveyor safe operation and offer a strong support.for the realization of the state maintenance of equipment.

  19. Phase II of the Small Main-Belt Asteroid Spectroscopic Survey

    Microsoft Academic Search

    Schelte J. Bus; Richard P. Binzel

    2002-01-01

    We present visible-wavelength (0.435–0.925 ?m) spectroscopic measurements for 1341 main-belt asteroids observed during the second phase of the Small Main-belt Asteroid Spectroscopic Survey (SMASSII). The purpose of this survey is to provide a new basis for studying the compositional structure of the asteroid belt. Through the large sample size and the relatively high spectral resolution (R?100) of the SMASSII data,

  20. Self-reported safety belt use among emergency department patients in Boston, Massachusetts

    Microsoft Academic Search

    William G Fernandez; Supriya D Mehta; Tara Coles; James A Feldman; Patricia Mitchell; Jonathan Olshaker

    2006-01-01

    BACKGROUND: Safety belt use is 80% nationally, yet only 63% in Massachusetts. Safety belt use among potentially at-risk groups in Boston is unknown. We sought to assess the prevalence and correlates of belt non-use among emergency department (ED) patients in Boston. METHODS: A cross-sectional survey with systematic sampling was conducted on non-urgent ED patients age ?18. A closed-ended survey was