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Sample records for active kolbeinsey ridge

  1. Melt Flux Around Iceland: The Kolbeinsey Ridge Seismic Experiment.

    NASA Astrophysics Data System (ADS)

    Brandsdóttir, B.; Hooft, E. E.

    2007-12-01

    Seafloor spreading within the Iceland region has been complex since the opening of the North Atlantic in late Paleocene-early Eocene. Whereas symmetric magnetic anomalies can be traced parallel to the Reykjanes Ridge and Mohns Ridge back to chrons 23-24, anomalies within the Iceland Plateau and Aegir Ridge in the Norwegian Sea, as well as along the Greenland-Iceland-Faeroe Ridge reflect plate-boundary irregularities associated with multiple-branched crustal accretion zones, rift jumps and plate boundary segmentation (volcanic systems). We observe large variations in crustal structure along two refraction/reflection/gravity profiles, a 700 km EW-profile straddling 66.5°N between the Aegir and Kolbeinsey Ridges and a 225 km NS-profile along the southern Kolbeinsey Ridge. These profiles enable us to quantify how melt flux at the N-Atlantic spreading center has been influenced by the Iceland hotspot from the initiation of spreading to present time. The westernmost 300 km of the EW profile lies across the Iceland shelf, considered to have formed by rifting at the Kolbeinsey Ridge whereas the easternmost 400 km lie across the Iceland Plateau and Norway Basin, a region formed by rifting at the Aegir Ridge and possibly containing slivers of older crust rifted off the east Greenland margin along with the Jan Mayen Ridge. Crustal thickness varies from 4-5 km across the Aegir Ridge, 12 km just east of the Iceland shelf, and 24-28 km beneath the outer shelf, to 12-13 km near the southern tip of the Kolbeinsey Ridge and 9-10 km further north along the ridge axis. Pronounced undulations in lower crustal structure across the Iceland Plateau are most likely associated with extinct spreading centers indicating that branched crustal accretion zones existed west of the Aegir Ridge prior to the westward ridge jump forming the KR at 26 Ma. Crustal thickness at the Kolbeinsey and Reykjanes Ridges support the asymmetry in plume-ridge interaction north and south of Iceland that has been

  2. Segment-scale volcanic episodicity: Evidence from the North Kolbeinsey Ridge, Atlantic

    NASA Astrophysics Data System (ADS)

    Yeo, I. A.; Devey, C. W.,; LeBas, T. P.; Augustin, N.; Steinführer, A.

    2016-04-01

    The upper oceanic crust is produced by magmatism at mid-ocean ridges, a process thought to be characterized by cyclic bouts of intense magmatic activity, separated by periods when faulting accommodates most or even all of the plate motion. It is not known whether there is a distinct periodicity to such magmatic-tectonic cycles. Here we present high-resolution sidescan sonar data from the neovolcanic zone of the North Kolbeinsey Ridge, a shallow slow-spreading ridge where high glacial and steady post-glacial sedimentation rates allow relative flow ages to be determined with a resolution of around 2 kyr using backscatter amplitude as a proxy for sediment thickness and hence age. We identify 18 lava flow fields covering 40% of the area surveyed. A group of 7 flow fields showing the highest (and similar) backscatter intensity are scattered along 75 km of axial valley surveyed, suggesting that at least this length of the segment was magmatically active within a 1.2 kyr time window. Based on conservative age estimates for all datable flows and estimated eruption volumes, the post-glacial volcanic activity imaged is insufficient to maintain crustal thickness, implying that episode(s) of enhanced activity must have preceded the volcanism we image.

  3. Neogene magmatism northeast of the Aegir and Kolbeinsey ridges, NE Atlantic: Spreading ridge-mantle plume interaction?

    NASA Astrophysics Data System (ADS)

    Breivik, AsbjøRn Johan; Faleide, Jan Inge; Mjelde, Rolf

    2008-02-01

    According to mantle plume theory the Earth's interior cools partly by localized large vertical mass transport, causing extensive decompression melting. The Iceland melt anomaly is regarded as a typical example of a mantle plume. However, there are centers of Miocene to recent magmatism in the Norwegian-Greenland Sea not easily explained by the plume theory. Here we present new data to document diffuse late Miocene magmatic underplating of older oceanic crust located mostly north of the Aegir Ridge, an extinct seafloor spreading axis in the Norway Basin. There is also a region with similar magmatism northeast of the presently spreading Kolbeinsey Ridge north of Iceland. Intraplate magmatism in these locations is not easily explained by local plume models, edge-driven convection, or by asthenosphere flow-lithosphere thickness interaction. On the basis of correlation between the magmatism and the active or extinct spreading ridges, we propose the mid-ocean ridge basalt-capture model, in which this magmatism can be understood through plume-spreading ridge interaction: The asthenosphere flow out from Iceland captures deeper, low-degree partially molten asthenospheric regions from underneath the spreading ridges and carry these across the terminating fracture zones, to subsequently underplate oceanic crust or to intrude and build seamounts. This model is similar to lithospheric cracking models for intraplate magmatism in requiring that low-degree partial melt can be retained in the asthenosphere over time but differ in that the magma is extracted by internal magma movement processes and not by external tectonic forces.

  4. Hydrodynamic properties and grain-size characteristics of volcaniclastic deposits on the mid-Atlantic Ridge north of Iceland (Kolbeinsey Ridge)

    SciTech Connect

    Oehmig, R.; Wallrabe-Adams, H. )

    1993-01-01

    Surface sediments from a transect across the mid-ocean ridge north of Iceland (Kolbeinsey Ridge) have been analyzed according to their compositional, textural and hydromechanical characteristics. The results were used to reconstruct sediment formation and depositional processes. The ridge sediments are dominated by volcaniclastic particles of hyaloclastic and pyroclastic origin. These particles show a wide variety in size, shape and density. Single-grain settling velocities of the different glass types reveal the suitability of this parameter as a reflector of the particle properties of size, shape and density, which are also known to be relevant to grain transport. Observations concerning different current expositions of central ridge sediments, combined with the parameters of settling velocity distribution, grain-size distribution and sediment particle composition, were applied to distinguish between transport association with rare, easily movable glass shards and poorly sorted sediments in sheltered ponds. A bimodal settling velocity distribution of steep ridge-flank sediments probably indicates the effect of sediment admixture from poorly sorted mass flows. Alternating coarse- and fine-grained layers characterize the transition between ridge-glass sands and the ridge-adjacent plain, which is dominated by slow-settling pelagic material.

  5. Structural development of the Jan Mayen microcontinent (JMMC): An update of its role during the rift transition from the Ægir Ridge to the Kolbeinsey Ridge, and effects on the formation of the Greenland-Iceland-Faroe ridge complex.

    NASA Astrophysics Data System (ADS)

    Blischke, Anett; Gaina, Carmen; Hopper, John R.; Peron-Pinvidic, Gwenn; Brandsdóttir, Bryndis; Guarnieri, Pierpaolo; Erlendsson, Ögmundur

    2016-04-01

    This study presents results of an ongoing PhD research project and proposes a revision of the Jan Mayen microcontinent's Cenozoic evolution with a special emphasis on the structural relationship to the Greenland-Iceland Faroe ridge complex. Recently acquired and publicly available geophysical and borehole data collected offshore Iceland since the early 1970s, facilitate a thorough review of Tertiary rift systems and their association with the Jan Mayen microcontinent, updating recent kinematic modelling that details the timing of the North Atlantic opening along the Jan Mayen transfer systems, and the Iceland-Faroe-Greenland transfer system bordering the Greenland-Iceland Faroe ridge complex, which covers a large area of thick crust that stretches across the North Atlantic Ocean between the central East Greenland and the North-West European margins. The established regional reflection seismic dataset interpretations and plate tectonic reconstructions indicate that the microcontinent may represent the southern extension of the East Greenland Jameson Land basin, suggesting a similar structural trend as the Faroe-Shetland basin. The Cenozoic structural evolution of the Jan Mayen microcontinent and surrounding oceanic crust includes six main phases that correlate to several major unconformities and related structures. Important events include the pre-break-up unconformity, the break-up to drift phase, a drifting phase and establishment of the Ægir Ridge seafloor spreading during the early Eocene, oblique seafloor spreading direction east of JMMC during mid-Eocene caused the formation of transform systems and uplift along the southern flank Jan Mayen microcontinent forming the Iceland Plateau Rift (Brandsdóttir et al. 2015), accompanied by igneous activity along the northeastern margin of the Blosseville Kyst (Larsen et al. 2014), ridge relocation via a southeast to northwest en-echelon ridge system transition from the southern extent of the microcontinent during the

  6. Structural development of the Jan Mayen microcontinent (JMMC): An update of its role during the rift transition from the Ægir Ridge to the Kolbeinsey Ridge, and effects on the formation of the Greenland-Iceland-Faroe ridge complex.

    NASA Astrophysics Data System (ADS)

    Blischke, Anett; Gaina, Carmen; Hopper, John R.; Peron-Pinvidic, Gwenn; Brandsdóttir, Bryndis; Guarnieri, Pierpaolo; Erlendsson, Ögmundur

    2016-04-01

    This study presents results of an ongoing PhD research project and proposes a revision of the Jan Mayen microcontinen&tacute;s Cenozoic evolution with a special emphasis on the structural relationship to the Greenland-Iceland Faroe ridge complex. Recently acquired and publicly available geophysical and borehole data collected offshore Iceland since the early 1970s, facilitate a thorough review of Tertiary rift systems and their association with the Jan Mayen microcontinent, updating recent kinematic modelling that details the timing of the North Atlantic opening along the Jan Mayen transfer systems, and the Iceland-Faroe-Greenland transfer system bordering the Greenland-Iceland Faroe ridge complex, which covers a large area of thick crust that stretches across the North Atlantic Ocean between the central East Greenland and the North-West European margins. The established regional reflection seismic dataset interpretations and plate tectonic reconstructions indicate that the microcontinent may represent the southern extension of the East Greenland Jameson Land basin, suggesting a similar structural trend as the Faroe-Shetland basin. The Cenozoic structural evolution of the Jan Mayen microcontinent and surrounding oceanic crust includes six main phases that correlate to several major unconformities and related structures. Important events include the pre-break-up unconformity, the break-up to drift phase, a drifting phase and establishment of the Ægir Ridge seafloor spreading during the early Eocene, oblique seafloor spreading direction east of JMMC during mid-Eocene caused the formation of transform systems and uplift along the southern flank Jan Mayen microcontinent forming the Iceland Plateau Rift (Brandsdóttir et al. 2015), accompanied by igneous activity along the northeastern margin of the Blosseville Kyst (Larsen et al. 2014), ridge relocation via a southeast to northwest en-echelon ridge system transition from the southern extent of the microcontinent

  7. Hydrothermal activity at the Arctic mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Pedersen, Rolf B.; Thorseth, Ingunn H.; Nygård, Tor Eivind; Lilley, Marvin D.; Kelley, Deborah S.

    Over the last 10 years, hydrothermal activity has been shown to be abundant at the ultraslow spreading Arctic Mid-Ocean Ridges (AMOR). Approximately 20 active and extinct vent sites have been located either at the seafloor, as seawater anomalies, or by dredge sampling hydrothermal deposits. Decreasing spreading rates and decreasing influence of the Icelandic hot spot toward the north along the AMOR result in a north-south change from a shallow and magmatically robust to a deep and magmatically starved ridge system. This contrast gives rise to large variability in the ridge geology and in the nature of the associated hydrothermal systems. The known vent sites at the southern part of the ridge system are either low-temperature or white smoker fields. At the deep, northern parts of the ridge system, a large black smoker field has been located, and seawater anomalies and sulfide deposits suggest that black smoker-type venting is common. Several of these fields may be peridotite-hosted. The hydrothermal activity at parts of the AMOR exceeds by a factor of 2 to 3 what would be expected by extrapolating from observations on faster spreading ridges. Higher fracture/fault area relative to the magma volume extracted seems a likely explanation for this. Many of the vent fields at the AMOR are associated with axial volcanic ridges. Strong focusing of magma toward these ridges, deep rifting of the ridges, and subsequent formation of long-lived detachment faults that are rooted below the ridges may be the major geodynamic mechanisms causing the unexpectedly high hydrothermal activity.

  8. Hydrothermal Activity on ultraslow Spreading Ridge: new hydrothermal fields found on the Southwest Indian ridge

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Deng, X.; Lei, J.; Wang, Y.; Zhang, K.; Zhou, J.; Liu, W.

    2014-12-01

    Ultraslow spreading ridge makes up about 25% of global mid-ocean ridge length. Previous studies believed that hydrothermal activity is not widespread on the ultraslow spreading ridge owing to lower magma supply. Southwest Indian ridge (SWIR) with the spreading rate between 1.2cm/a to 1.4cm/a, represents the ultraslow spreading ridge. In 2007, Chinese Cruise (CC) 19th discovered the Dragon Flag deposit (DFD) on the SWIR, which is the first active hydrothermal field found on the ultraslow spreading ridge. In recent years, over 10 hydrothermal fields have been found on the SWIR between Indomed and Gallieni transform faults by the Chinese team. Tao et al. (2012) implied that the segment sections with excess heat from enhanced magmatism and suitable crustal permeability along slow and ultraslow ridges might be the most promising areas for searching for hydrothermal activities. In 2014, CC 30thdiscovered five hydrothermal fields and several hydrothermal anomalies on the SWIR. Dragon Horn Area (DHA). The DHA is located on the southern of segment 27 SWIR, with an area of about 400 km2. The geophysical studies indicated that the DHA belongs to the oceanic core complex (OCC), which is widespread on the slow spreading ridges (Zhao et al., 2013). The rocks, such as gabbro, serpentinized peridotite, and consolidated carbonate were collected in the DHA, which provide the direct evidence with the existence of the OCC. However, all rock samples gathered by three TV-grab stations are basalts on the top of the OCC. A hydrothermal anomaly area, centered at 49.66°E,37.80° S with a range of several kms, is detected in the DHA. It is probably comprised of several hydrothermal fields and controlled by a NW fault. New discovery of hydrothermal fields. From January to April 2014, five hydrothermal fields were discovered on the SWIR between 48°E to 50°E during the leg 2&3 of the CC 30th, which are the Su Causeway field (48.6°E, 38.1°S), Bai Causeway field (48.8°E, 37.9 °S), Dragon

  9. Hydrothermal Activity Along Multiple Ridge Segments of the Northern Central Indian Ridge, 8°-17°S

    NASA Astrophysics Data System (ADS)

    Son, J.; Kim, J.; Pak, S.; Son, S.; Moon, J.; Baker, E. T.

    2012-12-01

    We report the first systematic hydrothermal plume surveys conducted on the northern Central Indian Ridge (CIR, 8°-17°S), a slow spreading ridge with rates between ~35 and 40 mm/yr, during the CIR research program of KORDI between 2009 and 2011. Using a combined CTD/Miniature Autonomous Plume Recorder (MAPR) package we occupied 208 vertical casts and 82 tows along seven segments of the CIR totaling ~700 km of ridge length to estimate the frequency of hydrothermal activity on this slow-spreading ridge. Evidence for hydrothermal activity was found on each of the seven segments, with most plumes found between 3000 and 3500 m. Using only stations within the rift valley, the estimated value of plume incidence (ph=0.19) coincides with the global trend between the spatial density of hydrothermal plumes and full-spreading rate (an indicator of magmatic budget). However, there are also indications of possible discharge from hydrothermal activity or serpentinization from the ridge flanks (possible ocean core complexes), as has been observed along the Mid-Atlantic Ridge. For example, some sites show methane anomalies unaccompanied by any optical anomaly. Our preliminary results support the increasing role of tectonic control on hydrothermal activity as spreading rates decrease. Further examination of the plume signals, combined with chemical composition of sampled water and geological data, will provide valuable insights into hydrothermal activity on slow spreading ridges.

  10. A History of Classified Activities at Oak Ridge National Laboratory

    SciTech Connect

    Quist, A.S.

    2001-01-30

    The facilities that became Oak Ridge National Laboratory (ORNL) were created in 1943 during the United States' super-secret World War II project to construct an atomic bomb (the Manhattan Project). During World War II and for several years thereafter, essentially all ORNL activities were classified. Now, in 2000, essentially all ORNL activities are unclassified. The major purpose of this report is to provide a brief history of ORNL's major classified activities from 1943 until the present (September 2000). This report is expected to be useful to the ORNL Classification Officer and to ORNL's Authorized Derivative Classifiers and Authorized Derivative Declassifiers in their classification review of ORNL documents, especially those documents that date from the 1940s and 1950s.

  11. Kinematics of Mid-Ocean Ridge Relative Motions in the Indo-Atlantic Frame of Reference: Passive and Active Spreading Ridges

    NASA Astrophysics Data System (ADS)

    Rowan, C. J.; Rowley, D. B.; Forte, A. M.

    2011-12-01

    ridge parallel (N-S) motion in the past 30 Ma. Between 80 and 30 Ma, the midpoint of the Nazca-Pacific segment of the EPR moved ~2500 km parallel with the trend of the ridge. The absence of significant longitudinal motion of the EPR extends northward to the now subducted portion beneath eastern North America. We interpret this as an actively spreading ridge segment linked directly to and driven by active mantle upwelling associated with the mantle convective system.

  12. Experimental study of structure-forming deformations in ultra-slow spreading Arctic and Polar Atlantic ridges

    NASA Astrophysics Data System (ADS)

    Dubinin, E. P.; Grokholsky, A. L.; Kokhan, A. V.

    2010-05-01

    The system of regional spreading ridges includes Reikjanes, Kolbeinsey, Mohns, Knipovich and Gakkel ridges. They are rather young (spreading initiated 58-60 Myr ago) and ultra-slow (spreading velocity < 20 mm/year). But all of them have peculiarities in structure patterns, kinematics, and morphology. In order to study geodynamical features of structure-forming on these ridges we apply experimental modeling. This study covers three of the ridges mentioned above: Reikjanes, Knipovich and Gakkel. The specified experimental complex and model material were used in modeling sets. The model material used in modeling is a colloidal system composed of mineral oils, solid hydrocarbon and surface-active substances. It has elastic-viscous-plastic properties, under temperature and strain rate, it is capable of failure like a brittle body. All experiments were held according to similarity conditions. Reikjanes ridge is situated south-west of Iceland. It shows changes of morphology from north to south. The northern part of it is characterized by axial rise, the southern part - by axial valley. The main feature of axial morphology is presence of s-shaped axial volcanic ridges (AVRs). The angle between ridge trend and plate divergence trend is nearly 60°. All these features are explained by influence of mantle flow from the Iceland mantle plum initiating the increasing of mantle temperature. It results in decreasing of litospheric brittle layer with approaching to Iceland. The experimental setting was following. The weak zone was emplaced obliquely, crustal thickness and width of weak zone varied in sets. Conditions of northern part of the ridge were reproduced in sets with the widest weak zone and the smallest crustal thickness and vice versa. In sets reproducing conditions of northern province we received long and non-discontinued AVRs, on the other hand we received short and displaced AVRs in south-like conditions. Knipovich ridge stretches along Spitsbergen continental margin

  13. Annual report on surveillance and maintenance activities at Oak Ridge National Laboratory, Oak Ridge, Tennessee, fiscal year 1996

    SciTech Connect

    1996-11-01

    In fiscal year (FY) 1995, the sites and facilities from both the Remedial Action (RA) and Decontamination and Decommissioning (D and D) programs were combined to form the Oak Ridge National Laboratory (ORNL) Environmental Restoration (ER) Surveillance and Maintenance (S and M) Program. Surveillance and Maintenance activities were conducted throughout FY 1996 at the RA facilities. Overall, the RA S and M Program consists of approximately 650 acres that include 14 waste area groupings with approximately 200 sites. These sites include 46 major facilities, several leak and contaminated soil sites, 38 inactive tanks, approximately 50 environmental study areas and approximately 2,973 wells and boreholes. Site inspections were conducted at established frequencies on appropriate sites in the RA S and M Program in accordance with the established S and M FY 1996 Incentive Task Order (ITO).

  14. Hotspot activity and plume pulses recorded by geometry of spreading axes

    NASA Astrophysics Data System (ADS)

    Abelson, Meir; Agnon, Amotz

    2001-06-01

    Anomalous plan view geometry (planform) of spreading axes is shown to be a faithful indicator of hotspot influence, possibly capable of detecting pulses of hotspot discharge. A planform anomaly (PA) occurs when the orientation of second-order ridge segments is prominently oblique to the spreading direction. PA is found in the vicinity of hotspots at shallow ridges (<1.5 km), suggesting hotspot influence. In places the PA and shallow bathymetry are accompanied by geochemical anomalies, corroborating hotspot influence. This linkage is best expressed in the western Gulf of Aden, where the extent of the PA from the Afar hotspot coincides with the extent of La/Sm and Sr isotopic anomalies. Using fracture mechanics we predict PA to reflect overpressurized melt that dominates the stresses in the crust, consistent with hotspot regime. Accordingly, the temporal variations of the planform previously inferred from magnetic anomalies around the Kolbeinsey Ridge (KR), north of Iceland, record episodes of interaction with the hotspot and major pulses of the plume. This suggestion is corroborated by temporal correlation of episodes showing PA north of Iceland with plume pulses previously inferred by the V-shaped ridges around the Reykjanes Ridge (RR), south of Iceland. In contrast to the RR, the temporal correlation suggests simultaneous incidence of the plume pulses at Iceland and KR, hundreds of kilometers to the north. A deep northward branch of the Iceland plume active during pulse-periods may explain these observations.

  15. Asymmetric active seismicity along the ultra-slow spreading Gakkel Ridge

    NASA Astrophysics Data System (ADS)

    Hopper, John R.; Voss, Peter H.; Lavier, Luc L.

    2015-04-01

    Ultra-slow spreading ridges are frequently characterised by spreading segments that are largely magma starved. Spreading along such segments does not occur by crustal creation/accretion processes such as intrusions, diking and volcanism, but rather by mechanical extension of the lithosphere, exposing the mantle to seafloor where it interacts with seawater to form serpentinite. Such exhumation is thought to occur along detachment faults that form concave down surfaces and produce an extensional geometry that is highly asymmetric. A consequence of all models that have been developed to simulate this type of extension is that stress and strain is focused primarily on the footwall block of the spreading system. This would predict that at any given time, only one side of the system should show active seismicity. In 2001, the Gakkel Ridge was extensively sampled by dredging during the AMORE cruise. These samples showed that the ridge is divided into distinct segments that today are either magmatically robust (only basalts recovered) or magmatically starved (dominantly serpentinised peridotite and gabbros recovered). We extracted earthquake data along the Gakkel Ridge from the global catalogs to investigate if these distinct segments exhibit any differences in active seismicity. We show that the western volcanic zone shows symmetric active seismicity, with earthquakes occurring on both sides of the ridge axis along a relatively restricted region. In contrast, the sparsely magmatic zone shows active seismicity dominantly along along the southern half of the ridge, with comparatively little seismicity to the north. These results are consistent with the proposed models for the formation of amagmatic spreading centers.

  16. Hydrothermal activity on near-arc sections of back-arc ridges: Results from the Mariana Trough and Lau Basin

    NASA Astrophysics Data System (ADS)

    Baker, Edward T.; Massoth, Gary J.; Nakamura, Ko-Ichi; Embley, Robert W.; de Ronde, Cornel E. J.; Arculus, Richard J.

    2005-09-01

    The spatial density of hydrothermal venting is strongly correlated with spreading rate on mid-ocean ridges (with the interesting exception of hot spot-affected ridges), evidently because spreading rate is a reliable proxy for the magma budget. This correlation remains untested on spreading ridges in back-arc basins, where the magma budget may be complicated by subduction-induced variations of the melt supply. To address this uncertainty, we conducted hydrothermal plume surveys along slow-spreading (40-60 mm/yr) and arc-proximal (10-60 km distant) sections of the southern Mariana Trough and the Valu Fa Ridge (Lau Basin). On both sections we found multiple plumes overlying ˜15-20% of the total length of each section, a coverage comparable to mid-ocean ridges spreading at similar rates. These conditions contrast with earlier reported results from the two nearest-arc segments of a faster spreading (60-70 mm/yr) back-arc ridge, the East Scotia Ridge, which approaches no closer than 100 km to its arc. There, hydrothermal venting is relatively scarce (˜5% plume coverage) and the ridge characteristics are distinctly slow-spreading: small central volcanic highs bookended by deep median valleys, and axial melt lenses restricted to the volcanic highs. Two factors may contribute to an unexpectedly low hydrothermal budget on these East Scotia Ridge segments: they may lie too far from the adjacent arc to benefit from near-arc sources of melt supply, and subduction-aided migration of mantle from the Bouvet hot spot may reduce hydrothermal circulation by local crustal warming and thickening, analogous to the Reykjanes Ridge. Thus the pattern among these three ridge sections appears to mirror the larger global pattern defined by mid-ocean ridges: a well-defined trend of spreading rate versus hydrothermal activity on most ridge sections, plus a subset of ridge sections where unusual melt delivery conditions diminish the expected hydrothermal activity.

  17. Hydrothermal activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge): Distribution, heatflux, and geological controls

    NASA Astrophysics Data System (ADS)

    Escartin, J.; Barreyre, T.; Cannat, M.; Garcia, R.; Gracias, N.; Deschamps, A.; Salocchi, A.; Sarradin, P. M.; Ballu, V.

    2015-12-01

    We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment to evaluate the distribution of hydrothermal activity. The Lucky Strike segment hosts three active hydrothermal fields: Capelinhos, Ewan, and the known Main Lucky Strike Hydrothermal Field (MLSHF). Capelinhos is located 1.3 km E of the axis and the MLSHF, and consists of a ~20 m sulfide mound with black smoker vents. Ewan is located ~1.8 km south from the MLSHF along the axial graben, and displays only diffuse flow along and around scarps of collapse structures associated with fault scarps. At the MLSHF we have identified an inactive site, thus broadening the extent of this field. Heat flux estimates from these new sites are relatively low and correspond to ~10% of the heat flux estimated for the Main field, with an integrated heatflux of 200-1200 MW. Overall, most of the flux (up to 80-90%) is associated with diffuse outflow, with the Ewan site showing solely diffuse flow and Capelinhos mostly focused flow. Microbathymetry also reveals a large, off-axis (~2.4 km) hydrothermal field, similar to the TAG mound in size, on the flanks of a rifted volcano. The association of these fields to a central volcano, and the absence of indicators of hydrothermal activity along the ridge segment, suggest that sustained hydrothermal activity is maintained by the enhanced melt supply and the associated magma chamber(s) required to build central volcanoes. Hydrothermal outflow zones at the seafloor are systematically controlled by faults, indicating that hydrothermal circulation in the shallow crust exploits permeable fault zones. Central volcanoes are thus associated with long-lived hydrothermal activity, and these sites may play a major role in the distribution and biogeography of vent communities.

  18. 78 FR 69447 - Agency Information Collection Activities; Existing Collection, Comments Requested: Friction Ridge...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Federal Bureau of Investigation Agency Information Collection Activities; Existing Collection, Comments Requested: Friction Ridge Cards: Arrest and Institution; Applicant; Personal Identification; FBI Standard Palm Print; Supplemental Finger and Palm...

  19. DATA SHARING REPORT CHARACTERIZATION OF POPULATION 7: PERSONAL PROTECTIVE EQUIPMENT, DRY ACTIVE WASTE, AND MISCELLANEOUS DEBRIS, SURVEILLANCE AND MAINTENANCE PROJECT OAK RIDGE NATIONAL LABORATORY OAK RIDGE, TENNESSEE

    SciTech Connect

    Harpenau, Evan M

    2013-10-10

    The U.S. Department of Energy (DOE) Oak Ridge Office of Environmental Management (EM-OR) requested that Oak Ridge Associated Universities (ORAU), working under the Oak Ridge Institute for Science and Education (ORISE) contract, provide technical and independent waste management planning support under the American Recovery and Reinvestment Act (ARRA). Specifically, DOE EM-OR requested that ORAU plan and implement a sampling and analysis campaign targeting certain URS|CH2M Oak Ridge, LLC (UCOR) surveillance and maintenance (S&M) process inventory waste. Eight populations of historical and reoccurring S&M waste at the Oak Ridge National Laboratory (ORNL) have been identified in the Waste Handling Plan for Surveillance and Maintenance Activities at the Oak Ridge National Laboratory, DOE/OR/01-2565&D2 (WHP) (DOE 2012) for evaluation and processing to determine a final pathway for disposal. Population 7 (POP 7) consists of 56 containers of aged, low-level and potentially mixed S&M waste that has been staged in various locations around ORNL. Several of these POP 7 containers primarily contain personal protective equipment (PPE) and dry active waste (DAW), but may contain other miscellaneous debris. This data sharing report addresses the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) specified waste in a 13-container subpopulation (including eight steel boxes, three 55-gal drums, one sealand, and one intermodal) that lacked sufficient characterization data for possible disposal at the Environmental Management Waste Management Facility (EMWMF) using the approved Waste Lot (WL) 108.1 profile.

  20. Activity of Wind-Blown Sand and the Formation of Feathered Sand Ridges in the Kumtagh Desert, China

    NASA Astrophysics Data System (ADS)

    Liao, Kongtai; Qu, Jianjun; Tang, Jinnian; Ding, Feng; Liu, Hujun; Zhu, Shujuan

    2010-05-01

    We study the activity of wind-blown sand and its effects on the evolution of feathered sand ridges in the Kumtagh Desert, China, and attempt to reveal the formation process of feathered sand ridges using wind-tunnel experiments, remote sensing data, and detailed field observations from 2005 to 2008. The prevailing wind direction in the Kumtagh Desert is easterly in winter and north-easterly in other seasons. The average annual wind speed is 5.9 ms-1, and winds sufficiently strong to entrain sand occur on 143 days per annum. The sand transport rate within 0.4 m of the ground is strongly influenced by local landforms, and is related to wind speed by a power function. Wind erosion occurs on the crest, the windward slope of crescent sand ridges and inter-ridge sand strips, where the blowing sand cloud is in an unsaturated state; in contrast, sand accumulation occurs on the leeward slope of the crescent sand ridges, where the blowing sand cloud is in an over-saturated state. These results indicate that the development of feathered sand ridges in the Kumtagh Desert is mainly controlled by the local wind regime. The dominant winds (from the north, north-north-east and north-east) and additional winds (from the east-north-east, east and east-south-east) determine the development of crescent sand ridges, but winds that are approximately parallel to sand ridges form the secondary inter-ridge sand strips.

  1. Hydrothermal activity at slow-spreading ridges: variability and importance of magmatic controls

    NASA Astrophysics Data System (ADS)

    Escartin, Javier

    2016-04-01

    Hydrothermal activity along mid-ocean ridge axes is ubiquitous, associated with mass, chemical, and heat exchanges between the deep lithosphere and the overlying envelopes, and sustaining chemiosynthetic ecosystems at the seafloor. Compared with hydrothermal fields at fast-spreading ridges, those at slow spreading ones show a large variability as their location and nature is controlled or influenced by several parameters that are inter-related: a) tectonic setting, ranging from 'volcanic systems' (along the rift valley floor, volcanic ridges, seamounts), to 'tectonic' ones (rift-bounding faults, oceanic detachment faults); b) the nature of the host rock, owing to compositional heterogeneity of slow-spreading lithosphere (basalt, gabbro, peridotite); c) the type of heat source (magmatic bodies at depth, hot lithosphere, serpentinization reactions); d) and the associated temperature of outflow fluids (high- vs.- low temperature venting and their relative proportion). A systematic review of the distribution and characteristics of hydrothermal fields along the slow-spreading Mid-Atlantic Ridge suggests that long-lived hydrothermal activity is concentrated either at oceanic detachment faults, or along volcanic segments with evidence of robust magma supply to the axis. A detailed study of the magmatically robust Lucky Strike segment suggests that all present and past hydrothermal activity is found at the center of the segment. The association of these fields to central volcanos, and the absence of indicators of hydrothermal activity along the remaining of the ridge segment, suggests that long-lived hydrothermal activity in these volcanic systems is maintained by the enhanced melt supply and the associated magma chamber(s) required to build these volcanic edifices. In this setting, hydrothermal outflow zones at the seafloor are systematically controlled by faults, indicating that hydrothermal fluids in the shallow crust exploit permeable fault zones to circulate. While

  2. Active spreading processes at ultraslow mid-ocean ridges: The 1999-2001 seismo-volcanic episode at 85°E Gakkel ridge, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Schlindwein, Vera; Riedel, Carsten; Korger, Edith; Läderach, Christine

    2010-05-01

    The rate of magma and crustal production at mid-ocean ridges is thought to decrease with decreasing spreading rate. At ultraslow spreading rates below 10-20 mm/y full rate, heat loss by conduction greatly reduces melt production with less melt produced at increasingly greater depths. Gakkel Ridge, the actively spreading mid-ocean ridge in the Arctic Ocean, opens at rates of 14 mm/y in the west decreasing to less than 6 mm/y at its eastern termination and demonstrates that magma production is not only a function of spreading rate. Whereas amagmatic spreading takes place at rates of about 12-10 mm/y, focussed melt production occurs at even lower spreading rates in long-lived discrete volcanic centres. One such centre is the 85°E volcanic complex at eastern Gakkel ridge where in 1999 a teleseismically recorded earthquake swarm consisting of more than 250 earthquakes over 9 months signalled the onset of an active spreading episode. The earthquake swarm is believed to be associated with volcanic activity although no concurrent lava effusion was found. We analysed the teleseismic earthquake swarm together with visual observation and microseismic data recorded at this site in 2001 and 2007 and noted the following characteristics which may be indicative for volcanic spreading events at the still poorly explored ultraslow spreading ridges: - unusual duration: The 1999 earthquake swarm lasted over 9 months rather than a few weeks as observed on faster spreading ridges. In addition, in 2001 seismoacoustic sounds which we interpret as gas discharge in Strombolian eruptions and a giant event plume maintained over more than one year indicate waxing and waning volcanic activity since 1999. - unusual strength: The earthquake swarm was detected at teleseismic distances of more than 1000 km and included 11 events with a magnitude >5. No other confirmed mid-ocean ridge eruption released a comparable seismic moment. Rather than focussing in a narrow area or showing pronounced

  3. Rapid cooling rates at an active mid-ocean ridge from zircon thermochronology

    NASA Astrophysics Data System (ADS)

    Schmitt, Axel K.; Perfit, Michael R.; Rubin, Kenneth H.; Stockli, Daniel F.; Smith, Matthew C.; Cotsonika, Laurie A.; Zellmer, Georg F.; Ridley, W. Ian; Lovera, Oscar M.

    2011-02-01

    Oceanic spreading ridges are Earth's most productive crust generating environment, but mechanisms and rates of crustal accretion and heat loss are debated. Existing observations on cooling rates are ambiguous regarding the prevalence of conductive vs. convective cooling of lower oceanic crust. Here, we report the discovery and dating of zircon in mid-ocean ridge dacite lavas that constrain magmatic differentiation and cooling rates at an active spreading center. Dacitic lavas erupted on the southern Cleft segment of the Juan de Fuca ridge, an intermediate-rate spreading center, near the intersection with the Blanco transform fault. Their U-Th zircon crystallization ages (29.3 - 4.6 + 4.8 ka; 1σ standard error s.e.) overlap with the (U-Th)/He zircon eruption age (32.7 ± 1.6 ka) within uncertainty. Based on similar 238U- 230Th disequilibria between southern Cleft dacite glass separates and young mid-ocean ridge basalt (MORB) erupted nearby, differentiation must have occurred rapidly, within ~ 10-20 ka at most. Ti-in-zircon thermometry indicates crystallization at 850-900 °C and pressures > 70-150 MPa are calculated from H 2O solubility models. These time-temperature constraints translate into a magma cooling rate of ~ 2 × 10 - 2 °C/a. This rate is at least one order-of-magnitude faster than those calculated for zircon-bearing plutonic rocks from slow spreading ridges. Such short intervals for differentiation and cooling can only be resolved through uranium-series ( 238U- 230Th) decay in young lavas, and are best explained by dissipating heat convectively at high crustal permeability.

  4. Human factors activities in teleoperator development at the Oak Ridge National Laboratory

    SciTech Connect

    Draper, J.V.; Herndon, J.N.

    1986-01-01

    The Consolidated Fuel Reprocessing Program (CFRP) at the Oak Ridge National Laboratory is developing advanced teleoperator systems for maintenance of future nuclear reprocessing facilities. Remote maintenance systems developed by the CFRP emphasize man-in-the-loop teleoperation. Consequently, human factors issues which affect teleoperator performance must be addressed. This papers surveys research and development activities carried out by the human factors group within the Remote Control Engineering Task of the CFRP.

  5. Detailed leak detection test plan and schedule for the Oak Ridge National Laboratory LLLW active tanks

    SciTech Connect

    Douglas, D.G.; Maresca, J.W. Jr. )

    1993-03-01

    This document provides a detailed leak detection test plan and schedule for leak testing many of the tanks that comprise the active portion of the liquid low-level waste (LLLW) system at the Oak Ridge National Laboratory (ORNL). This plan was prepared in response to the requirements of the Federal Facility Agreement (FFA) between the US Department of Energy (DOE) and two other agencies, the US Environmental Protection Agency (EPA) and the Tennessee Department of Environment and Conservation (TDEC).

  6. Major off-axis hydrothermal activity on the northern Gorda Ridge

    SciTech Connect

    Rona, P.A. ); Denlinger, R.P. ); Fisk, M.R.; Howard, K.J.; Taghon, G.L. ); Klitgord, K.D. ); McClain, J.S. ); McMurray, G.R. ); Wiltshire, J.C. )

    1990-06-01

    The first hydrothermal field on the northern Gorda Ridge, the Sea Cliff hydrothermal field, was discovered and geologic controls of hydrothermal activity in the rift valley were investigated on a dive series using the DSV Sea Cliff. The Sea Cliff hydrothermal field was discovered where predicted at the intersection of axis-oblique and axis-parallel faults at the south end of a linear ridge at mid-depth (2700 m) on on the east wall. Preliminary mapping and sampling of the field reveal: a setting nested on nearly sediment-free fault blocks 300 m above the rift valley floor 2.6 km from the axis; a spectrum of venting types from seeps to black smokers; high conductive heat flow estimated to be equivalent to the convective flux of multiple black smokers through areas of the sea floor sealed by a caprock of clastic breccia primarily derived from basalt with siliceous cement and barite pore fillings; and a vent biota with Juan de Fuca Ridge affinities. These findings demonstrate the importance of off-axis hydrothermal activity and the role of the intersection of tectonic lineations in controlling hydrothermal sites at sea-floor spreading centers.

  7. The crustal structure of central East Greenland-II: From the Precambrian shield to the recent mid-oceanic ridges

    NASA Astrophysics Data System (ADS)

    Schmidt-Aursch, Mechita C.; Jokat, Wilfried

    2005-02-01

    We present a 3-D crustal model of the East Greenland Fjord Region between 69°N and 74°N. The model covers the Precambrian shield and the Caledonian orogenic belt, the adjoining Devonian and Mesozoic basins, the continent-ocean transition and the Cenozoic oceanic areas as far as the Kolbeinsey and the Mohns mid-oceanic ridges. Existing seismic models of the crustal structure are extrapolated into adjacent areas using 3-D gravity modelling. For this purpose, we compile a new regional-scale Bouguer anomaly map. The Precambrian shield, west of the Caledonian orogen (approximately west of 32°W), shows a mean thickness of 35 km with only small-scale undulations. This thickness is at the lower limit of the global range in shield thickness. The Caledonian orogen exhibits a pronounced mountain root with overall crustal thicknesses up to 51 km. Beside the Urals, the East Greenland Caledonides are one of the two Palaeozoic mountain belts where a crustal root has preserved to the present day. Continuation of the crustal model to the east, beyond the continent-ocean transition, yielded thicknesses of the crystalline oceanic crust from 9 km near the Kolbeinsey Ridge to 3 km west of the Mohns Ridge. Differences in the thermal structures of the old continental and the young oceanic lithosphere are responsible for the low-density mantle beneath the oceanic crust, which is also demonstrated by 3-D gravity modelling.

  8. Significant Centers of Tectonic Activity as Identified by Wrinkle Ridges for the Western Hemisphere of Mars

    NASA Technical Reports Server (NTRS)

    Anderson, R.C.; Haldemann, A. F. C.; Golombek, M. P.; Franklin, B. J.; Dohm, J. M.; Lias, J.

    2000-01-01

    The western hemisphere region of Mars has been the site of numerous scientific investigations regarding its tectonic evolution. For this region of Mars, the dominant tectonic region is the Tharsis province. Tharsis is characterized by an enormous system of radiating grabens and a circumferential system of wrinkle ridges. Past investigations of grabens associated with Tharsis have identified specific centers of tectonic activity. A recent structural analysis of the western hemisphere region of Mars which includes the Tharsis region, utilized 25,000 structures to determine the history of local and regional centers of tectonic activity based primarily on the spatial and temporal relationships of extensional features. This investigation revealed that Tharsis is more structurally complex (heterogeneous) than has been previously identified: it consists of numerous regional and local centers of tectonic activity (some are more dominant and/or more long lived than others). Here we use the same approach as Anderson et al. to determine whether the centers of tectonic activity that formed the extensional features also contributed to wrinkle ridge (compressional) formation.

  9. Widespread active detachment faulting and core complex formation near 13 degrees N on the Mid-Atlantic Ridge.

    PubMed

    Smith, Deborah K; Cann, Johnson R; Escartín, Javier

    2006-07-27

    Oceanic core complexes are massifs in which lower-crustal and upper-mantle rocks are exposed at the sea floor. They form at mid-ocean ridges through slip on detachment faults rooted below the spreading axis. To date, most studies of core complexes have been based on isolated inactive massifs that have spread away from ridge axes. Here we present a survey of the Mid-Atlantic Ridge near 13 degrees N containing a segment in which a number of linked detachment faults extend for 75 km along one flank of the spreading axis. The detachment faults are apparently all currently active and at various stages of development. A field of extinct core complexes extends away from the axis for at least 100 km. Our observations reveal the topographic characteristics of actively forming core complexes and their evolution from initiation within the axial valley floor to maturity and eventual inactivity. Within the surrounding region there is a strong correlation between detachment fault morphology at the ridge axis and high rates of hydroacoustically recorded earthquake seismicity. Preliminary examination of seismicity and seafloor morphology farther north along the Mid-Atlantic Ridge suggests that active detachment faulting is occurring in many segments and that detachment faulting is more important in the generation of ocean crust at this slow-spreading ridge than previously suspected. PMID:16871215

  10. Crevasse-squeeze ridge corridors: Diagnostic features of late-stage palaeo-ice stream activity

    NASA Astrophysics Data System (ADS)

    Evans, David J. A.; Storrar, Robert D.; Rea, Brice R.

    2016-04-01

    A 200-km-long and 10-km-wide linear assemblage of till-filled geometrical ridges on the bed of the Maskwa palaeo-ice stream of the late Wisconsinan southwest Laurentide Ice Sheet are interpreted as crevasse-squeeze ridges (CSR) developed during internal flow unit reorganization, immediately prior to ice stream shutdown. Ridge orientations are predominantly orientated WNW-ESE, with a subordinate WSW-ENE alignment, both indicative of ice fracture development transverse to former ice stream flow, as indicated by NNE-SSW aligned MSGL. Subglacial till injection into basal and/or full depth, mode I and II crevasses occurred at the approximate centreline of the ice stream, in response to extension and fracturing. Landform preservation indicates that this took place during the final stages of ice streaming, immediately prior to ice stream shutdown. This linear zone of ice fracturing therefore likely represents the narrowing of the fast-flowing trunk, similar to the plug flow identified in some surging valley glaciers. Lateral drag between the final active flow unit and the slower moving ice on either side is likely recorded by the up-ice bending of the CSR limbs. The resulting CSR corridor, here related to an individual ice stream flow unit, constitutes a previously unreported style of crevasse infilling and contrasts with two existing CSR patterns: (1) wide arcuate zones of CSRs related to widespread fracturing within glacier surge lobes; and (2) narrow concentric arcs of CSRs and recessional push moraines related to submarginal till deformation at active temperate glacier lobes.

  11. Using Hydrothermal Plumes and Their Chemical Composition to Identify and Understand Hydrothermal Activity at Explorer Ridge

    NASA Astrophysics Data System (ADS)

    Resing, J.; Lebon, G.; Baker, E.; Walker, S.; Nakamura, K.; Silvers, B.

    2002-12-01

    During June and July, 2002, an extensive survey of the hydrothermal systems of the Explorer Ridge was made aboard the R/V Thomas Thompson. This survey employed hydrocasts and the Autonomous Benthic Explorer (ABE) to locate and map hydrothermal vent fields. A total of 28 hydrocasts (17 verticals and 11 tow-yos) were used to search for hydrothermal activity from 49.5°N to 50.3°N on the Explorer Ridge. During the hydrocasts continuous measurements were made of conductivity, temperature, pressure, light backscatter, eH, Fe, Mn, and pH. Discrete samples were collected for total dissolved Fe and Mn, methane, pH, total CO2, and particulate matter. Most of the strong hydrothermal venting was near the Magic Mountain area of the Explorer Ridge at ~49.76° N, 130.26° W, where strong particulate backscatter signals (~0.130 NTUs) and moderate temperature anomalies (~ 0.05 °C) were detected. The particulate matter causing the backscatter was made up primarily of volatile particulate sulfur (PS) with little to no hydrothermal PFe. PS:PFe ratios exceeded 25 in the areas of most intense venting, . These PFe and PS data suggest that the hydrothermal Fe, if any, is deposited as sulfide minerals beneath the sea floor and that S is far in excess of Fe in the hydrothermal fluids. In the most intense plumes,total dissolvable Fe and Mn were between 20 and 30 nM, pH anomalies exceeded 0.025 pH units (indicating an increase of ~10uM CO2), and methane reached 16nM. These results suggest that the fluids exiting the sea floor are metal-poor and moderately gas-rich.

  12. Data Sharing Report for the Quantification of Removable Activity in Various Surveillance and Maintenance Facilities at the Oak Ridge National Laboratory Oak Ridge TN

    SciTech Connect

    King, David A

    2013-12-12

    The U.S. Department of Energy (DOE) Oak Ridge Office of Environmental Management (OR-EM) requested that Oak Ridge Associated Universities (ORAU), working under the Oak Ridge Institute for Science and Education (ORISE) contract, provide technical and independent waste management planning support using American Recovery and Reinvestment Act (ARRA) funds. Specifically, DOE OR-EM requested that ORAU plan and implement a sampling and analysis campaign targeting potential removable radiological contamination that may be transferrable to future personal protective equipment (PPE) and contamination control materials—collectively referred to as PPE throughout the remainder of this report—used in certain URS|CH2M Oak Ridge, LLC (UCOR) Surveillance and Maintenance (S&M) Project facilities at the Oak Ridge National Laboratory (ORNL). Routine surveys in Bldgs. 3001, 3005, 3010, 3028, 3029, 3038, 3042, 3517, 4507, and 7500 continuously generate PPE. The waste is comprised of Tyvek coveralls, gloves, booties, Herculite, and other materials used to prevent worker exposure or the spread of contamination during routine maintenance and monitoring activities. This report describes the effort to collect and quantify removable activity that may be used by the ORNL S&M Project team to develop radiation instrumentation “screening criteria.” Material potentially containing removable activity was collected on smears, including both masselin large-area wipes (LAWs) and standard paper smears, and analyzed for site-related constituents (SRCs) in an analytical laboratory. The screening criteria, if approved, may be used to expedite waste disposition of relatively clean PPE. The ultimate objectives of this effort were to: 1) determine whether screening criteria can be developed for these facilities, and 2) provide process knowledge information for future site planners. The screening criteria, if calculated, must be formally approved by Federal Facility Agreement parties prior to use for

  13. Crustal Structure of the Northern and Southern Jan Mayen Ridge Segments, Norwegian Sea, Based on Ocean Bottom Seismometer Data.

    NASA Astrophysics Data System (ADS)

    Breivik, A. J.; Mjelde, R.; Shimamura, H.; Murai, Y.; Nishimura, Y.

    2003-12-01

    The Jan Mayen Ridge (JMR) is a submarine ridge trending south from the volcanic Jan Mayen island in the Norwegian Sea, towards Iceland. In the north, it is a distinct, single ridge, but in the south it is divided into several smaller ridges. JMR is interpreted as a micro-continent, being part of Greenland during the volcanically active rifting off Norway in the latest Paleocene. In the late Oligocene, JMR was rifted off Greenland when seafloor spreading shifted from the now extinct Aegir Ridge, to the presently active Kolbeinsey Ridge. The southern termination of the micro-continent is uncertain, though it may extend into the Icelandic shelf. Earlier studies of the northern ridge found extrusive volcanism, and an asymmetrical crustal root, displaced to the east. Two OBS profiles were shot across the northern and southern part in year 2000. The northern ( ˜69° N) terminates in the Jan Mayen Fracture Zone, and the southern ( ˜66.5° N) crosses the Aegir Ridge. The vertical and horizontal components were modeled by ray-tracing into two-dimensional velocity transects. In the north, a maximum crustal thickness of 16 km was found in a narrow root below the eastern part of the ridge. The P-wave velocity at the bottom of the eastern part of the root (7-7.2 km/s) indicates igneous rocks, while the western part (6.8 km/s) is typical for continental rocks, with a 40 km wide transition zone between. The supposed extrusive basalts do not stand out in the data, but may have a low velocity contrast to underlying pre-breakup sedimentary strata. The top oceanic basement is very rough near the Jan Mayen Fracture Zone, with upper basement P-wave velocity of 3.5-4 km/s. A slight increase in the Vp/Vs ratios indicates an increase in fracturing of the deep crust here. Adjacent to the JMR, the top oceanic basement becomes very smooth, and the velocity increases to 5.5 km/s. Average oceanic crustal thickness is 5.3 km. For the southern profile, the average thickness is 5.2 km around

  14. The Pine Ridge-Mayo National Aeronautics and Space Administration Telemedicine Project: Program Activities and Participant Reactions

    NASA Technical Reports Server (NTRS)

    Kottke, T. E.; Little Finger, L.; Trapp, M. A.; Panser, L. A.; Novotny, P. J.

    1996-01-01

    OBJECTIVE: To determine the response of participants to the Pine Ridge-Mayo National Aeronautics and Space Administration telemedicine project. DESIGN: We describe a 3-month demonstration project of medical education and clinical consultations conducted by means of satellite transmission. Postparticipation questionnaires and a postproject survey were used to assess the success of the activity. MATERIAL AND METHODS: Patients and employees at the Pine Ridge Indian Health Service Hospital in southwestern South Dakota and employees at Mayo Clinic Rochester participated in a telemedicine project, after which they completed exit surveys and a postproject questionnaire to ascertain the acceptability of this mode of health care. RESULTS: Almost all Pine Ridge and Mayo Clinic participants viewed the project as beneficial. The educational sessions received favorable evaluations, and almost two-thirds of the patients who completed evaluations thought the consultation had contributed to their medical care. More than 90% of the respondents from Pine Ridge and more than 85% of the respondents from Mayo Clinic Rochester said that they would recommend participation in this project to others. More than 90% of respondents from Pine Ridge and 80% of Mayo respondents agreed with the statement that the project should continue. CONCLUSION: These data suggest that a program of clinical consultation services, professional education, and patient education available by telemedicine might be viewed as beneficial.

  15. Hydrothermal activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge): Distribution, heatflux, and geological controls

    NASA Astrophysics Data System (ADS)

    Escartin, J.; Barreyre, T.; Cannat, M.; Garcia, R.; Gracias, N.; Deschamps, A.; Salocchi, A.; Sarradin, P.-M.; Ballu, V.

    2015-12-01

    We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment, to evaluate the distribution of hydrothermal activity. We have identified a new on-axis site with diffuse flow, Ewan, and an active vent structure ∼1.2 km from the axis, Capelinhos. These sites are minor relative to the Main field, and our total heatflux estimate for all active sites (200-1200 MW) is only slightly higher than previously published estimates. We also identify fossil sites W of the main Lucky Strike field. A circular feature ∼200 m in diameter located on the flanks of a rifted off-axis central volcano is likely a large and inactive hydrothermal edifice, named Grunnus. We find no indicator of focused hydrothermal activity elsewhere along the segment, suggesting that the enhanced melt supply and the associated melt lenses, required to form central volcanoes, also sustain hydrothermal circulation to form and maintain large and long-lived hydrothermal fields. Hydrothermal discharge to the seafloor occurs along fault traces, suggesting focusing of hydrothermal circulation in the shallow crust along permeable fault zones.

  16. Active spreading processes at ultraslow-spreading ridges: Relocalization and analysis of the 1999 earthquake swarm at Gakkel Ridge, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Korger, Edith; Schlindwein, Vera; Riedel, Carsten

    2010-05-01

    Gakkel Ridge is situated within the Arctic Ocean and spans from eastern Greenland to the continental Siberian shelf. It is termed an ultraslow spreading ridge (full spreading rate 6-14 mm/yr). At ultraslow spreading ridges, heat loss by conductive cooling is thought to decrease magma supply and focus magmatism in widely spaced discrete volcanic centres. In 1999 lasting over 7 months, the largest ever earthquake swarm at a mid-ocean ridge was teleseismically registered worldwide. It originated from around 85°E which was postulated to be a volcanic complex and featured 252 recorded events, including 11 events with a magnitude mb > 5.0. The unprecedented duration, magnitude and number of events ran counter to expectations at this location. Preliminary analysis with unreviewed datasets showed changing source-mechanisms from extensional to events with a greater non-double-couple component at around March, 4th and an abrupt decrease in the number of events on the 15th of April. Also the epicentres of the larger events seemed to migrate with advancing time to the NW, farther away from the volcanic centre. As these analyses were based on preliminary datasets it seemed indicated to relocalize the earthquakes when the reviewed bulletin of the International Seismological Centre was released. This relocalization was done with the earthquake localization programme NonLinLoc using a probabilistic approach and grid-search. The calculation of travel times used as velocity model both AK135 and IASP91 combined with a regional velocity model for recording stations with epicentral distance < 30°. We tested extensively the influence of localization algorithm, velocity model, station coverage and weighting on the localization result. The new locations of the epicentres show a clustering of events within the central rift valley and the southern rift flank. The dataset was further reviewed with regard to the quality of the localization and reduced to 93 well located events whose

  17. The relationships between volcanism, tectonism and hydrothermal activity on the Mid-Atlantic Ridge south of the equator

    NASA Astrophysics Data System (ADS)

    Devey, C. W.; German, C. R.; Haase, K. M.; Lackschewitz, K. S.; Melchert, B.; Connelly, D.; Parson, L. M.

    2009-04-01

    Using data from the complete bathymetric and side-scan (TOBI) coverage of the Mid-Atlantic Ridge 2-14 °S collected since 2004 in conjunction with the results of extensive prospecting for hydrothermal systems in this area we attempt to formulate a general model for the interplay between volcanism, tectonics and hydrothermalism on a slow-spreading ridge. The model defines three basic types of ridge morphology with specific hydrothermal characteristics: (a) A deep, tectonically-dominated rift valley where hydrothermalism is seldom associated with volcanism and much more likely confined to long-lived bounding faults (b) a shallower, segment-centre bulge where a combination of repeated magmatic activity and tectonism results in repeated, possibly temporally overlapping periods of hydrothermal activity on the ridge axis and (c) a very shallow, inflated axis beneath which temperatures in all but the uppermost crust are so high that deformation is ductile, inhibiting the formation of high-porosity deep fractures and severely depressing hydrothermal circulation. This model is used together with predicted bathymetry to provide forecasts of the best places to look for hydrothermal sites in the remaining unexplored regions of the South Atlantic

  18. Active and relict sea-floor hydrothermal mineralization at the TAG hydrothermal field, Mid-Atlantic Ridge

    SciTech Connect

    Rona, P.A. . Atlantic Oceanographic and Meteorological Labs.); Hannington, M.D. ); Raman, C.V. ); Thompson, G.; Tivey, M.K.; Humphris, S.E. ); Lalou, C. . Lab. CNRS-CEA); Petersen, S. Aachen Univ. of Technology )

    1993-12-01

    The TAG hydrothermal field is a site of major active and inactive volcanic-hosted hydrothermal mineralization in the rift valley of the slow-spreading Mid-Atlantic Ridge at 26[degree]N. The axial high is the principal locus of present magmatic intrusions. The TAG field contains three main areas of present and past hydrothermal activity: (1) an actively venting high-temperature sulfide mound; (2) two former high-temperature vent areas; (3) a zone of low-temperature venting and precipitation of Fe and Mn oxide deposits. The volcanic centers occur at the intersections between ridge axis-parallel normal faults and projected axis-transverse transfer faults. The intersections of these active fault systems may act as conduits both for magmatic intrusions from sources beneath the axial high that build the volcanic centers and for hydrothermal upwelling that taps the heat sources. Radiometric dating of sulfide samples and manganese crusts in the hydrothermal zones and dating of sediments intercalated with pillow lava flows in the volcanic center adjacent to the active sulfide mound indicate multiple episodes of hydrothermal activity throughout the field driven by heat supplied by episodic intrusions over a period of at least 140 [times] 10[sup 3] yr. The sulfide deposits are built by juxtaposition and superposition during relatively long residence times near episodic axial heat sources counterbalanced by mass wasting in the tectonically active rift valley of the slow-spreading oceanic ridge. Hydrothermal reworking of a relict hydrothermal zone by high-temperature hydrothermal episodes has recrystallized sulfides and concentrated the first visible primary gold reported in a deposit at an oceanic ridge.

  19. Magnetic Measurements of Bacterial Activity in Mid Oceanic Ridge Basalt Samples.

    NASA Astrophysics Data System (ADS)

    Carlut, J.; Horen, H.; Brunet, F.; Janots, D.; Pozzi, J.

    2004-12-01

    Magnetic properties of the young oceanic crust gives insights on the 3D structure at ridges axis and on variations of the Earth's magnetic field. Accurate interpretations depend on our understanding of the magnetic stability of titanomagnetite crystals carrying the magnetic signal. The mean remanent intensity of young ocean basalts shows significant variations with age and it has been suggested that rapid chemical alteration of titanomagnetite could be responsible. Ubiquitous presence of bacteria in deep marine environment and their ability to interact with iron oxides suggest a possible important impact of these life forms on the stability of titanomagnetites. In vivo experiments have been conducted on more than 15 fresh lava macro samples with a batch of selected sulfate reducing bacteria of the desulfovibrio genus, relevant to the deep biosphere. Remanent magnetization of samples was measured at regular time interval, in addition to more complete magnetic and chemical characterization at beginning and end of experiments. After a few months results show a significant contribution of bacterial activity on magnetic properties of samples, in particular a well defined drop in remanence. Our results suggest a strong impact of bacteria on the alteration rate of iron oxides carrying the magnetic signal within the oceanic crust.

  20. Magnetic Monitoring and Characterization at the Nanoscale of Bacterial Activity in Mid Oceanic Ridge Basalt Samples

    NASA Astrophysics Data System (ADS)

    Carlut, J.; Benzerara, K.; Horen, H.; Baronnet, A.

    2011-12-01

    Microbial communities have been shown over the last few years to be a significant component of the sub-sea floor crustal environment. The ubiquitous presence of these life forms suggests an important chemical impact on the host rocks. Among the diverse species, sulfate-reducing bacteria have been suggested, based on sulfur isotope studies, to be a major actor of the oceanic rocks alteration. Laboratory experiments were thus conducted on basalts from the East Pacific Ridge incubated with model sulfate-reducing bacteria. Results show that such bacteria can have a strong impact on the alteration rate of iron oxides carrying the magnetic signal of oceanic rocks. To some extent microbial processes can thus play a role in the decrease of sea floor magnetic signal. Such findings also open ways for the remote monitoring of bacterial activity through magnetic measurements. In order to gain insights on the mechanisms involved we characterized alteration features of iron oxides at the nanoscale in laboratory bio-altered samples and natural samples. We used a combination of scanning electron microscope, focused ion beam milling, ion beam thinning, transmission electron microscopy and scanning transmission X-ray microscopy. Some of the iron oxide crystals from these samples show singular alteration rims mostly composed of Fe and S and measuring a few nanometers in thickness. These observations contribute to understand the potential role of microbes in the alteration of the oceanic crust and possible impact on the magnetic signal.

  1. Annual report of decommissioning and remedial action S&M activities for the Environmental Management Program at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1997-11-01

    The Oak Ridge National Laboratory (ORNL) Surveillance and Maintenance (S&M) Program performs a variety of activities to ensure that sites and facilities within its responsibility remain in a safe condition and in compliance with applicable regulations. All S&M Program activities during fiscal year (FY) 1997 were accomplished safely, with no health and safety incidents, no lost work days, and no environmental noncompliances. In addition, all activities were performed within schedule thresholds and under budget. Many remedial action (RA) sites and decontamination and decommissioning (D&D) facilities are inspected and maintained by the S&M Program. RA sites encompass approximately 650 acres and 33 D&D facilities, including 4 inactive reactors. During FY 1997, routine, preventative, and emergency maintenance activities were performed as needed at these sites and facilities. Stabilization activities were also performed to reduce risks and reduce future S&M costs. Major activities at the RA sites during FY 1997 included maintaining proper liquid levels in surface impoundments and inactive -liquid low-level waste storage tanks as well as installing a new cover at the tumulus pads in Waste Area Grouping (WAG) 6, planting trees in the First Creek Riparian Corridor, and performing over 900 well inspections. Postremediation monitoring was conducted at the 3001 Canal, Core Hole 8, the WAG 6 Resource Conservation and Recovery caps, and WAG 5 Seeps C and D; groundwater monitoring was performed in WAGs 4, 5, and 6 and at the 3001 Canal Well. At ORNL D&D facilities, significant accomplishments included contaminated lead brick removal, asbestos abatement, contaminated equipment and debris removal, and radiologically contaminated area painting.

  2. Surveillance and maintenance report on decontamination and decommissioning and remedial action activities at the Oak Ridge Y-12 plant, Oak Ridge, Tennessee. Fiscal year 1996

    SciTech Connect

    King, H.L.; Sollenberger, M.L.; Sparkman, D.E.; Reynolds, R.M.; Wayland, G.S.

    1996-12-01

    The Oak Ridge Y-12 Plant Decontamination and Decommissioning (D&D) and Remedial Action (RA) programs are part of the Environmental Restoration (ER) Division and are funded by the Office of Environmental Management (EM-40). Building 9201-4 (known as Alpha-4), three sites located within Building 9201-3 (the Oil Storage Tank, the Molten Salt Reactor Experiment Fuel Handling Facility, and the Coolant Salt Technology Facility), and Building 9419-1 (the Decontamination Facility) are currently the facilities at the Y-12 Plant included in the D&D program. The RA program provides surveillance and maintenance (S&M) and program management of ER sites at the Y-12 Plant, including selected sites listed in Appendix C of the Federal Facilities Agreement (FFA), sites listed in the Hazardous and Solid Waste Amendment (HSWA) permit Solid Waste Management Unit (SWM-U) list, and sites currently closed or undergoing post-closure activities under the Resource Conservation and Recovery Act of 1976 (RCRA) or the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). This report communicates the status of the program plans and specific S&M activities for the D&D and RA programs.

  3. Evidence of recent volcanic activity on the ultraslow-spreading Gakkel ridge.

    PubMed

    Edwards, M H; Kurras, G J; Tolstoy, M; Bohnenstiehl, D R; Coakley, B J; Cochran, J R

    2001-02-15

    Seafloor spreading is accommodated by volcanic and tectonic processes along the global mid-ocean ridge system. As spreading rate decreases the influence of volcanism also decreases, and it is unknown whether significant volcanism occurs at all at ultraslow spreading rates (<1.5 cm yr(-1)). Here we present three-dimensional sonar maps of the Gakkel ridge, Earth's slowest-spreading mid-ocean ridge, located in the Arctic basin under the Arctic Ocean ice canopy. We acquired this data using hull-mounted sonars attached to a nuclear-powered submarine, the USS Hawkbill. Sidescan data for the ultraslow-spreading (approximately 1.0 cm yr(-1)) eastern Gakkel ridge depict two young volcanoes covering approximately 720 km2 of an otherwise heavily sedimented axial valley. The western volcano coincides with the average location of epicentres for more than 250 teleseismic events detected in 1999, suggesting that an axial eruption was imaged shortly after its occurrence. These findings demonstrate that eruptions along the ultraslow-spreading Gakkel ridge are focused at discrete locations and appear to be more voluminous and occur more frequently than was previously thought. PMID:11236991

  4. Evidence of active ground deformation on the mid-ocean ridge: Axial seamount, Juan de Fuca Ridge, April-June 1988

    SciTech Connect

    Fox, C.G. )

    1990-08-10

    Since September 1987 a precision bottom pressure recorder (BPR) has been deployed within the summit caldera of Axial seamount. The instrument is capable of measuring pressure of 1 mbar resolution and recording these measurements at 64 samples per hour for up to 15 months. Any significant change in the pressure record should indicate a change of depth associated with vertical ground movement, commonly indicative of active inflation or deflation of underlying magma bodies. Results from the first 9 months of the BPR deployment revealed a significant change in pressure, which is interpreted to represent a 15-cm subsidence of the caldera floor during two 2- to 3-week periods in April-June 1988. Also during these periods, an anomalous decline in temperature at the site was recorded that is correlated with an apparent increase in current velocity at the Axial Seamount Hydrothermal Emissions Study (ASHES) vent field, suggesting vigorous advection of cold water into the caldera. Concurrent oceanographic data from Geosat and from current meter arrays do not indicate any large-scale oceanographic phenomena capable of generating these simultaneous events. One mechanism to explain simultaneous ground subsidence and temperature decline at the caldera center and increased bottom current at the caldera margin is the generation of a buoyant parcel of heated water in response to the intrusion or the eruption of magma associated with volcanic deflation. Similar volcanic events also may have generated large midwater plumes that have been described previously along the southern Juan de Fuca Ridge.

  5. Compositional Comparison of Iceland Rift Zones and Adjacent Portions of the Mid-Atlantic Ridge.

    NASA Astrophysics Data System (ADS)

    Kelley, D.; Barton, M.

    2007-12-01

    Iceland is a portion of the Mid-Atlantic Ridge (MAR) that has been built by anomalous crustal production throughout the 55ma spreading history of the opening of the Atlantic Ocean. The anomalously thick crust of Iceland contains the subaerial traces of the MAR which are the volcanically active rift zones. From the south, the Reykjanes Ridge (RR) continues on land as the Western Volcanic Zone (WVZ). In the north, the Northern Volcanic Zone (NVZ) traces into the sea where it offset from the Kolbeinsey Ridge (KR) by the Tjornnes Fracture Zone (TVZ). We report the results of petrologic comparison of the WVZ, the EVZ, and the NVZ of Iceland and the adjacent portions of the MAR - the RR and the KR. The EVZ, WVZ, and NVZ have been shown to have similar crustal structures with ~20 km thick crust thickening toward the hotspot in central Iceland with magma chambers located at the base of the crust and at some depth in the upper crust. Likewise, the KR and RR have melt chambers at the base of and within the crust. Melt compositions have been compared using a filtered database of 588 glass analyses from 29 localities throughout the rift zones, 57 glass analyses from the KR, and 521 glass analyses from the RR. This is the first such study carried out with such an extensive data set. Compositions are similar between the NVZ and WVZ with SiO2 wt.% of 49.0, and 48.6, MgO wt.% of 7.9, and 7.5, and FeOT wt.% of 10.9, and 11.7 respectively. The EVZ which is considered to be a propagating rift is a bit different with SiO2 wt.% of 49.4, MgO wt.% of 5.9, and FeOT wt.% of 13.8. The NVZ and WVZ have also been compared with their respectively adjacent ridge segments, the KR (SiO2 50.3 wt.%, MgO 6.9 wt.%, and FeOT 12.0 wt.%), and the RR (SiO2 50.8 wt.%, MgO 6.9 wt.%, and FeOT 12.3 wt.%). Mg#s for the NVZ and the WVZ are 0.56, and .053 respectively while the Mg# for both the KR and RR is 0.50. For further comparison, a database of 9035 glass analyses from mid-ocean ridge basalts worldwide

  6. Hydrothermal activity in Tertiary Icelandic crust: Implication for cooling processes along slow-spreading mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Pałgan, D.; Devey, C. W.; Yeo, I. A.

    2015-12-01

    Known hydrothermal activity along the Mid-Atlantic Ridge is mostly high-temperature venting, controlled by volcano-tectonic processes confined to ridge axes and neotectonic zones ~15km wide on each side of the axis (e.g. TAG or Snake Pit). However, extensive exploration and discoveries of new hydrothermal fields in off-axis regions (e.g. Lost City, MAR) show that hydrothermalism may, in some areas, be dominated by off-axis venting. Little is known about nature of such systems, including whether low-temperature "diffuse" venting dominates rather than high-temperature black-smokers. This is particularly interesting since such systems may transport up to 90% of the hydrothermal heat to the oceans. In this study we use Icelandic hot springs as onshore analogues for off-shore hydrothermal activity along the MAR to better understand volcano-tectonic controls on their occurrence, along with processes supporting fluid circulation. Iceland is a unique laboratory to study how new oceanic crust cools and suggests that old crust may not be as inactive as previously thought. Our results show that Tertiary (>3.3 Myr) crust of Iceland (Westfjords) has widespread low-temperature hydrothermal activity. Lack of tectonism (indicated by lack of seismicity), along with field research suggest that faults in Westfjords are no longer active and that once sealed, can no longer support hydrothermal circulation, i.e. none of the hot springs in the area occur along faults. Instead, dyke margins provide open and permeable fluid migration pathways. Furthermore, we suggest that the Reykjanes Ridge (south of Iceland) may be similar to Westfjords with hydrothermalism dominated by off-axis venting. Using bathymetric data we infer dyke positions and suggest potential sites for future exploration located away from neotectonic zone. We also emphasise the importance of biological observations in seeking for low-temperature hydrothermal activity, since chemical or optical methods are not sufficient.

  7. Oak Ridge National Laboratory's (ORNL) Weigh-In-Motion (WIM) Configuration and Data Management Activities

    SciTech Connect

    Abercrombie, Robert K; Sheldon, Frederick T; Schlicher, Bob G

    2006-01-01

    The Oak Ridge National Laboratory (ORNL) involvement in the Weigh-in-Motion (WIM) research with both government agencies and private companies dates back to 1989. The discussion here will focus on the US Army's current need for an automated WIM system to weigh and determine the center-of-balance for military wheeled vehicles and cargo and the expanded uses of WIM data. ORNL is addressing configuration and data management issues as they relate to deployments for both military and humanitarian activities. The transition from the previous WIM Gen I to the current Gen II system illustrates a configuration and data management solution that ensures data integration, integrity, coherence and cost effectiveness. Currently, Army units use portable and fixed scales, tape measures, and calculators to determine vehicle axle, total weights and center of balance for vehicles prior to being transshipped via railcar, ship, or airlifted. Manually weighing and measuring all vehicles subject to these transshipment operations is time-consuming, labor-intensive, hazardous and is prone to human errors (e.g., misreading scales and tape measures, calculating centers of balance and wheel, axle, and vehicle weights, recording data, and transferring data from manually prepared work sheets into an electronic data base and aggravated by adverse weather conditions). Additionally, in the context of the military, the timeliness, safety, success, and effectiveness of airborne heavy-drop operations can be significantly improved by the use of an automated system to weigh and determine center of balance of vehicles while they are in motion. The lack of a standardized airlift-weighing system for joint service use also creates redundant weighing requirements at the cost of scarce resources and time. This case study can be judiciously expanded into commercial operations related to safety and enforcement. The WIM program will provide a means for the Army to automatically identify/weigh and monitor

  8. A reduced crustal magnetization zone near the first observed active hydrothermal vent field on the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Lin, Jian; Chen, Yongshun J.; Tao, Chunhui; German, Christopher R.; Yoerger, Dana R.; Tivey, Maurice A.

    2010-09-01

    Inversion of near-bottom magnetic data reveals a well-defined low crustal magnetization zone (LMZ) near a local topographic high (37°47‧S, 49°39‧E) on the ultraslow-spreading Southwest Indian Ridge (SWIR). The magnetic data were collected by the autonomous underwater vehicle ABE on board R/V DaYangYiHao in February-March 2007. The first active hydrothermal vent field observed on the SWIR is located in Area A within and adjacent to the LMZ at the local topographic high, implying that this LMZ may be the result of hydrothermal alteration of magnetic minerals. The maximum reduction in crustal magnetization is 3 A/M. The spatial extent of the LMZ is estimated to be at least 6.7 × 104 m2, which is larger than that of the LMZs at the TAG vent field on the Mid-Atlantic Ridge (MAR), as well as the Relict Field, Bastille, Dante-Grotto, and New Field vent-sites on the Juan de Fuca Ridge (JdF). The calculated magnetic moment, i.e., the product of the spatial extent and amplitude of crustal magnetization reduction is at least -3 × 107 Am2 for the LMZ on the SWIR, while that for the TAG field on the MAR is -8 × 107 Am2 and that for the four individual vent fields on the JdF range from -5 × 107 to -3 × 107 Am2. Together these results indicate that crustal demagnetization is a common feature of basalt-hosted hydrothermal vent fields at mid-ocean ridges of all spreading rates. Furthermore, the crustal demagnetization of the Area A on the ultraslow-spreading SWIR is comparable in strength to that of the TAG area on the slow-spreading MAR.

  9. Active spreading processes at ultraslow mid-ocean ridges: Unusual seismicity at the amagmatic Lena Trough, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Läderach, Christine; Schlindwein, Vera; Riedel, Carsten

    2010-05-01

    Lena Trough is the southern continuation of the ultraslow-spreading Gakkel Ridge and with its position in the Fram Strait between Greenland and Spitsbergen it is the only deep-sea gateway to the Arctic Ocean. DFG funded Emmy Noether group 'Mid-Ocean Volcanoes and Earthquakes' located at Alfred Wegener Institute for Polar and Marine Research is focusing on the seismicity of ultraslow spreading ridges and is especially interested in Lena Trough as an ultraslow spreading ridge in a developing stage. The southern Lena Trough shows similarities to the northern Red Sea spreading centre which is in the early stage of development from continental to oceanic rift. Cochran postulated in 2003 that the continental crust within the water-covered Red Sea is less than 10 km thick and that the northern part of the Red Sea rift spreads ultraslow as well. At Lena Trough an actively spreading mid-ocean ridge with a narrow rift valley has already developed but continental crust lies within a short distance. Lena Trough is extending from 83°N/5°W to 80.3°N/2°W where it passes into the transform fault of the Spitsbergen Fracture Zone. The geometry of Lena Trough and certain asymmetric structures in the rift valley indicate oblique spreading and mostly tectonic and amagmatic rifting. There are several topographic highs west of the ridge axis which could be bounded by deep faults with normal faulting or detachment character exposing mantle material at the surface. Seismicity at the Lena Trough shows apparently the same asymmetric character with epicenters of teleseismically recorded earthquakes concentrating predominantly west of the ridge axis. The most frequent focal mechanism of the earthquakes within the rift valley is normal faulting, whereas strike-slip faults occur in the Spitsbergen Fracture Zone. We relocalized teleseismic earthquakes recorded from May 1973 to April 2009 in the region using a refined localization algorithm and could confirm systematic asymmetry in the

  10. Heat Flow on the South West Indian Ridge at 14°E and the Consequences for Microbiological Activity

    NASA Astrophysics Data System (ADS)

    Kaul, N. E.; Molari, M.; Boetius, A.

    2014-12-01

    During RV POLARSTERN cruise PS81 to the South West Indian Ridge (SWIR) at 52°S, 14°E an integrated study was carried out in more than 4000 m water depth employing seismology, geology, microbiology, deep-sea ecology, heat flow and others. Heat flow is supposed to be an indicator for the varying depth of the magma chamber beneath the ridge axis. Bottom observations from previous work on the SWIR are scarce and visual information about geostructures, habitat landscapes, benthic faunal communities and their distribution in this area have so far been missing. Vigorous fluid flow in the form of black smokers or shimmering water could not be detected but enhanced heat flow due to upward pore water migration occurred. This leads to values of very high heat flow (up to 850 mW/m2) and advection rates up to 25 cm/a Darcy velocity. Enhanced biomass and a greater variation of megafauna along those sites of high heat flow could be inferred from reconnaissance observations with a camera sledge. A closer investigation of microbial activity in the material of gravity corers revealed favorable living conditions for microorganisms. We find the inorganic carbon fixation rates, here applied like a proxy of microbial metabolic activity, were significantly higher (up to 7 times higher) in surficial sediments in proximity of the station PS 81/640 compared to other stations along the ridge. Conversely the extracellular enzymatic activities did not show any significant difference in the potential organic matter degradation between the stations investigated. These results suggest an increase of chemosynthetic activities at St PS 81/649, possibly related to increase of availability of reduced compounds (i.e. sulphide, reduced metals) in presence of pore water flow.

  11. Annual Report on Environmental Monitoring Activities for FY 1995 (Baseline Year) at Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-06-01

    This report describes baseline contaminant release conditions for Waste Area Grouping (WAG) 6 at Oak Ridge National Laboratory (ORNL). The sampling approach and data analysis methods used to establish baseline conditions were presented in ``Environmental Monitoring Plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee (EMP).`` As outlined in the EMP, the purpose of the baseline monitoring year at WAG 6 was to determine the annual contaminant releases from the site during fiscal year 1995 (FY95) against which any potential changes in releases over time could be compared. The baseline year data set provides a comprehensive understanding of release conditions from all major waste units in the WAG through each major contaminant transport pathway. Due to a mandate to reduce all monitoring work, WAG 6 monitoring was scaled back and reporting efforts on the baseline year results are being minimized. This report presents the quantified baseline year contaminant flux conditions for the site and briefly summarizes other findings. All baseline data cited in this report will reside in the Oak Ridge Environmental Information system (OREIS) database, and will be available for use in future years as the need arises to identify potential release changes.

  12. 4D Time-Lapse Seismic Analysis of Active Gas Seepage Systems on the Vestnesa Ridge, Offshore W-Svalbard

    NASA Astrophysics Data System (ADS)

    Bunz, S.; Hurter, S.; Plaza-Faverola, A. A.; Mienert, J.

    2014-12-01

    Active gas venting occurs on the Vestnesa Ridge, an elongated sediment drift north of the Molloy Transform and just east of the Molloy Ridge, one of the shortest segments of the slow spreading North-Atlantic Ridge system. The crest of the Vestnesa Ridge at water depth between 1200-1300 m is pierced with fluid-flow features. Seafloor pockmarks vary in size up to 1 km in diameter with significant morphological features consisting of small ridges, diapiric structures and small pits. Detailed hydro-acoustic surveying shows that gas mostly emanates from the small-scale pits, where also hydrates have been recovered by sediment sampling. High-resolution P-Cable 3D seismic data acquired in 2012 show vertical focused fluid flow features beneath the seafloor pockmarks. These co-called chimneys extend down to the free-gas zone underneath a bottom-simulating reflection (BSR). Here, they link up with small fault systems that might provide pathways to the deeper subsurface. The chimney features show a high variability in their acoustic characteristics with alternating blanked or masked zones and high-amplitude anomalies scattered through the whole vertical extent of the chimneys. The amplitude anomalies indicate high-impedance contrasts due to the likely presence of gas or a high-velocity material like gas hydrates or carbonates. In most cases, the high-amplitude anomalies line up along specific vertical pathways that connect nicely with the small-scale pits at the surface where gas bubbles seep from the seafloor. We re-acquired the 3D seismic survey in 2013 for time-lapse seismic studies in order to better understand the origin of the amplitude anomalies and in order to track potentially migrating gas fronts up along the chimney structure. The time-lapse seismic analysis indicates several areas, where gas migration may have led to changes in acoustic properties of the subsurface. These areas are located along chimney structures and the BSR. This work provides a basis for better

  13. Data base management activities for the Remedial Action Program at Oak Ridge National Laboratories (ORNL)

    SciTech Connect

    Hook, L.A.; Voorhees, L.D.; Gentry, M.J.; Faulkner, M.A.; Shaakir-Ali, J.A.; Newman, K.A.; McCord, R.A.; Goins, L.F.; Owen, P.T.

    1990-07-01

    The Oak Ridge National Laboratory (ORNL) Remedial Action Program (RAP) was established in 1985 in response to state and federal regulations requiring comprehensive control over facility discharges and cleanup of contaminated sites. A computerized Data and Information Management System (DIMS) was developed for RAP to (1) provide a centralized repository for data pertinent to RAP and (2) provide support for the investigations and assessments leading to the long-term remediation of contaminated facilities and sites. The current status of DIMS and its role in supporting RAP during 1989 are described. The DIMS consists of three components: (1) the Numeric Data Base, (2) the Bibliographic Data Base, and (3) the Records Control Data Base. This report addresses all three data bases, but focuses on the contents of the Numeric Data Base. Significant progress was made last year with the geographic information system (GIS) and ARC/INFO, which can be interfaced with SAS/GRAPH to provide combined mapping and statistical graphic products. Several thematic layers of GIS data for the Oak Ridge Reservation are now available. 18 refs., 8 figs., 19 tabs.

  14. 4D seismic study of active gas seepage systems on the Vestnesa Ridge, offshore W-Svalbard

    NASA Astrophysics Data System (ADS)

    Bünz, Stefan; Plaza-Faverola, Andreia; Hurter, Sandra; Mienert, Jürgen

    2014-05-01

    Active gas venting occurs on the Vestnesa Ridge, an elongated sediment drift north of the Molloy Transform and just east of the Molloy Ridge, one of the shortest segments of the slow spreading North-Atlantic Ridge system. The crest of the Vestnesa Ridge at water depth between 1200-1300 m is pierced with fluid-flow features. Seafloor pockmarks vary in size up to 1 km in diameter. High-resolution P-Cable 3D seismic data acquired in 2012 show vertical focused fluid flow features beneath the seafloor pockmarks. These co-called chimneys extend down to the free-gas zone underneath a bottom-simulating reflection. Here, they link up with small fault systems that might provide pathways to the deeper subsurface. The chimney features show a high variability in their acoustic characteristics with alternating blanked or masked zones and high-amplitude anomalies scattered through the whole vertical extent of the chimneys. The amplitude anomalies indicate high-impedance contrasts due to the likely presence of gas or a high-velocity material like gas hydrates or carbonates. We re-acquired the 3D seismic survey in 2013 for time-lapse seismic studies in order to better understand the origin of the amplitude anomalies and in order to track potentially migrating gas fronts up along the chimney structure. Here, we will present the preliminary results of this time-lapse analysis, which will allow us to better understand gas migration and seafloor plumbing systems in continental margins. This work is part of CAGE - Centre of Excellence for Arctic Gas Hydrate, Environment and Climate. Details on the CAGE research plan and organization can be found on www.cage.uit.no to foster opportunities for cross-disciplinary collaboration. Based in Tromsø, at the world's northernmost University, CAGE establishes the intellectual and infrastructure resources for studying the amount of methane hydrate and magnitude of methane release in Arctic Ocean environments on time scales from the Neogene to the

  15. Follow-on Research Activities for the Rensselaer Isothermal Dendritic Growth Experiment (RIDGE)

    NASA Technical Reports Server (NTRS)

    LaCombe, J. C.; Koss, M. B.; Lupulescu, A. O.; Frei, J. E.; Giummarra, C.; Glicksman, M. E.

    2001-01-01

    The RIDGE effort continues the aegis of the earlier, NASA-sponsored, Isothermal Dendritic Growth Experiment (IDGE) series of experiments through the continued analysis of microgravity data acquired during these earlier space flights. The preliminary observations presented here demonstrate that there are significant differences between SCN and the more anisotropic PVA dendrites. The side branch structure becomes amplified only further behind the tip, and the interface shape is generally wider (i.e. more hyperbolic than parabolic) in PVA than in SCN. These characteristics are seen to affect the process of heat transport. Additionally, the dendrites grown during the fourth United States Microgravity Payload (USMP-4) exhibit time-dependent growth characteristics and may not always have reached steady-state growth during the experiment.

  16. COMSOL-Related Activities within the Research Reactors Division of Oak Ridge National Laboratory

    SciTech Connect

    Freels, James D

    2015-01-01

    Our group at Oak Ridge National Laboratory (ORNL) started using COMSOL shortly after version 3.0 was released in the Spring of 2004. Over 11 years later and several new releases of the code, the application usage has grown along with the number of licenses we are responsible for. This paper focuses not on details of results and modeling methods, but instead, takes a look at our past and present applications, and evaluates where we are headed with COMSOL in the future. In doing so, we reveal some lessons learned along our pathway, provide some insight on how best to use COMSOL in a group setting, and perhaps help both users and developers to improve how the code is utilized.

  17. Seismicity and active accretion processes at the ultraslow-spreading Southwest and intermediate-spreading Southeast Indian ridges from hydroacoustic data

    NASA Astrophysics Data System (ADS)

    Tsang-Hin-Sun, Eve; Royer, Jean-Yves; Perrot, Julie

    2016-08-01

    Volcanic and tectonic events are the main processes involved in the generation of the oceanic crust and responsible for the seismicity associated with seafloor spreading. To monitor this activity, usually not or poorly detected by land-based seismological stations, we deployed from February 2012 to February 2013 a network of autonomous hydrophones to compare the behaviour of the ultraslow-spreading Southwest Indian ridge (SWIR) with that of the intermediate-spreading Southeast Indian ridge (SEIR). The rate of seismicity is similar for both ridges, suggesting that there is no systematic relationship between seismicity and spreading rates. The along-axis distribution of the seismic events, however, does differ, reflecting the rate dependence of accretion modes. Earthquakes are sparse and regularly spaced and scattered along the SWIR, reflecting prevailing tectonic processes. By contrast, along the SEIR, events are irregularly distributed and focus at ridge-segment ends and transforms faults, reflecting the ridge segmentation; only two swarms occurred at a segment centre and are probably caused by a magmatic event. This seismicity distribution thus looks controlled by segment-scale crustal heterogeneities along the SEIR and by regional-scale contrasting accretion processes along the SWIR, probably driven by different lithospheric and asthenospheric dynamics on either side of the Melville fracture zone. The comparison of hydroacoustic and teleseismic catalogues shows that, along these spreading ridges, the background seismicity observed in 1 yr by a hydroacoustic network is representative of the seismicity observed over two decades by land-based networks.

  18. Hydrothermal activity and core complex formation at the Arctic Mid-Ocean Ridge: An overview of preliminary results of the H2DEEP expedition to the southern Knipovich Ridge at 73N

    NASA Astrophysics Data System (ADS)

    Pedersen, R. B.; Thorseth, I. H.; Olson, E.; Hellevang, H.; Okland, I.; Baumberger, T.; Lilley, M.; Bruvoll, V.; Mjelde, R.; Haflidason, H.

    2007-12-01

    The oblique spreading Mohns Ridge passes into the highly oblique spreading Knipovich Ridge through a near 90 degree bend in the ridge axis at 73-74N. Multibeam mapping of this area shows that a 30 km long axial volcanic ridge (AVR) with a 500m high summit occupy the rift valley floor in the central part of the bend where the axis is perpendicular to the spreading direction. The volcanic activity decreases northwards as the obliquity of the spreading increases and this is associated with an increase in the water depth from 2000-2500 m to 3000-3500 m. A hydrothermal plume was located at the eastern side of the AVR with methane values reaching 260 nmol/l and hydrogen values 53 nmol/l. These anomalies are associated with small positive temperature anomaly, but no significant particle anomaly could be detected. The rift valley in the area is partly filled with sediments derived from the nearby Bjornoya fan, and reflection seismic profiles across the ridge demonstrate that sediments thicknesses in the rift valley locally exceeds several hundred meters. Gravity cores of the upper 4 m of these sediments show multiple glass- and iron-rich laminas and layers, demonstrating that these sediments represent a record of hydrothermal and volcanic activity in the area. Seamounts at the western flank of the ridge extend to 600 m below sea level and are limited by low angle detachment faults to the east. A flat summit area suggests that one of the seamounts has been at or close to sea level. Gabbros, troctolites and serpentinites were sampled from the fault surfaces, demonstrating that lower crust and mantle rocks have been exhumed in the area, and bathymetry data indicates that this oceanic core complex cover an area of about 500 km2. A younger detachment fault appears to develop at the inner rift wall just west of the AVR. The rift valley sediments are affected by the faulting and the seismic stratigraphy of these sediments constrain the history of core complex formation.

  19. Leak testing plan for the Oak Ridge National Laboratory liquid low- level waste system (active tanks)

    SciTech Connect

    Douglas, D.G.; Wise, R.F.; Starr, J.W.; Maresca, J.W. Jr. )

    1992-06-01

    A leak testing plan for a portion of the Liquid Low-Level Waste (LLLW) system at the Oak Ridge National Laboratory (ORNL) is provided in the two volumes that form this document. This plan was prepared in response to the requirements of the Federal Facilities Agreement (FFA) between the US Department of Energy and two other agencies, the US Environmental Protection Agency (EPA) and the Tennessee Department of Environment and Conservation (TDEC). The effective date of this agreement was 1 January 1992. The LLLW system is an interconnected complex of tanks and pipelines. The FFA distinguishes four different categories of tank and pipeline systems within this complex: new systems (Category A), doubly contained systems (Category B), singly contained systems (Category C), and inactive systems (Category D). The FFA's specific requirements for leak testing of the Category C systems is addressed in this plan. The plan also addresses leak testing of the Category B portions of the LLLW system. Leak testing of the Category B components was brought into the plan to supplement the secondary containment design demonstration effort that is under way for these components.

  20. Summary of environmental characterization activities at the Oak Ridge National Laboratory Solid Waste Storage Area Six, FY 1986 through 1987

    SciTech Connect

    Davis, E.C.; Solomon, D.K.; Dreier, R.B.; Lee, S.Y.; Kelmers, A.D.; Lietzke, D.A.; Craig, P.M.

    1987-09-30

    The Oak Ridge National Laboratory (ORNL) Remedial Action Program (RAP), has supported characterization activities in Solid Waste Storage Area (SWSA 6) to acquire information necessary for identification and planning of remedial actions that may be warranted, and to facilitate eventual closure of the site. In FY 1986 investigations began in the areas of site hydrology, geochemistry, soils, geology, and geohydrologic model application. This report summarizes work carried out in each of these areas during FY`s 1986 and 1987 and serves as a status report pulling together the large volume of data that has resulted. Characterization efforts are by no means completed; however, a sufficient data base has been generated to begin data interpretation and analysis of site contaminants.

  1. Summary of environmental characterization activities at the Oak Ridge National Laboratory Solid Waste Storage Area Six, FY 1986 through 1987

    SciTech Connect

    Davis, E.C.; Solomon, D.K.; Dreier, R.B.; Lee, S.Y.; Kelmers, A.D.; Lietzke, D.A. ); Craig, P.M. )

    1987-09-30

    The Oak Ridge National Laboratory (ORNL) Remedial Action Program (RAP), has supported characterization activities in Solid Waste Storage Area (SWSA 6) to acquire information necessary for identification and planning of remedial actions that may be warranted, and to facilitate eventual closure of the site. In FY 1986 investigations began in the areas of site hydrology, geochemistry, soils, geology, and geohydrologic model application. This report summarizes work carried out in each of these areas during FY's 1986 and 1987 and serves as a status report pulling together the large volume of data that has resulted. Characterization efforts are by no means completed; however, a sufficient data base has been generated to begin data interpretation and analysis of site contaminants.

  2. Interaction of a mantle plume and a segmented mid-ocean ridge: Results from numerical modeling

    NASA Astrophysics Data System (ADS)

    Georgen, Jennifer E.

    2014-04-01

    Previous investigations have proposed that changes in lithospheric thickness across a transform fault, due to the juxtaposition of seafloor of different ages, can impede lateral dispersion of an on-ridge mantle plume. The application of this “transform damming” mechanism has been considered for several plume-ridge systems, including the Reunion hotspot and the Central Indian Ridge, the Amsterdam-St. Paul hotspot and the Southeast Indian Ridge, the Cobb hotspot and the Juan de Fuca Ridge, the Iceland hotspot and the Kolbeinsey Ridge, the Afar plume and the ridges of the Gulf of Aden, and the Marion/Crozet hotspot and the Southwest Indian Ridge. This study explores the geodynamics of the transform damming mechanism using a three-dimensional finite element numerical model. The model solves the coupled steady-state equations for conservation of mass, momentum, and energy, including thermal buoyancy and viscosity that is dependent on pressure and temperature. The plume is introduced as a circular thermal anomaly on the bottom boundary of the numerical domain. The center of the plume conduit is located directly beneath a spreading segment, at a distance of 200 km (measured in the along-axis direction) from a transform offset with length 100 km. Half-spreading rate is 0.5 cm/yr. In a series of numerical experiments, the buoyancy flux of the modeled plume is progressively increased to investigate the effects on the temperature and velocity structure of the upper mantle in the vicinity of the transform. Unlike earlier studies, which suggest that a transform always acts to decrease the along-axis extent of plume signature, these models imply that the effect of a transform on plume dispersion may be complex. Under certain ranges of plume flux modeled in this study, the region of the upper mantle undergoing along-axis flow directed away from the plume could be enhanced by the three-dimensional velocity and temperature structure associated with ridge-transform-ridge

  3. Age, Episodicity and Migration of Hydrothermal Activity within the Axial Valley, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Jamieson, J. W.; Hannington, M. D.; Kelley, D. S.; Clague, D. A.; Holden, J. F.; Tivey, M. K.; Delaney, J. R.

    2011-12-01

    Hydrothermal sulfide deposits record the history of high-temperature venting along the Endeavour Segment. Active venting is currently located within five discreet vent fields, with minor diffuse venting occurring between the fields. However, inactive and/or extinct sulfide structures are found throughout the entire axial valley of the ridge segment, suggesting that hydrothermal activity has been more vigorous in the past or focused venting has migrated with time. Here, we present age constraints from U-series dating of 44 sulfide samples collected by manned submersible from between the Mothra Field in the south to Sasquatch in the north. Samples are dated using 226Ra/Ba ratios from hydrothermal barite that precipitates along with the sulfide minerals. Most samples have been collected from within or near the active vent fields. Fifteen samples from the Main Endeavour Field (MEF) show a spectrum of ages from present to 2,430 years old, indicating that this field has been continuously active for at least ~2,400 years. MEF appears to be oldest currently active field. This minimum value for the age of hydrothermal activity also provides a minimum age of the axial valley itself. Ages from thirteen samples from the High-Rise Field indicate continuous venting for at least the past ~1,250 years. These age data are used in conjunction with age constraints of the volcanic flows to develop an integrated volcanic, hydrothermal and tectonic history of the Endeavour Segment. The total volume of hydrothermal sulfide within the axial valley, determined from high-resolution bathymetry, is used in conjunction with the age constraints of the sulfide material to determine the mass accumulation rates of sulfide along the Endeavour Segment. These data can be used to calibrate the efficiency of sulfide deposition from the hydrothermal vents, and provide a time-integrated history of heat, fluid and chemical fluxes at the ridge-segment scale. The comparison of time-integrated rates with

  4. Metopic ridge

    MedlinePlus

    ... infant is made up of bony plates. The gaps between the plates allow for growth of the skull. The places where these plates connect are called sutures or suture lines. They do not fully close until the 2nd or 3rd year of life. A metopic ridge occurs when the ...

  5. Seismicity and active accretion processes at the ultraslow-spreading Southwest and intermediate-spreading Southeast Indian ridges from hydroacoustic data

    NASA Astrophysics Data System (ADS)

    Tsang-Hin-Sun, Eve; Royer, Jean-Yves; Perrot, Julie

    2016-05-01

    Volcanic and tectonic events are the main processes involved in the generation of the oceanic crust and responsible for the seismicity associated with seafloor spreading. To monitor this activity, usually not or poorly detected by land-based seismological stations, we deployed from February 2012 to February 2013 a network of autonomous hydrophones to compare the behaviour of the ultraslow-spreading Southwest (SWIR) with that of the intermediate-spreading Southeast Indian ridges (SEIR). The rate of seismicity is similar for both ridges, suggesting that there is no systematic relationship between seismicity and spreading rates. The along-axis distribution of the seismic events, however, does differ, reflecting the rate-dependence of accretion modes. Earthquakes are sparse and regularly spaced and scattered along the SWIR, reflecting prevailing tectonic processes. By contrast, along the SEIR, events are irregularly distributed and focus at ridge-segment ends and transforms faults, reflecting the ridge segmentation; only two swarms occurred at a segment centre and are probably caused by a magmatic event. This seismicity distribution thus looks controlled by segment-scale crustal heterogeneities along the SEIR and by regional-scale contrasting accretion processes along the SWIR, probably driven by different lithospheric and asthenospheric dynamics on either side of the Melville FZ. The comparison of hydroacoustic and teleseismic catalogues shows that, along these spreading ridges, the background seismicity observed in one year by a hydroacoustic network is representative of the seismicity observed over two decades by land-based networks.

  6. US Department of Energy reservior research activities Oak Ridge National Laboratory

    SciTech Connect

    Railsback, S.F.

    1991-01-01

    The US Department of Energy (DOE) does not directly manage large reservoirs, but DOE laboratories conduct research on reservoir monitoring, assessment, and enhancement under several activities. These activities include (1) studies and remedial actions for reservoirs affected by releases from DOE facilities, (2) industry- sponsored research on reservoir and stream fish, (3) climate change research, (4) hydropower impact assessment studies conducted for the Federal Energy Regulatory Commission (FERC), and (5) the DOE hydropower program. These activities fall under DOE's missions of providing support for environmentally sound energy technologies and managing the legacies of past waste disposal practices at DOE facilities. 9 refs.

  7. FY 1994 annual summary report of the surveillance and maintenance activities for the Oak Ridge National Laboratory Environmental Restoration Program

    SciTech Connect

    Not Available

    1994-11-01

    The Oak Ridge National Laboratory (ORNL) Environmental Restoration (ER) Surveillance and Maintenance (S and M) Program was initiated to manage former waste management and environmental research sites contaminated with radioactive materials and/or hazardous chemicals. The S and M Program is responsible for managing designated sites/facilities from the end of their operating lives until final disposition or site stabilization. To effectively manage and perform the various S and M Program responsibilities, five summary-level work breakdown structure (WBS) elements have been established: S and M Preliminary Investigations, Special Projects, Routine S and M, Inactive Groundwater Wells, and Project Management. Routine S and M activities were conducted as scheduled throughout fiscal years (FY) 1994 at applicable inactive waste management (WM) and other contaminated areas. Overall, the ER S and M Program maintains 47 facilities, performs vegetation maintenance on approximately 230 acres, maintains 54 inactive tanks, and provides overall site management on over 700 acres. In addition to the routine S and M activities, detailed site inspections were conducted at established frequencies on appropriate sites in the ER S and M Program. This document provides a summary of the FY 1994 ORNL ER S and M Program accomplishments.

  8. 1993 annual report of hazardous waste activities for the Oak Ridge K-25 site

    SciTech Connect

    Not Available

    1994-02-01

    This report is a detailed listing of all of the Hazardous Waste activities occurring at Martin Marietta`s K-25 site. Contained herein are hazardous waste notification forms, waste stream reports, generator fee forms and various TSDR reports.

  9. Chemistry of fracture-filling raised ridges in Yellowknife Bay, Gale Crater: Window into past aqueous activity and habitability on Mars

    NASA Astrophysics Data System (ADS)

    Léveillé, Richard J.; Bridges, John; Wiens, Roger C.; Mangold, Nicolas; Cousin, Agnes; Lanza, Nina; Forni, Olivier; Ollila, Ann; Grotzinger, John; Clegg, Samuel; Siebach, Kirsten; Berger, Gilles; Clark, Ben; Fabre, Cécile; Anderson, Ryan; Gasnault, Olivier; Blaney, Diana; Deflores, Lauren; Leshin, Laurie; Maurice, Sylvestre; Newsom, Horton

    2014-11-01

    The ChemCam instrument package on the Curiosity rover was used to characterize distinctive raised ridges in the Sheepbed mudstone, Yellowknife Bay formation, Gale Crater. The multilayered, fracture-filling ridges are more resistant to erosion than the Sheepbed mudstone rock in which they occur. The bulk average composition of the raised ridges is enriched in MgO by 1.2-1.7 times (average of 8.3-11.4 wt %; single-shot maximum of 17.0 wt %) over that of the mudstone. Al2O3 is anticorrelated with MgO, while Li is somewhat enriched where MgO is highest. Some ridges show a variation in composition with different layers on a submillimeter scale. In particular, the McGrath target shows similar high-MgO resistant outer layers and a low-MgO, less resistant inner layer. This is consistent with the interpretation that the raised ridges are isopachous fracture-filling cements with a stratigraphy that likely reveals changes in fluid composition or depositional conditions over time. Overall, the average composition of the raised ridges is close to that of a Mg- and Fe-rich smectite, or saponite, which may also be the main clay mineral constituent of the host mudstone. These analyses provide evidence of diagenesis and aqueous activity in the early postdepositional history of the Yellowknife Bay formation, consistent with a low salinity to brackish fluid at near-neutral or slightly alkaline pH. The fluids that circulated through the fractures likely interacted with the Sheepbed mudstone and (or) other stratigraphically adjacent rock units of basaltic composition and leached Mg from them preferentially.

  10. Pleiotropic patterning response to activation of Shh signaling in the limb Apical Ectodermal Ridge

    PubMed Central

    Wang, Chi-Kuang Leo; Tsugane, Mizuyo H.; Scranton, Victoria; Kosher, Robert A.; Pierro, Louis J.; Upholt, William B.; Dealy, Caroline N.

    2012-01-01

    Sonic hedgehog (Shh) signaling in the limb plays a central role in coordination of limb patterning and outgrowth. Shh expression in the limb is limited to the cells of the Zone of Polarizing Activity (ZPA), located in posterior limb bud mesoderm. Shh is not expressed by limb ectoderm or AER, but recent studies suggest a role for AER-Shh signaling in limb patterning. Here, we have examined the effects of activation of Shh signaling in the AER. We find that targeted expression of Shh in the AER activates constitutive Shh signaling throughout the AER and subjacent limb mesoderm, and causes a range of limb patterning defects with progressive severity from mild polydactyly, to polysyndactyly with proximal defects, to severe oligodactyly with phocomelia and partial limb ventralization. Our studies emphasize the importance of control of the timing, level and location of Shh pathway signaling for limb AP, PD and DV patterning. PMID:21465622

  11. Surveillance and maintenance activities of waste area groupings at Oak Ridge National Laboratory

    SciTech Connect

    Ford, M.K.; Holder, L. Jr.; Jones, R.G.

    1991-12-01

    Surveillance and maintenance (S M) of 75 sites were conductd by the Remedial Action Section for the Environmental Restoration Program for surplus facilities and sites contaminated with radioactive materials and/or hazardous chemicals. S M activities on these sites were conducted from the end of their operating life until final facility disposal or site stabilization. The objectives of the Waste Area Grouping S M Program are met by maintaining a program of routine S M as well as by implementing interim corrective maintenance when deemed necessary as a result of site surveillance. This report briefly presents this program's activities and includes tables indicating tank levels and dry well data for FY 1991.

  12. Oak Ridge Health Studies Phase 1 report, Volume 2: Part C, Dose Reconstruction Feasibility Study. Tasks 5: A summary of information concerning historical locations and activities of populations potentially affected by releases from the Oak Ridge Reservation

    SciTech Connect

    DaMassa, C.L.; Widner, T.E.

    1993-09-01

    A significant number of information sources have been identified that are relevant to historical locations and activities of populations potentially affected by releases from the Oak Ridge Reservation. The information that has been reviewed as part of this Task 5 investigation has shown that numerous residences and farms have historically been present near the ORR boundary and that a variety of land uses and recreational activities have been practiced. Based on this information alone, it would appear that many routes of off-site exposure could have been plausible. Most of the available published information addresses demographic and land use data on a regional or county-wide basis over fairly broad time periods. The information sources that are most readily available do not support direct evaluation of potential exposure pathways at specific geographic locations near the Oak Ridge facilities at specific points in time. A number of information sources have been identified that can provide demography and land use information more specific to locations and time periods that are identified to be of interest. Examples of data sources in this category include individual USGS topographic maps, aerial photographs, lowest-level census tract data, and interviews with long-time local residents. However, specific release events and periods of interest should be identified prior to attempts to collect more specific demographic or land use information for actual dose reconstruction.

  13. Atomic and molecular physics and data activities for astrophysics at Oak Ridge National Laboratory

    SciTech Connect

    Jeffery, D.J.; Kristic, P.S.; Liu, W.; Schultz, D.R.; Stancil, P.C.

    1998-04-01

    The atomic astrophysics group at ORNL produces, collects, evaluates, and disseminates atomic and molecular data relevant to astrophysics and actively models various astrophysical environments utilizing this information. With the advent of the World Wide Web, these data are also being placed on-line to facilitate their use by end-users. In this brief report, the group`s recent activities in data production and in modeling are highlighted. For example, the authors describe recent calculations of elastic and transport cross sections relevant to ionospheric and heliospheric studies, charge transfer between metal ions and metal atoms and novel supernova nebular spectra modeling, ion-molecule collision data relevant to planetary atmospheres and comets, and data for early universe modeling.

  14. Regional inventory of karst activity in the Valley and Ridge Province, eastern Tennessee: Phase 1

    SciTech Connect

    Newton, J.G.; Tanner, J.M.

    1987-09-01

    A data collection form was developed for use in compiling information in the inventory. Information sources included files on subsidence, state and county highway departments, county agents and executives, soil conservation service representative, etc. Data obtained included location, date of occurrence, number of subsidence features at the reported site, size, topographic setting, geologic setting, and probable causative factors. The regional inventory obtained information on over 300 historic subsidence events at more than 200 sites in East Tennessee. Areas having the greatest areal density of active subsidence include Hamblen, Jefferson, and Loudon Counties. Reported subsidence events occurred between 1945 and 1986. The Knox Group dolomites account for about two-thirds of all reported sinkholes in the inventory. Most of the karst activity occurs in valleys or flat areas. In cases where causative factors could be established, the combination of surface water drainage alteration or impoundment combined with soil disturbance associated with construction activity were most often precursors to subsidence. 54 refs., 10 figs., 4 tabs.

  15. Polar Ridges

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03662 Polar Ridges

    This ridge system is located in the south polar region.

    Image information: VIS instrument. Latitude -81.7N, Longitude 296.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  16. Detailed leak detection test plan and schedule for the Oak Ridge National Laboratory LLLW active tanks. Waste Management and Environmental Restoration Programs

    SciTech Connect

    Douglas, D.G.; Maresca, J.W. Jr.

    1993-03-01

    This document provides a detailed leak detection test plan and schedule for leak testing many of the tanks that comprise the active portion of the liquid low-level waste (LLLW) system at the Oak Ridge National Laboratory (ORNL). This plan was prepared in response to the requirements of the Federal Facility Agreement (FFA) between the US Department of Energy (DOE) and two other agencies, the US Environmental Protection Agency (EPA) and the Tennessee Department of Environment and Conservation (TDEC).

  17. Remedial site evaluation report for the waste area grouping 10 wells associated with the new hydrofracture facility at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Volume 2: Field activities and well summaries

    SciTech Connect

    1996-08-01

    Four hydrofracture sites at the Oak Ridge National Laboratory (ORNL) were used for development, demonstration, and disposal from 1959 to 1984. More than 10 million gal of waste grout mix was disposed of via hydrofracture. Various types of wells were installed to monitor the hydrofracture operations. The primary goal of this remedial investigation was to gather information about the wells in order to recommend the type and best method of final disposition for the wells. Evaluations were performed to determine the integrity of well castings, confirm construction details for each well, evaluate the extent of contamination, assist in planning for future activities, and determine the suitability of the wells for future temporary site monitoring.

  18. Active normal fault network of the Apulian Ridge (Eastern Mediterranean Sea) imaged by multibeam bathymetry and seismic data

    NASA Astrophysics Data System (ADS)

    Pellegrini, Claudio; Marchese, Fabio; Savini, Alessandra; Bistacchi, Andrea

    2016-04-01

    The Apulian ridge (North-eastern Ionian margin - Mediterranean Sea) is formed by thick cretaceous carbonatic sequences and discontinuous tertiary deposits crosscut by a NNW-SSE penetrative normal fault system and is part of the present foreland system of both the Apennine to the west and the Hellenic arc to the east. The geometry, age, architecture and kinematics of the fault network were investigated integrating data of heterogeneous sources, provided by previous studies: regional scale 2D seismics and three wells collected by oil companies from the '60s to the '80s, more recent seismics collected during research projects in the '90s, very high resolution seismic (VHRS - Sparker and Chirp-sonar data), multi-beam echosounder bathymetry and results from sedimentological and geo-chronological analysis of sediment samples collected on the seabed. Multibeam bathymetric data allowed in particular assessing the 3D continuity of structures imaged in 2D seismics, thanks to the occurrence of continuous fault scarps on the seabed (only partly reworked by currents and covered by landslides), revealing the vertical extent and finite displacement associated to fault scarps. A penetrative network of relatively small faults, always showing a high dip angle, composes the NNW-SSE normal fault system, resulting in frequent relay zones, which are particularly well imaged by seafloor geomorphology. In addition, numerous fault scarps appear to be roughly coeval with quaternary submarine mass-wasting deposits colonised by Cold-Water Corals (CWC). Coral colonies, yielding ages between 11 and 14 kA, develop immediately on top of late Pleistocene mass-wasting deposits. Mutual cross-cutting relationships have been recognized between fault scarps and landslides, indicating that, at least in places, these features may be coeval. We suppose that fault activity lasted at least as far as the Holocene-Pleistocene boundary and that the NNW-SSW normal fault network in the Apulian Plateau can be

  19. Learning experiences at Oak Ridge

    SciTech Connect

    White, R.K.

    1990-01-01

    The Oak Ridge Operations (ORO) of DOE has organized an Environmental Restoration Program to handle environmental cleanup activitis for the Oak Ridge Reservation (ORR) following General Watkins' reorganization at DOE Headquarters. Based on the major facilities and locations of contamination sites, the Environmental Restoration Program is divided into five subprograms: Oak Ridge, National Laboatory (ORNL) sites, y-12 Plant sites, Oak Ridge Gaseous Diffusion Plant (ORGDP) sites, Oak Ridge Associated Universities (ORAU) sites and off-site areas. The Office of Risk Analysis at ORNL was established under the auspices of the Environmental Restoration Program to implement Superfun legislation in the five subprograms of DOE-ORO. Risk assessment must examine protetial human health and ecological impacts from contaminant sources that range from highly radioactive materials to toxic chemicals and mixed wastes. The remedial alternatives we are evaluating need to reach acceptable levels of risk effectively while also being cost-efficient. The purpose of this paper is to highlight areas of particular interest and concern at Oak Ridge and to discuss, where possible, solutions implemented by the Oak Ridge Environmental Restoation Program.

  20. Strategic Environmental Research and Development Project FY 1994: Assessing national remote sensing technologies for use in US Department of Energy Environmental Restoration Activities, Oak Ridge Solid Waste Storage Area 4 case study

    SciTech Connect

    King, A.L.; Smyre, J.L.; Evers, T.K.

    1995-02-01

    During FY 1994, the Oak Ridge Environmental Restoration (ER) Remote Sensing Program teamed with members of the Oak Ridge National Security Program Office (NSPO), the Environmental Research Institute of Michigan (ERIM) under contract to the National Exploitation Laboratory (NEL), the Oak Ridge Waste Area Group 4 (WAG 4) ER Program, and the US Department of Energy (DOE), Offices of Technology Development, Nonproliferation and National Security, and Environmental Restoration, to conduct a test and demonstration of the uses of national remote sensing technologies at DOE hazardous waste sites located in Oak Ridge, Tennessee. Objectives of the Oak Ridge study were to determine if national remote sensing technologies are useful in conducting prescreening, characterization, and/or monitoring activities to expedite the clean-up process at hazardous waste sites and to cut clean-up costs wherever possible. This project was sponsored by the Strategic Environmental Research and Development Project (SERDP).

  1. Initiation and collapse of active circulation in a hydrothermal system at the Mid-Atlantic Ridge, 23°N

    NASA Astrophysics Data System (ADS)

    Gallinatti, Barbara Cosens

    1984-05-01

    Gabbro and basalt, collected from an area south of the Kane Fracture Zone along the Mid-Atlantic Ridge, have three stages of alteration which record the cooling of a hydrothermal system: (1) Stage 1. Penetration of seawater began between 400° and 550°C, altering pyroxene to fibrous green amphibole. (2) Stage 2. Propylitic alteration formed along connected fractures between 250° and 300°C. As fracture density increased, the Fe/Mg ratio of chlorite increased, the final result being an Fe chlorite-quartz-sulfide breccia. (3) Stage 3. Late smectite veinlets formed at low temperatures (≤200°C) after active circulation ceased The study focuses on stage 2 alteration. By assuming local equilibrium between alteration minerals and the hydrothermal fluid, constraints can be placed on the fluid composition responsible for stage 2 alteration, the stage associated with deposition of sulfides. The following activities of species in solution were determined for the system FeO Na2O-CaO-MgO-Al2O3-SiO2-H2O at 350 bars and 250°C: log a (Ca++)/a2 (H+) = 8.0, log a (Na+)/a (H+) = 5.0, log a (Fe++)/a2 (H+) = 1.7, log a (Mg++)/a2 (H+) = 6.0. Log a (SiO2) was set at quartz saturation (-2.3 at 350 bars and 250°C). Fluid inclusions record the introduction of a low temperature, seawater-salinity fluid during formation of the latest quartz veins associated with stage 2 alteration. Mixing of this and the hydrothermal fluid caused a drop in temperature and increase in oxidation state, resulting in increased precipitation of quartz, pyrite and chalcopyrite. The salinities of fluid inclusions trapped in quartz during stage 2 alteration are as much as 3 times that of seawater. Concentration of a fluid initially of seawater salinity may be the result of boiling at ≥350°C and ≤3000 m depth.

  2. First-order major element variation in basalt glasses from the Mid-Atlantic ridge : 29/sup 0/N to 73/sup 0/N

    SciTech Connect

    Sigurdsson, H.

    1981-10-10

    Basaltic glasses from 29/sup 0/N to 73/sup 0/N on the Mid-Atlantic Ridge define two geographic and compositional groups that are characterized by different major element concentrations, phase assemblages and partition coefficients. Group A glasses occur on the ridge segment north of Gibbs Fracture Zone, from 54/sup 0/N, along the Reykjanes Ridge, the western volcanic zone of Iceland and Kolbeinsey Ridge, up to 70/sup 0/N. Similar glasses occur also on the ridge from 29/sup 0/N to 34/sup 0/N. Group A is characterized by pronounced alumina depletion and iron-enrichment trends, lower silica and alkalis and higher iron and high CaO/Al/sub 2/O/sub 3/. Clinopyroxene is only present in the more evolved group A glasses (Mg-value<58). Olivine-glass partition coefficients for Mg and Fe are systematically lower in group A than group B (Schilling and Sigurdsson, 1979), reflecting effects of melt composition on structure of the liquids. Group B glasses define the ridge segment north of 35/sup 0/N over the Azores platform and up to Gibbs F. Z., at 53/sup 0/N. They are also present on the Mohns Ridge north of the Jan Mayen F. Z. at 71/sup 0/N and at least as far north as 73/sup 0/. Group B glasses are characterized by higher silica and alkalis, low iron and lack of alumina depletion and iron-enrichment trends. They contain calcic clinopyroxene (Cpx) throughout the compositional range, whereas the sub-calcic augite is absent. The major-element variation within each group can be modeled quantitatively by fractional crystallization involving the phenocryst phases. The range of glass compositions in the two groups forms two distinct but parallel cotectic trends within the basalt tetrahedron, which are believed to define the quaternary univariant line 01-P1-Cpx-Liq along which the magmas evolved during fractionation at low to intermediate pressure.

  3. Hydrothermal activity on the southern Mid-Atlantic Ridge: Tectonically- and volcanically-controlled venting at 4 5°S

    NASA Astrophysics Data System (ADS)

    German, C. R.; Bennett, S. A.; Connelly, D. P.; Evans, A. J.; Murton, B. J.; Parson, L. M.; Prien, R. D.; Ramirez-Llodra, E.; Jakuba, M.; Shank, T. M.; Yoerger, D. R.; Baker, E. T.; Walker, S. L.; Nakamura, K.

    2008-09-01

    We report results from an investigation of the geologic processes controlling hydrothermal activity along the previously-unstudied southern Mid-Atlantic Ridge (3-7°S). Our study employed the NOC (UK) deep-tow sidescan sonar instrument, TOBI, in concert with the WHOI (USA) autonomous underwater vehicle, ABE, to collect information concerning hydrothermal plume distributions in the water column co-registered with geologic investigations of the underlying seafloor. Two areas of high-temperature hydrothermal venting were identified. The first was situated in a non-transform discontinuity (NTD) between two adjacent second-order ridge-segments near 4°02'S, distant from any neovolcanic activity. This geologic setting is very similar to that of the ultramafic-hosted and tectonically-controlled Rainbow vent-site on the northern Mid-Atlantic Ridge. The second site was located at 4°48'S at the axial-summit centre of a second-order ridge-segment. There, high-temperature venting is hosted in an ˜ 18 km 2 area of young lava flows which in some cases are observed to have flowed over and engulfed pre-existing chemosynthetic vent-fauna. In both appearance and extent, these lava flows are directly reminiscent of those emplaced in Winter 2005-06 at the East Pacific Rise, 9°50'N and reference to global seismic catalogues reveals that a swarm of large (M 4.6-5.6) seismic events was centred on the 5°S segment over a ˜ 24 h period in late June 2002, perhaps indicating the precise timing of this volcanic eruptive episode. Temperature measurements at one of the vents found directly adjacent to the fresh lava flows at 5°S MAR (Turtle Pits) have subsequently revealed vent-fluids that are actively phase separating under conditions very close to the Critical Point for seawater, at ˜ 3000 m depth and 407 °C: the hottest vent-fluids yet reported from anywhere along the global ridge crest.

  4. Growth of a tectonic ridge

    SciTech Connect

    Fleming, R.W.; Messerich, J.A.; Johnson, A.M.

    1997-12-31

    The 28 June 1992 Landers, California, earthquake of M 7.6 created an impressive record of surface rupture and ground deformation. Fractures extend over a length of more than 80 km including zones of right-lateral shift, steps in the fault zones, fault intersections and vertical changes. Among the vertical changes was the growth of a tectonic ridge described here. In this paper the authors describe the Emerson fault zone and the Tortoise Hill ridge including the relations between the fault zone and the ridge. They present data on the horizontal deformation at several scales associated with activity within the ridge and belt of shear zones and show the differential vertical uplifts. And, they conclude with a discussion of potential models for the observed deformation.

  5. Oceanic Core Complexes on the Mohns Ridge

    NASA Astrophysics Data System (ADS)

    Denny, A. R.; Pedersen, R. B.

    2013-12-01

    The Mohns Ridge, an ultra-slow spreading ridge in the Arctic Mid-Ocean Ridge system, is host to multiple volcanic and tectonic spreading segments. This oblique-spreading ridge is hotspot influenced at its southern terminus and is bound to the north by a curvilinear contact with the highly oblique Knipovich Ridge. This study examines EM120 multibeam bathymetry of the Mohns Ridge collected from 1999-2001 and gridded to 50 m cell size. Geomorphic interpretation of near-axis and off-axis structures reveals multiple expressions of potential oceanic core complexes (OCCs) along the 550 km long spreading axis. The OCCs form only on the western side of the spreading axis, consistent with the increased tectonic vs. volcanic morphology of the western flank of the Mohns Ridge. In the southern Mohns Ridge OCCs occur adjacent to on-axis active volcanic spreading centers. In the northern Mohns Ridge OCCs appear related to both ';V' shaped northern-propagating ridge spreading centers and spreading-parallel strings of core complexes extending at least 60 km off axis in the direction of spreading. This geomorphic interpretation should be further refined by dedicated ship-based investigations to fully describe this unique oblique-spreading Arctic Ridge system.

  6. High-resolution bathymetry reveals contrasting landslide activity shaping the walls of the Mid-Atlantic Ridge axial valley

    NASA Astrophysics Data System (ADS)

    Cannat, Mathilde; Mangeney, Anne; OndréAs, HéLèNe; Fouquet, Yves; Normand, Alain

    2013-04-01

    Axial valleys are found along most slow-spreading mid-ocean ridges and are one of the most prominent topographic features on Earth. In this paper, we present the first deep-tow swath bathymetry for the axial valley walls of the Mid-Atlantic Ridge. These data allow us to analyze axial valley wall morphology with a very high resolution (0.5 to 1 m compared to ≥ 50 m for shipboard multibeam bathymetry), revealing the role played by landslides. Slow-spreading ridge axial valleys also commonly expose mantle-derived serpentinized peridotites in the footwalls of large offset normal faults (detachments). In our map of the Ashadze area (lat. 13°N), ultramafic outcrops have an average slope of 18° and behave as sliding deformable rock masses, with little fragmentation. By contrast, the basaltic seafloor in the Krasnov area (lat. 16°38'N) has an average slope of 32° and the erosion of the steep basaltic rock faces leads to extensive fragmentation, forming debris with morphologies consistent with noncohesive granular flow. Comparison with laboratory experiments suggests that the repose angle for this basaltic debris is > 25°. We discuss the interplay between the normal faults that bound the axial valley and the observed mass wasting processes. We propose that, along axial valley walls where serpentinized peridotites are exposed by detachment faults, mass wasting results in average slopes ≤ 20°, even in places where the emergence angle of the detachment is larger.

  7. The non-transform discontinuity on the Central Indian Ridge at 11°S: The transtensional basin formation and hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Pak, S. J.; Kim, H. S.; Son, J.; Kim, J.; Moon, J. W.; Son, S. K.

    2014-12-01

    The bathymetric and magnetic survey, hydrocasting and seabed sampling have been carried out in the middle portion of the Central Indian Ridge (MCIR) between 7°S and 17°S. The MCIR constitutes six first-order segments and seven second-order segments with four non-transform discontinuities (NTDs) and twelve ocean core complexes (OCCs). These segments are characterized by asymmetric accretion that corresponds to about 70% of the surveyed MCIR segment. One of the outstanding NTD in the area is a basin like NTD3-1 at 11°S (50km in length) which strike at 035°, approximately 45° oblique in a clockwise direction to the orientation of two adjoining second-order segments. The hydrothermal activity is recognized at the tips of NTD3-1. No abyssal hills paralleling to basin-shape NTD3-1 are observed. Anomalous depth of the basin, lack of positive magnetic anomaly across the basin and rare seismic activities in the basin floor suggests that extensional tectonism with a sparse volcanism is the dominant process occurring along the NTD3-1. Based on the previous researches that the counterclockwise rotation of ridge is predominant in the area, the region of NTD3-1 largely accommodates shear strain by left-lateral sense motion and consequently forms a transtensional basin, i.e., a pull-apart basin. The strong and frequent hydrothermal plume signals, and highly tectonized rocks in both tips of the NTD3-1 are reflective of the dilation zones or tensional fractures accompanied by the pull-apart basin formation. It is the first identification of a pull-apart basin associated with hydrothermal activity in the Central Indian Ridge.

  8. What`s an ARAR?: Regulatory requirements for CERCLA remedial activities at D&D sites on the Oak Ridge Reservation

    SciTech Connect

    Houlberg, L.M.; Etnier, E.L.

    1994-09-01

    Many government-owned facilities that supported early nuclear energy research and defense programs have no current use and have been retired. Some of these facilities have residual radioactive or chemical contamination that require remediation. The Department of Energy (DOE) Decontamination and Decommissioning (D&D) Program is responsible for managing these surplus facilities. Remedial activities for contaminated environs and inactive land-based units (e.g., landfills, surface impoundments) at the Oak Ridge Reservation (ORR) are conducted under the direction of the Environmental Restoration (ER) Program.

  9. Detailed leak detection test plan and schedule for Oak Ridge National Laboratory liquid low-level waste active tanks

    SciTech Connect

    1995-01-01

    This document provides a plan and schedule for leak testing a portion of the Liquid Low-Level Waste (LLLW) system at the Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee. It is a concise version of a more general leak testing plan that was prepared in response to the requirements of the Federal Facility Agreement (FFA) for the Oak Ridge Reservation (ORR). This plan includes a schedule for the initial reporting of the leak test results from the various tanks that will be tested. The FFA distinguishes four categories of tank and pipeline systems: new systems (Category A), doubly contained systems (Category B), singly contained systems (Category C), and inactive systems (Category D). The FFA specifically requires leak testing of the Category C systems; there are 14 such tanks addressed in this plan, plus one tank (W-12) that has been temporarily returned to service based on EPA and TDEC concurrence. A schedule for testing these tanks is also included. The plan and schedule also addresses an additional 15 Category B tanks have been demonstrated to meet secondary containment requirements. While these 15 tanks are addressed in this plan for the sake of completeness, they have been removed from the leak testing program based on the design demonstrations that show secondary containment. It is noted that the general plan included 42 tanks. Since that report was issued, 26 of those tanks have passed secondary containment design demonstrations and subsequently have been removed from this leak testing plan. In addition, one tank (LA-104) has been removed from service. Accordingly, this document addresses 15 of the LLLW tanks in the system; plans for testing the pipelines will be described in a separate document.

  10. The origin of the asymmetry in the Iceland hotspot along the Mid-Atlantic Ridge from continental breakup to present-day

    NASA Astrophysics Data System (ADS)

    Howell, Samuel M.; Ito, Garrett; Breivik, Asbjørn J.; Rai, Abhishek; Mjelde, Rolf; Hanan, Barry; Sayit, Kaan; Vogt, Peter

    2014-04-01

    configuration in which plume influence along the Reykjanes Ridge is steady, but is still widening along the Kolbeinsey Ridge, as it has been since this ridge formed at ∼25 Ma.

  11. Juan de Fuca Plate Ridge-to-Trench Experiment: initial results from active source seismic imaging of the Juan de Fuca plate and Cascadia fore-arc (Invited)

    NASA Astrophysics Data System (ADS)

    Carbotte, S. M.; Canales, J.; Carton, H. D.; Han, S.; Gibson, J. C.; Janiszewski, H. A.; Horning, G.; Nedimovic, M. R.; Abers, G. A.; Trehu, A. M.

    2013-12-01

    Active source seismic data were acquired during the Juan de Fuca Ridge-to-Trench experiment (June-July 2012) to characterize the evolution and structure of the Juan de Fuca plate from formation at the ridge, through evolution in the plate interior, to subduction at the Cascadia trench. The survey provides plate-scale images of the sediments, crust, and shallowest mantle along two ridge-perpendicular transects, one extending from Axial seamount to the Oregon margin near Hydrate Ridge and the other from near Endeavour segment to Grays Harbor offshore Washington. In addition, a 450 km long trench-parallel line ~10 km seaward of the Cascadia deformation front was acquired to characterize variations in plate structure along the margin. Coincident long-streamer (8 km) multi-channel seismic (MCS) and wide-angle ocean bottom seismometer (OBS) data were collected along each transect. Using these data, our current investigations focus on the properties of the thick sediment blanket covering the Juan de Fuca plate and evidence for fluid flow at the deformation front, crustal structure within the plate interior and near the deformation front, and tracking the downgoing plate beneath the margin. Highlights include the discovery of numerous pockmarks on the seafloor providing evidence of active fluid flow up to 60 km west of the deformation front. Along the Oregon transect, a bright decollement horizon is imaged at ~1sec twtt above basement whereas at the Washington margin, protothrusts of the deformation front reach to the top of the oceanic crust. Variations in sediment properties are documented within the margin-parallel transect with changes in the stratigraphic level of decollement. While crustal thickness is quite uniform along the margin (~ 6 km), variations in crustal reflectivity and in shallowest mantle velocities are observed over ~30-50 km length scales that could be related to structural variations in the Cascadia subduction zone. Further landward, the top of the

  12. Mapping oceanic ridge segments in Oman ophiolite

    NASA Astrophysics Data System (ADS)

    Nicolas, A.; Boudier, F.

    1995-04-01

    This paper presents the results of detailed mapping of high-temperature flow structures in the mantle and crust of two massifs of the Oman ophiolite. In these massifs, the dominant structures, including large-scale folds, shear zones, and fractures, were generated at elevated temperatures and are ascribed to the ridge or ridge environment activity; this means that the structural maps presented can be viewed as those of partly dissected ridge segments. It has been possible in the two massifs to locate the paleoaxis of the oceanic ridge which created this crust. This location, which is constrained by several independent tests, is a prerequisite to reconstruct the structure and to investigate the dynamics of a fast spreading ridge. In the Nakhl-Rustaq massif, high temperature tectonic activity at the ridge rotated the Moho toward a vertical altitude and folded the layered gabbros on the scale of several hundred meters. This tectonism is attributed to a propagating ridge deforming a slightly older lithosphere. The propagating ridge segment extends in the field from a diapir area to a domain located along strike some 20 km away, where the sheeted dike complex roots directly in the mantle, without layered gabbros in between. The diapir area represents the mantle feeder for the ridge segment, and the rooted dikes represent the propagating tip. Other results include the detailed mapping of two mantle diapirs and of the diverging mantle flow issued from them. Magma chambers are centered over diapirs and are tent-shaped, in accord with our previous models.

  13. Grafts for Ridge Preservation

    PubMed Central

    Jamjoom, Amal; Cohen, Robert E.

    2015-01-01

    Alveolar ridge bone resorption is a biologic phenomenon that occurs following tooth extraction and cannot be prevented. This paper reviews the vertical and horizontal ridge dimensional changes that are associated with tooth extraction. It also provides an overview of the advantages of ridge preservation as well as grafting materials. A Medline search among English language papers was performed in March 2015 using alveolar ridge preservation, ridge augmentation, and various graft types as search terms. Additional papers were considered following the preliminary review of the initial search that were relevant to alveolar ridge preservation. The literature suggests that ridge preservation methods and augmentation techniques are available to minimize and restore available bone. Numerous grafting materials, such as autografts, allografts, xenografts, and alloplasts, currently are used for ridge preservation. Other materials, such as growth factors, also can be used to enhance biologic outcome. PMID:26262646

  14. Broadening the Spectrum of Actin-Based Protrusive Activity Mediated by Arp2/3 Complex-Facilitated Polymerization: Motility of Cytoplasmic Ridges and Tubular Projections

    PubMed Central

    Henson, John H.; Gianakas, Anastasia D.; Henson, Lauren H.; Lakin, Christina L.; Voss, Meagen K.; Bewersdorf, Joerg; Oldenbourg, Rudolf; Morris, Robert L.

    2014-01-01

    Arp2/3 complex-facilitated actin polymerization plays an essential role in a variety of cellular functions including motility, adherence, endocytosis and trafficking. In the present study we employ the sea urchin coelomocyte experimental model system to test the hypotheses that Arp2/3 complex-nucleated actin assembly mediates the motility of two unusual cellular protrusions; the cytoplasmic ridges present during coelomocyte spreading, and inducible, tubular-shaped, and neurite-like projections. Our investigations couple pharmacological manipulation employing inhibitors of actin polymerization and the Arp2/3 complex with a wide array of imaging methods including digitally enhanced phase contrast, DIC and polarization light microscopy of live cells; conventional, confocal and super-resolution light microscopy of fluorescently labeled cells; and scanning and transmission electron microscopy. Taken together, the results of this study indicate that Arp2/3 complex-facilitated actin polymerization underlies the motility of coelomocyte cytoplasmic ridges and tubular projections, that these processes are related to each other, and that they have been preliminarily identified in other cell types. The results also highlight the broad spectrum of actin-based protrusive activities dependent on the Arp2/3 complex and provide additional insights into the pervasive nature of this ubiquitous actin nucleator. Furthermore we provide the first evidence of a possible mechanistic difference between the impacts of the small molecule drugs BDM and CK666 on the Arp2/3 complex. PMID:25111797

  15. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-11-01

    Little is known about fixed nitrogen (N) transformation and elimination at diffuse hydrothermal vents where anoxic fluids are mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N loss pathways (denitrification, anammox) and dissimilatory nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e., temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithoautotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always < 5 nmol N l-1 day-1 and below the detection limit at most of the sites. DNRA rates were up to ~150 nmol N l-1 day-1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlations were found between fixed N loss (i.e., denitrification, anammox) rates and in situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence times, we estimated

  16. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-04-01

    Little is known about nitrogen (N) transformations in general, and the elimination of N in particular, at diffuse vents where anoxic hydrothermal fluids have mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N-loss pathways (denitrification, anammox) and dissimilative nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e. temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N-loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always <5 nmol N l-1 day-1 and below the detection limit at most of the sites. DNRA rates were up to 152 nmol N l-1 day-1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlation existed between fixed N-loss (i.e., denitrification, anammox) rates and in-situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N-loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence

  17. Summary of activities of the life cycle costing workshop conducted by the Environmental Restoration Program of Oak Ridge National Laboratory. Enviromental Restoration Program

    SciTech Connect

    Not Available

    1992-08-01

    A five-day life cycle workshop was conducted by the Environmental Restoration (FR) Program of Oak Ridge National Laboratory (ORNL) to develop appropriate remediation scenarios for each Waste Area Grouping (WAG) at ORNL and to identify associated data needs (e.g., remedial investigations, special studies, and technology demonstrations) and required interfaces. Workshop participants represented the Department of Energy, Martin Marietta Energy Systems, Inc., Bechtel National, Radian Corporation, EBASCO Corporation, and M-K Ferguson. The workshop was used to establish a technical basis for remediation activities at each WAG. The workshop results are documented in this report and provide the baseline for estimating the technical scope for each WAG. The scope and associated budgets and schedules will be summarized in baseline reports for each WAG, which, in turn, will be compiled into an overall strategy document for ORNL ER.

  18. Characterization of Active Hydrothermal Fluid Discharge and Recharge Zones in the Endeavour Axial Valley, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Salmi, M.; Hutnak, M.; Hearn, C.; Tivey, M.; Bjorklund, T.; Johnson, H. P.

    2012-12-01

    Sites where warm hydrothermal fluid vents at mid-ocean spreading centers are important for understanding a wide range of critical oceanic processes, but discharge zones represent a very limited portion of crustal fluid circulation pathways. Mapping the distribution of both fluid recharge and discharge sites within the axial valley provides wider insight into the larger scale features of hydrothermal circulation. Our 2011 survey consisted of 180 conductive heat flow stations within the Endeavour axial valley in roughly a 400 m by 1000 m grid, extending across the entire axial valley from the outer flank of the western boundary ridge to the eastern wall. Data acquisition used thermal blankets which measured conductive heat flow without requiring substantial sediment cover. A surprising result from this survey was zones of high heat flow extending across-strike, from the summit of the west valley wall across the entire axial valley floor. This trend was correlated with anomalously low seafloor magnetization from a near-bottom survey with the ROV JASON. Unexpectedly, over half of the axial valley floor was anomalously low at <50 mW m-2, while a small portion of the sites within the 'warm zone' had heat flow values >1 W m-2. The areas of extremely low heat flow values are interpreted as being directly influenced by recharge zones. Based on MCS estimates of partial melt depth below the axial valley and the assumption of no fluid advection, the purely conductive heat flow for this region should be on the order of 1 W m-2.The observation that conductive heat flux is suppressed over large portions of the axial valley floor suggests that heat transfer within the crustal sub-surface fluid reservoir is widespread, and impacts a large portion of our survey area. The largely bi-modal distribution of high and low conductive heat flow, coupled with geophysical and video observations, suggest current Endeavour axial valley crustal fluid circulation models need to be re-evaluated.

  19. U-series disequilibrium constraints on magma generation at the Jan Mayen hotspot

    NASA Astrophysics Data System (ADS)

    Rivers, E. R.; Chernow, R.; Elkins, L. J.; Sims, K. W.; Blichert-Toft, J.; Devey, C. W.

    2013-12-01

    The incompatible element-enriched magma source beneath the Jan Mayen Island hotspot influences melt generation on the adjacent northern Mid-Atlantic Ridge system and likely derives from either a small, local mantle plume, ancient Icelandic plume material emplaced in the mantle source, and/or sub-continental lithospheric mantle remnants emplaced locally by rifting of Greenland. The slow spreading Northern Kolbeinsey and Southern Mohns Ridges are immediately adjacent to Jan Mayen Island. Both have relatively shallow ridge axes, particularly the extremely shallow Eggvin Bank region of the Northern Kolbeinsey Ridge, which host anomalously large central volcanic edifices. We are currently collecting U-series disequilibrium and long-lived radiogenic isotope data for fresh, glassy mid-ocean ridge basalts from the Northern Kolbeinsey and Southern Mohns Ridge segments to better constrain source composition, depth of melting in the garnet peridotite stability field, solid mantle upwelling rates, and the nature of melt extraction beneath those segments. In particular, we are measuring isotopic data for geographically well-located samples collected from hummocky pillow basalt flows within the axial valley of the Northern Kolbeinsey Ridge segment as well as from the large volcanoes on both ridge segments, to further determine the role of the Jan Mayen hotspot in crustal construction on the Mid-Atlantic Ridge. Recently collected data show particularly high strontium isotope ratios consistent with trace element patterns that suggest a distinct local plume located beneath the Jan Mayen hotspot. A plume model for Jan Mayen is supported by new bathymetric imaging of adjacent ridge segments that reveals excess volcanism beneath the large axial volcanoes and a radial distribution of enrichment surrounding Jan Mayen Island. We predict that age-constrained U-series disequilibrium measurements will support active mantle upwelling focused beneath both Jan Mayen Island and the large axial

  20. Drill core-based facies reconstruction of a deep-marine felsic volcano hosting an active hydrothermal system (Pual Ridge, Papau New Guinea, ODP Leg 193)

    NASA Astrophysics Data System (ADS)

    Paulick, H.; Vanko, D. A.; Yeats, C. J.

    2004-02-01

    Pual Ridge is a deep-marine, felsic volcanic edifice in the eastern Manus back-arc basin (Papua New Guinea) with an estimated volume of ˜6 to 9 km 3. It is 1-1.5 km wide, 20 km long and rises 500-600 m above the surrounding ocean floor. The active PACMANUS hydrothermal field on the crest of Pual Ridge at 1640-1690 m below sea level was the target of Ocean Drilling Program Leg 193. Variably altered dacite lavas have been recovered from the subsurface of a low-T discharge site (Snowcap) and a high-T black smoker site (Roman Ruins) reaching a maximum depth of 380 m below seafloor (mbsf). Volcanic facies interpretation of these cores is difficult due to incomplete recovery and widespread pseudoclastic textures generated by fracturing and multi-phase, incomplete fluid-dacite interaction. However, distinction of genuine volcaniclastic facies and facies with alteration-related clastic appearance is important in order to define paleo-seafloor positions within the volcanic stratigraphy, that may be prospective for massive sulfide mineralization. This has been accomplished using remnant primary characteristics indicative of transportation such as polymictic composition, grading or textural evidence for differential movement of individual clasts. Three phases of volcanic activity can be distinguished and a proximal facies association dominated by coherent facies of dacite lavas exists below Snowcap. At Roman Ruins, a medial facies association consists of lava flows with about equal proportions of coherent and volcaniclastic facies. Endogenous growth was an important process during lava flow emplacement and groundmass textures such as perlite, flow banding and spherulites indicate that cooling rates were variable, locally allowing for high-temperature devitrification. A tube pumice breccia unit is interpreted as the resedimented facies of a quench fragmented, highly vesicular dacite lava carapace. Sulfide accumulations in the subsurface are restricted to Roman Ruins

  1. Quality Assurance Plan for Field Activities at the Natural and Accelerated Bioremediation Research (NABIR) Field Research Center (FRC), Oak Ridge, Tennessee

    SciTech Connect

    Brandt, C.C.

    2002-02-28

    The Environmental Sciences Division (ESD) at Oak Ridge National Laboratory (ORNL) has established a Natural and Accelerated Bioremediation Research (NABIR) program Field Research Center (FRC) for the U.S. Department of Energy (DOE) Office of Biological and Environmental Research. The FRC is located in Bear Creek Valley within the Y-12 Plant area of responsibility on DOE's Oak Ridge Reservation in Tennessee. The NABIR program is a long-term effort designed to increase the understanding of fundamental biogeochemical processes that would allow the use of bioremediation approaches for cleaning up DOE's contaminated legacy waste sites. The FRC provides a site for investigators in the NABIR program to conduct research and obtain samples related to in situ bioremediation. The FRC is integrated with existing and future laboratory and field research and provides a means of examining the biogeochemical processes that influence bioremediation under controlled small-scale field conditions. This Quality Assurance Plan (QAP) documents the quality assurance protocols for field and laboratory activities performed by the FRC staff. It supplements the requirements in the ORNL Nuclear Quality Assurance Program and the ESD Quality Assurance Program. The QAP addresses the requirements in Title 10 CFR, Part 830 Subpart A, ''Quality Assurance Requirements'', using a graded approach appropriate for Research and Development projects based on guidance from ''Implementation Guide for Quality Assurance Programs for Basic and Applied Research'' (DOE-ER-STD-6001-92). It also supports the NABIR FRC Management Plan (Watson and Quarles 2000a) which outlines the overall procedures, roles and responsibilities for conducting research at the FRC. The QAP summarizes the organization, work activities, and qualify assurance and quality control protocols that will be used to generate scientifically defensible data at the FRC. The QAP pertains to field measurements and sample collection conducted by the

  2. Morphology of the Knipovich Ridge Area

    NASA Astrophysics Data System (ADS)

    Zarayskaya, Y.; Abramova, A.; Dobrolyubova, K.; Mazarovich, A.; Moroz, E.

    2014-12-01

    continues from the eastern flange through the second northern axial high to the western flange under the azimuth of 320º. It is an indication of long-term magmatic activity in this segment. Detailed bathymetry reveals small-scale features that are important for our understanding of the ridge nature.

  3. Status of Blue Ridge Reservoir

    SciTech Connect

    Not Available

    1990-09-01

    This is one in a series of reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Blue Ridge Reservoir summarizes reservoir and watershed characteristics, reservoir uses and use impairments, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most current reports and data available, as well as interview with water resource professionals in various federal, state, and local agencies. Blue Ridge Reservoir is a single-purpose hydropower generating project. When consistent with this primary objective, the reservoir is also operated to benefit secondary objectives including water quality, recreation, fish and aquatic habitat, development of shoreline, aesthetic quality, and other public and private uses that support overall regional economic growth and development. 8 refs., 1 fig.

  4. The deep hydrogeologic flow system underlying the Oak Ridge Reservation -- Assessing the potential for active groundwater flow and origin of the brine

    SciTech Connect

    Nativ, R.; Halleran, A.; Hunley, A.

    1997-08-01

    The deep hydrogeologic system underlying the Oak Ridge Reservation (ORR) contains contaminants such as radionuclides, heavy metals, nitrates, and organic compounds. The groundwater in the deep system is saline and has been considered to be stagnant in previous studies. This study was designed to address the following questions: is groundwater in the deep system stagnant; is contaminant migration controlled by diffusion only or is advection a viable mechanism; where are the potential outlet points? On the basis of existing and newly collected data, the nature of saline groundwater flow and potential discharge into shallow, freshwater systems was assessed. Data used for this purpose included (1) spatial and temporal pressures and hydraulic heads measured in the deep system, (2) hydraulic parameters of the formations in question, (3) spatial and temporal temperature variations at depth, and (4) spatial and temporal chemical and isotopic composition of the saline groundwater. The observations suggest that the saline water contained at depth is old but not isolated (in terms of recharge and discharge) from the overlying active, freshwater-bearing units. Influx of recent water does occur. Groundwater volumes involved in this flow are likely to be small. The origin of the saline groundwater was assessed by using existing and newly acquired chemical and isotopic data. The proposed model that best fits the data is modification of residual brine from which halite has been precipitated. Other models, such as ultrafiltration and halite dissolution, were also evaluated.

  5. Upper plate responses to active spreading ridge/transform subduction: The tectonics, basin evolution, and seismicity of the Taita area, Chile Triple Junction

    SciTech Connect

    Flint, S.; Prior, D. ); Styles, P.; Murdie, R. ); Agar, S.; Turner, P. )

    1993-02-01

    Integrated field geophysical, structural and stratigraphic studies are attempting to elucidate the mechanisms and consequences of the Late Miocene-present day subduction of the Chile Ridge triple junction system. Preliminary data indicate a shallow plane of seismicity at about 15 km to 20 km depth below the Taitao peninsula. The depths correspond to the predicted depth range of subducted upper ocean crust. The calculated Bouguer anomaly map cannot be explained by the upper plate geology, suggesting that gravity is influenced by heterogeneities in the subducting oceanic plate. Seismic data imply that a subducted transform system underlying the inner Taitao Peninsula is still an active structure. A series of Middle-Late Tertiary sedimentary basins lie inboard of the triple junction. Within the Cosmelli basin, abrupt marine to continental facies transitions give clear evidence of base level changes. The amount of basinward shift of facies across sequence boundaries gets progressively greater up stratigraphy, indicating progressively greater base level changes. The lower part of the basin fill is folded and then thrusted eastward as a series of imbricates, while the overlying, greater thickness of fluvial sediments are only gently tilted westwards. We provisionally interpret this geometry to indicate that the early basin fill was deforming due to contractional tectonics while the later basin fill was being deposited. This complex basin history may reflect initiation and development of triple junction subduction.

  6. Ridge Regression Signal Processing

    NASA Technical Reports Server (NTRS)

    Kuhl, Mark R.

    1990-01-01

    The introduction of the Global Positioning System (GPS) into the National Airspace System (NAS) necessitates the development of Receiver Autonomous Integrity Monitoring (RAIM) techniques. In order to guarantee a certain level of integrity, a thorough understanding of modern estimation techniques applied to navigational problems is required. The extended Kalman filter (EKF) is derived and analyzed under poor geometry conditions. It was found that the performance of the EKF is difficult to predict, since the EKF is designed for a Gaussian environment. A novel approach is implemented which incorporates ridge regression to explain the behavior of an EKF in the presence of dynamics under poor geometry conditions. The basic principles of ridge regression theory are presented, followed by the derivation of a linearized recursive ridge estimator. Computer simulations are performed to confirm the underlying theory and to provide a comparative analysis of the EKF and the recursive ridge estimator.

  7. PUSCH RIDGE WILDERNESS, ARIZONA.

    USGS Publications Warehouse

    Hinkle, Margaret E.; Ryan, George S.

    1984-01-01

    On the basis of a mineral survey, the Pusch Ridge Wilderness, located at the northern boundary of the city of Tucson, Arizona, offers little or no promise for the occurrence of energy resources. Only one area contains a probable potential for small, isolated contact-metamorphic deposits containing copper, molybdenum, tungsten, lead, and zinc. This area is located around the southwestern end of Pusch Ridge, adjacent to a residential area.

  8. 60 Years of Great Science (Oak Ridge National Laboratory)

    DOE R&D Accomplishments Database

    2003-01-01

    This issue of Oak Ridge National Laboratory Review (vol. 36, issue 1) highlights Oak Ridge National Laboratory's contributions in more than 30 areas of research and related activities during the past 60 years and provides glimpses of current activities that are carrying on this heritage.

  9. Oak Ridge Reservation environmental report for 1989

    SciTech Connect

    Jacobs, V.A.; Wilson, A.R.

    1990-10-01

    This two-volume report, the Oak Ridge Reservation Environmental Report for 1989, is the nineteenth in an annual series that began in 1971. It reports the results of a comprehensive, year-round program to monitor the impact of operations at the three major US Department of Energy (DOE) production and research installations in Oak Ridge on the immediate areas' and surrounding region's groundwater and surface waters, soil, air quality, vegetation and wildlife, and through these multiple and varied pathways, the resident human population. Information is presented for the environmental monitoring Quality Assurance (QA) Program, audits and reviews, waste management activities, land special environmental studies. Data are included for the Oak Ridge Y-12 Plant, Oak Ridge National Laboratory (ORNL), and Oak Ridge Gaseous Diffusion Plant (ORGDP). Volume 1 presents narratives, summaries, and conclusions based on environmental monitoring at the three DOE installations and in the surrounding environs during calendar year (CY) 1989. Volume 1 is intended to be a stand-alone'' report about the Oak Ridge Reservation (ORR) for the reader who does not want an in-depth review of 1989 data. Volume 2 presents the detailed data from which these conclusions have been drawn and should be used in conjunction with Volume 1.

  10. Fingermark ridge drift.

    PubMed

    De Alcaraz-Fossoul, Josep; Roberts, Katherine A; Feixat, Carme Barrot; Hogrebe, Gregory G; Badia, Manel Gené

    2016-01-01

    Distortions of the fingermark topography are usually considered when comparing latent and exemplar fingerprints. These alterations are characterized as caused by an extrinsic action, which affects entire areas of the deposition and alters the overall flow of a series of contiguous ridges. Here we introduce a novel visual phenomenon that does not follow these principles, named fingermark ridge drift. An experiment was designed that included variables such as type of secretion (eccrine and sebaceous), substrate (glass and polystyrene), and degrees of exposure to natural light (darkness, shade, and direct light) indoors. Fingermarks were sequentially visualized with titanium dioxide powder, photographed and analyzed. The comparison between fresh and aged depositions revealed that under certain environmental conditions an individual ridge could randomly change its original position regardless of its unaltered adjacent ridges. The causes of the drift phenomenon are not well understood. We believe it is exclusively associated with intrinsic natural aging processes of latent fingermarks. This discovery will help explain the detection of certain dissimilarities at the minutiae/ridge level; determine more accurate "hits"; identify potentially erroneous corresponding points; and rethink identification protocols, especially the criteria of "no single minutiae discrepancy" for a positive identification. PMID:26646735

  11. 3D modelling of the active normal fault network in the Apulian Ridge (Eastern Mediterranean Sea): Integration of seismic and bathymetric data with implicit surface methods

    NASA Astrophysics Data System (ADS)

    Bistacchi, Andrea; Pellegrini, Caludio; Savini, Alessandra; Marchese, Fabio

    2016-04-01

    The Apulian ridge (North-eastern Ionian Sea, Mediterranean), interposed between the facing Apennines and Hellenides subduction zones (to the west and east respectively), is characterized by thick cretaceous carbonatic sequences and discontinuous tertiary deposits crosscut by a penetrative network of NNW-SSE normal faults. These are exposed onshore in Puglia, and are well represented offshore in a dataset composed of 2D seismics and wells collected by oil companies from the '60s to the '80s, more recent seismics collected during research projects in the '90s, recent very high resolution seismics (VHRS - Sparker and Chirp-sonar data), multibeam echosounder bathymetry, and sedimentological and geo-chronological analyses of sediment samples collected on the seabed. Faults are evident in 2D seismics at all scales, and their along-strike geometry and continuity can be characterized with multibeam bathymetric data, which show continuous fault scarps on the seabed (only partly reworked by currents and covered by landslides). Fault scarps also reveal the finite displacement accumulated in the Holocene-Pleistocene. We reconstructed a 3D model of the fault network and suitable geological boundaries (mainly unconformities due to the discontinuous distribution of quaternary and tertiary sediments) with implicit surface methods implemented in SKUA/GOCAD. This approach can be considered very effective and allowed reconstructing in details complex structures, like the frequent relay zones that are particularly well imaged by seafloor geomorphology. Mutual cross-cutting relationships have been recognized between fault scarps and submarine mass-wasting deposits (Holocene-Pleistocene), indicating that, at least in places, these features are coeval, hence the fault network should be considered active. At the regional scale, the 3D model allowed measuring the horizontal WSW-ENE stretching, which can be associated to the bending moment applied to the Apulian Plate by the combined effect

  12. Ridged Layer Outcrop

    NASA Technical Reports Server (NTRS)

    2004-01-01

    15 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a strange ridged pattern developed in an eroding layer of material on the floor of a Labyrinthus Noctis depression in the Valles Marineris system. The ridges bear some resemblance to ripple-like dunes seen elsewhere on Mars, but they are linked to the erosion of a specific layer of material--i.e., something in the rock record of Mars. Similar ridged textures are found in eroded dark-toned mantling layers in regions as far away as northern Sinus Meridiani and Mawrth Vallis. The explanation for these landforms is as elusive as this image is evocative. The image is located near 8.2oS, 93.6oW, and covers an area 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.

  13. US Department of Energy Oak Ridge Operations Environmental Management Public Involvement Plan for the Oak Ridge Reservation

    SciTech Connect

    1996-03-01

    This document was prepared in accordance with CERCLA requirements for writing community relations plans. It includes information on how the DOE Oak Ridge Operations Office prepares and executes Environmental Management Community relations activities. It is divided into three sections: the public involvement plan, public involvement in Oak Ridge, and public involvement in 1995. Four appendices are also included: environmental management in Oak Ridge; community and regional overview; key laws, agreements, and policy; and principal contacts.

  14. Miocene to Late Quaternary Patagonian basalts (46 47°S): Geochronometric and geochemical evidence for slab tearing due to active spreading ridge subduction

    NASA Astrophysics Data System (ADS)

    Guivel, Christèle; Morata, Diego; Pelleter, Ewan; Espinoza, Felipe; Maury, René C.; Lagabrielle, Yves; Polvé, Mireille; Bellon, Hervé; Cotten, Joseph; Benoit, Mathieu; Suárez, Manuel; de la Cruz, Rita

    2006-01-01

    Miocene to Quaternary large basaltic plateaus occur in the back-arc domain of the Andean chain in Patagonia. They are thought to result from the ascent of subslab asthenospheric magmas through slab windows generated from subducted segments of the South Chile Ridge (SCR). We have investigated three volcanic centres from the Lago General Carrera-Buenos Aires area (46-47°S) located above the inferred position of the slab window corresponding to a segment subducted 6 Ma ago. (1) The Quaternary Río Murta transitional basalts display major, trace elements, and Sr and Nd isotopic features similar to those of oceanic basalts from the SCR and from the Chile Triple Junction near Taitao Peninsula (e.g., ( 87Sr/ 86Sr) o = 0.70396-0.70346 and ɛNd = + 5.5 - + 3.0). We consider them as derived from the melting of a Chile Ridge asthenospheric mantle source containing a weak subduction component. (2) The Plio-Quaternary (< 3.3 Ma) post-plateau basanites from Meseta del Lago Buenos Aires (MLBA), Argentina, likely derive from small degrees of melting of OIB-type mantle sources involving the subslab asthenosphere and the enriched subcontinental lithospheric mantle. (3) The main plateau basaltic volcanism in this region is represented by the 12.4-3.3-Ma-old MLBA basalts and the 8.2-4.4-Ma-old basalts from Meseta Chile Chico (MCC), Chile. Two groups can be distinguished among these main plateau basalts. The first group includes alkali basalts and trachybasalts displaying typical OIB signatures and thought to derive from predominantly asthenospheric mantle sources similar to those of the post-plateau MLBA basalts, but through slightly larger degrees of melting. The second one, although still dominantly alkalic, displays incompatible element signatures intermediate between those of OIB and arc magmas (e.g., La/Nb > 1 and TiO 2 < 2 wt.%). These intermediate basalts differ from their strictly alkalic equivalents by having lower High Field Strength Element (HFSE) and higher ɛNd (up to

  15. Dynamical instability produces transform faults at mid-ocean ridges.

    PubMed

    Gerya, Taras

    2010-08-27

    Transform faults at mid-ocean ridges--one of the most striking, yet enigmatic features of terrestrial plate tectonics--are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps. PMID:20798313

  16. Indian Ocean ridge seismicity observed with a permanent hydroacoustic network

    NASA Astrophysics Data System (ADS)

    Hanson, Jeffrey A.; Bowman, J. Roger

    2005-03-01

    The distribution of earthquakes along the Indian Ocean ridge system between January 18 and October 20, 2003 is investigated using data from two hydrophone stations of the International Monitoring System's global network. Coherent array processing of earthquake-induced hydroacoustic T-waves is used to determine precise arrival times and back azimuths that allow automatic location of the earthquakes. We observed 4725 events throughout the Indian Ocean Basin. Here, we examine 1146 earthquakes from the Central and Southeast Indian Ridge. Source level estimates from the hydroacoustic signals indicate that the hydroacoustic network is at least one magnitude unit more sensitive than the seismic network for Indian Ocean ridge earthquakes. The seismicity primarily clusters at ridge transform offsets. Events are observed off the ridge axis near Boomerang and St. Pierre Seamounts, the active expression of the Amsterdam-St. Paul Hotspot. Seismic gaps are observed at several ridge segments with anomalous bathymetric highs.

  17. Remedial Investigation Work Plan for Chestnut Ridge Operable Unit 1 (Chestnut Ridge Security Pits) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-03-01

    This document outlines the activities necessary to conduct a Remedial Investigation (RI) of the Chestnut Ridge Security Pits (CRSP) at the Oak Ridge Y-12 Plant. The CRSP, also designated Chestnut Ridge Operable Unit (OU) 1, is one of four OUs along Chestnut Ridge on the Oak Ridge Reservation (ORR). The purpose of the RI is to collect data to (1) evaluate the nature and extent of known and suspected contaminants, (2) support an Ecological Risk Assessment (ERA) and a Human Health Risk Assessment (HHRA), (3) support the feasibility study in the development and analysis of remedial alternatives, and (4) ultimately, develop a Record of Decision (ROD) for the site. This chapter summarizes the regulatory background of environmental investigation on the ORR and the approach currently being followed and provides an overview of the RI to be conducted at the CRSP. Subsequent chapters provide details on site history, sampling activities, procedures and methods, quality assurance (QA), health and safety, and waste management related to the RI.

  18. Ridge from strings

    NASA Astrophysics Data System (ADS)

    Braun, M. A.; Pajares, C.; Vechernin, V. V.

    2015-04-01

    In the colour string picture with fusion and percolation it is shown that long-range azimuthal-rapidity correlations (ridge) can arise from the superposition of many events with exchange of clusters of different number of strings and not from a single event. Relation of the ridge with the flow harmonics coefficients is derived. By direct Monte Carlo simulations, in the technique previously used to calculate these coefficients, ridge correlations are calculated for AA, pA and pp collisions. The azimuthal anisotropy follows from the assumed quenching of the emitted particles in the strong colour fields inside string clusters. It is confirmed that in pp collisions the ridge structure only appears in rare events with abnormally high multiplicity. Comparison with the experimental data shows a good agreement. Good agreement is also found for pPb collisions. For AA collisions a reasonable agreement is found for both near-side and away-side angular correlations although it worsens at intermediate angles.

  19. 60 years of great science [Oak Ridge National Laboratory

    SciTech Connect

    2003-01-01

    This issue highlights Oak Ridge National Laboratory's contributions in more than 30 areas of research and related activities during the past 60 years and provides glimpses of current activities that are carrying on this heritage.

  20. Fingerprint Ridge Count: A Polygenic Trait Useful in Classroom Instruction.

    ERIC Educational Resources Information Center

    Mendenhall, Gordon; And Others

    1989-01-01

    Describes the use of the polygenic trait of total fingerprint ridge count in the classroom as a laboratory investigation. Presents information on background of topic, fingerprint patterns which are classified into three major groups, ridge count, the inheritance model, and activities. Includes an example data sheet format for fingerprints. (RT)

  1. Ridges and scarps in the equatorial belt of Mars

    USGS Publications Warehouse

    Lucchitta, B.K.; Klockenbrink, J.L.

    1981-01-01

    The morphology and distribution of ridges and scarps on Mars in the ?? 30?? latitude belt were investigated. Two distinct types of ridges were recognized. The first is long and linear, resembling mare ridges on the Moon; it occurs mostly in plains areas. The other is composed of short, anastomosing segments and occurs mostly in ancient cratered terrain and intervening plateaus. Where ridges are eroded, landscape configurations suggest that they are located along regional structures. The age of ridges is uncertain, but some are as young as the latest documented volcanic activity on Mars. The origins of ridges are probably diverse-they may result from wrinkling due to compression or from buckling due to settling over subsurface structures. The similar morphologic expressions of ridge types of various origins may be related to a similar deformation mechanism caused by two main factors: (1) most ridges are developed in thick layers of competent material and (2) ridges formed under stresses near a free surface. ?? 1981 D. Reidel Publishing Co.

  2. Central Indian Ridge and Reunion Hotspot in Rodrigues Area : Another Type of Ridge - Hotspot Interaction ?

    NASA Astrophysics Data System (ADS)

    DYMENT, J.; HEMOND, C.; GUILLOU, H.; MAIA, M.; BRIAIS, A.; GENTE, P.

    2001-12-01

    The Rodrigues Ridge is an E-W volcanic structure which extends at 19° S from the Mascarene Plateau (59° 30'E) to 100 km East of Rodrigues Island (64° 30'E). It is neither parallel to seafloor spreading flow-lines nor to the "absolute" motion of Africa in the hotspot reference frame. 39Ar-40Ar dating of dredged samples has shown that the whole ridge formed at 8-10 Ma, suggesting a rather rapid emplacement between the former position of the Reunion hotspot and the nearest segment of the CIR at 10-8 Ma. This rules out the hypothesis that the Rodrigues Ridge was progressively built near the CIR axis, at the end of a "channeled" asthenospheric flow originating from Reunion hotspot. Sr, Nd and Pb isotopes show gradual fading of the Reunion hotspot influence with increasing distance from the Mascarene Plateau. Signs for a more recent activity are the Rodrigues Island, dated about 1 Ma, and a set of recently discovered en-echelon volcanic ridges, the Three Magi and Gasitao Ridges. They extend the Rodrigues Ridge up to the CIR axis. These ridges display a clear sigmoid shape and align along an E-W direction at 19° 40'S. Another parallel, less prominent volcanic alignment is observed about 30 km north, at 19° 25'S. K-Ar dating (Cassignol method) provides ages of 0.4 and 1.8 Ma for the easternmost Gasitao Ridge. This second age is slightly younger than that of the underlying crust given by the magnetic anomalies. Isotopic compositions are intermediate between those measured on Rodrigues Ridge and the CIR axis. The lack of conjugate bathymetric feature and the age measured on the Gasitao Ridge demonstrate that it was built off axis, in the close vicinity of the CIR. The sigmoid morphology and en-echelon alignment of Three Magi and Gasitao Ridges suggest that they correspond to tension cracks filled by magmas resulting from decompression melting of underlying mantle. Repetition of such magmatic events results in increasing volume as ridges get older, in agreement with the

  3. Ridge network in crumpled paper.

    PubMed

    Andresen, Christian André; Hansen, Alex; Schmittbuhl, Jean

    2007-08-01

    The network formed by ridges in a straightened sheet of crumpled paper is studied using a laser profilometer. Square sheets of paper were crumpled into balls, unfolded, and their height profile measured. From these profiles the imposed ridges were extracted as networks. Nodes were defined as intersections between ridges, and links as the various ridges connecting the nodes. Many network and spatial properties have been investigated. The tail of the ridge length distribution was found to follow a power law, whereas the shorter ridges followed a log-normal distribution. The degree distribution was found to have an exponentially decaying tail, and the degree correlation was found to be disassortative. The facets created by the ridges and the Voronoi diagram formed by the nodes have also been investigated. PMID:17930105

  4. Ridge regression processing

    NASA Technical Reports Server (NTRS)

    Kuhl, Mark R.

    1990-01-01

    Current navigation requirements depend on a geometric dilution of precision (GDOP) criterion. As long as the GDOP stays below a specific value, navigation requirements are met. The GDOP will exceed the specified value when the measurement geometry becomes too collinear. A new signal processing technique, called Ridge Regression Processing, can reduce the effects of nearly collinear measurement geometry; thereby reducing the inflation of the measurement errors. It is shown that the Ridge signal processor gives a consistently better mean squared error (MSE) in position than the Ordinary Least Mean Squares (OLS) estimator. The applicability of this technique is currently being investigated to improve the following areas: receiver autonomous integrity monitoring (RAIM), coverage requirements, availability requirements, and precision approaches.

  5. Microbial and Mineral Descriptions of the Interior Habitable Zones of Active Hydrothermal Chimneys from the Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Holden, J. F.; Lin, T.; Ver Eecke, H. C.; Breves, E.; Dyar, M. D.; Jamieson, J. W.; Hannington, M. D.; Butterfield, D. A.; Bishop, J. L.; Lane, M. D.

    2013-12-01

    Actively venting hydrothermal chimneys and their associated hydrothermal fluids were collected from the Endeavour Segment, Juan de Fuca Ridge to determine the mineralogy, chemistry and microbial community composition of their interiors. To characterize the mineralogy, Mössbauer, FTIR, VNIR and thermal emission spectroscopies were used for the first time on this type of sample in addition to thin-section petrography, x-ray diffraction and elemental analyses. A chimney from the Bastille edifice was Fe-sulfide rich and composed primarily of chalcopyrite, marcasite-sphalerite, and pyrrhotite while chimneys from the Dante and Hot Harold edifices were Fe-sulfide poor and composed primarily of anhydrite. The bulk emissivity and reflectance spectroscopies corroborated well with the petrography and XRD analyses. The microbial community in the interior of Bastille was most closely related to mesophilic-to-thermophilic anaerobes of the deltaproteobacteria and hyperthermophilic archaea while those in the interiors of Dante and Hot Harold were most closely related to mesophilic-to-thermophilic aerobes of the beta-, gamma- and epsilonproteobacteria. The fluid temperatures (282-321°C) and chemistries of the three chimneys were very similar suggesting that differences in mineralogy and microbial community compositions were more dependent on fluid flow characteristics and paragenesis within the chimney. Thin-section petrography of the interior of another hydrothermal chimney collected from the Dante edifice (emitting 336°C fluid) shows a thin coat of Fe3+ oxide associated with amorphous silica on the exposed outer surfaces of pyrrhotite, sphalerite and chalcopyrite in pore spaces, along with anhydrite precipitation in the pores that is indicative of seawater ingress. The Fe-sulfide minerals were likely oxidized to ferrihydrite with increasing pH and Eh due to cooling and seawater exposure, providing reactants for bioreduction. Culture-based most-probable-number estimates of

  6. Mantle plume capture, anchoring and outflow during ridge interaction

    NASA Astrophysics Data System (ADS)

    Gibson, S. A.; Richards, M. A.; Geist, D.

    2015-12-01

    Geochemical and geophysical studies have shown that >40% of the world's mantle plumes are currently interacting with the global ridge system and such interactions may continue for up to 180 Myr[1]. At sites of plume-ridge interaction up to 1400 km of the spreading centre is influenced by dispersed plume material but there are few constraints on how and where the ridge-ward transfer of deep-sourced material occurs, and also how it is sustained over long time intervals. Galápagos is an archetypal example of an off-axis plume and sheds important light on these mechanisms. The Galápagos plume stem is located ~200 km south of the spreading axis and its head influences 1000 km of the ridge. Nevertheless, the site of enriched basalts, greatest crustal thickness and elevated topography on the ridge, together with active volcanism in the archipelago, correlate with a narrow zone (~150 km) of low-velocity, high-temperature mantle that connects the plume stem and ridge at depths of ~100 km[2]. The enriched ridge basalts contain a greater amount of partially-dehydrated, recycled oceanic crust than basalts elsewhere on the spreading axis, or indeed basalts erupted in the region between the plume stem and ridge. The presence of these relatively volatile-rich ridge basalts requires flow of plume material below the peridotite solidus (i.e.>80 km). We propose a 2-stage model for the development and sustainment of a confined zone of deep ridge-ward plume flow. This involves initial on-axis capture and establishment of a sub-ridge channel of plume flow. Subsequent anchoring of the plume stem to a contact point on the ridge during axis migration results in confined ridge-ward flow of plume material via a deep network of melt channels embedded in the normal spreading and advection of the plume head[2]. Importantly, sub-ridge flow is maintained. The physical parameters and styles of mantle flow we have defined for Galápagos are less-well known at other sites of plume-ridge

  7. Characteristics of Hydrothermal Mineralization in Ultraslow Spreading Ridges

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Yang, Q.; Ji, F.; Dick, H. J.

    2014-12-01

    Hydrothermal activity is a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth's crust and oceans, and a locus for intense biological activity on the seafloor and underlying crust. In other hand, the structure and composition of hydrothermal systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes. Ultraslow spreading ridges, including the Southwest Indian Ridge, the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys in last decades, it is suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining hydrothermal activities. This increased efficiency could attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004). Distinct from in faster spreading ridges, one characteristics of hydrothermal mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag hydrothermal field at 49.6 degree of the Southwest Indian Ridge, is abundant and pervasive distribution of lower temperature precipitated minerals ( such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite etc. ) in hydrothermal fields. Structures formed by lower temperature activities in active and dead hydrothermal fields are also obviously. High temperature precipitated minerals such as chalcopyrite etc. are rare or very limited in hydrothermal chimneys. Distribution of diverse low temperature hydrothermal activities is consistence with the deep heating mechanisms and hydrothermal circulations in the complex background of ultraslow spreading tectonics. Meanwhile, deeper and larger mineralization at certain locations along the

  8. Internal architecture and mobility of tidal sand ridges in the East China Sea

    NASA Astrophysics Data System (ADS)

    Liu, Zhenxia; Berné, Serge; Saito, Yoshiki; Yu, Hua; Trentesaux, Alain; Uehara, Katsuto; Yin, Ping; Paul Liu, J.; Li, Chaoxing; Hu, Guanghai; Wang, Xiangqin

    2007-07-01

    On the basis of bathymetric and seismic data and data from piston cores collected by the Chinese-French marine geology and geophysics investigation of 1996, we discuss the internal architecture and mobility of tidal sand ridges in the East China Sea (ECS). We characterized the sand ridges on the middle to outer shelf of the ECS as tide-dominated sand ridges with southwest dipping beds, indicating that the regional net sediment transport is toward the southwest. As the sand ridges gradually migrate toward the southwest, new sand ridges are continually replacing old ones, and several generations of sand ridges have developed in the study area. High-resolution seismic data, acoustic Doppler current profiler data, and two 14C-dated piston cores, DGKS9614 and DGKS9612—from a sand ridge swale and crest, respectively—show that these sand ridges, which are at water depths of 90-100 m, have been migrating for the last ca. 2-3 kyr at least, though these ridges have previously been interpreted as moribund or relict. Sequence stratigraphic interpretation of seismic profiles and core data show that tidal ridges in the ECS evolved from muddier sand ridges formed during the last transgression to sandier shelf sand ridges in response to the shoreline retreat, which resulted in a decrease of riverine muddy sediments and recycling of sandy materials by tidal currents. Most active sand ridge formation occurred during the last transgression, but the present sand ridges on the middle to outer shelf are still being influenced by the modern hydrodynamics. Therefore, these sand ridges on the ECS shelf should be referred to as "quasi-active sand ridges" rather than as moribund or relict sand ridges.

  9. Divergent Ridge Features on the Juan de Fuca and Gorda Ridges

    NASA Astrophysics Data System (ADS)

    Eaton, M. E.; Sautter, L.; Steele, M.

    2014-12-01

    Multibeam data collected using a Kongsberg EM122 sonar system on the NOAA ship R/V Marcus G. Langseth led by chief scientist Douglas Toomey (University of Oregon) in 2009 and with a Simrad EM302 sonar system on two NOAA ship Okeanos Explorer cruises led by chief scientists James Gardner (University of New Hampshire) and Catalina Martinez (University of Rhode Island) in 2009 show the morphology of the Juan de Fuca and Gorda Ridges, as well as the Blanco and Mendocino Fracture Zones. These ridges and fracture zones comprise the divergent plate boundary of the eastern edge of the Pacific Plate and the western edges of the Juan de Fuca and Gorda Plates. Both plates are being subducted beneath the western edge of the North American Plate. CARIS HIPS 8.1 software was used to process the multibeam data and create bathymetric images. The ridge axes, located off the coast of Washington and Oregon (USA) adjacent to the Cascadia Basin, indicate obvious signs of spreading, due to the series of faults and rocky ridges aligned parallel to the plate boundaries. Fault and ridge orientations are used to compare the direction of seafloor spreading, and indicate that both the Juan de Fuca Plate and Gorda Plate are spreading in a southeastern direction. Younger ridges from the Gorda Ridge system mapped in the study run parallel to the boundary, however older ridges do not show the same orientation, indicating a change in spreading direction. The presence of hydrothermal vents along the Juan de Fuca Ridge is also evidence of the active boundary, as the vent chimneys are composed of minerals and metals precipitated from the hot water heated by magma from beneath the spreading seafloor. In this study, the data are used to compare and contrast earthquake seismicity and ridge morphologies at a depth range of approximately 762 to 2134 meters. The diverging Pacific, Juan de Fuca, and Gorda Plates along with the San Andreas Fault have potential to increase seismic and volcanic activity around

  10. Seismic Structure of the Endeavour Segment, Juan de Fuca Ridge: Correlations of Crustal Magma Chamber Properties With Seismicity, Faulting, and Hydrothermal Activity

    NASA Astrophysics Data System (ADS)

    van Ark, E. M.; Detrick, R. S.; Canales, J. P.; Carbotte, S. M.; Diebold, J. B.; Harding, A.; Kent, G.; Nedimovic, M. R.; Wilcock, W. S.

    2003-12-01

    Multichannel seismic reflection data collected in July 2002 at the RIDGE2000 Integrated Studies Site at the Endeavour segment, Juan de Fuca Ridge show a high-amplitude, mid-crustal reflector underlying all of the known hydrothermal vent fields at this segment. This reflector, which has been identified with a crustal magma body [Detrick et al., 2002], is found at a two-way travel time of 0.85-1.5 s (1.9-4.0 km) below the seafloor and extends approximately 25 km along axis although it is only 1-2 km wide on the cross-axis lines. The reflector is shallowest (2.5 km depth on the along-axis line) beneath the central, elevated part of the Endeavour segment and deepens toward the segment ends, with a maximum depth of 4 km. The cross axis lines show the mid-crustal reflector dipping from 9 to 50? to the east with the shallowest depths under the ridge axis and greater depths under the eastern flank of the ridge. The amplitude-offset behavior of this mid-crustal axial reflector is consistent with a negative impedance contrast, indicating the presence of melt or a crystallizing mush. We have constructed partial offset stacks at 2-3 km offset to examine the variation of melt-mush content of the axial magma chamber along axis. We see a decrease in P-wave amplitudes with increasing offset for the mid-crustal reflector beneath the Mothra and Main Endeavour vent fields and between the Salty Dawg and Sasquatch vent fields, indicating the presence of a melt-rich body. Beneath the High Rise, Salty Dawg, and Sasquatch vent fields P-wave amplitudes vary little with offset suggesting the presence of a more mush-rich magma chamber. Hypocenters of well-located microseismicity in this region [Wilcock et al., 2002] have been projected onto the along-axis and cross-axis seismic lines, revealing that most axial earthquakes are concentrated in a depth range of 1.5 - 2.7 km, just above the axial magma chamber. In general, seismicity is distributed diffusely within this zone indicating thermal

  11. Chemical signatures from hydrothermal venting on slow spreading ridges

    NASA Astrophysics Data System (ADS)

    Edmonds, Henrietta N.

    At least 24 sites of active venting have been confirmed on slow and ultraslow spreading ridges, with dozens more indicated on the basis of hydrothermal plume distributions and/or dredge recovery of massive sulfides. Fluid chemistry data have been published for 13 sites: 8 on the northern Mid-Atlantic Ridge, 3 on the southern Mid-Atlantic Ridge, and 2 on the Central Indian Ridge. Three of these 13 sites (Rainbow, Logatchev, and Lost City) are known to be hosted in ultramafic terrain, and their fluid chemistries reflect the influence of serpentinization reactions, including elevated hydrogen and methane, and low silica concentrations. This brief review presents the published fluid chemistry for all 13 sites, including time series where available, and demonstrates the diversity of chemical compositions engendered by the myriad settings (near and off axis, young volcanic to ultramafic terrain, and depths up to 4100 m) of hydrothermal systems on slow and ultraslow spreading ridges.

  12. Oak Ridge National Laboratory Waste Management Plan

    SciTech Connect

    Not Available

    1992-12-01

    The objective of the Oak Ridge National Laboratory Waste Management Plan is to compile and to consolidate information annually on how the ORNL Waste Management Program is conducted, which waste management facilities are being used to manage wastes, what forces are acting to change current waste management systems, what activities are planned for the forthcoming fiscal year (FY), and how all of the activities are documented.

  13. Hydroforming Applications at Oak Ridge

    SciTech Connect

    bird, e.l.; ludtka, g.m.

    1999-03-10

    Hydroforming technology is a robust forming process that produces components with high precision and complexity. The goal of this paper is to present a brief description of the sheet hydroforming process with respect to the authors' experience and capabilities. Following the authors' discussion of the sheet-metal forming application, the tubular hydroforming process is described in the context of one of our technology development programs with an automotive industrial partner. After that is a summary of the tubular hydroforming advisor (expert system) development activity, which was a significant part of this overall program based on previous experience in developing a design and manufacturing support hydroforming advisor for the Oak Ridge Y-12 Plant's weapons-component manufacturing needs. Therefore, this paper is divided into three sections: (1) Hydroforming of Stainless Steel Parts, (2) Tubular Hydroforming, and (3) Components of a Tubular Hydroforming Advisor.

  14. Ridge-trench collision in Archean and Post-Archean crustal growth: Evidence from southern Chile

    NASA Technical Reports Server (NTRS)

    Nelson, E. P.; Forsythe, R. D.

    1988-01-01

    The growth of continental crust at convergent plate margins involves both continuous and episodic processes. Ridge-trench collision is one episodic process that can cause significant magmatic and tectonic effects on convergent plate margins. Because the sites of ridge collision (ridge-trench triple junctions) generally migrate along convergent plate boundaries, the effects of ridge collision will be highly diachronous in Andean-type orogenic belts and may not be adequately recognized in the geologic record. The Chile margin triple junction (CMTJ, 46 deg S), where the actively spreading Chile rise is colliding with the sediment-filled Peru-Chile trench, is geometrically and kinematically the simplest modern example of ridge collision. The south Chile margin illustrates the importance of the ridge-collision tectonic setting in crustal evolution at convergent margins. Similarities between ridge-collision features in southern Chile and features of Archean greenstone belts raise the question of the importance of ridge collision in Archean crustal growth. Archean plate tectonic processes were probably different than today; these differences may have affected the nature and importance of ridge collision during Archean crustal growth. In conclusion, it is suggested that smaller plates, greater ridge length, and/or faster spreading all point to the likelihood that ridge collision played a greater role in crustal growth and development of the greenstone-granite terranes during the Archean. However, the effects of modern ridge collision, and the processes involved, are not well enough known to develop specific models for the Archean ridge collison.

  15. Oak Ridge Health Studies Phase 1 report, Volume 2: Part A, Dose Reconstruction Feasibility Study. Tasks 1 and 2, A summary of historical activities on the Oak Ridge Reservation with emphasis on information concerning off-site emissions of hazardous materials

    SciTech Connect

    Bruce, G.M.; Buddenbaum, J.E.; Lamb, J.K.; Widner, T.E.

    1993-09-01

    The Phase I feasibility study has focused on determining the availability of information for estimating exposures of the public to chemicals and radionuclides released as a result of historical operation of the facilities at the Oak Ridge Reservation (ORR). The estimation of such past exposures is frequently called dose reconstruction. The initial project tasks, Tasks 1 and 2 were designed to identify and collect information that documents the history of activities at the ORR that resulted in the release of contamination and to characterize the availability of data that could be used to estimate the magnitude of the contaminant releases or public exposures. A history of operations that are likely to have generated off-site releases has been documented as a result of Task 1 activities. The activities required to perform this task involved the extensive review of historical operation records and interviews with present and past employees as well as other knowledgeable individuals. The investigation process is documented in this report. The Task 1 investigations have led to the documentation of an overview of the activities that have taken place at each of the major complexes, including routine operations, waste management practices, special projects, and accidents and incidents. Historical activities that appear to warrant the highest priority in any further investigations were identified based on their likely association with off-site emissions of hazardous materials as indicated by the documentation reviewed or information obtained in interviews.

  16. Subduction of the South-Chile active spreading ridge: a 17 Ma to 3 Ma magmatic record in central Patagonia (western edge of Meseta del Lago Buenos Aires, Argentina)

    NASA Astrophysics Data System (ADS)

    Boutonnet, Emmanuelle; Arnaud, Nicolas; Guivel, Christèle; Lagabrielle, Yves; Scalabrino, Bruno; Espinoza, Felipe

    2010-05-01

    The Chile Triple Junction is a natural laboratory to study the interactions between magmatism and tectonics during the subduction of an active spreading ridge beneath a continent. The MLBA plateau (Meseta del Lago Buenos Aires) is one of the Neogene alkali basaltic plateaus located in the back-arc region of the Andean Cordillera at the latitude of the current Chile Triple Junction. The genesis of MLBA can be related with successive opening of slabs windows beneath Patagonia: within the subducting Nazca Plate itself and between the Nazca and Antarctic plates. Detailed 40Ar/39Ar dating and geochemical analysis of bimodal magmatism from the western flank of the MLBA show major changes in the back-arc magmatism which occurred between 14.5 Ma and 12.5 Ma with the transition from calc-alkaline lavas (Cerro Plomo) to alkaline lavas (MLBA) in relation with slab window opening. In a second step, at 4- 3 Ma, alkaline felsic intrusions were emplaced in the western flank of the MLBA coevally with the MLBA basalts with which they are genetically related. These late OIB-like alkaline to transitional basalts were generated by partial melting of the subslab asthenosphere of the subducting Nazca plate during the opening of the South Chile spreading ridge-related slab window. These basalts differentiated with small amounts of assimilation in shallow magma chambers emplaced along transtensional to extensional zones. The close association of bimodal magmatism with extensional tectonic features in the western MLBA is a strong support to the model of Patagonian collapse event proposed to have taken place between 5 and 3 Ma as a consequence of the presence of the asthenospheric window (SCR-1 segment of South Chile Ridge) below the MLBA area.

  17. Contextual view of Point Bonita Ridge, showing Bonita Ridge access ...

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

    Contextual view of Point Bonita Ridge, showing Bonita Ridge access road retaining wall and location of Signal Corps Radar (S.C.R.) 296 Station 5 Transmitter Building foundation (see stake at center left), camera facing north - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  18. Remedial Investigation Work Plan for Chestnut Ridge Operable Unit 1 (Chestnut Ridge Security Pits) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-09-01

    This Remedial Investigation (RI) Work Plan specifically addresses Chestnut Ridge Operable Unit 1, (OU1) which consists of the Chestnut Ridge Security Pits (CRSP). The CRSP are located {approximately}800 ft southeast of the central portion of the Y-12 Plant atop Chestnut Ridge, which is bounded to the northwest by Bear Creek Valley and to the southeast by Bethel Valley. Operated from 1973 to 1988, the CRSP consisted of a series of trenches used for the disposal of classified hazardous and nonhazardous waste materials. Disposal of hazardous waste materials was discontinued in December 1984, while nonhazardous waste disposal ended on November 8, 1988. An RI is being conducted at this site in response to CERCLA regulations. The overall objectives of the RI are to collect data necessary to evaluate the nature and extent of contaminants of concern (COC), support an ecological risk assessment (ERA) and a human health risk assessment (HHRA), support the evaluation of remedial alternatives, and ultimately develop a Record of Decision for the site. The purpose of this Work Plan is to outline RI activities necessary to define the nature and extent of suspected contaminants at Chestnut Ridge OU1. Potential migration pathways also will be investigated. Data collected during the RI will be used to evaluate the overall risk posed to human health and the environment by OU1.

  19. Wrinkle Ridges and Young Fresh Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    's the excitement of science, as the scientific hypotheses and debates continue. Geologists have narrowed down the possibilities to two likely candidates. On the one hand, a volcano could have sent thick streams of lava out that later hardened to form the ridges. On the other, a crushing tectonic force could have pushed the land together, causing it to fault and fold upward. Whichever theory is true, we do know the planet has been subjected to some tremendously active geologic shaping in its past. Don't miss the nearly perfect crater near the bottom of the image. Its sharp crater rim tells us that it is probably pretty young as craters go, because erosion hasn't dulled its edges. Bright material also seems to form a dusty, hazy halo around it. That's all of the material that was blasted out of the crater and sprinkled back down around it in an 'ejecta blanket.' Seeing it so clearly, seemingly untouched by erosion, also indicates the crater's relative youth.

  20. Revisiting the Ridge-Push Force Using the Lithospheric Geoid

    NASA Astrophysics Data System (ADS)

    Richardson, R. M.; Coblentz, D. D.

    2014-12-01

    energy required through filtering of the geoid. We evaluate the role of revised ridge push forces with plate-scale stress models. Our revised estimate of the ridge push force based on the lithospheric geoid, and corresponding stress models, further emphasizes the "active" rather than "passive" nature of the plates themselves in plate tectonics.

  1. Structural Responses to the Chile Ridge Subduction, Southern South America

    NASA Astrophysics Data System (ADS)

    Rodriguez, E. E.; Russo, R. M.; Mocanu, V. I.; Gallego, A.; Murdie, R.; Comte, D.

    2015-12-01

    The Nazca-Antarctic plate boundary, the Chile spreading ridge, subducts beneath South America, forming the northward-migrating Chile Triple Junction (CTJ), now at ~46.5°S, where an actively spreading segment is currently in the Nazca trench. Ridge subduction is associated with diachronously developed variable structure and magmatism of overriding South America. To assess the effects of ridge subduction, we deployed a network of 39 broadband seismometers in southern Chile between 43 - 49°S and 71 - 76°W from Dec. 2004 - Feb. 2007, recording 102 earthquakes suitable for receiver function analyses, i.e., M > 5.9, of various backazimuths, and at epicentral distances of 30 - 90°. The network encompassed onland portions of the current triple junction and ridge subduction, areas to the south of the CTJ where ridge segments subducted during the last 6 m.y., and regions north of the CTJ not yet affected by ridge subduction, allowing the assessment of the effects of ridge subduction on crustal structure of overriding South America. We constructed 551 teleseismic receiver functions to estimate crustal thicknesses, H, and average compressional to shear wave velocity ratios, Vp/Vs = k, using the iterative time deconvolution method of Ligorria and Ammon (1999). H and k were calculated using the grid search method of Zhu and Kanamori (2000). Beneath stations closest to the trench, where the Nazca plate subducts, we found Moho depths between 28 and 55 km, thickening northward. At the locus of current ridge subduction, in the Taitao Pennisula, thinner crust ranges from 27 - 36 km. H is 36-38 km where the Antarctic plate subducts and the Chile ridge recently subducted. The direct effect of the subducting ridge on South America can be seen in H differences between forearc regions that have sustained ridge subduction versus those that have not. South American forearc crust above the subducted Nazca plate is as much as 28 km thicker than forearc crust recently affected by ridge

  2. Complexities in rift initiation and development within the Iceland Plateau, North-Atlantic.

    NASA Astrophysics Data System (ADS)

    Brandsdóttir, Bryndís; Hooft, Emilie; Mjelde, Rolf; Murai, Yoshio

    2015-04-01

    Spreading north of Iceland has been complex since the break-up of the North Atlantic in late Paleocene-early Eocene. Magnetic anomalies within the Iceland Plateau, west of the Ægir Ridge and along the Greenland-Iceland-Faeroe Ridge are irregular, formed by plate boundary complexities at breakup, branched accretion zones, westward rifting relocations, and large overlapping rifts. The 700 km long KRISE7 seismic refraction/reflection and gravity profile, straddles 66.5°N, between the Kolbeinsey and Ægir Ridges, crossing the three physiographic provinces that characterize this region: the Iceland Shelf, Iceland Plateau and Norway Basin. On the basis of crustal thickness and velocity structure, combined with older seismic reflection profiles and drill cores, these provinces correspond to three individual spreading rifts that were active at different time periods. The deep, fan shaped Norway basin was formed during the initial opening of the Atlantic by spreading at the now extinct Ægir Ridge. The oldest crust in the western Norway Basin has thickness 8-10 km and this thins to 4-5 km at the Ægir Ridge reflecting the progressive abandonment of spreading at this rift axis. The eastern Iceland Plateau was the locus of an extinct spreading center, which was segmented and overlapped the Ægir Ridge by 300 km. Spreading on the Iceland Plateau rift occurred simultaneously with that on the Ægir Ridge prior to 26 Ma, when the Kolbeinsey Ridge was initiated by a westward rift jump. The Iceland Plateau rift formed by rifting along the continent-ocean transition at the former central E-Greenland margin, associated with the formation of the Jan Mayen Ridge. Lower crustal domes and corresponding gravity highs across the Iceland Plateau mark the location of the extinct rift axis. The crust at the Iceland Plateau rift is thicker (12-15 km) that that at the conjugate Ægir Ridge and formed under active upwelling conditions (normal lower crustal velocities), which we attribute to

  3. Periodic bedrock ridges on Mars

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.; Bandfield, Joshua L.; Becker, Scott K.

    2012-03-01

    Evidence for sediment transport and erosion by wind is widespread over the surface of Mars today and was likely a major geomorphic process for much of its geological past. Although Martian surface features resembling aeolian dunes and ripples have been recognized since the Mariner and Viking missions, such features have been interpreted previously as active, indurated, or exhumed sedimentary forms. Here we report evidence based on High Resolution Imaging Science Experiment images that show some megaripple forms are eroded into cohesive substrate rather than being composed of loose granular material or fossilized dunes. Exposure of stratigraphic continuity within layered, cohesive material extending crest to trough through features with mean wavelengths of 18 to 51 m demonstrates the primarily erosional formation of what we term periodic bedrock ridges (PBRs). Hence some surfaces on Mars previously considered to be covered by wind-deposited material are actually wind-carved exposures that offer windows into Martian history. PBRs lack the distinctive streamlining associated with wind-parallel yardangs and comparison of PBR orientation to yardangs, megayardangs, and active sedimentary dunes in the same vicinity confirm that these PBRs formed transverse to prevailing winds. Observed wavelengths of PBRs are comparable to those predicted by a simple model for erosional wavelengths of periodic transverse bed forms owing to the spacing of flow separations within the flow. Recognition of these transverse aeolian erosional forms brings up the question of how widespread Martian PBRs are and how many have been misinterpreted as active or indurated (fossilized) sedimentary dunes.

  4. Effect of ridge-ridge interactions in crumpled thin sheets

    NASA Astrophysics Data System (ADS)

    Liou, Shiuan-Fan; Lo, Chun-Chao; Chou, Ming-Han; Hsiao, Pai-Yi; Hong, Tzay-Ming

    2014-02-01

    We study whether and how the energy scaling based on the single-ridge approximation is revised in an actual crumpled sheet, namely, in the presence of ridge-ridge interactions. Molecular dynamics simulation is employed for this purpose. In order to improve the data quality, modifications are introduced to the common protocol. As crumpling proceeds, we find that the average storing energy changes from being proportional to one-third of the ridge length to a linear relation, while the ratio of bending and stretching energies decreases from 5 to 2. The discrepancy between previous simulations and experiments on the material-dependence for the power-law exponent is resolved. We further determine the average ridge length to scale as 1/D1/3, the ridge number as D2/3, and the average storing energy per unit ridge length as D0.881 where D denotes the volume density of the crumpled ball. These results are accompanied by experimental proofs and are consistent with mean-field predictions. Finally, we extend the existent simulations to the high-pressure region and verify the existence of a scaling relation that is more general than the familiar power law at covering the whole density range.

  5. The Oak Ridge Reservation Annual Site Environmental Report Summary, 2007

    SciTech Connect

    None, None

    2009-02-28

    The Oak Ridge Reservation Annual Site Environmental Report is prepared and published each year to inform the public of the environmental activities that take place on the reservation and in the surrounding areas. It is written to comply with DOE Order 231.1A, Environment, Safety, and Health Reporting. This document has been prepared to present the highlights of the Oak Ridge Reservation Annual Site Environmental Report 2007 in an easy-to-read, summary format.

  6. Ridge 2000 Data Management System

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.; Carbotte, S. M.; Arko, R. A.; Haxby, W. F.; Ryan, W. B.; Chayes, D. N.; Lehnert, K. A.; Shank, T. M.

    2005-12-01

    Hosted at Lamont by the marine geoscience Data Management group, mgDMS, the NSF-funded Ridge 2000 electronic database, http://www.marine-geo.org/ridge2000/, is a key component of the Ridge 2000 multi-disciplinary program. The database covers each of the three Ridge 2000 Integrated Study Sites: Endeavour Segment, Lau Basin, and 8-11N Segment. It promotes the sharing of information to the broader community, facilitates integration of the suite of information collected at each study site, and enables comparisons between sites. The Ridge 2000 data system provides easy web access to a relational database that is built around a catalogue of cruise metadata. Any web browser can be used to perform a versatile text-based search which returns basic cruise and submersible dive information, sample and data inventories, navigation, and other relevant metadata such as shipboard personnel and links to NSF program awards. In addition, non-proprietary data files, images, and derived products which are hosted locally or in national repositories, as well as science and technical reports, can be freely downloaded. On the Ridge 2000 database page, our Data Link allows users to search the database using a broad range of parameters including data type, cruise ID, chief scientist, geographical location. The first Ridge 2000 field programs sailed in 2004 and, in addition to numerous data sets collected prior to the Ridge 2000 program, the database currently contains information on fifteen Ridge 2000-funded cruises and almost sixty Alvin dives. Track lines can be viewed using a recently- implemented Web Map Service button labelled Map View. The Ridge 2000 database is fully integrated with databases hosted by the mgDMS group for MARGINS and the Antarctic multibeam and seismic reflection data initiatives. Links are provided to partner databases including PetDB, SIOExplorer, and the ODP Janus system. Improved inter-operability with existing and new partner repositories continues to be

  7. Ocean Ridges and Oxygen

    NASA Astrophysics Data System (ADS)

    Langmuir, C. H.

    2014-12-01

    The history of oxygen and the fluxes and feedbacks that lead to its evolution through time remain poorly constrained. It is not clear whether oxygen has had discrete steady state levels at different times in Earth's history, or whether oxygen evolution is more progressive, with trigger points that lead to discrete changes in markers such as mass independent sulfur isotopes. Whatever this history may have been, ocean ridges play an important and poorly recognized part in the overall mass balance of oxidants and reductants that contribute to electron mass balance and the oxygen budget. One example is the current steady state O2 in the atmosphere. The carbon isotope data suggest that the fraction of carbon has increased in the Phanerozoic, and CO2 outgassing followed by organic matter burial should continually supply more O2 to the surface reservoirs. Why is O2 not then increasing? A traditional answer to this question would relate to variations in the fraction of burial of organic matter, but this fraction appears to have been relatively high throughout the Phanerozoic. Furthermore, subduction of carbon in the 1/5 organic/carbonate proportions would contribute further to an increasingly oxidized surface. What is needed is a flux of oxidized material out of the system. One solution would be a modern oxidized flux to the mantle. The current outgassing flux of CO2 is ~3.4*1012 moles per year. If 20% of that becomes stored organic carbon, that is a flux of .68*1012 moles per year of reduced carbon. The current flux of oxidized iron in subducting ocean crust is ~2*1012 moles per year of O2 equivalents, based on the Fe3+/Fe2+ ratios in old ocean crust compared to fresh basalts at the ridge axis. This flux more than accounts for the incremental oxidizing power produced by modern life. It also suggests a possible feedback through oxygenation of the ocean. A reduced deep ocean would inhibit oxidation of ocean crust, in which case there would be no subduction flux of oxidized

  8. Dielectric ridge waveguide gas laser apparatus

    SciTech Connect

    DeMaria, A.J.; Bridges, W.

    1989-03-14

    A dielectric ridged waveguide flowing gas laser apparatus is described, comprising in combination; a dielectric substrate having a predetermined number of the grooves formed theron, the grooves extending along the longitudinal axis of the dielectric substrate, an electrically conductive member in parallel alignment with the grooved side of the dielectric substrate such that an air gasp is formed therebetween the air gap containing an active laser gas medium, electrically conductive strips disposed on the outside of the dielectric substrate forming electrodes, the conductive strips being aligned with the grooves and having the same length and width as the grooves, and an excitation source connected between the conductive member and the conductive strips, to provide lasing in the ridged waveguide.

  9. Discovery of New Hydrothermal Activity and Chemosynthetic Fauna on the Central Indian Ridge at 18°–20°S

    PubMed Central

    Nakamura, Kentaro; Watanabe, Hiromi; Miyazaki, Junichi; Takai, Ken; Kawagucci, Shinsuke; Noguchi, Takuro; Nemoto, Suguru; Watsuji, Tomo-o; Matsuzaki, Takuya; Shibuya, Takazo; Okamura, Kei; Mochizuki, Masashi; Orihashi, Yuji; Ura, Tamaki; Asada, Akira; Marie, Daniel; Koonjul, Meera; Singh, Manvendra; Beedessee, Girish; Bhikajee, Mitrasen; Tamaki, Kensaku

    2012-01-01

    Indian Ocean hydrothermal vents are believed to represent a novel biogeographic province, and are host to many novel genera and families of animals, potentially indigenous to Indian Ocean hydrothermal systems. In particular, since its discovery in 2001, much attention has been paid to a so-called ‘scaly-foot’ gastropod because of its unique iron-sulfide-coated dermal sclerites and the chemosynthetic symbioses in its various tissues. Despite increasing interest in the faunal assemblages at Indian Ocean hydrothermal vents, only two hydrothermal vent fields have been investigated in the Indian Ocean. Here we report two newly discovered hydrothermal vent fields, the Dodo and Solitaire fields, which are located in the Central Indian Ridge (CIR) segments 16 and 15, respectively. Chemosynthetic faunal communities at the Dodo field are emaciated in size and composition. In contrast, at the Solitaire field, we observed faunal communities that potentially contained almost all genera found at CIR hydrothermal environments to date, and even identified previously unreported taxa. Moreover, a new morphotype of ‘scaly-foot’ gastropod has been found at the Solitaire field. The newly discovered ‘scaly-foot’ gastropod has similar morphological and anatomical features to the previously reported type that inhabits the Kairei field, and both types of ‘scaly-foot’ gastropods genetically belong to the same species according to analyses of their COI gene and nuclear SSU rRNA gene sequences. However, the new morphotype completely lacks an iron-sulfide coating on the sclerites, which had been believed to be a novel feature restricted to ‘scaly-foot’ gastropods. Our new findings at the two newly discovered hydrothermal vent sites provide important insights into the biodiversity and biogeography of vent-endemic ecosystems in the Indian Ocean. PMID:22431990

  10. The Mid-Ocean Ridge.

    ERIC Educational Resources Information Center

    Macdonald, Kenneth C.; Fox, Paul J.

    1990-01-01

    Described are concepts involved with the formation and actions of the Mid-Ocean Ridge. Sea-floor spreading, the magma supply model, discontinuities, off-axis structures, overlaps and deviation, and aquatic life are discussed. (CW)

  11. Radioisotope production and management at Oak Ridge National Laboratory

    SciTech Connect

    Collins, E.D.; Aaron, W.S.; Alexander, C.W.; Bigelow, J.E.; Parks, J.T.; Tracy, J.G.; Wham, R.M.

    1994-09-01

    The production of radioisotopes has been one of the basic activities at Oak Ridge since the end of World War II. The importance of this work was best described by Alvin Weinberg, former Laboratory Director, when he wrote ``... If God has a golden book and writes down what it is that Oak Ridge National Laboratory did that had the biggest influence on science, I would guess that was the production and distribution of isotopes.`` Radioisotopes production continues to be an important aspect of Oak Ridge programs today and of those planned for the future. Past activities, current projects, and future plans and potentials will be described briefly in this paper. Also, some of the major issues facing the continued production of radioisotopes will be described. The scope of the program has always been primarily that of process development, followed by special batch-type productions, where no other supply exists. The technology developed has been available for adoption by US commercial corporations, and in cases where this has occurred, Oak Ridge has withdrawn as a supplier of the particular isotopes involved. One method of production that will not be described is that of target bombardment with an accelerator. This method was used at Oak Ridge prior to 1978 in the 86-inch Cyclotron. However, this method has not been used at Oak Ridge since then for radioisotope production, except as a research tool.

  12. SRTM Anaglyph: Wheeler Ridge, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Wheeler Ridge and vicinity, California, is a site of major tectonic activity, both historically and over recent geologic time. The epicenter of the 7.5 magnitude Kern County earthquake occurred here on July 21,1952, and numerous geologic and topographic features indicate rapid geologic processes. The ridge itself (upper-right center) is a geologic fold that is growing out of the southern San Joaquin Valley. A prominent 'wind gap,' now used for passage of the California aquaduct (with the aid of a pumping station), is evidence that the ridge grew faster than tranversing streams could erode down. Nearby abrupt and/or landslid mountain fronts similarly indicate a vigorous tectonic setting here, just north of the San Andreas fault. The Interstate 5 freeway can be seen crossing agricultural fields on the right and entering the very rugged and steep Grapevine Canyon toward the bottom.

    This anaglyph was generated by first draping a Landsat satellite image over a preliminary topographic map from the Shuttle Radar Topography Mission (SRTM), then generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30 meter resolution of most Landsat images and will substantially help in analyses of the large and growing Landsat image archive.

    The elevation data used in this image was acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect

  13. Mineralogical and geochemical evidence for hydrothermal activity at the west wall of 12°50′N core complex (Mid-Atlantic ridge): a new ultramafic-hosted seafloor hydrothermal deposit?

    USGS Publications Warehouse

    Dekov, Vesselin; Boycheva, Tanya; Halenius, Ulf; Billstrom, Kjell; Kamenov, George D.; Shanks, Wayne C.; Stummeyer, Jens

    2011-01-01

    Dredging along the west wall of the core complex at 12°50′N Mid-Atlantic Ridge sampled a number of black oxyhydroxide crusts and breccias cemented by black and dark brown oxyhydroxide matrix. Black crusts found on top of basalt clasts (rubble) are mainly composed of Mn-oxides (birnessite, 10-Å manganates) with thin films of nontronite and X-ray amorphous FeOOH on their surfaces. Their chemical composition (low trace- and rare earth-element contents, high Li and Ag concentrations, rare earth element distribution patterns with negative both Ce and Eu anomalies), Sr–Nd–Pb-isotope systematic and O-isotope data suggest low-temperature (~ 20 °C) hydrothermal deposition from a diffuse vent area on the seafloor. Mineralogical, petrographic and geochemical investigations of the breccias showed the rock clasts were hydrothermally altered fragments of MORBs. Despite the substantial mineralogical changes caused by the alteration the Sr–Nd–Pb-isotope ratios have not been significantly affected by this process. The basalt clasts are cemented by dark brown and black matrix. Dark brown cement exhibits geochemical features (very low trace- and rare earth- element contents, high U concentration, rare earth element distribution pattern with high positive Eu anomaly) and Nd–Pb-isotope systematics (similar to that of MORB) suggesting that the precursor was a primary, high-temperature Fe-sulfide, which was eventually altered to goethite at ambient seawater conditions. The data presented in this work points towards the possible existence of high- and low-temperature hydrothermal activity at the west wall of the core complex at 12°50′N Mid-Atlantic Ridge. Tectonic setting at the site implies that the proposed hydrothermal field is possibly ultramafic-hosted.

  14. The Jasper Ridge elevated CO{sub 2} experiment: Root acid phosphatase activity in Bromus hordeaceus and Avena barbata remains unchanged under elevated [CO{sub 2}

    SciTech Connect

    Cardon, Z.G.; Jackson, R.

    1995-06-01

    Root acid phosphatase activity increases phosphate available to plants by cleaving phosphate esters in soil organic matter. Because of increased plant growth potential under elevated [CO{sub 2}], we hypothesized that high [CO{sub 2}]-grown plants might exhibit higher phosphatase activity than low [CO{sub 2}]-grown plants. We assayed phosphatase activity in two species grown on two substrates (Bromus on serpentine soil and Bromus and Avena on sandstone soil) under high and low [CO{sub 2}] and under several nutrient treatments. Phosphatase activity was expressed per gram fresh weight of roots. Phosphatase activity of Bromus roots (on sandstone) was first assayed in treatments where only P and K, or only N, were added to soil. Bromus roots in this case showed strong induction of phosphatase activity when N only had been added to soil, indicating that Bromus regulated its phosphatase activity in response to phosphate availability. Both Bromus and Avena growing in sandstone, and Bromus growing in serpentine, showed enhanced phosphatase activity at high nutrient (N, P, and K) levels over that at low nutrient levels, but no differences between phosphatase activity were apparent between [CO{sub 2}] treatments. The increased phosphatase activity at high N, P, and K may indicate enhanced {open_quotes}growth demand{close_quotes} (reflected in higher biomass) in both Avena and Bromus. In contrast, though Bromus {open_quotes}growth demand{close_quotes} (biomass) increased under high [CO{sub 2}] on sandstone, phosphatase activity did not increase.

  15. The Galapagos Spreading Center. Galapagos Rifts Expedition--Grades 9-12. Mid-Ocean Ridges.

    ERIC Educational Resources Information Center

    National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

    This activity introduces students to the basic concept of seafloor spreading, the processes involved in creating new seafloor at a mid- ocean ridge, the Galapagos Spreading Center system, and the different types of plate motion associated with ridge segments and transform faults. The activity provides learning objectives, a list of needed…

  16. Geological perspectives of metalliferous sulfides: offshore exploration in the Gorda Ridge area

    SciTech Connect

    Beauchamp, R.G.

    1984-05-01

    The Gorda Ridge is a submarine mountain range located between 86 nautical miles (160km) and 178 nautical miles (330km) off the coasts of northern California and Oregon. Preliminary results from recent investigations of samples from the Ridge suggest both low and high temperature hydrothermal activity. Sea Marc II (Sea Mapping and Remote Characterization) maps of the Gorda Ridge assist in the identification of the central rift valley, seamounts, continuous and discontinuous ridges, and ridge offsets. Volcanic samples dredged from the Gorda Ridge contain traces of sulfide minerals (e.g., pyrite, pyrrhotite, and sphalerite). Fresh volcanic glass occurred in most of the dredge samples. Other samples showed evidence of hydrothermal activity including the occurrence of geothite and nontronite. Manganese minerals todorokite and birnessite occur as encrustations over basalt. Abundant worm tubes were found in association with nontronite. Agglutinated benthic foramifera, some with tests constructed of volcanic glass, are abundant and found in a majority of dredge hauls.

  17. Carpenter Ridge Tuff, CO

    NASA Astrophysics Data System (ADS)

    Bachmann, Olivier; Deering, Chad D.; Lipman, Peter W.; Plummer, Charles

    2014-06-01

    The ~1,000 km3 Carpenter Ridge Tuff (CRT), erupted at 27.55 Ma during the mid-tertiary ignimbrite flare-up in the western USA, is among the largest known strongly zoned ash-flow tuffs. It consists primarily of densely welded crystal-poor rhyolite with a pronounced, highly evolved chemical signature (high Rb/Sr, low Ba, Zr, Eu), but thickly ponded intracaldera CRT is capped by a more crystal-rich, less silicic facies. In the outflow ignimbrite, this upper zone is defined mainly by densely welded crystal-rich juvenile clasts of trachydacite composition, with higher Fe-Ti oxide temperatures, and is characterized by extremely high Ba (to 7,500 ppm), Zr, Sr, and positive Eu anomalies. Rare mafic clasts (51-53 wt% SiO2) with Ba contents to 4,000-5,000 ppm and positive Eu anomalies are also present. Much of the major and trace-element variations in the CRT juvenile clasts can be reproduced via in situ differentiation by interstitial melt extraction from a crystal-rich, upper-crustal mush zone, with the trachydacite, crystal-rich clasts representing the remobilized crystal cumulate left behind by the melt extraction process. Late recharge events, represented by the rare mafic clasts and high-Al amphiboles in some samples, mixed in with parts of the crystal cumulate and generated additional scatter in the whole-rock data. Recharge was important in thermally remobilizing the silicic crystal cumulate by partially melting the near-solidus phases, as supported by: (1) ubiquitous wormy/sieve textures and reverse zoning patterns in feldspars and biotites, (2) absence of quartz in this very silicic unit stored at depths of >4-5 km, and (3) heterogeneous melt compositions in the trachydacite fiamme and mafic clasts, particularly in Ba, indicating local enrichment of this element due mostly to sanidine and biotite melting. The injection of hot, juvenile magma into the upper-crustal cumulate also imparted the observed thermal gradient to the deposits and the mixing overprint that

  18. Ultraslow spreading processes along the Arctic mid-ocean ridge system

    NASA Astrophysics Data System (ADS)

    Schlindwein, Vera

    2013-04-01

    Generation of new seafloor in the Arctic Ocean occurs along the more than 2800 km long Arctic Ridge System from the Knipovich Ridge in the south to Gakkel ridge in the northeast. The plates separate at velocities of only 6-15 mm/y making the Arctic Ridge System the most prominent representative of an ultraslow spreading mid-ocean ridge. The engine of crustal production splutters at very low spreading rates such that ultraslow spreading ridges show a unique morphology: Isolated volcanoes, capable of vigorous eruptions, pierce the seafloor at distances of several hundred kilometres; in between there are long stretches without volcanism. My work group studies at global, regional and local scale the spreading processes of the Arctic ridge system, using earthquake records of ocean bottom seismometers, seismometers on drifting ice floes and of the global seismic network. We discovered that, contrary to faster spreading ridges, amagmatic portions of the Arctic ridge system are characterised by decreased seismicity rates with few and relatively weak earthquakes, whereas magmatically robust segments display more frequent seismic events. The maximum depth of earthquake hypocentres varies markedly along axis reaching maxima of 22 km depth below sea floor. Volcanic centres are characterized by vigorous earthquake swarm activity including large earthquake swarms that are recorded teleseismically. These earthquake swarms appear to be connected to episodes of active spreading as demonstrated at the 85°E volcanic complex at eastern Gakkel ridge which experienced an unusual spreading event between 1999 and 2001. The varying patterns of seismicity along the ridge axis correlate well with the pronounced differences in ridge morphology and petrology and its magnetic and gravimetric signatures. Our results support current theories of magma production at ultraslow spreading ridges which postulate a lateral melt flow towards isolated volcanic centres.

  19. Wrinkle ridge assemblages on the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Watters, Thomas R.

    1988-01-01

    The morphological and dimensional similarities of the structures within the wrinkle ridge assemblages observed on terrestrial planets are investigated, including structures that occur in mare basalts on the moon and in smooth plains on Mars and Mercury. These structures can be classified as either arches or ridges on the basis of morphology, and ridges can be subdivided onto first-, second-, and third-order ridges on the basis of dimensions. Using ridge structures on the Columbia Plateau (U.S.) as analogs, a basis for a structural interpretation of the wrinkle ridge assemblages on the terrestrial planets is established. It is shown that the anticlinal ridges of the Columbia Plateau are appropriate analogs to the first-order ridges, supporting tectonic interpretations for the ridges.

  20. Calendar year 1996 annual groundwater monitoring report for the Chestnut Ridge Hydrogeologic Regime at the U.S. Department of Energy Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1997-02-01

    This annual monitoring report contains groundwater and surface water monitoring data obtained in the Chestnut Ridge Hydrogeologic Regime (Chestnut Ridge Regime) during calendar year (CY) 1996. The Chestnut Ridge Regime encompasses a section of Chestnut Ridge west of Scarboro Road and east of an unnamed drainage feature southwest of the US Department of Energy (DOE) Oak Ridge Y-12 Plant (unless otherwise noted, directions are in reference to the Y-12 Plant administrative grid). The Chestnut Ridge Regime contains several sites used for management of hazardous and nonhazardous wastes associated with plant operations. Groundwater and surface water quality monitoring associated with these waste management sites is performed under the auspices of the Y-12 Plant Groundwater Protection Program (GWPP). Included in this annual monitoring report are the groundwater monitoring data obtained in compliance with the Resource Conservation and Recovery Act (RCRA) Post-Closure Permit for the Chestnut Ridge Regime (post-closure permit) issued by the Tennessee Department of Environment and Conservation (TDEC) in June 1996. Besides the signed certification statement and the RCRA facility information summarized below, condition II.C.6 of the post-closure permit requires annual reporting of groundwater monitoring activities, inclusive of the analytical data and results of applicable data evaluations, performed at three RCRA hazardous waste treatment, storage, or disposal (TSD) units: the Chestnut Ridge Sediment Disposal Basin (Sediment Disposal Basin), the Chestnut Ridge Security Pits (Security Pits), and Kerr Hollow Quarry.

  1. PROPAGATION AND LINKAGE OF OCEANIC RIDGE SEGMENTS.

    USGS Publications Warehouse

    Pollard, David D.; Aydin, Atilla

    1984-01-01

    An investigation was made of spreading ridges and the development of structures that link ridge segments using an analogy between ridges and cracks in elastic plates. The ridge-propagation force and a path factor that controls propagation direction were calculated for echelon ridge segments propagating toward each other. The ridge-propagation force increases as ridge ends approach but then declines sharply as the ends pass, so ridge segments may overlap somewhat. The sign of the path factor changes as ridge ends approach and pass, so the overlapping ridge ends may diverge and then converge following a hook-shaped path. The magnitudes of shear stresses in the plane of the plate and orientations of maximum shear planes between adjacent ridge segments were calculated to study transform faulting. For different loading conditions simulating ridge push, plate pull, and ridge suction, a zone of intense mechanical interaction between adjacent ridge ends in which stresses are concentrated was identified. The magnitudes of mean stresses in the plane of the plate and orientations of principal stress planes were also calculated.

  2. Comparison of Ridges on Triton and Europa

    NASA Technical Reports Server (NTRS)

    Prockter, L. M.; Pappalardo, R. .

    2003-01-01

    Triton and Europa each display a variety of ridges and associated troughs. The resemblance of double ridges on these two satellites has been previously noted [R. Kirk, pers. comm.], but as yet, the similarities and differences between these feature types have not been examined in any detail. Triton s ridges, and Europa s, exhibit an evolutionary sequence ranging from isolated troughs, through doublet ridges, to complex ridge swaths [1, 2]. Comparison of ridges on Europa to those on Triton may provide insight into their formation on both satellites, and thereby have implications for the satellites' histories.

  3. Training and Technology. Report of Program Activities January 1--June 30, 1973. Conducted at the U.S. Atomic Energy Commissions Oak Ridge Y-12 Plant. Summary Report.

    ERIC Educational Resources Information Center

    Oak Ridge Associated Universities, TN. Manpower Development Div.

    The report is a description of the program activities carried on by Training and Technology (TAT) during the first six months of 1973. In the general category of manpower research and development, brief but detailed descriptions are given of each of the projects conducted in the development and extension of the TAT training model in Albuquerque,…

  4. Evidence for Thin Oceanic Crust on the Extinct Aegir Ridge, Norwegian Basin, N.E. Atlantic Derived from Satellite Gravity Inversion

    NASA Astrophysics Data System (ADS)

    Greenhalgh, E. E.; Kusznir, N. J.

    2006-12-01

    Satellite gravity inversion incorporating a lithosphere thermal gravity correction has been used to map crustal thickness and lithosphere thinning factor for the N.E. Atlantic. The inversion of gravity data to determine crustal thickness incorporates a lithosphere thermal gravity anomaly correction for both oceanic and continental margin lithosphere. Predicted crustal thicknesses in the Norwegian Basin are between 7 and 4 km on the extinct Aegir oceanic ridge which ceased sea-floor spreading in the Oligocene. Crustal thickness estimates do not include a correction for sediment thickness and are upper bounds. Crustal thicknesses determined by gravity inversion for the Aegir Ridge are consistent with recent estimates derived using refraction seismology by Breivik et al. (2006). Failure to incorporate a lithosphere thermal gravity anomaly correction produces an over-estimate of crustal thickness. Oceanic crustal thicknesses within the Norwegian Basin are predicted by the gravity inversion to increase to 9-10 km eastwards towards the Norwegian (Moere) and westwards towards the Jan Mayen micro-continent, consistent with volcanic margin continental breakup at the end of the Palaeocene. The observation (from gravity inversion and seismic refraction studies) of thin oceanic crust produced by the Aegir ocean ridge in the Oligocene has implications for the temporal evolution of asthenosphere temperature under the N.E. Atlantic during the Tertiary. Thin Oligocene oceanic crust may imply cool (normal) asthenosphere temperatures during the Oligocene in contrast to elevated asthenosphere temperatures in the Palaeocene and Miocene-Recent as indicated by volcanic margin formation and the formation of Iceland respectively. Gravity inversion also predicts a region of thin oceanic crust to the west of the northern part of the Jan Mayen micro-continent and to the east of the thicker oceanic crust currently being formed at the Kolbeinsey Ridge. Thicker crust (c.f. ocean basins) is

  5. Where are the undiscovered hydrothermal vents on oceanic spreading ridges?

    NASA Astrophysics Data System (ADS)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.

    2015-11-01

    In nearly four decades since the discovery of deep-sea vents, one-third of the length of global oceanic spreading ridges has been surveyed for hydrothermal activity. Active submarine vent fields are now known along the boundaries of 46 out of 52 recognized tectonic plates. Hydrothermal survey efforts over the most recent decade were sparked by national and commercial interests in the mineral resource potential of seafloor hydrothermal deposits, as well as by academic research. Here we incorporate recent data for back-arc spreading centers and ultraslow- and slow-spreading mid-ocean ridges (MORs) to revise a linear equation relating the frequency of vent fields along oceanic spreading ridges to spreading rate. We apply this equation globally to predict a total number of vent fields on spreading ridges, which suggests that ~900 vent fields remain to be discovered. Almost half of these undiscovered vent fields (comparable to the total of all vent fields discovered during 35 years of research) are likely to occur at MORs with full spreading rates less than 60 mm/yr. We then apply the equation regionally to predict where these hydrothermal vents may be discovered with respect to plate boundaries and national jurisdiction, with the majority expected to occur outside of states' exclusive economic zones. We hope that these predictions will prove useful to the community in the future, in helping to shape continuing ridge-crest exploration.

  6. Source document for waste area groupings at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Osborne, P.L.; Kuhaida, A.J., Jr.

    1996-09-01

    This document serves as a source document for Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and other types of documents developed for and pertaining to Environmental Restoration (ER) Program activities at Oak Ridge National Laboratory (ORNL). It contains descriptions of the (1) regulatory requirements for the ORR ER Program, (2) Oak Ridge Reservation (ORR) ER Program, (3) ORNL site history and characterization, and (4) history and characterization of Waste Area Groupings (WAGS) 1-20. This document was created to save time, effort, and money for persons and organizations drafting documents for the ER Program and to improve consistency in the documents prepared for the program. By eliminating the repetitious use of selected information about the program, this document will help reduce the time and costs associated with producing program documents. By serving as a benchmark for selected information about the ER Program, this reference will help ensure that information presented in future documents is accurate and complete.

  7. A distinct and active bacterial community in cold oxygenated fluids circulating beneath the western flank of the Mid-Atlantic ridge.

    PubMed

    Meyer, Julie L; Jaekel, Ulrike; Tully, Benjamin J; Glazer, Brian T; Wheat, C Geoffrey; Lin, Huei-Ting; Hsieh, Chih-Chiang; Cowen, James P; Hulme, Samuel M; Girguis, Peter R; Huber, Julie A

    2016-01-01

    The rock-hosted, oceanic crustal aquifer is one of the largest ecosystems on Earth, yet little is known about its indigenous microorganisms. Here we provide the first phylogenetic and functional description of an active microbial community residing in the cold oxic crustal aquifer. Using subseafloor observatories, we recovered crustal fluids and found that the geochemical composition is similar to bottom seawater, as are cell abundances. However, based on relative abundances and functional potential of key bacterial groups, the crustal fluid microbial community is heterogeneous and markedly distinct from seawater. Potential rates of autotrophy and heterotrophy in the crust exceeded those of seawater, especially at elevated temperatures (25 °C) and deeper in the crust. Together, these results reveal an active, distinct, and diverse bacterial community engaged in both heterotrophy and autotrophy in the oxygenated crustal aquifer, providing key insight into the role of microbial communities in the ubiquitous cold dark subseafloor biosphere. PMID:26935537

  8. Surveillance and maintenance activities of waste area groupings at Oak Ridge National Laboratory. Annual summary report for period ending September 30, 1991: Environmental Restoration Program

    SciTech Connect

    Ford, M.K.; Holder, L. Jr.; Jones, R.G.

    1991-12-01

    Surveillance and maintenance (S & M) of 75 sites were conductd by the Remedial Action Section for the Environmental Restoration Program for surplus facilities and sites contaminated with radioactive materials and/or hazardous chemicals. S & M activities on these sites were conducted from the end of their operating life until final facility disposal or site stabilization. The objectives of the Waste Area Grouping S & M Program are met by maintaining a program of routine S & M as well as by implementing interim corrective maintenance when deemed necessary as a result of site surveillance. This report briefly presents this program`s activities and includes tables indicating tank levels and dry well data for FY 1991.

  9. A distinct and active bacterial community in cold oxygenated fluids circulating beneath the western flank of the Mid-Atlantic ridge

    PubMed Central

    Meyer, Julie L.; Jaekel, Ulrike; Tully, Benjamin J.; Glazer, Brian T.; Wheat, C. Geoffrey; Lin, Huei-Ting; Hsieh, Chih-Chiang; Cowen, James P.; Hulme, Samuel M.; Girguis, Peter R.; Huber, Julie A.

    2016-01-01

    The rock-hosted, oceanic crustal aquifer is one of the largest ecosystems on Earth, yet little is known about its indigenous microorganisms. Here we provide the first phylogenetic and functional description of an active microbial community residing in the cold oxic crustal aquifer. Using subseafloor observatories, we recovered crustal fluids and found that the geochemical composition is similar to bottom seawater, as are cell abundances. However, based on relative abundances and functional potential of key bacterial groups, the crustal fluid microbial community is heterogeneous and markedly distinct from seawater. Potential rates of autotrophy and heterotrophy in the crust exceeded those of seawater, especially at elevated temperatures (25 °C) and deeper in the crust. Together, these results reveal an active, distinct, and diverse bacterial community engaged in both heterotrophy and autotrophy in the oxygenated crustal aquifer, providing key insight into the role of microbial communities in the ubiquitous cold dark subseafloor biosphere. PMID:26935537

  10. A distinct and active bacterial community in cold oxygenated fluids circulating beneath the western flank of the Mid-Atlantic ridge

    NASA Astrophysics Data System (ADS)

    Meyer, Julie L.; Jaekel, Ulrike; Tully, Benjamin J.; Glazer, Brian T.; Wheat, C. Geoffrey; Lin, Huei-Ting; Hsieh, Chih-Chiang; Cowen, James P.; Hulme, Samuel M.; Girguis, Peter R.; Huber, Julie A.

    2016-03-01

    The rock-hosted, oceanic crustal aquifer is one of the largest ecosystems on Earth, yet little is known about its indigenous microorganisms. Here we provide the first phylogenetic and functional description of an active microbial community residing in the cold oxic crustal aquifer. Using subseafloor observatories, we recovered crustal fluids and found that the geochemical composition is similar to bottom seawater, as are cell abundances. However, based on relative abundances and functional potential of key bacterial groups, the crustal fluid microbial community is heterogeneous and markedly distinct from seawater. Potential rates of autotrophy and heterotrophy in the crust exceeded those of seawater, especially at elevated temperatures (25 °C) and deeper in the crust. Together, these results reveal an active, distinct, and diverse bacterial community engaged in both heterotrophy and autotrophy in the oxygenated crustal aquifer, providing key insight into the role of microbial communities in the ubiquitous cold dark subseafloor biosphere.

  11. Sinkholes, collapse structures and large landslides in an active salt dome submerged by a reservoir: The unique case of the Ambal ridge in the Karun River, Zagros Mountains, Iran

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Francisco; Lizaga, Iván

    2016-02-01

    Ambal ridge, covering 4 km2, is a salt pillow of Gachsaran Formation with significant salt exposures in direct contact with the Karun River, Zagros Mountains. The highly cavernous salt dome is currently being flooded by the Gotvand Reservoir, second largest in Iran. Geomorphic evidence, including the sharp deflection of the Karun River and defeated streams indicate that Ambal is an active halokinetic structure, probably driven by erosional unloading. Around 30% of the salt dome is affected by large landslides up to ca. 50 × 106 m3 in volume. Slope oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor. A total of 693 sinkholes have been inventoried (170 sinkholes/km2), for which a scaling relationship has been produced. The depressions occur preferentially along a belt with a high degree of clustering. This spatial distribution is controlled by the proximity to the river, slope gradient and halite content in the bedrock. A large compound depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by water table rise forming a lake. The impoundment of the reservoir has induced peculiar collapse structures 220-280 m across, expressed by systems of arcuate fissures and scarps. Rapid subsurface salt dissolution is expected to generate and reactivate a large number of sinkholes and may reactivate landslides with a significant vertical component due to lack of basal support.

  12. The Ridge, the Glasma and Flow

    SciTech Connect

    McLerran,L.

    2008-09-15

    I discuss the ridge phenomena observed in heavy ion collisions at RHIC. I argue that the ridge may be due to flux tubes formed from the Color Glass Condensate in the early Glasma phase of matter produced in such collisions.

  13. Ridge Regression for Interactive Models.

    ERIC Educational Resources Information Center

    Tate, Richard L.

    1988-01-01

    An exploratory study of the value of ridge regression for interactive models is reported. Assuming that the linear terms in a simple interactive model are centered to eliminate non-essential multicollinearity, a variety of common models, representing both ordinal and disordinal interactions, are shown to have "orientations" that are favorable to…

  14. Oak Ridge callibration recall program

    SciTech Connect

    Falter, K.G.; Wright, W.E.; Pritchard, E.W.

    1996-12-31

    A development effort was initiated within the Oak Ridge metrology community to address the need for a more versatile and user friendly tracking database that could be used across the Oak Ridge complex. This database, which became known as the Oak Ridge Calibration Recall Program (ORCRP), needed to be diverse enough for use by all three Oak Ridge facilities, as well as the seven calibration organizations that support them. Various practical functions drove the initial design of the program: (1) accessible by any user at any site through a multi-user interface, (2) real-time database that was able to automatically generate e-mail notices of due and overdue measuring and test equipment, (3) large memory storage capacity, and (4) extremely fast data access times. In addition, the program needed to generate reports on items such as instrument turnaround time, workload projections, and laboratory efficiency. Finally, the program should allow the calibration intervals to be modified, based on historical data. The developed program meets all of the stated requirements and is accessible over a network of computers running Microsoft Windows software.

  15. Ridge filter design for a particle therapy line

    NASA Astrophysics Data System (ADS)

    Kim, Chang Hyeuk; Han, Garam; Lee, Hwa-Ryun; Kim, Hyunyong; Jang, Hong Suk; Kim, Jeong Hwan; Park, Dong Wook; Jang, Sea Duk; Hwang, Won Taek; Kim, Geun-Beom; Yang, Tae-Keun

    2014-05-01

    The beam irradiation system for particle therapy can use a passive or an active beam irradiation method. In the case of an active beam irradiation, using a ridge filter would be appropriate to generate a spread-out Bragg peak (SOBP) through a large scanning area. For this study, a ridge filter was designed as an energy modulation device for a prototype active scanning system at MC-50 in Korea Institute of Radiological And Medical Science (KIRAMS). The ridge filter was designed to create a 10 mm of SOBP for a 45-MeV proton beam. To reduce the distal penumbra and the initial dose, [DM] determined the weighting factor for Bragg Peak by applying an in-house iteration code and the Minuit Fit package of Root. A single ridge bar shape and its corresponding thickness were obtained through 21 weighting factors. Also, a ridge filter was fabricated to cover a large scanning area (300 × 300 mm2) by Polymethyl Methacrylate (PMMA). The fabricated ridge filter was tested at the prototype active beamline of MC-50. The SOBP and the incident beam distribution were obtained by using HD-810 GaF chromatic film placed at a right triangle to the PMMA block. The depth dose profile for the SOBP can be obtained precisely by using the flat field correction and measuring the 2-dimensional distribution of the incoming beam. After the flat field correction is used, the experimental results show that the SOBP region matches with design requirement well, with 0.62% uniformity.

  16. Hot spot-ridge crest convergence in the northeast Pacific

    SciTech Connect

    Karsten, J.L.; Delaney, J.R. )

    1989-01-10

    Evolution of the Juan de Fuca Ridge during the past 7 m.y. has been reconstructed taking into account both the propagating rift history and migration of the spreading center in the 'absolute' (fixed hot spot) reference frame. Northwestward migration of the spreading center (at a rate of 30 km/m.y.) has resulted in progressive encroachment of the ridge axis on the Cobb Hot Spot and westward jumping of the central third of the ridge axis more recently than 0.5 Ma. Seamounts in the Cobb-Eickelberg chain are predicted to display systematic variations in morphology and petrology, and a reduction in the age contrast between the edifice and underlying crust, as a result of the ridge axis approach. Relative seamount volumes also indicate that magmatic output of the hot spot varied during this interval, with a reduction in activity between 2.5 and 4.5 Ma, compared with relatively more robust activity before and after this period. Spatial relationships determined in this reconstruction allow hypotheses relating hot spot activity and rift propagation to be evaluated. In most cases, rift propagation has been directed away from the hot spot during the time period considered. Individual propagators show some reduction in propagation rate as separation between the propagating rift tip and hot spot increases, but cross comparison of multiple propagators does not uniformly display the same relationship. No obvious correlation exists between propagation rate and increasing proximity of the hot spot to the ridge axis or increasing hot spot output. Taken together, these observations do not offer compelling support for the concept of hot spot driven rift propagation. However, short-term reversals in propagation direction at the Cobb Offset coincide with activity of the Heckle melting anomaly, suggesting that local propagation effects may be related to excess magma supply at the ridge axis.

  17. Mosaic of Europa's Ridges, Craters

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This view of the icy surface of Jupiter's moon, Europa, is a mosaic of two pictures taken by the Solid State Imaging system on board the Galileo spacecraft during a close flyby of Europa on February 20, 1997. The pictures were taken from a distance of 2,000 kilometers (1,240 miles). The area shown is about 14 kilometers by 17 kilometers (8.7 miles by 10.6 miles), and has a resolution of 20 meters (22 yards) per pixel. Illumination is from the right (east). The picture is centered at about 14.8 north latitude, 273.8 west longitude, in Europa's trailing hemisphere.

    One of the youngest features seen in this area is the double ridge cutting across the picture from the lower left to the upper right. This double ridge is about 2.6 kilometers (1.6 miles) wide and stands some 300 meters (330 yards) high. Small craters are most easily seen in the smooth deposits along the south margin of the prominent double ridge, and in the rugged ridged terrain farther south. The complexly ridged terrain seen here shows that parts of the icy crust of Europa have been modified by intense faulting and disruption, driven by energy from the planet's interior.

    The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at: http://galileo.jpl.nasa.gov.

  18. Alkalic Basalt in Ridge Axis of 53˚E Amagmatic Segment Center, Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Wang, J.; Liu, Y.; Ji, F.; Dick, H. J.

    2014-12-01

    Mid-ocean ridge basalt (MORB) is key tracer of composition and process in the mantle. It is interesting to notice that some alkalic basalts occur in amagmatic spreading center of ultraslow spreading ridges, for examples, 9-16˚E of the Southwest Indian ridge (Standish et al., 2008) and Lena Trough of Arctic Ocean (Snow et al., 2011). The latter is interpreted as the result of the pre-existence of continental transform fault or the especially cold thermal structure of ancient continental lithosphere. 53˚E segment, east of the Gallieni transform fault, was discovered as an amagmatic segment (Zhou and Dick, 2013). On both sides of the ridge axis, peridotites with a little gabbro are exposed in an area more than 3200 km2. Basalts exist in the southern portion of 53˚E segment, indicating the transformation from magmatic to amagmatic spreading about 9.4 million years ago. In April of 2014, Leg 4 of the RV Dayang Yihao cruise 30, basaltic glasses was dredged at one location (3500 m water depth) in the ridge axis of 53˚E segment center. It is shown by electric probe analysis that the samples have extremely high sodium content (4.0-4.49 wt% Na­2O ), relative higher potassium content (0.27-0.32 wt% K2O) and silica (50.67-51.87 wt% SiO2), and lower MgO content (5.9-6.4 wt% MgO). Mg-number is 0.55-0.59. It is distinctly different from the N-MORB (2.42-2.68 wt% Na2O, 0.03-0.06 wt% K2O, 48.6-49.6 wt% Si2O, 8.8-9.0 wt% MgO, Mg-numbers 0.63) distributed in the 560-km-long supersegment, west of the Gallieni transform fault, where the active Dragon Flag hydrothermal field was discovered at 49.6˚E in 2007. The reasons for the alkalic basalt in the ridge axis of 53˚E amagmatic segment center, either by low melting degree of garnet stability field, by melting from an ancient subcontinental lithospheric mantle, or by sodium-metasomatism or even other mantle processes or their combination in the deep mantle, are under further studies.

  19. Central Appalachian Valley and Ridge Province Cenozoic igneous activity and its relation in space and time with the Late Jurassic rift-to-drift-related alkalic dikes

    NASA Astrophysics Data System (ADS)

    Meyer, R.; Schultz, L.; Hendriks, B. W.; Harbor, D. J.; Connors, C. D.

    2011-12-01

    A Swarm of Late Jurassic alkalic intrusions, geographically limited mainly to the Augusta County in western Virginia has been studied geochemically. These dykes were emplaced along a northwest-southeast cross-strike basement fracture zone during Mesozoic extension. However, not all igneous rocks in Virginia are Jurassic; published K-Ar ages already suggested an Eocene age activity around Monterey, VA. We systematically sampled and studied these rocks geochemically and used the Ar-Ar dating technique to define a more precise age for this youngest volcanic activity East of the Mississippi. The younger igneous bodies have traditionally been interpreted as intrusive bodies representing old plumbing systems of eroded volcanic centers. This hypothesis is based on studies of aphanitic to porphyritic and occasionally vesicular hard rocks from quarries and road cuts. Pyroclastic deposits have mainly been neglected during theses earlier studies. However additional petrographic studies of volcanic sediments are able to shed light not only on the volcanic nature of these pyroclastic rocks but also on eruption mechanisms and magma crust interactions. Our petrographic studies indicate that these volcanic sediments contain different clasts of igneous and sedimentary country rocks (sandstones and limestones of different formations), fresh glass shards and crystals of predominantly pyroxene, hornblende and micas. A previously unmapped, massive, m-thick andesitic pyroclastic deposit has been studied in detail to shed light on the formation of theses volcanic sediments. Field relations and observations (e.g. denser rock fragments are enriched in the lower part of the sequence and bedding is largely parallel to the present topography) are consistent with a massive welded ignimbrite. As a result, surface erosion after the eruption must be less significant than previously believed and some rocks are clearly volcanic in nature. Petrogenetically the Jurassic magmas are much more alkalic

  20. Central Appalachian Valley and Ridge Province Cenozoic igneous activity and their relation in space and time with the Late Jurassic rift to drift related alkalic dikes.

    NASA Astrophysics Data System (ADS)

    Meyer, R.; Schultz, L.; Hendriks, B. W. H.; Harbor, D.; van Wijk, J.; Connors, C.

    2012-04-01

    A Swarm of Late Jurassic alkalic intrusions and geographically limited mainly to the Augusta County in western Virginia has been studied geochemically. These dykes were emplaced along a northwest-southeast cross-strike basement fracture zone during Mesozoic extension. However, not all igneous rocks in Virginia are Jurassic; published K-Ar ages already suggested an Eocene age activity around Monterey, VA (e.g. Fullagar & Bottino 1969). We first systematically sampled and studied these rocks geochemically and used the Ar-Ar dating technique to define a more precise age (around 48Ma) for this youngest volcanic activity East of the Mississippi. The younger igneous bodies have traditionally been interpreted as intrusive bodies representing old plumbing systems of eroded volcanic centers. This hypothesis is based on studies of aphanitic to porphyritic and occasionally vesicular hard rocks from quarries and road cuts. Pyroclastic deposits have mainly been neglected during theses earlier studies. However additional petrographic studies of volcanic sediments are able to shed light not only on the volcanic nature of these pyroclastic rocks but also on eruption mechanisms and magma crust interactions. Our petrographic studies defined that these volcanic sediments contain different clasts of igneous and sedimentary country rocks (sandstones and limestones of different formations), fresh glass shards and crystals of predominantly pyroxene, hornblende and micas. A previously unmapped, massive, m-thick andesitic pyroclastic deposit has been studied in detail to shed light on the formation of theses volcanic sediments. Field relations and observations (e.g.denser rock fragments are enriched in the lower part of the sequence and bedding is largely parallel to the present topography) are consistent with a massive welded ignimbrite. As a result, surface erosion after the eruption must be less significant than previously believed and some rocks are clearly volcanic in nature

  1. The timescales of magma evolution at mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Brandl, Philipp A.; Regelous, Marcel; Beier, Christoph; O'Neill, Hugh St. C.; Nebel, Oliver; Haase, Karsten M.

    2016-01-01

    Oceanic crust is continuously created at mid-ocean ridges by decompression melting of the upper mantle as it upwells due to plate separation. Decades of research on active spreading ridges have led to a growing understanding of the complex magmatic, tectonic and hydrothermal processes linked to the formation of new oceanic igneous crust. However, less is known about the timescales of magmatic processes at mid-ocean ridges, including melting in and melt extraction from the mantle, fractional crystallisation, crustal assimilation and/or magma mixing. In this paper, we review the timescales of magmatic processes by integrating radiometric dating, chemical and petrological observations of mid-ocean ridge basalts (MORBs) and geophysical models. These different lines of evidence suggest that melt extraction and migration, and crystallisation and mixing processes occur over timescales of 1 to 10,000 a. High-resolution geochemical stratigraphic profiles of the oceanic crust using drill-core samples further show that at fast-spreading ridges, adjacent flow units may differ in age by only a few 100 a. We use existing chemical data and new major- and trace-element analyses of fresh MORB glasses from drill-cores in ancient Atlantic and Pacific crust, together with model stratigraphic ages to investigate how lava chemistry changes over 10 to 100 ka periods, the timescale of crustal accretion at spreading ridges which is recorded in the basalt stratigraphy in drilled sections through the oceanic crust. We show that drilled MORBs have compositions that are similar to those of young MORB glasses dredged from active spreading ridges (lavas that will eventually be preserved in the lowermost part of the extrusive section covered by younger flows), showing that the dredged samples are indeed representative of the bulk oceanic crust. Model stratigraphic ages calculated for individual flows in boreholes, together with the geochemical stratigraphy of the drilled sections, show that at

  2. INDEPENDENT VERIFICATION OF THE BUILDING 3550 SLAB AT OAK RIDGE NATIONAL LABORATORY OAK RIDGE, TENNESSEE

    SciTech Connect

    Weaver, Phyllis C.

    2012-05-08

    The Oak Ridge Institute for Science and Education (ORISE) has completed the independent verification survey of the Building 3550 Slab. The results of this effort are provided. The objective of this verification survey is to provide independent review and field assessment of remediation actions conducted by Safety and Ecology Corporation (SEC) to document that the final radiological condition of the slab meets the release guidelines. Verification survey activities on the Building 3550 Slab that included scans, measurements, and the collection of smears. Scans for alpha, alpha plus beta, and gamma activity identified several areas that were investigated.

  3. Successful Characterization Strategies for the Active High Risk Y-12 National Security Complex 9201-5 (Alpha-5) Facility, Oak Ridge, TN - 12164

    SciTech Connect

    Birchfield, Joseph W. III; Albrecht, Linda

    2012-07-01

    Building 9201-5 (Alpha 5) was completed in May 1944 and served as a production facility for National Nuclear Security Administration (NNSA) Y-12 Weapons Plant. During the Manhattan Project, it functioned as a uranium enrichment facility. The facility was renovated and altered over the years, converting the calutrons to support other missions. Alpha 5 consists of 4 floors and a basement measuring approximately 600,000 square feet. The facility contains various pieces of equipment remaining from legacy operations. A significant amount (approximately 200,000 kgs) of mercury (Hg) has been spilled in the facility over the operational history of the building. To further complicate matters, beryllium (Be) contamination in 9201-5 is found throughout approximately sixty percent of the facility. Concentrations varying from very low (< 0.2 micrograms (μg)/100 cm{sup 2}) to areas where concentrations are relatively high, approximately 600 μg/100 cm{sup 2}, in regulated beryllium areas. The primary site related contaminants (SRCs) for the waste in this facility are enriched uranium, depleted uranium, beryllium and mercury. This facility represents the highest environmental risk for DOE-ORO EM and NNSA at Y-12 and must be quickly addressed to minimize impacts to future Y-12 missions, as well as human health and the environment. As part of the American Recovery and Reinvestment Act (ARRA), approximately 700,000 cubic feet of legacy material was removed in 2010 and 2011. In addition, characterization of the 9201-5 facility was scheduled in the winter and spring of 2011. This activity was initiated in January 2011 and was completed in July 2011. Heavy schedule pressure was further complicated by the fact that this building has active utility, security and process systems. Given these complex variables, a unique, out of the box characterization strategy was forged in an effort to bound radiological and chemical contaminants, as well as providing the appropriate level of quality to

  4. Submarine sand ridges and sand waves in the eastern part of the China Sea

    NASA Astrophysics Data System (ADS)

    Wu, Ziyin; Li, Shoujun; Shang, Jihong; Zhou, Jieqiong; Zhao, Dineng; Liang, Yuyang

    2016-04-01

    Integrated with multi-beam and single-beam echo sounding data, as well as historical bathymetric data, submarine bathymetric maps of the eastern part of the China Sea, including the Bohai Sea, Huanghai Sea, and East China Sea, are constructed to systematically study submarine sand ridges and sand waves in the eastern part of the China Sea, combined with high-resolution seismic, sub-bottom profile and borehole data. Submarine sand ridges are extraordinarily developed in the eastern part of the China Sea, and 7 sand ridge areas can be divided from north to south, that is, the Laotieshan Channel sand ridge area in the Bohai Sea, the Korea Bay sand ridge area in the southern Huanghai Sea, the sand ridge area in the eastern Huanghai islands and the Huanghai Troughs, the Jianggang sand ridge area in the western Huanghai Sea, the sand ridge area in the East China Sea shelf, and the sand ridge and sand wave area in the Taiwan Strait and Taiwan Banks. The distribution area of the sand ridges and sand waves covers more than 450,000 km2, wherein ~10,000 km2 in the Bohai Bay, ~200,000 km2 in the Huanghai Sea, ~200,000 km2 in the East China Sea shelf, and ~40,000 km2 in the Taiwan Strait and Taiwan Banks, respectively. The great mass of sand ridges are distributed within water depth of 5-160 m, with a total length of over 160 km and a main width of 5-10 km. The inner structure of the sand ridges presents features of high-angle inclined beddings, with main lithology of sands, sand-mud alternations partly visible, and a small number of mud cores. Dating results indicate that the sand ridges in the eastern part of the China Sea are mainly developed in the Holocene. Sea-level variation dominates the sand ridge evolution in the eastern part of the China Sea since the LGM, and the sand ridges developed in the area of < 60m water depth are appeared in bad activity, meanwhile sand ridges with good activity are still developed in large scale.

  5. Active Submarine Volcanoes and Electro-Optical Sensor Networks: The Potential of Capturing and Quantifying an Entire Eruptive Sequence at Axial Seamount, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Delaney, J. R.; Kelley, D. S.; Proskurowski, G.; Fundis, A. T.; Kawka, O.

    2011-12-01

    The NE Pacific Regional Scale Nodes (RSN) component of the NSF Ocean Observatories Initiative is designed to provide unprecedented electrical power and bandwidth to the base and summit of Axial Seamount. The scientific community is engaged in identifying a host of existing and innovative observation and measurement techniques that utilize the high-power and bandwidth infrastructure and its real-time transmission capabilities. The cable, mooring, and sensor arrays will enable the first quantitative documentation of myriad processes leading up to, during, and following a submarine volcanic event. Currently planned RSN instrument arrays will provide important and concurrent spatial and temporal constraints on earthquake activity, melt migration, hydrothermal venting behavior and chemistry, ambient currents, microbial community structure, high-definition (HD) still images and HD video streaming from the vents, and water-column chemistry in the overlying ocean. Anticipated, but not yet funded, additions will include AUVs and gliders that continually document the spatial-temporal variations in the water column above the volcano and the distal zones. When an eruption appears imminent the frequency of sampling will be increased remotely, and the potential of repurposing the tracking capabilities of the mobile sensing platforms will be adapted to the spatial indicators of likely eruption activity. As the eruption begins mobile platforms will fully define the geometry, temperature, and chemical-microbial character of the volcanic plume as it rises into the thoroughly documented control volume above the volcano. Via the Internet the scientific community will be able to witness and direct adaptive sampling in response to changing conditions of plume formation. A major goal will be to document the eruptive volume and link the eruption duration to the volume of erupted magma. For the first time, it will be possible to begin to quantify the time-integrated output of an underwater

  6. Structural style and petroleum prospects of Tonga Ridge

    SciTech Connect

    Pflueger, J.; Havard, K.; Gatliff, R.; Helu, B.

    1989-03-01

    Recent reprocessing of seismic data from the Tonga Ridge has provided a clearer picture of the tectonic style of a forearc basin. Sediments along the ridge achieve a maximum thickness of more than 4000 m. Many faults have been observed, almost all of which are normal. The presence of scarps on the sea floor show that a significant percentage of the faults are active today. Although seismic transverses are not spaced closely enough to allow unambiguous definition of fault orientations, they believe that most of the tensional faults are parallel to the ridge axis. A second set of near-vertical faults with apparent transcurrent movement exists at a high angle to the ridge axis. Bathymetry has played a major role in defining the strikes of the second set of faults. The tensional failures are due to the flexing of the ridge as the leading edge of the Indo-Australian plate is pulled down and under by frictional attachment to the subducting Pacific plate. The development of major fault blocks is related to the subduction of Pacific plate seamounts. Fault-bounded closures and Eocene to Miocene reefs would form excellent traps for hydrocarbons. Oil seeps of biodegaded but thermally mature crude oil on the island of Tongatanu encouraged the drilling of five exploratory test wells, but the source rock feeding the seeps was not discovered. Burial history and geothermal modeling indicate that mature source rocks could occur deeper than depths penetrated by the test wells.

  7. Basalts dredged from the Amirante ridge, western Indian ocean

    USGS Publications Warehouse

    Fisher, R.L.; Engel, C.G.; Hilde, T.W.C.

    1968-01-01

    Oceanic tholeiitic basalts were dredged from 2500 to 3000 m depth on each flank of the Amirante Ridge, 1200 km southeast of Somalia in the western Indian Ocean, by R.V. Argo in 1964. One sample, probably shed from a flow or dike in basement beneath the coralline cap, gave a wholerock KAr age of 82??16??106 years. The age is similar to those reported by others for agglomerate from Providence Reef, nearer Madagascar, and for gabbro from Chain Ridge, the southwest member of Owen Fracture Zone, nearer the Somali coast. The Amirante Cretaceous-Early Tertiary occurrence lies between the "continental" 650 ?? 106 years granites of Seychelles Archipelago and the large Precambrian "continental" block of Madagascar. Trends of major structures and distribution of the related topographic and magnetic-anomaly lineations in 7-8 ?? 106 km2of the surrounding Indian Ocean suggest that in addition to spreading of the seafloor from the seismically-active Mid-Indian Ocean Ridge-Carlsberg Ridge complex there has been, since mid-Mesozoic time, distributed left-lateral shear along 52??-54??E that has moved Madagascar at least 700 km south relative to Seychelles Bank. Measurements by other indicate the absolute movement of Madagascar has been southward as well. The emplacement of oceanic tholeiitic basalts at shallow depth, the development of volcanic topography between the sedimented Somali and Mascarene basins, and the existence of the faulted Amirante Trench and Ridge are consequences of the displacement. ?? 1968.

  8. Microbial Life in Ridge Flank Crustal Fluids at Baby Bare Seamount, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Huber, J. A.; Johnson, H. P.; Butterfield, D. A.; Baross, J. A.

    2005-12-01

    To determine the microbial community diversity within old oceanic crust, a novel sampling strategy was used to collect crustal fluids at Baby Bare Seamount, a 3.5 Ma old outcrop located in the northeast Pacific Ocean on the eastern flank of the Juan de Fuca Ridge. Stainless steel probes were driven directly into the igneous ocean crust to obtain samples of ridge flank crustal fluids. Genetic signatures and enrichment cultures of microorganisms demonstrate that these crustal fluids host a microbial community composed of species indigenous to the subseafloor, including anaerobic thermophiles, and species from other deep-sea habitats, such as seawater and sediments. Evidence using molecular techniques indicates the presence of a relatively small but active microbial population, dominated by bacteria. The microbial community diversity found in the crustal fluids may indicate habitat variability in old oceanic crust, with inputs of nutrients from seawater, sediment pore-water fluids and possibly hydrothermal sources. This report further supports the presence of an indigenous microbial community in ridge flank crustal fluids and advances our understanding of the potential physiological and phylogenetic diversity of this community.

  9. Site descriptions of environmental restoration units at the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Goddard, P.L.; Legeay, A.J.; Pesce, D.S.; Stanley, A.M.

    1995-11-01

    This report, Site Descriptions of Environmental Restoration Units at the Oak Ridge K-25 Site, Oak Ridge, Tennessee, is being prepared to assimilate information on sites included in the Environmental Restoration (ER) Program of the K-25 Site, one of three major installations on the Oak Ridge Reservation (ORR) built during World War III as part of the Manhattan Project. The information included in this report will be used to establish program priorities so that resources allotted to the K-25 ER Program can be best used to decrease any risk to humans or the environment, and to determine the sequence in which any remedial activities should be conducted. This document will be updated periodically in both paper and Internet versions. Units within this report are described in individual data sheets arranged alphanumerically. Each data sheet includes entries on project status, unit location, dimensions and capacity, dates operated, present function, lifecycle operation, waste characteristics, site status, media of concern, comments, and references. Each data sheet is accompanied by a photograph of the unit, and each unit is located on one of 13 area maps. These areas, along with the sub-area, unit, and sub-unit breakdowns within them, are outlined in Appendix A. Appendix B is a summary of information on remote aerial sensing and its applicability to the ER program.

  10. Europa Ridges, Hills and Domes

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This moderate-resolution view of the surface of one of Jupiter's moons, Europa, shows the complex icy crust that has been extensively modified by fracturing and the formation of ridges. The ridge systems superficially resemble highway networks with overpasses, interchanges and junctions. From the relative position of the overlaps, it is possible to determine the age sequence for the ridge sets. For example, while the 8-kilometer-wide (5-mile) ridge set in the lower left corner is younger than most of the terrain seen in this picture, a narrow band cuts across the set toward the bottom of the picture, indicating that the band formed later. In turn, this band is cut by the narrow 2- kilometer-wide (1.2-mile) double ridge running from the lower right to upper left corner of the picture. Also visible are numerous clusters of hills and low domes as large as 9 kilometers (5.5 miles) across, many with associated dark patches of non-ice material. The ridges, hills and domes are considered to be ice-rich material derived from the subsurface. These are some of the youngest features seen on the surface of Europa and could represent geologically young eruptions.

    This area covers about 140 kilometers by 130 kilometers (87 miles by 81 miles) and is centered at 12.3 degrees north latitude, 268 degrees west longitude. Illumination is from the east (right side of picture). The resolution is about 180 meters (200 yards) per pixel, meaning that the smallest feature visible is about a city block in size. The picture was taken by the Solid State Imaging system on board the Galileo spacecraft on February 20, 1997, from a distance of 17,700 kilometers (11,000 miles) during its sixth orbit around Jupiter.

    The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov.

  11. Removal action report on the Building 3001 canal at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1997-05-01

    Oak Ridge National Laboratory (ORNL) is a federal facility managed by Lockheed Martin C, Energy Research, Inc., for the U.S. Department of Energy (DOE). ORNL on the Oak Ridge Reservation in East Tennessee at the Anderson and Roane County lines, approximately 38 km (24 miles) west of Knoxville, Tennessee, and 18 km (11 miles) southwest of downtown Oak Ridge. The Oak Ridge Graphite Reactor and its storage and transfer canal are located in Bldg. 3001 in the approximate center of Waste Area Grouping I in the ORNL main complex. 4:1 The Bldg. 3001 Storage Canal is an L-shaped, underground, reinforced-concrete structure running from the back and below the Graphite Reactor in Bldg. 3001 to a location beneath a hot cell in the adjacent Bldg. 3019. The Graphite Reactor was built in 1943 to produce small quantities of plutonium and was subsequently used to produce other isotopes for medical research before it was finally shut down in 1963. The associated canal was used to transport, under water, spent fuel slugs and other isotopes from the back of the reactor to the adjacent Bldg. 31319 hot cell for further processing. During its operation and years subsequent to operation, the canal`s concrete walls and floor became contaminated with radioisotopes from the water.This report documents the activities involved with replacing the canal water with a solid, controlled, low-strength material (CLSM) in response to a Comprehensive Environmental Response, Compensation, and Liability Act non-time-critical removal action.

  12. The Davie Ridge: a Marginal Transform Ridge not Formed During Continental Breakup

    NASA Astrophysics Data System (ADS)

    Phethean, J. J. J.; Van Hunen, J.; McCaffrey, K. J. W.; Davies, R. J.

    2014-12-01

    The breakup of Gondwana translated Madagascar southwards relative to Africa along the Davie Fracture Zone (DFZ). This fracture zone now forms the Transform Passive Continental Margin (TPCM) from Kenya to Mozambique. The Davie Ridge (DR), a transform marginal ridge, has formed along the DFZ between 5 and 2°S and 22 and 11°S, but with little expression in-between. It has been proposed that this marginal ridge was formed by the thermal effects of a passing Mid Ocean Ridge (MOR) during the separation of Gondwana. Plate kinematic reconstructions, however, constrained by ocean magnetic anomalies, show that the MOR only passed between the north and south expressions of the DR. Therefore the positive linear gravity anomalies of the DR cannot be attributed to the effects of a passing MOR, and some other mechanism must be found to explain their formation. Interpretation of seismic reflection profiles along the DR shows that the gravity highs occur adjacent to large basin structures. In the north this correlates with a basin-bounding basement high of ~Albian age, and in the south with the rift flank uplifts of the currently active Quirimbas graben. This suggests that the northern and southern DR segments are instead shoulder uplifts resulting from two separate extensional episodes during different stress regimes. These are the Cretaceous NE-SW extension during the breakup of the south Atlantic, and the E-W extension of the Neogene-recent Afar-East Africa rift system, respectfully. The lack of deformation and DR formation along the region of the TPCM passed by the MOR suggests it has been coupled by thermal effects and/or the injection of magma.

  13. Thermal resistance of ridge-waveguide lasers mounted upside down

    SciTech Connect

    Amann, M.

    1987-01-05

    The heat dissipation in upside down mounted ridge-waveguide lasers equipped with a double-channel structure is analyzed by a simplified device model. Assuming an isothermal active region, the thermal resistance is obtained by means of conformal mapping. A comparison to published experimental results shows good agreement.

  14. The Oak Ridge Reservation Annual Site Environmental Report, 2007

    SciTech Connect

    Hughes, Joan; Thompson, Sharon; Page, David

    2008-09-30

    The Oak Ridge Reservation (ORR) consists of three major government-owned, contractor-operated facilities: the Y-12 National Security Complex, Oak Ridge National Laboratory, and East Tennessee Technology Park. The ORR was established in the early 1940s as part of the Manhattan Project, a secret undertaking that produced materials for the first atomic bombs. The reservation’s role has evolved over the years, and it continues to adapt to meet the changing defense, energy, and research needs of the United States. Both the work carried out for the war effort and subsequent research, development, and production activities have involved, and continue to involve, the use of radiological and hazardous materials. The Oak Ridge Reservation Annual Site Environmental Report and supporting data are available at Http://www.ornl.gov/sci/env_rpt or from the project director.

  15. Magdalena Ridge Observatory Project Overview

    NASA Astrophysics Data System (ADS)

    Laubscher, Bryan E.; Buscher, David F.; Chang, Mark J.; Cobb, Michael L.; Haniff, Chris A.; Horton, Richard F.; Jorgensen, Anders M.; Klinglesmith, Dan; Loos, Gary; Nemzek, Robert J.

    The Magdalena Ridge Observatory (MRO) is a project with the goal of building a state of the art observatory on Magdalena Ridge west of Socorro New Mexico. This observatory will be sited above 3700 meters and will consist of a 10-element 400-meter baseline optical/infrared imaging interferometer and a separate 2.4-meter telescope with fast response capability. The MRO consortium members include New Mexico Institute of Mining and Technology University of Puerto Rico Mew Mexico Highlands University New Mexico State University and the Los Alamos National Laboratory. The University of Cambridge is a joint participant in the current design phase of the interferometer and expects to join the consortium. We will present an overview of the optical interferometer and single telescope designs and review their instrumentation and science programs

  16. Enabling Integration and Synthesis through the Ridge 2000 Data Portal

    NASA Astrophysics Data System (ADS)

    Ryan, W. B.; Ferrini, V.; Carbotte, S. M.; O'Hara, S.; Arko, R. A.; Bonczkowski, J.; Chan, S.

    2009-12-01

    Achieving an integrated, holistic understanding of global mid-ocean ridge (MOR) processes through the Ridge 2000 Program relies heavily on the sharing of data across disciplinary boundaries. Although most Ridge 2000 research has been focused on three Integrated Study Sites (ISSs), data from throughout the global mid-ocean ridge (MOR) system will also be important in the integration and synthesis phase of the program. The Ridge 2000 Data Portal (www.marine-geo.org/portals/ridge2000) is a resource established to facilitate the sharing, discovery, and integration of Ridge 2000-relevant data by providing data documentation and access. The Data Portal includes an inventory of field programs and activities, raw and derived data files, and access to publications and remote data sets in specialized data systems (e.g. PetDB, www.petdb.org; GenBank, www.ncbi.nlm.nih.gov; NGDC, www.ngdc.noaa.gov). Access to the R2K database is provided through several pathways, including a web-based search interface (www.marine-geo.org/tools/search) that now includes basic and advanced search functionality. New versions of our data exploration and visualization tool GeoMapApp (www.geomapapp.org) includes a newly designed menu system with cascading and tear-off menus, a new Layer Manager that lists selected layers and enables re-ordering and rendering with variable transparency, a Go To option that allows direct zooming to areas of interest, and an Add Image Overlay option for importing georeferenced images. New data sets are continually added to both GeoMapApp and Virtual Ocean (www.virtualocean.org), a 3D virtual globe with GeoMapApp functionality. Several Ridge 2000 data sets are also bundled for viewing in Google Earth (www.marine-geo.org/tools/kmls.php). This poster will highlight new functionality and data sets relevant to Ridge 2000 Integration and Synthesis, and will provide comparisons of several data sets that exist for each ISS.

  17. Reactive spreading: Adsorption, ridging and compound formation

    SciTech Connect

    Saiz, E.; Cannon, R.M.; Tomsia, A.P.

    2000-09-11

    Reactive spreading, in which a chemically active element is added to promote wetting of noble metals on nonmetallic materials, is evaluated. Theories for the energetics and kinetics of the necessary steps involved in spreading are outlined and compared to the steps in compound formation that typically accompany reactive wetting. These include: fluid flow, active metal adsorption, including nonequilibrium effects, and triple line ridging. All of these can be faster than compound nucleation under certain conditions. Analysis and assessment of recently reported experiments on metal/ceramic systems lead to a focus on those conditions under which spreading proceeds ahead of the actual formation of a new phase at the interface. This scenario may be more typical than believed, and perhaps the most effective situation leading to enhanced spreading. A rationale for the pervasive variability and hysteresis observed during high temperature wetting also emerges.

  18. Oak Ridge National Laboratory Review

    SciTech Connect

    Krause, C.; Pearce, J.; Zucker, A.

    1992-01-01

    This report presents brief descriptions of the following programs at Oak Ridge National Laboratory: The effects of pollution and climate change on forests; automation to improve the safety and efficiency of rearming battle tanks; new technologies for DNA sequencing; ORNL probes the human genome; ORNL as a supercomputer research center; paving the way to superconcrete made with polystyrene; a new look at supercritical water used in waste treatment; and small mammals as environmental monitors.

  19. Prominent Doublet Ridges on Europa

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of Jupiter's satellite Europa was obtained from a range of 7364 miles (11851 km) by the Galileo spacecraft during its fourth orbit around Jupiter and its first close pass of Europa. The image spans 30 miles by 57 miles (48 km x 91 km) and shows features as small as 800 feet (240 meters) across, a resolution more than 150 times better than the best Voyager coverage of this area. The sun illuminates the scene from the right. The large circular feature in the upper left of the image could be the scar of a large meteorite impact. Clusters of small craters seen in the right of the image may mark sites where debris thrown from this impact fell back to the surface. Prominent doublet ridges over a mile (1.6 km) wide cross the plains in the right part of the image; younger ridges overlap older ones, allowing the sequence of formation to be determined. Gaps in ridges indicate areas where emplacement of new surface material has obliterated pre-existing terrain.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  20. The formation and linking of mid-segment detachment faults at the slow-spreading Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Schouten, H.; Smith, D. K.; Dick, H. J.; Escartin, J.

    2011-12-01

    The Mid-Atlantic Ridge axis at 16.5N has a remarkably high rate of teleseismic and hydrophone-recorded seismicity, and we have identified it as a region of active detachment faulting. Limited multibeam bathymetry data on the west side of the median valley show two parallel, linear ridges: 50-km-long West Ridge at 15 km west of the volcanic axis, and 10-km-long East Ridge at only 6 km from the axis. The ridges are interpreted to be the tops of rotated detachment fault scarps (breakaways), indicating significant fault rotation (> 25 degrees). A striated surface, characteristic of a core complex, is associated with West Ridge. This region stands out because it presents a dramatic demonstration of a new detachment fault forming nearer to the axis (East Ridge) and interrupting the overall development of what we interpret to be a longer, older and still active detachment fault that has its breakaway at the older West Ridge. We hypothesize that the section of the West Ridge detachment behind the East Ridge detachment was deactivated when East Ridge formed and furthermore, that the East Ridge detachment has linked into the West Ridge detachment to form a single detachment fault. This area represents an opportunity to address the initiation and cessation of mid-segment detachment faulting as well as how the faults link along the axis. Sampling of the detachment footwall will allow us to relate the subcrustal architecture of the segment to the local magmatic budget, and how this influences the initiation and geometry of the faulting. A broad, well-developed neovolcanic zone at the adjacent spreading axis suggests abundant volcanism. The greater depth of the local off-axis morphology, though, indicates that East Ridge may have formed in a relatively amagmatic corridor. Massifs at the western limit of the multibeam bathymetry data suggest asymmetric spreading through detachment faulting has dominated this region for at least the last several million years and perhaps much

  1. Oak Ridge Reservation, annual site environmental report for 1993

    SciTech Connect

    Not Available

    1994-11-01

    The US DOE currently oversees activities on the Oak Ridge Reservation, a government-owned, contractor-operated facility. Three sites compose the reservation; Y-12, Oak Ridge National Laboratory, and K-25. This document contains a summary of environmental monitoring activities on the Oak Ridge Reservation (ORR) and its surroundings. The results summarized in this report are based on the data collected during calendar year (CY) 1993 and compiled in; Environmental Monitoring in the Oak Ridge Reservation: CY 1993 Results. Annual environmental monitoring on the ORR consists of two major activities: effluent monitoring and environmental surveillance. Effluent monitoring is the collection and analysis of samples or measurements of liquid, gaseous, or airborne effluents for the purpose of characterizing and quantifying contaminants and process stream characteristics, assessing radiation and chemical exposures to members of the public, and demonstrating compliance with applicable standards. Environmental surveillance is the collection and analysis of samples of air, water, soil, foodstuffs, biota, and other media from DOE sites and their environs and the measurement of external radiation for purposes of demonstrating compliance with applicable standards, assessing radiation and chemical exposures to members of the public, and assessing effects, if any, on the local environment.

  2. Environmental Compliance and Protection Program Description Oak Ridge, Tennessee

    SciTech Connect

    Bechtel Jacobs

    2009-02-26

    The objective of the Environmental Compliance and Protection (EC and P) Program Description (PD) is to establish minimum environmental compliance requirements and natural resources protection goals for the Bechtel Jacobs Company LLC (BJC) Oak Ridge Environmental Management Cleanup Contract (EMCC) Contract Number DE-AC05-98OR22700-M198. This PD establishes the work practices necessary to ensure protection of the environment during the performance of EMCC work activities on the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) in Oak Ridge, Tennessee, by BJC employees and subcontractor personnel. Both BJC and subcontractor personnel are required to implement this PD. A majority of the decontamination and demolition (D and D) activities and media (e.g., soil and groundwater) remediation response actions at DOE sites on the ORR are conducted under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). CERCLA activities are governed by individual CERCLA decision documents (e.g., Record of Decision [ROD] or Action Memorandum) and according to requirements stated in the Federal Facility Agreement for the Oak Ridge Reservation (DOE 1992). Applicable or relevant and appropriate requirements (ARARs) for the selected remedy are the requirements for environmental remediation responses (e.g., removal actions and remedial actions) conducted under CERCLA.

  3. Quality assurance project plan for the Chestnut Ridge Fly Ash Pond Stabilization Project at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1996-07-01

    The Chestnut Ridge Fly Ash Pond Stabilization (CRFAPS) Project will stabilize a 19-m-high (62-ft-high) earthen embankment across Upper McCoy Branch situated along the southern slope of Chestnut Ridge. This task will be accomplished by raising the crest of the embankment, reinforcing the face of the embankment, removing trees from the face and top of the embankment, and repairing the emergency spillway. The primary responsibilities of the team members are: Lockheed Martin Energy Systems, Inc., (Energy Systems) will be responsible for project integration, technical support, Title 3 field support, environmental oversight, and quality assurance (QA) oversight of the project; Foster Wheeler Environmental Corporation (FWENC) will be responsible for design and home office Title 3 support; MK-Ferguson of Oak Ridge Company (MK-F) will be responsible for health and safety, construction, and procurement of construction materials. Each of the team members has a QA program approved by the US Department of Energy (DOE) Oak Ridge Operations. This project-specific QA project plan (QAPP), which is applicable to all project activities, identifies and integrates the specific QA requirements from the participant`s QA programs that are necessary for this project.

  4. Best management practices plan for the Chestnut Ridge-Filled Coal Ash Pond at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1996-05-01

    The Chestnut Ridge Filled Coal Ash Pond (FCAP) Project has been established to satisfy Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) requirements for the Chestnut Ridge Operable Unit 2. FCAP is on Chestnut Ridge, approximately 0.5 miles south of the Y-12 Plant. A 62-foot high earthen dam across Upper McCoy Branch was constructed in 1955 to create a pond to serve as a settling basin for fly and bottom ashes generated by burning coal at the Y-12 Steam Plant. Ash from the steam was mixed with water to form a slurry and then pumped to the crest of Chestnut Ridge and released through a large pipe to flow across the Sluice Channel area and into the pond. The ash slurry eventually overtopped the dam and flowed along Upper McCoy Branch to Rogers Quarry. The purpose of this document is to provide a site-specific Best Management Practices (BMP) Plan for construction associated with environmental restoration activities at the FCAP Site.

  5. Experimental study of structure-forming deformations in obliquely spreading ultra-slow ridges

    NASA Astrophysics Data System (ADS)

    Dubinin, Evgeniy; Kokhan, Andrey; Grokholsky, Andrey

    2013-04-01

    This paper is dedicated to obliquely spreading ultra-slow ridges of North Atlantic and Arctic. The study covers four ridges: Reikjanes, Kolbeynsey, Mohns and Knipovich They are rather young (spreading initiated 58-60 Myr ago) and angles between their trends and spreading direction are from 33 to 85°. All the ridges have peculiarities in structure patterns, kinematics, and morphology and develop in specific geodynamical environments. Kolbeynsey and Reikjanes ridges are developing under influence of Iceland hotspot. Knipovich ridge is developing in ancient slip zone along the heavily sedimented Spitzbergen margin. Spreading at Mohns ridge occurs in conditions of thick lithosphere and extremely narrow heating zone. In order to study geodynamical features of structure-forming on these ridges we apply experimental modeling The model material used in modeling is a colloidal system composed of mineral oils, solid hydrocarbon and surface-active substances. It has elastic-viscous-plastic properties, under temperature and strain rate, it is capable of failure like a brittle body. Reikjanes (ridge obliquity 60-65°) and Kolbeynsey (80-85°) ridges show changes of morphology with increasing distance from Iceland mantle plume. In proximity with Iceland they are characterized by axial rise with long s-shaped axial volcanic ridges (AVRs) offset by small discontinuities. Far from Iceland the AVRs are short and offset by large non-transform offsets which are situated in axial valley. In conditions of all these features are explained by influence of mantle flow from the Iceland mantle plum initiating the increasing of mantle temperature. It results in decreasing of lithospheric brittle layer with approaching to Iceland. In experimental sets reproducing conditions of proximate to Iceland part of the ridge were reproduced in sets with the widest weak zone and the smallest crustal thickness and vice versa. In sets reproducing conditions of proximate to Iceland received long and non

  6. Changing characteristics of arctic pressure ridges

    NASA Astrophysics Data System (ADS)

    Wadhams, Peter; Toberg, Nick

    2012-04-01

    The advent of multibeam sonar permits us to obtain full three-dimensional maps of the underside of sea ice. In particular this enables us to distinguish the morphological characteristics of first-year (FY) and multi-year (MY) pressure ridges in a statistically valid way, whereas in the past only a small number of ridges could be mapped laboriously by drilling. In this study pressure ridge distributions from two parts of the Arctic Ocean are compared, in both the cases using mainly data collected by the submarine “Tireless” in March 2007 during two specific grid surveys, in the Beaufort Sea at about 75° N, 140° W (N of Prudhoe Bay), and north of Ellesmere Island at about 83° 20‧ N, 64° W. In the Beaufort Sea the ice was mainly FY, and later melted or broke up as this area became ice-free during the subsequent summer. N of Ellesmere Island the ice was mainly MY. Ridge depth and spacing distributions were derived for each region using the boat's upward looking sonar, combined with distributions of shapes of the ridges encountered, using the Kongsberg EM3002 multibeam sonar. The differing shapes of FY and MY ridges are consistent with two later high-resolution multibeam studies of specific ridges by AUV. FY ridges are found to fit the normal triangular shape template in cross-section (with a range of slope angles averaging 27°) with a relatively constant along-crest depth, and often a structure of small ice blocks can be distinguished. MY ridges, however, are often split into a number of independent solid, smooth blocks of large size, giving an irregular ridge profile which may be seemingly without linearity. Our hypothesis for this difference is that during its long lifetime an MY ridge is subjected to several episodes of crack opening; new cracks in the Arctic pack often run in straight lines across the ridges and undeformed ice alike. Such a crack will open somewhat before refreezing, interpolating a stretch of thin ice into the structure, and breaking up

  7. Teleseismic earthquake swarms at ultraslow spreading ridges: indicator for dyke intrusions?

    NASA Astrophysics Data System (ADS)

    Schlindwein, V.

    2012-07-01

    Earthquakes at mid-ocean ridges reflect the active magmatic and tectonic processes that form new oceanic crust. Studies of large earthquakes observed on land and smaller earthquakes observed locally or regionally by ocean bottom seismometers or autonomous underwater hydrophones have greatly contributed to our understanding of the structure and active spreading processes at the mid-ocean ridges of the Atlantic and Pacific Ocean opening with velocities in excess of 25 mm yr-1. At spreading rates below 20 mm yr-1 full rate, the appearance and the accretion processes of mid-ocean ridges undergo fundamental changes as the melt supply is drastically reduced. The active spreading processes at these so-called ultraslow spreading ridges are still poorly known, as the main representatives, the Arctic Ridge System and the Southwest Indian Ridge, are poorly accessible and neither autonomous underwater hydrophone nor ocean bottom seismometer records of local seismicity are available. In an attempt to compare on a large scale the accretion style of ultraslow spreading ridge sections, I analyse the teleseismically recorded seismicity in 11 sections of the Arctic Ridge System and the Southwest Indian Ridge spanning altogether 7200 km. Epicentres located within 30-35 km of the rift axis were extracted from the catalogue of the International Seismological Centre for a time period of 35 yr. On the basis of a single-link cluster analysis, I identified 27 swarms with eight or more events. These swarms occur almost exclusively at centres of focussed magmatism suggesting that the swarms are probably initiated by magmatism. Normal faults along several tens of kilometres surrounding the volcanic centres react in large earthquakes (M > 5) to dyke emplacement. The routine generation of large earthquakes in the cold, brittle lithosphere of ultraslow spreading ridges makes the teleseismic record a valuable means to study ultraslow accretion processes and to provide a global framework for the

  8. Stochastic analysis of exit fluid temperature records from the active TAG hydrothermal mound (Mid-Atlantic Ridge, 26°N): 1. Modes of variability and implications for subsurface flow

    NASA Astrophysics Data System (ADS)

    Sohn, R. A.

    2007-07-01

    Yearlong time series records of exit fluid temperature from the active TAG hydrothermal mound (Mid-Atlantic Ridge, 26°N) reveal a complex space-time pattern of flow variability within the mineral deposit. Exit fluid temperatures were measured every 8-10 min from 17 sites distributed across the upper terrace of the mound from June 2003 to June 2004. High-temperature records were obtained using Deep Sea Power and Light SeaLogger® probes deployed in fractures discharging ˜360°C black smoker fluids, and low-temperature records were obtained using VEMCO Ltd. Minilog probes deployed in cracks discharging ˜20°C diffuse flow fluids. The temperature records are considerably more variable than those acquired from vent fields on the fast spreading East Pacific Rise and exhibit a complex mix of both episodic and periodic variability. The diffuse flow records alternate between periods of discharge and periods of what I infer to be recharge when fluid temperatures are equal to background water column levels (˜2.7°C) as ambient seawater is drawn into the seafloor. The space-time patterns of these episodic variations suggest that they represent reorganizations of the secondary circulation system driving diffuse discharge on the upper terrace of the mound on timescales from a few hours to a few days, most likely in response to permeability perturbations. Harmonic temperature oscillations were observed over a range of periods, with the principal lunar semidiurnal tidal period (M2) being most dominant. During certain times, exit fluid temperatures at diffuse sites pulse at diurnal and semidiurnal tidal periods when they are hovering near background water column levels, which I interpret as flow reversals associated with the vertical displacement of a fluid boundary layer at the seafloor interface when the local net flux is near zero. The pulsing behavior is predicted by poroelastic models of tidal loading but is not consistent with effects from tidal currents, which

  9. Quality assurance plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-01-01

    This Quality Assurance Plan (QAP) is concerned with design and construction (Sect. 2) and characterization and monitoring (Sect. 3). The basis for Sect. 2 is the Quality Assurance Plan for the Design and Construction of Waste Area Grouping 6 Closure at Oak Ridge National Laboratory, Oak Ridge, Tennessee, and the basis for Sect. 3 is the Environmental Restoration Quality Program Plan. Combining the two areas into one plan gives a single, overall document that explains the requirements and from which the individual QAPs and quality assurance project plans can be written. The Waste Area Grouping (WAG) 6 QAP establishes the procedures and requirements to be implemented for control of quality-related activities for the WAG 6 project. Quality Assurance (QA) activities are subject to requirements detailed in the Martin Marietta Energy Systems, Inc. (Energy Systems), QA Program and the Environmental Restoration (ER) QA Program, as well as to other quality requirements. These activities may be performed by Energy Systems organizations, subcontractors to Energy Systems, and architect-engineer (A-E) under prime contract to the US Department of Energy (DOE), or a construction manager under prime contract to DOE. This plan specifies the overall Energy Systems quality requirements for the project. The WAG 6 QAP will be supplemented by subproject QAPs that will identify additional requirements pertaining to each subproject.

  10. Remedial investigation work plan for Chestnut Ridge Operable Unit 4 (Rogers Quarry/Lower McCoy Branch) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-09-01

    The Oak Ridge Y-12 Plant includes - 800 acres near the northeast comer of the reservation and adjacent to the city of Oak Ridge (Fig. 1-1). The plant is a manufacturing and developmental engineering facility that produced components for various nuclear weapons systems and provides engineering support to other Energy Systems facilities. More than 200 contaminated sites have been identified at the Y-12 Plant that resulted from past waste management practices. Many of the sites have operable units (OUs) based on priority and on investigative and remediation requirements. This Remedial Investigation RI work plan specifically addresses Chestnut Ridge OU 4. Chestnut Ridge OU 4 consists of Rogers Quarry and Lower McCoy Branch (MCB). Rogers Quarry, which is also known as Old Rogers Quarry or Bethel Valley Quarry was used for quarrying from the late 1940s or early 1950s until about 1960. Since that time, the quarry has been used for disposal of coal ash and materials from Y-12 production operations, including classified materials. Disposal of coal ash ended in July 1993. An RI is being conducted at this site in response to CERCLA regulations. The overall objectives of the RI are to collect data necessary to evaluate the nature and extent of contaminants of concern, support an Ecological Risk Assessment and a Human Health Risk Assessment, support the evaluation of remedial alternatives, and ultimately develop a Record of Decision for the site. The purpose of this work plan is to outline RI activities necessary to define the nature and extent of suspected contaminants at Chestnut Ridge OU 4. Potential migration pathways also will be investigated. Data collected during the RI will be used to evaluate the risk posed to human health and the environment by OU 4.

  11. Calendar year 1994 groundwater quality report for the Chestnut Ridge Hydrogeologic Regime, Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1995-09-01

    This groundwater quality report (GWQR) contains an evaluation of the groundwater quality data obtained during the 1994 calendar year (CY) at several hazardous and non-hazardous waste management facilities associated with the US Department of Energy (DOE) Y-12 Plant located on the DOE Oak Ridge Reservation (ORR) southeast of Oak Ridge, Tennessee (Figure 1). These sites lie within the boundaries of the Chestnut Ridge Hydrogeologic Regime (Chestnut Ridge Regime), which is one of three hydrogeologic regimes defined for the purposes of groundwater quality monitoring at the Y-12 Plant (Figure 2). The Environmental Management Department of the Y-12 Plant Health, Safety, Environment, and Accountability (HSEA) Organization manages the groundwater monitoring activities in each regime under the auspices of the Y-12 Plant Groundwater Protection Program (GWPP). The purpose of the GWPP is to characterize the hydrogeology and to monitor groundwater quality at the Y-12 Plant and surrounding area to protect local groundwater resources in accordance with federal, state, and local regulations, DOE Orders, and Lockheed Martin Energy Systems, Inc. (Energy Systems) corporate policy. The annual GWQR for the Chestnut Ridge Regime is completed in two parts. Part 1 consists primarily of data appendices and serves as a reference for the groundwater quality data obtained each CY under the lead of the Y-12 Plant GWPP. Because it contains information needed to comply with reporting requirements of Resource Conservation and Recovery Act (RCRA) interim status assessment monitoring, the Part 1 GWQR is submitted to the Tennessee Department of Environment and Conservation (TDEC) by the RCRA reporting deadline (March 1 of the following CY); Energy Systems submitted the 1994 Part 1 GWQR for the Chestnut Ridge Regime to the TDEC in February 1995 (HSW Environmental Consultants, Inc. 1995a).

  12. FOSSIL RIDGE WILDERNESS STUDY AREA, COLORADO.

    USGS Publications Warehouse

    DeWitt, Ed; Kluender, Steven E.

    1984-01-01

    The Fossil Ridge Wilderness Study Area, approximately 20 mi northeast of Gunnison in central Colorado, was studied and its mineral-resource potential assessed. Portions of the study area have substantiated resource potential for gold, silver, copper, lead, zinc, molybdenum, uranium, thorium, rare-earth elements, and high-calcium limestone. Much of the area has a probable resource potential for the preceeding commodities as well as for tin. Various other elements are found in anomalous concentrations within the study area, but there is likelihood for their occurrence in amounts sufficient to constitute resources. Exploration, especially for molybdenum, gold, and uranium, has been active in the past and is expected to continue in the future. No potential for fossil fuel resources was identified in this study.

  13. Lavinia Region Ridge Belts, Plains and Lava Flows

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This is a Magellan full resolution radar mosaic of the Lavinia region of Venus. The mosaic is centered at 50 degrees south latitude, 345 degrees east longitude, and spans 540 kilometers (338 miles) north to south and 900 kilometers (563 miles) east to west. As with all Magellan images acquired thus far, the illumination of the radar is from the left hand side of the image. This area shows a diverse set of geologic features. The bright area running from the upper right to the lower left is interpreted as part of a belt of ridges, formed by compression and thickening of the upper layers of the planet. The areas between ridges suggest flooding by radar dark (and thus presumably) smoother lavas. The varied texture of the lavas can be seen in the mottled appearance of the plains which are cut by the ridges; brighter, rougher flows are also quite common. The particularly bright flows in the lower right corner are the northern extension of Mylitta Fluctus. The bright ridges adjacent to Mylitta Fluctus at the bottom center of the image also appear to have been affected by the volcanic activity. Some of these bright features have been interpreted as down dropped areas roughly 5 kilometers (3 miles) wide. This would imply a region of extension where the crust has been pulled apart and thus was more easily flooded by the later lava flows. The thinner fractures running from the upper left seem to end at the ridge belt in the center of this mosaic. These thinner fractures are a continuation of a pattern seen throughout much of Lavinia and suggest a pattern of compression over a very large region. At the bottom of the image, overlying the ridges, is an impact crater 10 to 15 kilometers (6 to 10 miles) in diameter. The double or overlapped crater structure and asymmetrical ejecta pattern suggests that the incoming body broke up shortly before it hit, leaving closely spaced craters. The placement of the crater on top of the ridges implies it is younger than the ridges; in fact

  14. The Mid-Ocean Ridge

    SciTech Connect

    Macdonald, K.C. ); Fox, P.J. )

    1990-06-01

    The Mid-Ocean Ridge girdles the earth like the seam of a baseball. For more than 75,000 kilometers, this submerged range of razorback mountains--many higher than the greatest peaks on land--marks the restless boundary between continental plates. An analysis of this huge structure reveals a fascinating picture of how it is created by magma welling up as the plates pull apart. The paper discusses sea-floor spreading, the magma supply model, types of discontinuities, off-axis structures, small overlaps and DEVALs (slight DEViations in Axial Linearity), and aquatic life.

  15. Ridge effect and alignment phenomenon

    SciTech Connect

    Lokhtin, I. P. Managadze, A. K. Snigirev, A. M.

    2013-05-15

    It is assumed that the ridge effect observed by the CMS Collaboration in proton-proton collisions at the LHC and the phenomenon observed by the Pamir Collaboration in emulsion experiments with cosmic rays and characterized by the alignment of spots on a film is a manifestation of the same as-yet-unknown mechanism of the emergence of a coplanar structure of events. A large coplanar effect at the LHC in the region of forward rapidities is predicted on the basis of this hypothesis and an analysis of experimental data.

  16. Extinct mid-ocean ridges and insights on the influence of hotspots at divergent plate boundaries

    NASA Astrophysics Data System (ADS)

    MacLeod, Sarah; Dietmar Müller, R.; Williams, Simon; Matthews, Kara

    2016-04-01

    We review all global examples of confirmed or suspected extinct mid-ocean ridges that are preserved in present-day ocean basins. Data on their spreading rate prior to extinction, time of cessation, length of activity, bathymetric and gravity signature are analysed. This analysis identifies some differences between subgroups of extinct ridges, including microplate spreading ridges, back-arc basin ridges and large-scale mid-ocean ridges. Crustal structure of extinct ridges is evaluated using gravity inversion to seek to resolve a long-standing debate on whether the final stages of spreading leads to development of thinned or thickened crust. Most of the ridges we assess have thinner crust at their axes than their flanks, yet a small number are found to have a single segment that is overprinted by an anomalous feature such as a seamount or volcanic ridge. A more complex cessation mechanism is necessary in these cases. The location of spreading centres at their time of cessation relative to hotspots was also evaluated using a global plate reconstruction. This review provides strong evidence for the long-term interaction of spreading centres with hotspots and plate boundaries have been frequently modified within the radius of a hotspot zone of influence.

  17. Terrestrial Analogs for Planetary Wrinkle Ridges

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.; Golombek, M. P.

    1985-01-01

    Wrinkle ridges are common physiographic features on the terrestrial planets. Their origin has remained enigmatic, although two different types of models, volcanic and tectonic, have been proposed. The major impediment to deciphering the origin of wrinkle ridges has been the lack of a terrestrial analog. Seven terrestrial analogs were discussed, two in detail. Their implications for the origin for planetary wrinkle ridges were considered. All of the terrestrial analogs were formed in compressional environments and are the surface breaks of thrust faults.

  18. Ridge push engine of plate tectonics

    NASA Astrophysics Data System (ADS)

    Swedan, N. H.

    2015-07-01

    Convection of the upper mantle drives the tectonic plates. This convection is a thermodynamic cycle that exchanges heat and mechanical work between mantle and tectonic plates. Thermodynamics and observations indicate that the energy of the geological activities resulting from plate tectonics is equal to the latent heat of melting, calculated at mantle's pressure, of the new ocean crust regenerated at midocean ridges. This energy varies with the temperature of ocean floor, which is correlated with surface temperature. The main objective of this manuscript is to demonstrate that plate tectonics is a thermodynamic engine and can be calculated as such. Unlike existing tectonic models, the thermodynamic model is very sensitive to variations of the temperature of ocean floor, which is correlated with surface temperature. Therefore, the observed increase of geological activities can be projected with surface temperature rise. Other objectives of the manuscript are to calculate the force that drives the tectonic plates, estimate the energy released, and validate the calculations based on experiments and observations. In addition to the scientific merit of projecting the geological activities, a good projection can have a broader impact at the societal and economical levels. Investment and insurance related decisions are affected by climate change, and our ability to project the geological activities is of paramount importance for the economy and public safety. This work can thus provide tools to assess the risks and hazards associated with the trend of geological activities with surface temperature rise.

  19. Calendar year 1995 groundwater quality report for the Chestnut Ridge Hydrogeological Regime, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. 1995 Groundwater quality data and calculated rate of contaminant migration

    SciTech Connect

    1996-02-01

    This annual groundwater quality report (GWQR) contains groundwater quality data obtained during the 1995 calendar year (CY) at several hazardous and nonhazardous waste management facilities associated with the U.S. Department of Energy (DOE) Y-12 Plant located on the DOE Oak Ridge Reservation (ORR) southeast of Oak Ridge, Tennessee. These sites are located south of the Y-12 Plant in the Chestnut Ridge Hydrogeologic Regime (Chestnut Ridge Regime), which is one of three regimes defined for the purposes of groundwater quality monitoring at the Y-12 Plant. The Environmental Management Department of the Y-12 Plant Health, Safety, Environment, and Accountability (HSEA) Organization manages the groundwater monitoring activities in each regime as part of the Y-12 Plant Groundwater Protection Program (GWPP). The U.S. Environmental Protection Agency (EPA) identification number for the Y-12 Plant is TN.

  20. Characterization plan for the Oak Ridge National Laboratory Area-Wide Groundwater Program, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-08-01

    This characterization plan has been developed as part of the U.S. Department of Energy`s (DOE`s) investigation of the Groundwater Operable Unit (GWOU) at Oak Ridge National Laboratory (ORNL) located near Oak Ridge, Tennessee. The first iteration of the characterization plan is intended to serve as a strategy document to guide subsequent GWOU remedial investigations. The plan provides a rationale and organization for groundwater data acquisition, monitoring, and remedial actions to be performed during implementation of environmental restoration activities associated with the ORNL GWOU. It is important to note that the characterization plan for the ORNL GWOU is not a prototypical work plan. As such, remedial investigations will be conducted using annual work plans to manage the work activities, and task reports will be used to document the results of the investigations. Sampling and analysis results will be compiled and reported annually with a review of data relative to risk (screening level risk assessment review) for groundwater. This characterization plan outlines the overall strategy for the remedial investigations and defines tasks that are to be conducted during the initial phase of investigation. This plan is presented with the understanding that more specific addenda to the plan will follow.

  1. Tectonics of ridge-transform intersections at the Kane fracture zone

    NASA Astrophysics Data System (ADS)

    Karson, J. A.; Dick, H. J. B.

    1983-03-01

    The Kane Transform offsets spreading-center segments of the Mid-Atlantic Ridge by about 150 km at 24° N latitude. In terms of its first-order morphological, geological, and geophysical characteristics it appears to be typical of long-offset (>100 km), slow-slipping (2 cm yr-1) ridge-ridge transform faults. High-resolution geological observations were made from deep-towed ANGUS photographs and the manned submersible ALVIN at the ridge-transform intersections and indicate similar relationships in these two regions. These data indicate that over a distance of about 20 km as the spreading axes approach the fracture zone, the two flanks of each ridge axis behave in very different ways. Along the flanks that intersect the active transform zone the rift valley floor deepens and the surface expression of volcanism becomes increasingly narrow and eventually absent at the intersection where only a sediment-covered ‘nodal basin’ exists. The adjacent median valley walls have structural trends that are oblique to both the ridge and the transform and have as much as 4 km of relief. These are tectonically active regions that have only a thin (<200 m), highly fractured, and discontinuous carapace of volcanic rocks overlying a variably deformed and metamorphosed assemblage of gabbroic rocks. Overprinting relationships reveal a complex history of crustal extension and rapid vertical uplift. In contrast, the opposing flanks of the ridge axes, that intersect the non-transform zones appear to be similar in many respects to those examined elsewhere along slow-spreading ridges. In general, a near-axial horst and graben terrain floored by relatively young volcanics passes laterally into median valley walls with a simple block-faulted character where only volcanic rocks have been found. Along strike toward the fracture zone, the youngest volcanics form linear constructional volcanic ridges that transect the entire width of the fracture zone valley. These volcanics are continuous with

  2. Emergency preparedness at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Skipper, M.N.

    1990-03-01

    Emergency preparedness for industry was commonly believed to be an essential responsibility on the part of management. Therefore, this study was conducted to research and accumulate information and data on emergency preparedness at Oak Ridge National Laboratory (ORNL). The objective of this study was to conduct a thorough evaluation of emergency preparedness knowledge among employees to determine if they were properly informed or if they needed more training. Also, this study was conducted to provide insight to management as to what their responsibility was concerning this training. To assess employee emergency preparedness knowledge, a questionnaire was developed and administered to 100 employees at ORNL. The data was analyzed using frequencies and percentages of response and was displayed through the use of graphs within the report. 22 refs., 22 figs.

  3. Investigation of E-W Trending Parallel Ridges North of the Galápagos Archipelago

    NASA Astrophysics Data System (ADS)

    Mello, C.; Harpp, K. S.; Mittelstaedt, E. L.; Geist, D.; Fornari, D. J.; Soule, S.; R/v Melville Mv1007 Flamingo Cruise Scientific Party

    2010-12-01

    In 2010, the R/V Melville MV1007 cruise collected EM122 multibeam bathymetry, MR1 sidescan sonar reflectivity data, and seafloor rock samples from an area surrounding the Galápagos Spreading Center (GSC) in the vicinity of the Galápagos Islands. The GSC is cut by a large, N-S trending transform fault at 90°50’W. The Nazca Plate (west of the transform) is dominated by volcanic seamounts, most of which are aligned in NW-SE trending lineaments. In contrast, the Cocos Plate (east of the transform) is heavily faulted and features four major ridges that trend 90° to 110°. In comparison to the surrounding seafloor, the ridges are strongly fractured with faults that strike sub-parallel to the GSC. To the west, the ridges wrap into the transform and trend more NW-SE. These ridges are unusual and suggest complications to our current understanding of the tectonic history of the region. The faulted ridges extend to the transform and appear to be cut and deformed by it; therefore, they may be linked to the opening of the transform through a series of discrete ridge jumps. Moreover, the ridges’ roughly symmetrical topographic profiles mirror bathymetric profiles at abandoned spreading centers such as Mathematician Ridge, and are dissimilar to the asymmetric profiles of abyssal hills. Waning magma supplies at well-documented abandoned ridges yield differentiated rocks similar to the icelandites dredged from our study area, which exhibit SiO2 ~55-65% wt.%, and major element variations that indicate substantial removal of CPX and plagioclase. Incompatible trace element ratios (e.g., Nb/La) reveal the presence of Galápagos plume material throughout the tectonized region. Trace element ratios are similar to those in axial GSC lavas and suggest the faulted ridges may have originated at the active spreading center. Volcanic seamounts complicate the interpretation of the faulted ridges as being simple abandoned spreading centers, however, and may necessitate further

  4. High resolution bathymetric and sonar images of a ridge southeast of Terceira Island (Azores plateau)

    NASA Astrophysics Data System (ADS)

    Lourenço, N.; Miranda, J. M.; Luis, J.; Silva, I.; Goslin, J.; Ligi, M.

    2003-04-01

    The Terceira rift is a oblique ultra-slow spreading system where a transtensive regime results from differential movement between Eurasian and African plates. So far no classical ridge segmentation pattern has here been observed. The predominant morphological features are fault controlled rhombic shaped basins and volcanism related morphologies like circular seamounts and volcanic ridges. We present SIMRAD EM300 (bathymetry + backscatter) images acquired over one of these ridges located SE of Terceira Island, during the SIRENA cruise (PI J. Goslin), which complements previous TOBI mosaics performed over the same area during the AZZORRE99 cruise (PI M. Ligi). The ridge presents a NW-SE orientation, it is seismically active (a seismic crisis was documented in 1997) and corresponds to the southern branch of a V shape bathymetric feature enclosing the Terceira Island and which tip is located west of the Island near the 1998 Serreta ridge eruption site. NE of the ridge, the core of the V, corresponds to the North Hirondelle basin. All this area corresponds mainly to Brunhes magnetic epoch. The new bathymetry maps reveal a partition between tectonic processes, centred in the ridge, and volcanism present at the bottom of the North Hirondelle basin. The ridge high backscatter surface is cut by a set of sub-parallel anastomosed normal faults striking between N130º and N150º. Some faults present horse-tail terminations. Fault splays sometimes link to neighbour faults defining extensional duplexes and fault wedge basins and highs of rhombic shape. The faulting geometry suggests that a left-lateral strike slip component should be present. The top of the ridge consists on an arched demi-.horst, and it is probably a volcanic structure remnant (caldera system?), existing prior to onset of the tectonic stage in the ridge. Both ridge flanks display gullies and mass wasting fans at the base of the slope. The ridge vicinities are almost exclusively composed of a grayish homogeneous

  5. Geophysical Investigation of Australian-Antarctic Ridge Using High-Resolution Gravity and Bathymetry

    NASA Astrophysics Data System (ADS)

    Kim, S. S.; Lin, J.; Park, S. H.; Choi, H.

    2015-12-01

    Much of the Australian-Antarctic Ridge (AAR) has been remained uncharted until 2011 because of its remoteness and harsh weather conditions. From 2011, the multidisciplinary ridge program initiated by the Korea Polar Research Institute (KOPRI) surveyed the little-explored eastern ends of the AAR to characterize the tectonics, geochemistry, and hydrothermal activity of this intermediate spreading system. In this study, we present a detailed analysis of a 300-km-long supersegment of the AAR to quantify the spatial variations in ridge morphology and axial and off-axis volcanisms as constrained by high-resolution shipboard bathymetry and gravity. The ridge axis morphology alternates between rift valleys and axial highs within relatively short ridge segments. To obtain a geological proxy for regional variations in magma supply, we calculated residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography for neighboring seven sub-segments. The results of the analyses revealed that the southern flank of the AAR is associated with shallower seafloor, more negative RMBA, thicker crust, and/or less dense mantle in comparison to the conjugate northern flank. Furthermore, this north-south asymmetry becomes more prominent toward the KR1 supersegment of the AAR. The axial topography of the KR1 supersegment exhibits a sharp transition from axial highs at the western end to rift valleys at the eastern end, with regions of axial highs being associated with more robust magma supply as indicated by more negative RMBA. We also compare and contrast the characteristics of the AAR supersegment with that of other ridges of intermediate spreading rates, including the Juan de Fuca Ridge, Galápagos Spreading Center, and Southeast Indian Ridge west of the Australian-Antarctic Discordance, to investigate the influence of ridge-hotspot interaction on ridge magma supply and tectonics.

  6. Discovery of a black smoker vent field and vent fauna at the Arctic Mid-Ocean Ridge

    PubMed Central

    Pedersen, Rolf B.; Rapp, Hans Tore; Thorseth, Ingunn H.; Lilley, Marvin D.; Barriga, Fernando J. A. S.; Baumberger, Tamara; Flesland, Kristin; Fonseca, Rita; Früh-Green, Gretchen L.; Jorgensen, Steffen L.

    2010-01-01

    The Arctic Mid-Ocean Ridge (AMOR) represents one of the most slow-spreading ridge systems on Earth. Previous attempts to locate hydrothermal vent fields and unravel the nature of venting, as well as the provenance of vent fauna at this northern and insular termination of the global ridge system, have been unsuccessful. Here, we report the first discovery of a black smoker vent field at the AMOR. The field is located on the crest of an axial volcanic ridge (AVR) and is associated with an unusually large hydrothermal deposit, which documents that extensive venting and long-lived hydrothermal systems exist at ultraslow-spreading ridges, despite their strongly reduced volcanic activity. The vent field hosts a distinct vent fauna that differs from the fauna to the south along the Mid-Atlantic Ridge. The novel vent fauna seems to have developed by local specialization and by migration of fauna from cold seeps and the Pacific. PMID:21119639

  7. Site characterization plan for groundwater in Waste Area Grouping 1 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Lee, R.R.; Curtis, A.H.; Houlberg, L.M.; Purucker, S.T.; Singer, M.L.; Tardiff, M.F.; Wolf, D.A.

    1994-07-01

    The Waste Area Grouping (WAG) 1 Groundwater Operable Unit (OU) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, is undergoing a site characterization to identify environmental contamination that may be present. This document, Site Characterization Report for Groundwater in Waste Area Grouping I at Oak Ridge National Laboratory, Oak Ridge, Tennessee, identifies areas of concern with respect to WAG 1 groundwater and presents the rationale, justification, and objectives for conducting this continuing site characterization. This report summarizes the operations that have taken place at each of the areas of concern in WAG 1, summarizes previous characterization studies that have been performed, presents interpretations of previously collected data and information, identifies contaminants of concern, and presents an action plan for further site investigations and early actions that will lead to identification of contaminant sources, their major groundwater pathways, and reduced off-site migration of contaminated groundwater to surface water. Site characterization Activities performed to date at WAG I have indicated that groundwater contamination, principally radiological contamination, is widespread. An extensive network of underground pipelines and utilities have contributed to the dispersal of contaminants to an unknown extent. The general absence of radiological contamination in surface water at the perimeter of WAG 1 is attributed to the presence of pipelines and underground waste storage tank sumps and dry wells distributed throughout WAG 1 which remove more than about 40 million gal of contaminated groundwater per year.

  8. Ridges and tidal stress on Io

    USGS Publications Warehouse

    Bart, G.D.; Turtle, E.P.; Jaeger, W.L.; Keszthelyi, L.P.; Greenberg, R.

    2004-01-01

    Sets of ridges of uncertain origin are seen in twenty-nine high-resolution Galileo images, which sample seven locales on Io. These ridges are on the order of a few kilometers in length with a spacing of about a kilometer. Within each locale, the ridges have a consistent orientation, but the orientations vary from place to place. We investigate whether these ridges could be a result of tidal flexing of Io by comparing their orientations with the peak tidal stress orientations at the same locations. We find that ridges grouped near the equator are aligned either north-south or east-west, as are the predicted principal stress orientations there. It is not clear why particular groups run north-south and others east-west. The one set of ridges observed far from the equator (52?? S) has an oblique azimuth, as do the tidal stresses at those latitudes. Therefore, all observed ridges have similar orientations to the tidal stress in their region. This correlation is consistent with the hypothesis that tidal flexing of Io plays an important role in ridge formation. ?? 2004 Elsevier Inc. All rights reserved.

  9. Cedar Ridge Camp: Using the Local Environment

    ERIC Educational Resources Information Center

    Burke, Grayson

    2007-01-01

    In 2007 Cedar Ridge Camp opened for its first season as a traditional co-ed summer camp and year-round outdoor education and recreation centre. The mission would centre on creating a program that would encourage personal development and growth through a shared outdoor experience. Cedar Ridge's main goals were to promote the formation of close…

  10. Earthquakes and beach ridges on Kamchatka

    NASA Astrophysics Data System (ADS)

    Bourgeois, J.; Ortuno, M.; Thibault, C.; Higman, B.; Pinegina, T.

    2003-04-01

    There are several proposed origins for beach ridges, or berms, with the majority of studies focused on Atlantic-type margins. Primary factors invoked for beach-ridge formation include changes in sea-level, in wave climate, and in sediment supply. On subduction-zone margins, co-seismic deformation can force any of these three factors. For example, subsidence of the shoreline (local sea level rise) will generally lead to coastal erosion, whereas shoreline uplift (subduing local wave climate) will strand beach ridges. Earthquake-triggered landslides may significantly increase sediment supply. Some authors working on Pacific margins have correlated either beach ridges (e.g., A. Kurbatov on Kamchatka; P. Saltonstall and G. Carver on Kodiak), or buried erosional scarps (e.g. R.A. Meyers et al., Washington State) with subduction-zone earthquakes and the seismic cycle. Our work on Kamchatka provides examples where buried scarps and beach ridges are superimposed, each pair of which we interpret to be the result of a single seismic cycle, apparently consistent with some other data and interpretations (Kodiak, particularly). That is, in a setting where the shoreline subsides during an earthquake and recovers thereafter, beach ridges overlie buried scarps. In one case on Kamchatka, in southern Vestnik Bay, there is a spectacular outcrop illustrating this relationship. This model by no means explains all beach ridges, so identifying earthquake-forced beach ridges remains a challenge.

  11. Student Health Services at Orchard Ridge.

    ERIC Educational Resources Information Center

    Nichols, Don D.

    This paper provides a synoptic review of student health services at the community college level while giving a more detailed description of the nature of health services at Orchard Ridge, a campus of Oakland Community College. The present College Health Service program provides for a part-time (24 hrs./wk.) nurse at Orchard Ridge. A variety of…

  12. 27 CFR 9.158 - Mendocino Ridge.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Mendocino Ridge. 9.158 Section 9.158 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.158 Mendocino Ridge. (a) Name. The name of...

  13. Report on the remedial investigation of Bear Creek Valley at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Volume 2: Appendix A -- Waste sites, source terms, and waste inventory report; Appendix B -- Description of the field activities and report database; Appendix C -- Characterization of hydrogeologic setting report

    SciTech Connect

    1996-09-01

    This Remedial Investigation (RI) Report characterizes the nature and extent of contamination, evaluates the fate and transport of contaminants, and assesses risk to human health and the environment resulting from waste disposal and other US Department of Energy (DOE) operations in Bear Creek Valley (BCV). BCV, which is located within the DOE Oak Ridge Reservation (ORR) encompasses multiple waste units containing hazardous and radioactive wastes arising from operations at the adjacent Oak Ridge Y-12 Plant. The primary waste units discussed in this RI Report are the S-3 Site, Oil Landfarm (OLF), Boneyard/Burnyard (BYBY), Sanitary Landfill 1 (SL 1), and Bear Creek Burial Grounds (BCBG). These waste units, plus the contaminated media resulting from environmental transport of the wastes from these units, are the subject of this RI. This BCV RI Report represents the first major step in the decision-making process for the BCV watershed. The RI results, in concert with the follow-on FS will form the basis for the Proposed Plan and Record of Decision for all BCV sites. This comprehensive decision document process will meet the objectives of the watershed approach for BCV. Appendix A includes descriptions of waste areas and estimates of the current compositions of the wastes. Appendix B contains an extensive database of environmental data for the Bear Creek Valley Characterization Area. Information is also presented about the number and location of samples collected, the analytes examined, and the extent of data validation. Appendix C describes the hydrogeologic conceptual model for Bear Creek Valley. This model is one of the principal components of the conceptual site models for contaminant transport in BCV.

  14. Preferred orientation of Ridges in Phyllosilicate Terrains, Mars: Implications for Crustal Habitability

    NASA Astrophysics Data System (ADS)

    Mustard, J. F.; Saper, L.

    2012-12-01

    emplaced prior to the capping units or that rheological differences between the two units influenced the formation and expression of ridges. The mapped ridges have a preferred orientation centered at approximately 58° azimuth coinciding with the orientation of the major troughs of Nili Fossae, suggesting the influence of a common stress field. Ridges observed on Mars have been attributed to a variety of processes including exhumed igneous dikes, impact-generated pseudotachylyte and breccia dikes, eskers and eolian landforms. We consider an additional hypotheses: the ridges are mineralized fracture zones or relict conduits of fluid flow, that were established by impact-generated deformation in the crust, or by extensional stress during flexural readjustments due to loading after the Isidis basin-forming impact. The zones of concentrated flow were sealed, and preferentially hardened relative to the clay-bearing host rock and then exposed by differential erosion. Basin-scale impacts have the potential to remain hot for millions of years after the impact, providing a mechanism to drive hydrothermal circulation through the crust. We propose these ridges are preserved elements of regional subsurface hydrologic activity that was a key and persistent habitable zone. Head J. W., Mustard J. F. Meter. & Planet. Sci. 41, 1675-1690 [2006] Ehlmann B. L. et al., Nature, 479, pg. 53-60 [2011

  15. Environmental Monitoring Plan for the Oak Ridge Reservation, 2012

    SciTech Connect

    Thompson, Sharon D.

    2012-10-01

    The purpose of Oak Ridge Reservation (ORR) environmental surveillance is to characterize radiological and nonradiological conditions of the off-site environs and estimate public doses related to these conditions, confirm estimations of public dose based on effluent monitoring data, and, where appropriate, provide supplemental data to support compliance monitoring for applicable environmental regulations. This environmental monitoring plan (EMP) is intended to document the rationale, frequency, parameters, and analytical methods for the ORR environmental surveillance program and provides information on ORR site characteristics, environmental pathways, dose assessment methods, and quality management. ORR-wide environmental monitoring activities include a variety of media including air, surface water, vegetation, biota, and wildlife. In addition to these activities, site-specific effluent, groundwater, and best management monitoring programs are conducted at the Oak Ridge National Laboratory (ORNL), the Y-12 National Security Complex (Y-12), and the East Tennessee Technology Park (ETTP). This is revision 5.

  16. Manastash Ridge Observatory Autoguider Upgrade

    NASA Astrophysics Data System (ADS)

    Lozo, Jason; Huehnerhoff, Joseph; Armstrong, John; Davila, Adrian; Johnson, Courtney; McMaster, Alex; Olinger, Kyle

    2016-06-01

    The Astronomy Undergraduate Engineering Group (AUEG) at the University of Washington has designed and manufactured a novel autoguider system for the 0.8-meter telescope at the Manastash Ridge Observatory in Ellensburg, Washington. The system uses a pickoff mirror placed in the unused optical path, directing the outer field to the guide camera via a system of axi-symmetrically rotating relay mirrors (periscope). This allows the guider to sample nearly 7 times the area that would be possible with the same fixed detector. This system adds closed loop optical feedback to the tracking capabilities of the telescope. When tuned the telescope will be capable of acheiving 0.5 arcsecond tracking or better. Dynamic focusing of the primary optical path will also be an included feature of this system. This unique guider will be a much needed upgrade to the telescope allowing for increased scientific capability.

  17. Microbial diversity in subseafloor fluids from Explorer Ridge, Northeast Pacific

    NASA Astrophysics Data System (ADS)

    Bolton, S.; Huber, J. A.; Embley, R.; Butterfield, D. A.; Baross, J. A.

    2003-12-01

    The Gorda, Juan de Fuca and Explorer Ridges are first order spreading centers located in the northeast Pacific. While the Gorda and Juan de Fuca Ridges have been extensively sampled for chemical and microbiological analyses, what little is known about the Explorer Ridge is from preliminary observations made in the mid-1980's. A cruise in 2002 revisited the area and discovered vigorous hydrothermal activity at Magic Mountain, a site located outside the primary rift valley. Explorer Ridge is an important site to compare with other well-described vent sites on the Juan de Fuca Ridge. Our research has focused on describing the phylogenetic and physiological diversity of bacteria and archaea in low temperature hydrothermal fluids in an effort to identify subseafloor indicator organisms and to use the physiological characteristics of these organisms to help constrain subseafloor habitat characteristics. We have previously established that there are microbial taxa that are unique to subseafloor habitats associated with diffuse flow fluids at Axial Seamount and at Endeavour both located on the Juan de Fuca Ridge. These included cultured anaerobic, thermophilic and hyperthermophilic heterotrophs, methanogens and sulfur metabolizers. Moreover, results from molecular phylogeny analyses using the 16S rRNA sequences identified a phylogenetically diverse group of bacteria belonging to the epsilon-proteobacteria. While anaerobic hyperthermophiles were cultured from some diffuse-flow vent sites at Explorer, they were less abundant than at Axial Volcano and Endeavour, and curiously, no methanogens were cultured or detected in 16S rRNA clonal libraries. Like Axial, a diverse group of epsilon-proteobacterial clones were found with many similar to those identified from Axial Seamount and other hydrothermal vent sites, although there appears to be some unique species. The overall bacterial diversity at Explorer appears different than at Axial, possibly linked to temperature or chemical

  18. Are Axial Volcanic Ridges where all the (volcanic) action is?

    NASA Astrophysics Data System (ADS)

    Searle, R. C.

    2012-12-01

    Although axial volcanic ridges (AVRs) are generally recognised as the main loci for lithospheric generation at slow-spreading mid-ocean ridges, various recent studies have suggested that axial volcanism is not confined to them. Here I present evidence from three studies for significant amounts of off-AVR volcanism at three slow-spreading ridges. 1) Near-bottom side-scan sonar (TOBI) images of the Mid-Atlantic Ridge near 13°N show a complex pattern of closely-spaced, active oceanic core complexes (OCCs) where plate separation is largely a-volcanic, separated by short segments of vigorous volcanic spreading. In one such volcanic segment, the brightest sea floor and therefore inferred youngest volcanism occurs not on the topographic axis (an apparently 'old' AVR) but at the edge of a broad axial valley. 2) A similar TOBI survey of the Mid-Cayman Spreading Centre reveals AVRs in the north and south flanking an OCC (Mt. Dent) and a non-volcanic ridge interpreted as tectonically extruded peridotite ('smooth' sea floor). In both AVR segments there are clear, young lava flows that have erupted from perched sources part way up the median valley walls and have partly flowed down into the valley. 3) The third case is from the Mid-Atlantic Ridge at 45°N, where we conducted a detailed geophysical and geological study of an AVR and surrounding median valley floor. The AVR is largely surrounded by flat sea floor composed mainly of lobate and sheet flows, whereas the AVR comprises predominantly pillow lavas. Although we have no firm dates, various indicators suggest most lavas on the AVR are around 10ka old or somewhat less. The apparently youngest (brightest acoustic returns, thinnest sediment cover) of the flat-lying lava flows appears to have a similar age from its degree of sediment cover. Contact relations between these lavas and the AVR flanks show no evidence of a clear age difference between the two, and we think both types of eruption may have occurred roughly

  19. Public involvement plan for the Oak Ridge Reservation

    SciTech Connect

    1996-06-01

    This Public Information Plan is a user`s guide for getting involved in US Department of Energy environmental decisions in Oak Ridge, Tennessee. It outlines the many ways the public can help DOE find solutions to its environmental challenges. The plan focuses on DOE`s Environmental Management public involvement activities. Environmental Management is composed of the following programs: environmental restoration, technology development and waste management.

  20. Magmatic and amagmatic seafloor generation at the ultraslow-spreading Gakkel ridge, Arctic Ocean.

    PubMed

    Michael, P J; Langmuir, C H; Dick, H J B; Snow, J E; Goldstein, S L; Graham, D W; Lehnert, K; Kurras, G; Jokat, W; Mühe, R; Edmonds, H N

    2003-06-26

    A high-resolution mapping and sampling study of the Gakkel ridge was accomplished during an international ice-breaker expedition to the high Arctic and North Pole in summer 2001. For this slowest-spreading endmember of the global mid-ocean-ridge system, predictions were that magmatism should progressively diminish as the spreading rate decreases along the ridge, and that hydrothermal activity should be rare. Instead, it was found that magmatic variations are irregular, and that hydrothermal activity is abundant. A 300-kilometre-long central amagmatic zone, where mantle peridotites are emplaced directly in the ridge axis, lies between abundant, continuous volcanism in the west, and large, widely spaced volcanic centres in the east. These observations demonstrate that the extent of mantle melting is not a simple function of spreading rate: mantle temperatures at depth or mantle chemistry (or both) must vary significantly along-axis. Highly punctuated volcanism in the absence of ridge offsets suggests that first-order ridge segmentation is controlled by mantle processes of melting and melt segregation. The strong focusing of magmatic activity coupled with faulting may account for the unexpectedly high levels of hydrothermal activity observed. PMID:12827193

  1. Hydrothermal Exploration of Mid-Ocean Ridges: Where Might the Largest Sulfide Deposits Occur?

    NASA Astrophysics Data System (ADS)

    German, C. R.; Petersen, S.; Hannington, M. D.

    2015-12-01

    We review the distribution of modern-day seafloor hydrothermal activity along the global mid-ocean ridge crest (MOR) and the mineral deposits being formed at those sites. To date, one form of hydrothermal activity - "black smoker" venting - has been prospected for along >30% of the global mid ocean ridge crest and some important trends have emerged. Submarine venting can occur along all mid-ocean ridges, of all spreading rates, in all ocean basins. While the abundance of currently active venting (from water column signals), scales linearly with seafloor spreading rate (a proxy for magmatic heat-flux) there is an "excess" of high temperature venting along slow and ultra-slow spreading ridges when compared to early predictions. Consistent with this, no more than half of the sites responsible for "black smoker" plume signals along the slow spreading Mid Atlantic Ridge are associated with magmatic systems with the other half hosted under tectonic control. The latter appear both to be longer-lived than, and to give rise to much larger sulfide deposits than, their magmatic counterparts - presumably as a result of sustained fluid flow. Where these tectonic-hosted systems also involve water-rock interaction with ultramafic sources, seafloor massive sulfide deposits exhibit highly concentrated Cu and Au in surface samples (>10wt.% average Cu content and >3ppm average Au). Intriguingly, first detailed examinations of hydrothermally active sites along ultraslow-spreading ridges seems to indicate that they may depart beyond the slow-spreading Mid-Atlantic Ridge pattern. Hydrothermal plume distributions may follow the same (~50:50) distribution of "black smoker" plume signals between magmatic and tectonics settings, but the first three "black smoker" sites tracked to source have all revealed large polymetallic sulfide deposits - in both magmatic as well as tectonic settings. Could ultra-slow ridges represent the richest mineral resource potential along the global MOR?

  2. Wrinkle ridges of Arcadia Planitia, Mars

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.

    1993-01-01

    Wrinkle ridges of Arcadia Planitia were examined to determine their morphology, spatial distribution, and the amount of crustal shortening and strain they accommodate. Ridges trend generally northward, but their orientation and distribution are strongly controlled by the relief of the underlying hobby material. Ridges begin or end at inselbergs of older terrain and are associated with buried craters. Arcadia Planitia ridges have an average width of 3425 m and accommodate an average folding shortening of 3 m and a faulting shortening of 55 m; mean total shortening is 57 m. Three east-west transects were constructed at 20 deg 25 deg and 28 deg N to estimate regional shortening and strain. Average total shortening across the transects is about 900 m, corresponding to a regional compressive strain of 0.06 percent. The total shortening and compression across Arcadia Planitia are less than in Lungae Planum. Faults associated with the Arcadia ridges are inferred to have a westward dip compared with an eastward dip for Lungae Planum ridges. The general levels of compression and symmetric orientation of the ridges suggest a regionally organized stress system.

  3. Oak Ridge Reservation annual site environmental report for 2008

    SciTech Connect

    none,

    2009-09-01

    The Oak Ridge Reservation (ORR) consists of three major government-owned, contractor-operated facilities: the Y-12 National Security Complex, Oak Ridge National Laboratory, and East Tennessee Technology Park. The ORR was established in the early 1940s as part of the Manhattan Project, a secret undertaking that produced materials for the first atomic bombs. The reservation’s role has evolved over the years, and it continues to adapt to meet the changing defense, energy, and research needs of the United States. Both the work carried out for the war effort and subsequent research, development, and production activities have involved, and continue to involve, the use of radiological and hazardous materials. The Oak Ridge Reservation Annual Site Environmental Report and supporting data are available at http://www.ornl.gov/sci/env_rpt or from the project director. This document is prepared annually to summarize environmental activities, primarily environmental monitoring activities, on the Oak Ridge Reservation (ORR) and within the ORR surroundings. The document fulfills the requirement of Department of Energy (DOE) Order 231.1A, Environment, Safety and Health Reporting, for an annual summary of environmental data to characterize environmental performance. The environmental monitoring criteria are described in DOE Order 450.1A, Environmental Protection Program. The results summarized in this report are based on data collected prior to and through 2008. This report is not intended to provide the results of all sampling on the ORR. Additional data collected for other site and regulatory purposes, such as environmental restoration/remedial investigation reports, waste management characterization sampling data, and environmental permit compliance data, are presented in other documents that have been prepared in accordance with applicable DOE guidance and/or laws and are referenced herein as appropriate. Corrections to the report for the previous year are found in Appendix

  4. Hydrothermal Vents of Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Stark, Joyce

    As a member of REVEL (Research and Education: Volcanoes, Exploration and Life), I had an opportunity to participant in a scientific research cruise focused on the active volcanoes along the Juan de Fuca Ridge, the submarine spreading center off the Washington- Oregon-Canada coast. REVEL was sponsored by the National Science Foundation, University of Washington, Pennsylvania State University and the American Museum of Natural History. We studied the geological, chemical and biological processes associated with active hydrothermal systems and my research focused on the biological communities of the sulfide structures. We worked on board the Woods Hole Oceanographic Institution Vessel, R/V Atlantis and the submersible ALVIN was used to sample the "Black Smokers". As a member of the scientific party, I participated in collection and sorting of biological specimens from the vent communities, attended lectures by scientists, contributed to the cruise log website, maintained a journal and developed my own research project. It was my responsibility to bring this cutting-edge research back to the classroom.

  5. Episodes of Aleutian Ridge explosive volcanism

    USGS Publications Warehouse

    Hein, J.R.; Scholl, D. W.; Miller, J.

    1978-01-01

    Earlier workers have overlooked deep-sea bentonite beds when unraveling the Cenozoic volcanic history of an area. In the North Pacific, identification of Miocene and older volcanic episodes is possible only if both altered (bentonite) and unaltered ash beds are recognized. Our study, which includes bentonite beds, shows that volcanism on the Aleutian Ridge and Kamchatka Peninsula has been cyclic. Volcanic activity seems to have increased every 2.5 ?? 10 6 years for the past 10 ?? 106 years and every 5.0 ?? 106 years for the time span from 10 to 20 ?? 10 6 years ago. The middle and late Miocene and the Quaternary were times of greatly increased volcanic activity in the North Pacific and elsewhere around the Pacific Basin. The apparent absence of a volcanic record before the late Miocene at Deep Sea Drilling Project site 192 is the result not of plate motion, as suggested by Stewart and by Ninkovich and Donn, but rather of the diagenesis of ash layers. Major, apparently global volcanic episodes occurred at least twice in the last 20 ?? 106 years. Yet, only one major glacial epoch (the Pleistocene) has occurred. Therefore, even though glaciation coincided with an increase in Quaternary volcanism, the increased volcanism itself may not have been the primary cause of global cooling. Copyright ?? 1978 AAAS.

  6. Polar gravel beach-ridge systems as archive of climate variations (South Shetland Islands / Western Antarctic Peninsula)

    NASA Astrophysics Data System (ADS)

    Lindhorst, Sebastian; Schutter, Ilona; Betzler, Christian

    2014-05-01

    The architecture of polar gravel beach-ridge systems is presented and their potential as archive of past wave-climate conditions is evaluated. Raised beaches are common on paraglacial coasts which experienced a net uplift during the Holocene as the result of postglacial isostatic rebound. Ground-penetrating radar data obtained along the coasts of Potter Peninsula (King George Island) show that beach ridges unconformably overlie seaward-dipping strata of the strand plain. Whereas strand-plain progradation is the result of swash sedimentation at the beach face under enduring calm conditions, ridge construction reflects enhanced wave action at the beach as the result of increased storminess or reduced nearshore sea ice. The number of individual ridges which are preserved from a given time interval varies along the coast depending on the morphodynamic setting: Sheltered coasts are characterized by numerous small ridges, whereas fewer but larger ridges develop on exposed beaches. The sedimentary architecture of individual beach ridges is interpreted to reflect maximum wave-runup height during the time of ridge construction. Ridges at sheltered parts of the coast exhibit either seaward-dipping beds, interpreted to result from swash deposition, or an aggradational stacking pattern being the result of wave overtopping. At exposed beaches, larger ridges develop composed of seaward- as well as landward-dipping beds. Radiocarbon data indicate that the frequency of ridge building ranges from decades in low-energy settings to more than 1500 years under high-energy conditions. In the study area, beach ridges group into four distinct levels: up to 4 m, 5.5 m, 7.5 m, and 10 m above the present day storm beach. Hence, these levels are interpreted to reflect periods of increased wave activity in the area of the South Shetland Islands at about 4.3, 3.1, 1.9, and 0.35 ka cal BP.

  7. The structure of mid-ocean ridges

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.; Toomey, Douglas R.

    1992-01-01

    Recent research results on the structure of midocean ridges are reviewed. The new view of ridge-axis crustal structure obtained from high-resolution seismology is reviewed, emphasizing the variation of that structure with spreading rate and along-axis at a given spreading rate. Recent results on upper mantle structure beneath ridges are examined, including variations with seafloor age, indications from anisotropy for directions of mantle flow, and long-wavelength along-axis variations in structure and their implications for lateral heterogeneity in mantle temperature and composition.

  8. Physical Volcanology of the Huckleberry Ridge Tuff

    NASA Astrophysics Data System (ADS)

    Wilson, C. J.

    2009-12-01

    The 2.06 Ma Huckleberry Ridge Tuff, product of the oldest and largest (ca. 2500 cubic km) of the three caldera-forming eruptions from the Yellowstone system, consists of three major ignimbrite units (A, B, C) with underlying and intervening fall deposits. Despite intense welding, and subsequent significant faulting and erosion, the broad characteristics of the deposits provide valuable insights into the eruption dynamics. Field evidence shows unambiguously that the eruption was spasmodic and prolonged, in addition to complexities previously recognised in vent locations and eruptive compositions by R.L. Christiansen (US Geological Survey Professional Paper 729-G, 2001). The initial fall activity, although plinian in dispersal, was not exceptionally powerful or unusual in any respect, and gives no obvious hints of the scale of what was to follow. This initial fall activity was also prolonged, possibly over months, during which time intrafall reworking occurred at several stages. Ignimbrite unit A is much the largest in volume, and represents most of the thickness of tuff southwest of the caldera, including the rheomorphic tuff of Big Bend Ridge previously mapped as B. Units A and B are separated by weeks or more, based on cooling breaks, and units B and C separated by years or more, based on breaks in cooling and degassing histories. The fall deposit separating ignimbrite units B and C also was erupted spasmodically. Vent-derived lithics in the ignimbrite units are generally mm to cm across, and no coarse lithic-rich facies have been found in units A or B to indicate close proximity to caldera margins. There is also a diversity of juvenile ejecta: red-brown scoria, coarsely porphyritic dense juvenile clasts and their granophyric equivalents, and rhyolitic pumices of a great variety of textures and crystal contents. The overall tuff represents the product of three large and many other small events daisy-chained together and prolonged over a period of probably years to

  9. Ultraslow, slow, or fast spreading ridges: an interplay between plate tectonics and mantle convection

    NASA Astrophysics Data System (ADS)

    Husson, Laurent; Yamato, Philippe; Bézos, Antoine

    2015-04-01

    Oceanic spreading rates are highly variable. These variations are known to correlate to a variety of surface observables, like magmatic production, heat flow or bathymetry, which lead to classify ridges into fast and slow spreading ridges, but also as the more peculiar ultraslow spreading regime. Here we explore the dynamic relationships between spreading ridges, plate tectonics and mantle flow. For this, we first focus on the thermal signature at deeper levels that we infer from the global S-wave seismic tomography model of Debayle and Ricard (2012). We show that the thermal structure of ridges gradually departs from the half-space cooling model for slow, and above all ultraslow spreading ridges. We also infer that the sub- lithospheric mantle temperature decreases by more than 180K from fast spreading to ultraslow spreading regimes. Both observations indicate that the mantle convection pattern is increasingly altered underneath slow and ultraslow spreading ridges. We suggest that this is due to far-field tectonics on the other ends of lithospheric plates. Not only it modulates the spreading rates but it also alters the convection regime: collisions at active plate boundaries obstruct plate motion and decrease their velocities. We then test this hypothesis using a thermo-mechanical model that represents a convection cell carrying a positively buoyant continental lithosphere on top. The continent gradually drifts away from the spreading ridge, from which the oceanic lithosphere grows and cools while the continent eventually collides at the opposite side. In turn, this event drastically modifies the upper kinematic condition for the convecting mantle that evolves from a mobile lid regime to an almost stagnant lid regime. Implications on spreading ridges are prominent: heat advection is slower than thermal diffusion, which causes the oceanic lithosphere to thicken faster; the oceanic plates get compressed and destabilized by a growing number of small scale transient

  10. Evidence for accumulated melt beneath the slow-spreading Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Sinha, M. C.; Navin, D. A.; MacGregor, L. M.; Constable, S.; Peirce, C.; White, A.; Heinson, G.; Inglis, M. A.

    The analysis of data from a multi-component geophysical experiment conducted on a segment of the slow-spreading (20 mm yr-1) Mid-Atlantic Ridge shows compelling evidence for a significant crustal magma body beneath the ridge axis. The role played by a crustal magma chamber beneath the axis in determining both the chemical and physical architecture of the newly formed crust is fundamental to our understanding of the accretion of oceanic lithosphere at spreading ridges, and over the last decade subsurface geophysical techniques have successfully imaged such magma chambers beneath a number of intermediate and fast spreading (60-140 mm yr-1 full rate) ridges. However, many similar geophysical studies of slow-spreading ridges have, to date, found little or no evidence for such a magma chamber beneath them. The experiment described here was carefully targeted on a magmatically active, axial volcanic ridge (AVR) segment of the Reykjanes Ridge, centred on 57 degrees 43 minutes North. It consisted of four major components: wide-angle seismic profiles using ocean bottom seismometers; seismic reflection profiles; controlled source electromagnetic sounding; and magneto-telluric sounding. Interpretation and modelling of the first three of these datasets shows that an anomalous body lies at a depth of between 2 and 3 km below the seafloor beneath the axis of the AVR. This body is characterized by anomalously low seismic P-wave velocity and electrical resistivity, and is associated with a seismic reflector. The geometry and extent of this melt body shows a number of similarities with the axial magma chambers observed beneath ridges spreading at much higher spreading rates. Magneto-telluric soundings confirm the existence of very low electrical resistivities in the crust beneath the AVR and also indicate a deeper zone of low resistivity within the upper mantle beneath the ridge.

  11. Controls on melting at spreading ridges from correlated abyssal peridotite - mid-ocean ridge basalt compositions

    NASA Astrophysics Data System (ADS)

    Regelous, Marcel; Weinzierl, Christoph G.; Haase, Karsten M.

    2016-09-01

    Variations in the volume and major element composition of basalt erupted along the global mid-ocean ridge system have been attributed to differences in mantle potential temperature, mantle composition, or plate spreading rate and lithosphere thickness. Abyssal peridotites, the residues of mantle melting beneath mid-ocean ridges, provide additional information on the melting process, which could be used to test these hypotheses. We compiled a global database of abyssal peridotite compositions averaged over the same ridge segments defined by Gale et al. (2013). In addition, we calculated the distance of each ridge segment to the nearest hotspots. We show that Cr# in spinel in abyssal peridotites is negatively correlated with Na90 in basalts from the same ridge segments on a global scale. Ridge segments that erupt basalts apparently produced by larger degrees of mantle melting are thus underlain by peridotites from which large amounts of melt have been extracted. We find that near-ridge hotspots have a more widespread influence on mid-ocean ridge basalt (MORB) composition and ridge depth than previously thought. However, when these hotspot-influenced ridge segments are excluded, the remaining segments show clear relationships between MORB composition, peridotite composition, and ridge depth with spreading rate. Very slow-spreading ridges (<20 mm/yr) are deeper, erupt basalts with higher Na90, Al90, K90/Ti90, and lower Fe90, Ca90/Al90, and expose peridotites with lower Cr# than intermediate and fast-spreading ridges. We show that away from hotspots, the spreading-rate dependence of the maximum degree of mantle melting inferred from Cr# in peridotites (FM) and the bulk degree of melting inferred from Na90 in basalts (FB) from the same ridge segments is unlikely to be due to variations in mantle composition. Nor can the effects of dynamic mantle upwelling or incomplete melt extraction at low spreading rates satisfactorily explain the observed compositions of abyssal

  12. Oak Ridge K-25 Site Technology Logic Diagram

    SciTech Connect

    Fellows, R.L.

    1993-02-26

    The Oak Ridge K-25 Technology Logic Diagram (TLD), a decision support tool for the K-25 Site, was developed to provide a planning document that relates environmental restoration and waste management problems at the Oak Ridge K-25 Site to potential technologies that can remediate these problems. The TLD technique identifies the research necessary to develop these technologies to a state that allows for technology transfer and application to waste management, remedial action, and decontamination and decommissioning activities. The TLD consists of four separate volumes-Vol. 1, Vol. 2, Vol. 3A, and Vol. 3B. Volume 1 provides introductory and overview information about the TLD. Volume 2 contains logic diagrams. Volume 3 has been divided into two separate volumes to facilitate handling and use. This report is part A of Volume 3 concerning characterization, decontamination, and dismantlement.

  13. Oak Ridge Dose Reconstruction annual report for calendar year 1997

    SciTech Connect

    1998-09-01

    Calendar year 1997 was the third full year of work on the Oak Ridge Dose Reconstruction. Activities are summarized on the following individual project tasks: Task 1 -- Investigation of radioiodine releases from X-10 radioactive lanthanum processing; Task 2 -- Investigation of mercury releases from Y-12 lithium enrichment; Task 3 -- Investigation of PCBs in the environment near Oak Ridge; Task 4 -- Investigation of radionuclides released from White Oak Creek to the Clinch River; Task 5 -- Systematic searching of records repositories; Task 6 -- Evaluation of the quality of uranium monitoring data and a screening evaluation of potential off-site health risks; and Task 7 -- Performance of screening for additional materials not evaluated in the feasibility study.

  14. Oak Ridge K-25 Site Technology Logic Diagram

    SciTech Connect

    Fellows, R.L.

    1993-02-26

    The Oak Ridge K-25 Technology Logic Diagram (TLD), a decision support tool for the K-25 Site, was developed to provide a planning document that relates envirorunental restoration and waste management problems at the Oak Ridge K-25 Site to potential technologies that can remediate these problems. The TLD technique identifies the research necessary to develop these technologies to a state that allows for technology transfer and application to waste management, remedial action, and decontamination and decommissioning activities. The TLD consists of four separate volumes-Vol. 1, Vol. 2, Vol. 3A, and Vol. 3B. Volume 1 provides introductory and overview information about the TLD. This volume, Volume 2, contains logic diagrams with an index. Volume 3 has been divided into two separate volumes to facilitate handling and use.

  15. Level 3 Baseline Risk Assessment for Building 3515 at Oak Ridge National Lab., Oak Ridge, TN

    SciTech Connect

    Wollert, D.A.; Cretella, F.M.; Golden, K.M.

    1995-08-01

    The baseline risk assessment for the Fission Product Pilot Plant (Building 3515) at the Oak Ridge National laboratory (ORNL) provides the Decontamination and Decommissioning (D&D) Program at ORNL and Building 3515 project managers with information concerning the results of the Level 3 baseline risk assessment performed for this building. The document was prepared under Work Breakdown Structure 1.4.12.6.2.01 (Activity Data Sheet 3701, Facilities D&D) and includes information on the potential long-term impacts to human health and the environment if no action is taken to remediate Building 3515. Information provided in this document forms the basis for the development of remedial alternatives and the no-action risk portion of the Engineering Evaluation/Cost Analysis report.

  16. Anatomy of an Axial Volcanic Ridge: The Mid-Atlantic Ridge at 45°N

    NASA Astrophysics Data System (ADS)

    Achenbach, K. L.; Searle, R. C.

    2009-12-01

    Study of a single axial volcanic ridge in the Mid-Atlantic Ridge median valley at 45°N has enabled us to construct a detailed volcano-stratigraphic model and thrown new light on the structure and development of AVRs. Data sets include 50 m resolution multibeam bathymetry, comprehensive 3 m resolution deep-towed sidescan sonar, a grid of twenty-two 1.4 km-spaced lines of deep-towed magnetic field measurements, continuous video observations and 270 rock samples from eleven ROV dives, and two approximately 8 km2 areas of very-high-resolution bathymetry and magnetics. A continuous topographic ridge extends ~35 km along the segment, and strikes 010°, ~5-10° CCW of the regional ridge trend. The northernmost 10 km appears older, as attested by lower topographic relief, acoustic backscatter and crustal magnetisation and greater degree of faulting. The rest, which we infer to be most recently constructed, is 25 km long, ~ 4 km wide and ~500 m high. It has a sharp crest, and lateral spurs trending NE that we attribute to tectonic control from the right-stepping MAR axis. The recent AVR is covered by approximately 3000 small (<450 m diameter, 200 m high) circular volcanoes ranging from steep-sided (45°) cones to more rounded domes. They tend to align in rows parallel to the AVR axis, to its NE-trending spurs, or, on its lower flanks, sub-normal to the AVR trend. These latter lineaments, which are spaced 1-2 km apart, comprise short (1-2 km) rows of single cones. We infer that their emplacement is controlled by down-flank magma transport. The AVR itself contains only one volcano >450 m diameter, though about ten, all flat-topped and up to 1.2 km diameter, occur elsewhere on the median valley floor. The high-resolution surveys show all cones >70 m high suffered significant flank collapse, often with near-vertical collapse scars. The active AVR is partly flanked by hummocky volcanic terrain similar to the AVR but of lower acoustic backscatter, which we infer to be older, and

  17. Magnetic Anomaly Amplitudes on the Gakkel Ridge: Indicators of Ridge Variability

    NASA Astrophysics Data System (ADS)

    Childers, V. A.; Lawver, L. A.; Brozena, J. M.

    2002-12-01

    For most of its length, the Gakkel Ridge in the Arctic Ocean's Eurasia Basin is characterized by a discontinuous magnetic signature with regions of missing or low-amplitude central anomalies punctuated by short, high-amplitude segments. The ridge segment in between the Morris Jesup Rise and the Yermak Plateau has an unusually large amplitude central magnetic anomaly that is more than four times the amplitude of the flanking anomalies. This ridge segment is straight, without large offsets, for about 150 km. The difference in character between the central anomaly in this segment and the rest of Gakkel Ridge is striking. The western half of the Gakkel Ridge and the Eurasia Basin were surveyed in 1998-99 by a Naval Research Laboratory aerogeophysical campaign that measured magnetics, gravity, and sea-surface topography. The new magnetic data densify the historical US Navy aeromagnetic data and improve the resolution of the magnetic anomaly field in this region. This new field highlights the variability of the Gakkel Ridge over time, showing regions of strong anomalies that are continuous along strike and anomalies that fade away or become discontinuous. In particular, anomalies 15y to 21o show regions of high amplitudes on both sides of the ridge for varying distances along strike. We suggest that these high-amplitude segments were formed at times when the Gakkel Ridge at this location had a high-amplitude central magnetic anomaly like the present day high-amplitude segment or the shorter ones distributed along the ridge. The higher central anomaly amplitudes may be associated with variations in geochemistry and/or melt delivery along the ridge. Recent dredging of zero-aged crust along the Gakkel Ridge showed a good but not perfect correlation of high-amplitude central anomalies and basalt recovery (P. Michael, personal communication). This magnetic data set in conjunction with future dredging provides an opportunity to constrain past ridge variability.

  18. Closure certification report for the Bear Creek burial grounds B area and walk-in pits at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-06-01

    On July 5, 1993, the revised RCRA Closure Plan for the Bear Creek Burial Grounds B Area and Walk-In Pits at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, DOE/OR/01-1100&D3 and Y/ER-53&D3, was approved by the Tennessee Department of Environment and Conservation (TDEC). The closure activities described in that closure plan have been performed. The purpose of this document is to summarize the closure activities for B Area and Walk-In Pits (WIPs), including placement of the Kerr Hollow Quarry debris at the WIPs.

  19. Gorringe Ridge gravity and magnetic anomalies are compatible with thrusting at a crustal scale

    NASA Astrophysics Data System (ADS)

    Galindo-Zaldívar, J.; Maldonado, A.; Schreider, A. A.

    2003-06-01

    The main features of the deep structure of the Gorringe Ridge are analysed on the basis of gravity and magnetic measurements, as well as seismic profiles, drill holes, rock dredges, submersible observations and seismicity data. The gravity and magnetic models of the Gettysburg and Ormonde seamounts, which form the Gorringe Ridge, suggest that the Moho is approximately flat and the upper part of the ridge corresponds to a northwestwards vergent fold. This structure is the result of a northwestward vergent thrust that deformed the oceanic crust, with a minimum slip of approximately 20 km. The activity of the thrust probably started 20 Myr, and produced the recent stages of seamount uplift. The seamount is mainly composed of gabbros of the oceanic crust, serpentinized rocks and alkaline basalts. The large antiform, located in the hangingwall of the thrust, is probably deformed by minor faults. This oceanic ridge is a consequence of the oblique convergence between the African Plate and the overlapping Eurasian Plate.

  20. Calendar year 1993 groundwater quality report for the Chestnut Ridge Hydrogeologic Regime Y-12 Plant, Oak Ridge, Tennessee. 1993 Groundwater quality data interpretations and proposed program modifications

    SciTech Connect

    1994-09-01

    This groundwater quality report (GWQR) contains an evaluation of the groundwater quality data obtained during the 1993 calendar year (CY) at several hazardous and non-hazardous waste management facilities associated with the US DOE Y-12 Plant located on the DOE Oak Ridge Reservation (ORR) southeast of Oak Ridge, Tennessee. The groundwater quality data are presented in Part 1 of the GWQR submitted by Martin Marietta Energy Systems, Inc. to the Tennessee Department of Environment and Conservation (TDEC) in February 1994. Groundwater quality data evaluated in this report were obtained at several hazardous and non-hazardous waste management sites located within the Chestnut Ridge Hydrogeologic Regime (Chestnut Ridge Regime). The Chestnut Ridge Regime encompasses a section of Chestnut Ridge south of the Y-12 Plant and is one of three hydrogeologic regimes defined for the purposes of groundwater quality monitoring at the plant. The Environmental Management Department of the Y-12 Plant Health, Safety, Environment, and Accountability Organization manages the groundwater monitoring activities in each regime as part of the Y-12 Plant Groundwater Protection Program (GWPP). The annual GWQR for the Chestnut Ridge Regime is completed in two parts. Part 1 consists primarily of data appendices and serves as a reference for the groundwater quality data obtained each CY under the lead of the Y-12 Plant GWPP. Because it contains information needed to comply with Resource Conservation and Recovery Act (RCRA) interim status assessment monitoring and reporting requirements, the Part 1 GWQR is submitted to the TDEC by the RCRA reporting deadline (March 1 of the following CY). Part 2 (this report) contains an evaluation of the data with respect to regime-wide groundwater quality, presents the findings and status of ongoing hydrogeologic studies, describes changes in monitoring priorities, and presents planned modifications to the groundwater sampling and analysis activities.

  1. Project management plan for the gunite and associated tanks treatability studies project at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-12-01

    This plan for the Gunite and Associated Tanks (GAAT) Treatability Studies Project satisfies the requirements of the program management plan for the Oak Ridge National Laboratory (ORNL) Environmental Restoration (ER) Program as established in the Program Management Plan for the Martin Marietta Energy Systems, Inc., Oak Ridge National Laboratory Site Environmental Restoration Program. This plan is a subtier of several other ER documents designed to satisfy the US Department of Energy (DOE) Order 4700.1 requirement for major systems acquisitions. This project management plan identifies the major activities of the GAAT Treatability Studies Project; establishes performance criteria; discusses the roles and responsibilities of the organizations that will perform the work; and summarizes the work breakdown structure, schedule, milestones, and cost estimate for the project.

  2. Remedial investigation report on Waste Area Grouping 5 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Volume 1: Technical summary

    SciTech Connect

    1995-09-01

    A remedial investigation (RI) was performed to support environmental restoration activities for Waste Area Grouping (WAG) 5 at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The WAG 5 RI made use of the observational approach, which concentrates on collecting only information needed to assess site risks and support future cleanup work. This information was interpreted and is presented using the framework of the site conceptual model, which relates contaminant sources and release mechanisms to migration pathways and exposure points that are keyed to current and future environmental risks for both human and ecological receptors. The site conceptual model forms the basis of the WAG 5 remedial action strategy and remedial action objectives. The RI provided the data necessary to verify this model and allows recommendations to be made to accomplish those objectives.

  3. Remedial investigation report on Waste Area Group 5 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Volume 1: Technical summary

    SciTech Connect

    1995-03-01

    A remedial investigation (RI) was performed to support environmental restoration activities for Waste Area Grouping (WAG) 5 at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The WAG 5 RI made use of the observational approach, which concentrates on collecting only information needed to assess site risks and support future cleanup work. This information was interpreted and is presented using the framework of the site conceptual model, which relates contaminant sources and release mechanisms to migration pathways and exposure points that are keyed to current and future environmental risks for both human and ecological receptors. The site conceptual model forms the basis of the WAG 5 remedial action strategy and remedial action objectives. The RI provided the data necessary to verify this model and allows recommendations to be made to accomplish those objectives.

  4. Dark and Bright Ridges on Europa

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This high-resolution image of Jupiter's moon Europa, taken by NASA's Galileo spacecraft camera, shows dark, relatively smooth region at the lower right hand corner of the image which may be a place where warm ice has welled up from below. The region is approximately 30 square kilometers in area. An isolated bright hill stands within it. The image also shows two prominent ridges which have different characteristics; youngest ridge runs from left to top right and is about 5 kilometers in width (about 3.1 miles). The ridge has two bright, raised rims and a central valley. The rims of the ridge are rough in texture. The inner and outer walls show bright and dark debris streaming downslope, some of it forming broad fans. This ridge overlies and therefore must be younger than a second ridge running from top to bottom on the left side of the image. This dark 2 km wide ridge is relatively flat, and has smaller-scale ridges and troughs along its length.

    North is to the top of the picture, and the sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 15 kilometers by 20 kilometers (9 miles by 12 miles). The resolution is 26 meters (85 feet) per picture element. This image was taken on December 16, 1997 at a range of 1300 kilometers (800 miles) by Galileo's solid state imaging system.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

  5. Diffraction of sound by a smooth ridge

    NASA Technical Reports Server (NTRS)

    Berthelot, Yves H.; Pierce, Allan D.; Kearns, James A.; Main, Geoffrey L.

    1987-01-01

    The propagation of sound over uneven terrain and irregular topography is considered. Laboratory scale experiments were conducted on a 4.88 x 2.44 m plywood bench top with a cylindrical ridge whose radius of curvature is about 2.5 m. Experimental results include the insertion loss on the diffracting surface, and in the penumbra region, at several distances from the apex of the ridge.

  6. Stratigraphy, Structure, and Origin; A Geophysical Survey of the Mendeleev Ridge

    NASA Astrophysics Data System (ADS)

    Dove, D.; Coakley, B.; Hopper, J.

    2006-12-01

    The Mendeleev Ridge is a broad, aseismic ridge that extends from the Siberian Shelf into the central Arctic Ocean. While it is continuous with the Alpha Ridge and is inferred to be an oceanic plateau, it may have had a distinct and separate history. The origin of the Mendeleev ridge has only rarely been visited and, as a result, understanding the history of this region has largely been based on the presumption of a common origin for both features. In late summer 2005, a geophysical survey was conducted from USCGC Healy over the Mendeleev Ridge as part of a trans-arctic crossing. During this survey ~730 km of seismic reflection data was recovered over the ridge along with co-registered gravity and bathymetry data and seismic refraction profiles. The seismic source was two 250 cu in G-guns. The streamer length was limited by ice conditions to 300 meters. Wear and tear caused by towing the streamer through the ice pack eliminated hydrophones, so the number of active channels ranged from 24 to as few as 11. The seismic reflection data requires significant trace editing to eliminate random electrical noise and frequency-wave number filtering to eliminate low velocity noise caused by the streamer traveling through heavy ice. After trace editing the data are stacked and migrated with constant water velocity. Stacking velocities are used as input into initial ray tracing models. Derived boundary velocities from ray tracing models will be reapplied to the migration of reflection data and are converted through empirical relationships into densities, and used as input into gravity models. Brute stacked reflection images of the Mendeleev Ridge reveal pervasive extensional faulting of the basement and lower sediment layers, and a continuous, undeformed pelagic sediment layer mantling the ridge, indicative of recent tectonic inactivity. The age of the unconformity underlying this layer should date the end of significant deformation of the Alpha and Mendeleev Ridges. Consistency

  7. Leak testing plan for the Oak Ridge National Laboratory liquid low-level waste systems (active tanks): Revision 2. Volume 1: Regulatory background and plan approach; Volume 2: Methods, protocols, and schedules; Volume 3: Evaluation of the ORNL/LT-823DP differential pressure leak detection method; Appendix to Revision 2: DOE/EPA/TDEC correspondence

    SciTech Connect

    Douglas, D.G.; Wise, R.F.; Starr, J.W.; Maresca, J.W. Jr.

    1994-11-01

    This document, the Leak Testing Plan for the Oak Ridge National Laboratory Liquid Low-Level Waste System (Active Tanks), comprises three volumes. The first two volumes address the component-based leak testing plan for the liquid low-level waste system at Oak Ridge, while the third volume describes the performance evaluation of the leak detection method that will be used to test this system. Volume 1, describes that portion of the liquid low-level waste system at that will be tested; it provides the regulatory background, especially in terms of the requirements stipulated in the Federal Facilities Agreement, upon which the leak testing plan is based. Volume 1 also describes the foundation of the plan, portions of which were abstracted from existing federal documents that regulate the petroleum and hazardous chemicals industries. Finally, Volume 1 gives an overview the plan, describing the methods that will be used to test the four classes of components in the liquid low-level waste system. Volume 2 takes the general information on component classes and leak detection methods presented in Volume 1 and shows how it applies particularly to each of the individual components. A complete test plan for each of the components is presented, with emphasis placed on the methods designated for testing tanks. The protocol for testing tank systems is described, and general leak testing schedules are presented. Volume 3 describes the results of a performance evaluation completed for the leak testing method that will be used to test the small tanks at the facility (those less than 3,000 gal in capacity). Some of the details described in Volumes 1 and 2 are expected to change as additional information is obtained, as the viability of candidate release detection methods is proven in the Oak Ridge environment, and as the testing program evolves.

  8. The Reykjanes Ridge between 63°10‧N and Iceland

    NASA Astrophysics Data System (ADS)

    Höskuldsson, Ármann; Hey, Richard; Kjartansson, Einar; Guðmundsson, Gunnar B.

    2007-01-01

    Along the Reykjanes Ridge from 63°10'N to 63°50'N we identify 10 en-echelon shallow closely spaced axial volcanic ridges (AVR). The AVRs are confined to the crest of the Reykjanes Ridge. This has been suggested to imply intense tectonic erosion of the ridges and subsequent sediment covering as they drift off axis. All AVRs studied are small and their length does not exceed that of individual eruptive fissures on land. Recent seismic activity is concentrated near Fuglasker seamount and the two AVRs in the Húllið graben. Tectonic strike changes drastically at the Skerjadjúp graben from N28°E to N40°E. Historic volcanic activity has been intense in this area with up to 14 eruptions, the last confirmed eruption occurring in 1926. New multibeam and backscatter data in the area of AVR 1 and the northernmost tip of AVR 2 show that the ridges were created by multiple eruptions, with clearly defined volcanic centres or cones, in contrast to monogenetic Pleistocene hyaloclastite ridges on land in Iceland with similar dimensions. In this area there was a series of eruptions during the years 1226-1238 in which the craters could have formed. The data also show normal faults in the Húllið graben. The western boundary faults have a drop of more than 25 m, while the eastern faults are smaller but denser.

  9. Assessing the clarity of friction ridge impressions.

    PubMed

    Hicklin, R Austin; Buscaglia, JoAnn; Roberts, Maria Antonia

    2013-03-10

    The ability of friction ridge examiners to correctly discern and make use of the ridges and associated features in finger or palm impressions is limited by clarity. The clarity of an impression relates to the examiner's confidence that the presence, absence, and attributes of features can be correctly discerned. Despite the importance of clarity in the examination process, there have not previously been standard methods for assessing clarity in friction ridge impressions. We introduce a process for annotation, analysis, and interchange of friction ridge clarity information that can be applied to latent or exemplar impressions. This paper: (1) describes a method for evaluating the clarity of friction ridge impressions by using color-coded annotations that can be used by examiners or automated systems; (2) discusses algorithms for overall clarity metrics based on manual or automated clarity annotation; and (3) defines a method of quantifying the correspondence of clarity when comparing a pair of friction ridge images, based on clarity annotation and resulting metrics. Different uses of this approach include examiner interchange of data, quality assurance, metrics, and as an aid in automated fingerprint matching. PMID:23313600

  10. Magdalen Ridge Observatory: post Preliminary Design Review

    NASA Astrophysics Data System (ADS)

    Cobb, M. L.

    2002-12-01

    The Magdalena Ridge Observatory (MRO) has recently completed its Preliminary Design Review (PDR). The project consists of two sub projects: a 10 element optical interferometer and a rapid response 2.4 m stand alone telescope. This poster will give a brief overview of the preliminary design plans for both sub projects. The MRO interferometer will consist of 10, 1.5 m telescopes arraigned in a classical "Y" configuration. Unique properties are the inclusion of Adaptive Optics (AO) in the design and a novel telescope mount configuration which manages the polarization vector of the light through the optical system to the combining table. The array is designed to be reconfigurable in a weeks time frame which will be performed around 6 month configuration seasons and has a maximum baseline of 400m. The MRO rapid response telescope is designed around a government surplus 2.4 m mirror with an active control system to allow fast slew and settling times to quickly respond to transit phenomena. A primary use will be observations of solar system objects including asteroids. Initial instruments will include simple imaging capability with plans to build a low resolution spectrometer as well as an imaging spectropolarimeter.

  11. Oak Ridge Reservation environmental report for 1990

    SciTech Connect

    Wilson, A.R.

    1991-09-01

    The purpose of this report is to provide information to the public about the impact of the US Department of Energy's (DOE's) facilities located on the Oak Ridge Reservation (ORR) on the public and the environment. It describes the environmental surveillance and monitoring activities conducted at and around the DOE facilities operated by Martin Marietta Energy Systems, Inc. Preparation and publication of this report is in accordance with DOE Order 5400.1. The order specifies a publication deadline of June of the following year for each calendar year of data. The primary objective of this report is to summarize all information collected for the previous calendar year regarding effluent monitoring, environmental surveillance, and estimates of radiation and chemical dose to the surrounding population. When multiple years of information are available for a program, trends are also evaluated. The first seven sections of Volume 1 of this report address this objective. The last three sections of Volume 1 provide information on solid waste management, special environmental studies, and quality assurance programs.

  12. SRTM Stereo Pair: Wheeler Ridge, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Wheeler Ridge and vicinity, California, is a site of major tectonic activity, both historically and over recent geologic time. The epicenter of the 7.5 magnitude Kern County earthquake occurred here on July 21,1952, and numerous geologic and topographic features indicate rapid geologic processes. The ridge itself (upper-right center) is a geologic fold that is growing out of the southern San Joaquin Valley. A prominent 'wind gap,' now used for passage of the California aquaduct (with the aid of a pumping station), is evidence that the ridge grew faster than tranversing streams could erode down. Nearby abrupt and/or landslid mountain fronts similarly indicate a vigorous tectonic setting here, just north of the San Andreas fault. The Interstate 5 freeway can be seen crossing agricultural fields on the right and entering the very rugged and steep Grapevine Canyon toward the bottom.

    This stereoscopic image was generated by draping a Landsat satellite image over a preliminary Shuttle Radar Topography Mission (SRTM) elevation model. Two differing perspectives were then calculated, one for each eye. They can be seen in 3-D by viewing the left image with the right eye and the right image with the left eye (cross-eyed viewing), or by downloading and printing the image pair and viewing them with a stereoscope. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter resolution of most Landsat images and will substantially help in analyses of the large and growing Landsat image archive.

    The elevation data used in this image was acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle

  13. Oak Ridge National Laboratory Technology Logic Diagram. Indexes

    SciTech Connect

    Not Available

    1993-09-01

    The Decontamination and Decommissioning (D&D) Index provides a comprehensive list of site problems, problem area/constituents, remedial technologies, and regulatory terms discussed in the D&D sections of the Oak Ridge National Laboratory Technology Logic Diagram. All entries provide specific page numbers, or cross-reference entries that provide specific page numbers, in the D&D volumes (Vol. 1, Pt. A; Vol. 2, Pt. A; and appropriate parts of Vol. 3). The Oak Ridge National Laboratory Technology (TLD) was developed to provide a decision-support tool that relates environmental restoration (ER) and waste management (WM) problems at Oak Ridge National Laboratory (ORNL) to potential technologies that can remediate these problems. The TLD identifies the research, development, demonstration, testing, and evaluation needed to develop these technologies to a state that allows technology transfer and application to decontamination and decommissioning (D&D), remedial action (RA) and WM activities. It is essential that follow-on engineering studies be conducted to build on the output of this project. These studies will begin by selecting the most promising technologies identified in the TLD and finding an optimum mix of technologies that will provide a socially acceptable balance between cost and risk.

  14. On the origin of Umtanum Ridge: Kinematics of Neogene slip

    NASA Astrophysics Data System (ADS)

    Miller, Brendan A.

    Constraining the geometry of active faults is an important step in determining accurate estimates of regional seismic hazard. Where subsurface data are lacking, the shape of hanging wall folds can be used to interpret fault geometry at depth. In order to better understand the seismic hazard posed by the Yakima folds in central Washington, I produced a new geologic map and employ kinematic modeling techniques to probe the geometry of a reverse/thrust fault controlling folding of the Columbia River Basalt flows at Umtanum Ridge near Ellensburg, WA. Depending on the technique used, Umtanum Ridge may have formed from either thin or thick-skinned deformation. My preferred model, using a combination of fault-bend and trishear fault-propagation folding, is consistent will measured flow top attitudes along a line of section through the ridge. This model implies that up to 520 m of slip has occurred since 15.6 Ma on a fault soling in a detachment ˜4 km deep. The rate of deformation derived from the model underestimates (by a factor of 2) previously published rates derived from both geodetic and geomorphic data, implying that current rates of deformation may be higher than the long term average.

  15. Seismological imaging of ridge-arc interaction beneath the Eastern Lau Spreading Center from OBS ambient noise tomography

    NASA Astrophysics Data System (ADS)

    Zha, Yang; Webb, Spahr C.; Wei, S. Shawn; Wiens, Douglas A.; Blackman, Donna K.; Menke, William; Dunn, Robert A.; Conder, James A.

    2014-12-01

    The Lau Basin displays large along-strike variations in ridge characters with the changing proximity of the adjacent subduction zone. The mechanism governing these changes is not well understood but one hypotheses relates them to interaction between the arc and back-arc magmatic systems. We present a 3D seismic velocity model of the shallow mantle beneath the Eastern Lau back-arc Spreading Center (ELSC) and the adjacent Tofua volcanic arc obtained from ambient noise tomography of ocean bottom seismograph data. Our seismic images reveal an asymmetric upper mantle low velocity zone (LVZ) beneath the ELSC. Two major trends are present as the ridge-to-arc distance increases: (1) the LVZ becomes increasingly offset from the ridge to the north, where crust is thinner and the ridge less magmatically active; (2) the LVZ becomes increasingly connected to a sub-arc low velocity zone to the south. The separation of the ridge and arc low velocity zones is spatially coincident with the abrupt transition in crustal composition and ridge morphology. Our results present the first mantle imaging confirmation of a direct connection between crustal properties and uppermost mantle processes at ELSC, and support the prediction that as ELSC migrates away from the arc, a changing mantle wedge flow pattern leads to the separation of the arc and ridge melting regions. Slab-derived water is cutoff from the ridge, resulting in abrupt changes in crustal lava composition and crustal porosity. The larger offset between mantle melt supply and the ridge along the northern ELSC may reduce melt extraction efficiency along the ridge, further decreasing the melt budget and leading to the observed flat and faulted ridge morphology, thinner crust and the lack of an axial melt lens.

  16. Executive Order 12941 Implementation at the Oak Ridge National Laboratory

    SciTech Connect

    Hunt, R.J.; Kroon, R.J.; Shaffer, K.E.

    1998-08-01

    Congress enacted the Earthquake Hazards Reduction Act of 1977 (Public Law 95-124, as amended) to reduce risks to life and property from future earthquakes in the US. To implement the provisions of the Act, the Interagency Committee on Seismic Safety in Construction (ICSSC) was chartered. Approximately thirty Federal agencies, including the Department of Energy (DOE), participate in the ICSSC. The ICSSC is chaired by the National Institute of Standards (NIST) which also provides the technical secretariat. EO 12941, Seismic Safety of Existing Federally Owned or Leased Buildings, were prepared and issued by the ICSSC to reduce the vulnerability to buildings owned or leased by agencies or departments for Federal use. This report documents the implementation of EO 12941 at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. ORNL is managed and operated by Lockheed Martin Energy Research, Inc. (LMER) for the DOE-Oak Ridge Operations Office (DOE-ORO). The ORNL building inventory includes buildings that are physically located at ORNL, East Tennessee Technology Park (ETTP), and the Oak Ridge Y-12 Plant. This report addresses buildings physically located at the ORNL plant site. ORNL buildings located at ETTP and Y-12 plant sites will be included in the EO 12941 implementation reports for those sites. The scope of this effort included revising the building inventory for ORNL that was prepared prior to the development of the DOE management plan, evaluating owned buildings not exempt from the requirements of EO 12941, estimating the costs associated with the rehabilitation of vulnerable non-exempt buildings, and preparing this report in the TR-17 prescribed format (CNPE 1996). These activities were performed in accordance with the DOE management plan and as applicable, Phase I - Screening Guidelines To Determine The Structures Exempt From Executive Order 12941 (CNPE 1995).

  17. Soil Management Plan for the Oak Ridge Y-12 National Security Complex Oak Ridge, Tennessee

    SciTech Connect

    2005-03-02

    This Soil Management Plan applies to all activities conducted under the auspices of the National Nuclear Security Administration (NNSA) Oak Ridge Y-12 National Security Complex (Y-12) that involve soil disturbance and potential management of waste soil. The plan was prepared under the direction of the Y-12 Environmental Compliance Department of the Environment, Safety, and Health Division. Soil disturbances related to maintenance activities, utility and building construction projects, or demolition projects fall within the purview of the plan. This Soil Management Plan represents an integrated, visually oriented, planning and information resource tool for decision making involving excavation or disturbance of soil at Y-12. This Soil Management Plan addresses three primary elements. (1) Regulatory and programmatic requirements for management of soil based on the location of a soil disturbance project and/or the regulatory classification of any contaminants that may be present (Chap. 2). Five general regulatory or programmatic classifications of soil are recognized to be potentially present at Y-12; soil may fall under one or more these classifications: (a) Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) pursuant to the Oak Ridge Reservation (ORR) Federal Facilities Agreement; (b) Resource Conservation and Recovery Act (RCRA); (c) RCRA 3004(u) solid waste managements units pursuant to the RCRA Hazardous and Solid Waste Amendments Act of 1984 permit for the ORR; (d) Toxic Substances and Control Act-regulated soil containing polychlorinated biphenyls; and (e) Radiologically contaminated soil regulated under the Atomic Energy Act review process. (2) Information for project planners on current and future planned remedial actions (RAs), as prescribed by CERCLA decision documents (including the scope of the actions and remedial goals), land use controls implemented to support or maintain RAs, RCRA post-closure regulatory requirements for

  18. Physiography of eastern Mendocino Ridge, NE Pacific

    NASA Astrophysics Data System (ADS)

    Gardner, J. V.; Malik, M. A.; Verplank, N. S.

    2009-12-01

    The bathymetry of the eastern 850 km of Mendocino Ridge (MR) was mapped using NOAA Ship Okeanos Explorer’s Kongsberg EM302 multibeam as part of mapping trials to support the University of New Hampshire’s U.S. Law of the Sea mapping program. The ridge was mapped from the margin to ~500 km west of the intersection of the ridge with Gorda Ridge (GR) at a spatial resolution of 40 m/sounding. The mapped section can be subdivided into two morphologic styles. East of the GR intersection, along the transform fault, MR is a single 4-18 km wide ridge with summit depths of 1200 to 1700 m deep with slopes of 10-40°. West of the intersection, along the fracture zone, MR has summit depths of >2100 m deep. A series of drag folds formed by basement ridges west of GR and north of the fracture zone reflects the differential spreading rates of GR. The almost 90° bend in the drag folds is often accompanied by large volcanic fields with summit craters in many volcanoes in water depths of 2 to 4 km. Beginning ~45 km west of GR intersection, MR evolves into a series of en echelon ridges striking 290°, some with slopes as steep as 55°. The change in morphology appears to be the effects of compression in the transform fault section between the Gorda Plate to the north and the Pacific Plate to the south, whereas extension is evident in the fracture zone section of the ridge. Mendocino Channel immediately to the north of the easternmost MR was mapped from the margin to ~105 km to the west before the channel relief was below the resolution of the multibeam system. The channel walls have as much as 50 m of relief with decreasing relief down channel. Mendocino Channel is bordered on the north by a large field of levees with bedforms and on the south by the 1200 m high wall of MR. Several large sediment failures have occurred in the levee field. The channel is straight for the first 40+ km with an average channel slope of 0.7° but suddenly begins to meander when the channel slope is <0

  19. Ridge 2000 Data Integration and Synthesis

    NASA Astrophysics Data System (ADS)

    Fornari, D. J.; Ferrini, V.; Carbotte, S.; Blackman, D.

    2008-12-01

    The Ridge 2000 (R2K) program is transitioning toward an increased emphasis on integration and synthesis of data acquired on multi-disciplinary expeditions focused on understanding the geo-biological processes associated with hydrothermal systems on mid-ocean ridges (MORs). This phase of the program will focus not only on the compilation of existing data, but also on integration of results across disciplines, and development of models that examine the linkages between spreading, hydrothermal, and ecosystem processes. During this phase of the program, data from throughout the global mid-ocean ridge system will be important to achieve a more holistic understanding of MOR processes and how they relate to the Ridge 2000 data sets from each Integrated Study Site (ISS). A series of workshops were held in Fall 2008 to bring together researchers from each ISS to help coordinate the integration and synthesis phase of the program. While most cruises conducted during the R2K program have been cataloged and basic metadata made available through R2K Data Portal (http://www.marine- geo.org/ridge2000), additional data, including derived and interpreted data sets from R2K-funded expeditions and other ridge-related expeditions are important to make available during this phase in the program. Once data are available, a variety of data access and visualization tools including GeoMapApp, Google Earth, and IVS-Fledermaus can be used to help coordinate analysis and integration efforts. We focus on highlighting potential scientific applications made possible with currently available software tools, and report on the R2K community feedback and utilization of data bases and visualization tools brought to light during the Fall 2008 workshops. geo.org/ridge2000

  20. Formation and stability of ridge-ridge-ridge triple junctions in rheologically realistic lithosphere model

    NASA Astrophysics Data System (ADS)

    Gerya, Taras; Burov, Evgueni

    2015-04-01

    -branch junction formation and evolution by using high-resolution 3D numerical mechanical experiments that take into account realistic thermo-rheological structure and rheology of the lithosphere. We find that two major types of quadruple and triple junctions are formed under bi-directional or multidirectional far-field stress field: (i) plate rifting junctions are formed by the initial plate fragmentation and can be subsequently re-arranged into (ii) oceanic spreading junctions controlled by the new oceanic crust accretion. In particular, we document initial formation and destabilization of quadruple R-R-R-R junctions as initial plate rifting structures under bi-directional extension. In most cases, quadruple plate rifting junctions rapidly (typically within 1-2 Myr) evolve towards formation of two diverging triple oceanic spreading junctions connected by a linear spreading center lengthening with time. This configuration remains stable over long time scales. However, under certain conditions, quadruple junctions may also remain relatively stable. Asymmetric stretching results in various configurations, for example formation of "T-junctions" with trans-extensional components and combination of fast and slow spreading ridges. Combined with plume impingement, this scenario evolves in realistic patterns closely resembling observed plate dynamics. In particular, opening of the Red Sea and of the Afar rift system find a logical explanation within a single model. Numerical experiments also suggest that several existing oceanic spreading junctions form as the result of plate motions rearrangements after which only one of two plates spreading along the ridge become subjected to bi-directional spreading.

  1. Ridge Regression in Prediction Problems: Automatic Choice of the Ridge Parameter

    PubMed Central

    Cule, Erika; De Iorio, Maria

    2013-01-01

    To date, numerous genetic variants have been identified as associated with diverse phenotypic traits. However, identified associations generally explain only a small proportion of trait heritability and the predictive power of models incorporating only known-associated variants has been small. Multiple regression is a popular framework in which to consider the joint effect of many genetic variants simultaneously. Ordinary multiple regression is seldom appropriate in the context of genetic data, due to the high dimensionality of the data and the correlation structure among the predictors. There has been a resurgence of interest in the use of penalised regression techniques to circumvent these difficulties. In this paper, we focus on ridge regression, a penalised regression approach that has been shown to offer good performance in multivariate prediction problems. One challenge in the application of ridge regression is the choice of the ridge parameter that controls the amount of shrinkage of the regression coefficients. We present a method to determine the ridge parameter based on the data, with the aim of good performance in high-dimensional prediction problems. We establish a theoretical justification for our approach, and demonstrate its performance on simulated genetic data and on a real data example. Fitting a ridge regression model to hundreds of thousands to millions of genetic variants simultaneously presents computational challenges. We have developed an R package, ridge, which addresses these issues. Ridge implements the automatic choice of ridge parameter presented in this paper, and is freely available from CRAN. PMID:23893343

  2. Porosity development in the Copper Ridge Dolomite and Maynardville Limestone, Bear Creek Valley and Chestnut Ridge, Tennessee

    SciTech Connect

    Goldstrand, P.M.; Menefee, L.S.; Dreier, R.B.

    1995-12-01

    Matrix porosity data from deep core obtained in Bear Creek Valley indicate that porosities in the Maynardville Limestone are lithology and depth dependent. Matrix porosities are greater in the Cooper Ridge Dolomite than in the Maynardville Limestone, yet there is no apparent correlation with depth. Two interrelated diagenetic processes are the major controlling factors on porosity development in the Copper Ridge Dolomite and Maynardville Limestone; dissolution of evaporate minerals and dedolomitization. Both of these diagenetic processes produce matrix porosities between 2.1 and 1.3% in the Copper Ridge Dolomite and upper part of the Maynardville Limestone (Zone 6) to depths of approximately 600 ft bgs. Mean matrix porosities in Zones 5 through 2 of the Maynardville Limestone range from 0.8 to 0.5%. A large number of cavities have been intersected during drilling activities in nearly all zones of the Maynardville Limestone in Bear Creek Valley. Therefore, any maynardville Limestone zone within approximately 200 ft of the ground surface is likely to contain cavities that allow significant and rapid flow of groundwater. Zone 6 could be an important stratigraphic unit in the Maynardville Limestone for groundwater flow and contaminant transport because of the abundance of vuggy and moldic porosities. There are large variations in the thickness and lithology in the lower part of the Maynardville (Zones 2, 3, and 4 in the Burial Grounds region). The direction and velocity of strike-parallel groundwater flow may be altered in this area within the lower Maynardville Limestone.

  3. Work plan for the High Ranking Facilities Deactivation Project at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-03-01

    The High Ranking Facilities Deactivation Project (HRFDP), commissioned by the US Department of Energy Nuclear Materials and Facility Stabilization Program, is to place four primary high-risk surplus facilities with 28 associated ancillary facilities at Oak Ridge National Laboratory in a safe, stable, and environmentally sound condition as rapidly and economically as possible. The facilities will be deactivated and left in a condition suitable for an extended period of minimized surveillance and maintenance (S and M) prior to decontaminating and decommissioning (D and D). These four facilities include two reactor facilities containing spent fuel. One of these reactor facilities also contains 55 tons of sodium with approximately 34 tons containing activated sodium-22, 2.5 tons of lithium hydride, approximately 100 tons of potentially contaminated lead, and several other hazardous materials as well as bulk quantities of contaminated scrap metals. The other two facilities to be transferred include a facility with a bank of hot cells containing high levels of transferable contamination and also a facility containing significant quantities of uranyl nitrate and quantities of transferable contamination. This work plan documents the objectives, technical requirements, and detailed work plans--including preliminary schedules, milestones, and conceptual FY 1996 cost estimates--for the Oak Ridge National Laboratory (ORNL). This plan has been developed by the Environmental Restoration (ER) Program of Lockheed Martin Energy Systems (Energy Systems) for the US Department of Energy (DOE) Oak Ridge Operations Office (ORO).

  4. Inventory of karst subsidence in the Valley and Ridge Province of East Tennessee

    SciTech Connect

    Ketelle, R.H.; Newton, J.G.

    1986-01-01

    The first regional inventory of karst activity in the Valley and Ridge Province of East Tennessee was performed as a part of ongoing studies at Oak Ridge National Laboratory pertaining to environmental impact assessment of waste disposal in karst settings. More than half the land area in the Valley and Ridge Province of East Tennessee is underlain by karst-prone carbonate bedrock. The regional karst inventory was initiated to obtain current information on the extent of active karst subsidence in the region for use in decision making by the Department of Energy in planning future waste disposal facilities at Oak Ridge, Tennessee. The inventory was performed by contacting personnel of federal, state, and county agencies to obtain reports of known active karst subsidence within the region. Data from these interviews were tabulated resulting in identificaton of more than 250 karst subsidence incidents in East Tennessee, most of which have occurred since 1980. Although the infomation obtained was largely anecdotal, approximate location, date, size, and circumstances under which the collapses occurred were recorded for as many cases as could be documented. The study also included detailed reconnaissance of selected areas similar in geology and hydrology to a study area at Oak Ridge, Tennessee to identify causative factors which contribute to karst subsidence in the region and for comparison of the occurrence of visible karst features at different sites. Human activities affecting site hydrology such as large scale land clearing and earthmoving projects were related to most of the subsidence incidents inventoried.

  5. Buldir Depression - A Late Tertiary graben on the Aleutian Ridge, Alaska

    USGS Publications Warehouse

    Marlow, M. S.; Scholl, D. W.; Buffington, E.C.; Boyce, R.E.; Alpha, T.R.; Smith, P.J.; Shipek, C.J.

    1970-01-01

    Buldir Depression is a large, rectilinear basin that lies on the northern edge of the Aleutian Ridge and is aligned with the arcuate chain of active volcanoes on the ridge crest. The depression appears to be a volcanic-tectonic feature, which began to form in Late Tertiary time and which is still forming. It is a graben formed by extensional rifting and accompanied by contemporaneous volcanism on the Aleutian Ridge. Subsidence rates for the depression are estimated at 20-70 cm/1,000 years. Sediments in the depression are 300 m thick and are probably pelagic and turbidite deposits of Pleistocene age. The turbidites were apparently derived from the plateau area of the Aleutian Ridge surrounding the depression. Older sediments on the northern slope of the Aleutian Ridge have a maximum thickness of 550 m and are deformed and slumped toward the Bering Sea. These sediments are postulated to overlie a mid-flank terrace on the northern Aleutian Ridge that titled to the north during the formation of Buldir Depression. ?? 1970.

  6. Infaunal and megafaunal benthic community structure associated with cold seeps at the Vestnesa Ridge (79 N°)

    NASA Astrophysics Data System (ADS)

    Åström, Emmelie K. L.; Carroll, Michael L.; Sen, Arunima; Ambrose, William G., Jr.; Silyakova, Anna; Carroll, JoLynn

    2016-04-01

    Cold seeps are locations where hydrocarbons, sulfide or reduced compounds emanate from the seafloor, which may fuel chemoautotrophic production and form additional hard bottom substrate through carbonate precipitation. Chemosynthetic symbiosis, trophic interactions, and additional bottom substrate types can provide a heterogeneous environment for deep-sea organisms supporting macrofaunal communities including increased biodiversity and biomass. We combined quantitative benthic faunal samples with sea floor photographs from an active, methane seeping pockmark at Vestnesa Ridge (1200 meters depth) to examine community structure and biodiversity in a high Arctic deep cold seep. Quantitative data were compared with samples from the nearby inactive Svyatogor Ridge (1577-1706 meters depth). We measured highly elevated methane concentrations (up to 100x background levels) in the sediment at Vestnesa Ridge. Faunal abundance, species richness and biomass were significantly higher at the Vestnesa pockmark compared to inactive Svyatogor Ridge. Seabed photos from Vestnesa Ridge reveal high megafaunal diversity and biomass and cold seep features including carbonate crust and microbial mats. Our observations indicate that chemoautotrophic production enhances deep-sea biomass and diversity at Vestnesa Ridge. The focused methane emissions create a heterogeneous deep-sea habitat for chemo-associated organisms coexisting with heterotrophic conventional fauna in a high Arctic seep. Keywords: Arctic, benthic ecology, biodiversity, chemosynthesis, methane

  7. Environmental Monitoring Report - United States Department of Energy, Oak Ridge Facilities, Calendar Year 1984

    SciTech Connect

    Jordan, R.G.

    1999-01-01

    Each year since 1972, a report has been prepared on the environmental monitoring activities for the DOE facilities in oak Ridge, Tennessee, for the previous calendar year. previously, the individual facilities published quarterly and annual progress reports that contained some environmental monitoring data. The environmental monitoring program for 1984 includes sampling and analysis of air, water from surface streams, groundwater, creek sediment, biota, and soil for both radioactive and nonradioactive (including hazardous) materials. Special environmental studies that have been conducted in the Oak Ridge area are included in this report, primarily as abstracts or brief summaries. The annual report for 1984 on environmental monitoring and surveillance of the Oak Ridge community by Oak Ridge Associated Universities (ORAU) is included as an appendix. A brief description of the topography and climate of the Oak Ridge area and a short description of the three DOE facilities are provided below to enhance the reader's understanding of the direction and contents of the environmental monitoring program for Oak Ridge.

  8. Oak Ridge Reservation Site Management Plan for the Environmental Restoration Program

    SciTech Connect

    Not Available

    1994-06-01

    This site management plan for the Oak Ridge Reservation (ORR) describes the overall approach for addressing environmental contamination problems at the ORR Superfund site located in eastern Tennessee. The ORR consists of three major US Department of Energy (DOE) installations constructed in the early to mid 1940s as research, development, and process facilities in support of the Manhattan Project. In addition to the three installations -- Oak Ridge National Laboratory (ORNL), the Oak Ridge Y-12 Plant, and the Oak Ridge K-25 Site (formerly the Oak Ridge Gaseous Diffusion Plant) -- the ORR Superfund Site also includes areas outside the installations, land used by the Oak Ridge Associated Universities and waterways that have been contaminated by releases from the DOE installations. To date, {approximately} 400 areas (Appendix A) requiring evaluation have been identified. Cleanup of the ORR is expected to take two to three decades and cost several billion dollars. This site management plan provides a blueprint to guide this complex effort to ensure that the investigation and cleanup activities are carried out in an efficient and cost-effective manner.

  9. Oak Ridge Reservation annual site environmental report for 1996

    SciTech Connect

    1997-10-01

    The US Department of Energy currently oversees activities on the Oak Ridge Reservation (ORR), a government-owned, contractor-operated facility. Three sites compose the reservation: the Oak Ridge Y-12 Plant, Oak Ridge National Laboratory, and East Tennessee Technology Park (formerly the K-25 Site). The ORR was established in the early 1940s as part of the Manhattan Project, a secret undertaking that produced the materials for the first atomic bombs. The reservation`s role has evolved over the years, and it continues to adapt to meet the changing defense, energy, and research needs of the US. Both the work carried out for the war effort and subsequent research, development, and production activities have produced (and continue to produce) radiological and hazardous wastes. This document contains a summary of environmental monitoring activities on the ORR and its surroundings. Environmental monitoring on the ORR consists of two major activities: effluent monitoring and environmental surveillance. Effluent monitoring involves the collection and analysis of samples or measurements of liquid and gaseous effluents prior to release into the environment; these measurements allow the quantification and official reporting of contaminants, assessment of radiation exposures to the public, and demonstration of compliance with applicable standards and permit requirements. Environmental surveillance consists of the collection and analysis of environmental samples from the site and its environs; this provides direct measurement of contaminants in air, water, groundwater, soil, foods, biota, and other media subsequent to effluent release into the environment. Environmental surveillance data verify ORR`s compliance status and, combined with data from effluent monitoring, allow the determination of chemical and radiation dose/exposure assessment of ORR operations and effects, if any, on the local environment.

  10. Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean.

    PubMed

    Sohn, Robert A; Willis, Claire; Humphris, Susan; Shank, Timothy M; Singh, Hanumant; Edmonds, Henrietta N; Kunz, Clayton; Hedman, Ulf; Helmke, Elisabeth; Jakuba, Michael; Liljebladh, Bengt; Linder, Julia; Murphy, Christopher; Nakamura, Ko-Ichi; Sato, Taichi; Schlindwein, Vera; Stranne, Christian; Tausenfreund, Maria; Upchurch, Lucia; Winsor, Peter; Jakobsson, Martin; Soule, Adam

    2008-06-26

    Roughly 60% of the Earth's outer surface is composed of oceanic crust formed by volcanic processes at mid-ocean ridges. Although only a small fraction of this vast volcanic terrain has been visually surveyed or sampled, the available evidence suggests that explosive eruptions are rare on mid-ocean ridges, particularly at depths below the critical point for seawater (3,000 m). A pyroclastic deposit has never been observed on the sea floor below 3,000 m, presumably because the volatile content of mid-ocean-ridge basalts is generally too low to produce the gas fractions required for fragmenting a magma at such high hydrostatic pressure. We employed new deep submergence technologies during an International Polar Year expedition to the Gakkel ridge in the Arctic Basin at 85 degrees E, to acquire photographic and video images of 'zero-age' volcanic terrain on this remote, ice-covered ridge. Here we present images revealing that the axial valley at 4,000 m water depth is blanketed with unconsolidated pyroclastic deposits, including bubble wall fragments (limu o Pele), covering a large (>10 km(2)) area. At least 13.5 wt% CO(2) is necessary to fragment magma at these depths, which is about tenfold the highest values previously measured in a mid-ocean-ridge basalt. These observations raise important questions about the accumulation and discharge of magmatic volatiles at ultraslow spreading rates on the Gakkel ridge and demonstrate that large-scale pyroclastic activity is possible along even the deepest portions of the global mid-ocean ridge volcanic system. PMID:18580949

  11. Narrow ridge management with ridge splitting with piezotome for implant placement: report of 2 cases.

    PubMed

    Agrawal, Deepak; Gupta, Alka Sanjay; Newaskar, Vilas; Gupta, Amit; Garg, Subhash; Jain, Deshraj

    2014-09-01

    Narrow dentoalveolar ridges remain a serious challenge for the successful placement of endosseous implants. Several techniques for this procedure may be considered, such as guided bone regeneration, bone block grafting, and ridge splitting for bone expansion. The ridge split procedure provides a quicker method wherein an atrophic ridge can be predictably expanded and grafted with bone allograft or allograft, eliminating the need for second surgical site. Traditionally, osseous surgery has been performed by either manual or motor-driven instruments. Piezosurgery is a relatively new technique for osteotomy and osteoplasty that utilizes ultrasonic vibration which allows clean cutting with precise incisions. This case series describes reports of 2 such cases in which narrow mandibular ridge splitting was carried by mean of piezotome with immediate placement of implants in the osteotomy site. Five months later, the implants were uncovered followed by impression and restored with impant- supported porcelain-fused-to-metal crowns. PMID:25183917

  12. Site characterization summary report for dry weather surface water sampling upper East Fork Poplar Creek characterization area Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1996-08-01

    This report describes activities associated with conducting dry weather surface water sampling of Upper East Fork Poplar Creek (UEFPC) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. This activity is a portion of the work to be performed at UEFPC Operable Unit (OU) 1 [now known as the UEFPC Characterization Area (CA)], as described in the RCRA Facility Investigation Plan for Group 4 at the Oak- Ridge Y-12 Plant, Oak Ridge, Tennessee and in the Response to Comments and Recommendations on RCRA Facility Investigation Plan for Group 4 at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, Volume 1, Operable Unit 1. Because these documents contained sensitive information, they were labeled as unclassified controlled nuclear information and as such are not readily available for public review. To address this issue the U.S. Department of Energy (DOE) published an unclassified, nonsensitive version of the initial plan, text and appendixes, of this Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) Plan in early 1994. These documents describe a program for collecting four rounds of wet weather and dry weather surface water samples and one round of sediment samples from UEFPC. They provide the strategy for the overall sample collection program including dry weather sampling, wet weather sampling, and sediment sampling. Figure 1.1 is a schematic flowchart of the overall sampling strategy and other associated activities. A Quality Assurance Project Plan (QAPJP) was prepared to specifically address four rounds of dry weather surface water sampling and one round of sediment sampling. For a variety of reasons, sediment sampling has not been conducted and has been deferred to the UEFPC CA Remedial Investigation (RI), as has wet weather sampling.

  13. Underground storage tank management plan, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1997-09-01

    The Underground Storage Tank (UST) Program at the Oak Ridge Y-12 Plant was established to locate UST systems at the facility and to ensure that all operating UST systems are free of leaks. UST systems have been removed or upgraded in accordance with Tennessee Department of Environment and Conservation (TDEC) regulations and guidance. With the closure of a significant portion of the USTs, the continuing mission of the UST Management Program is to manage the remaining active UST systems and continue corrective actions in a safe regulatory compliant manner. This Program outlines the compliance issues that must be addressed, reviews the current UST inventory and compliance approach, and presents the status and planned activities associated with each UST system. The UST Program provides guidance for implementing TDEC regulations and guidelines for petroleum UST systems. The plan is divided into three major sections: (1) regulatory requirements, (2) active UST sites, and (3) out-of-service UST sites. These sections describe in detail the applicable regulatory drivers, the UST sites addressed under the Program, and the procedures and guidance for compliance.

  14. Role of gas hydrates in slope failure on frontal ridge of northern Cascadia margin

    NASA Astrophysics Data System (ADS)

    Yelisetti, S.; Spence, G.; Riedel, M.

    2011-12-01

    Although the relationship between slope failure and gas hydrate dissociation has not been confirmed yet, several studies support a potential connection. Mass failures on the frontal ridge area are of comparable size (e.g., 1-3 km3) to others that have generated large tsunamis. The main objective of the present study is to examine seismic velocity structure on a frontal ridge of the Cascadia accretionary margin using tomographic velocity models and to seek a possible connection between sedimentary slide features and the presence of gas hydrate beneath the ridge. The active-source seismic experiment was completed in July 2010 on a frontal ridge where a prominent landslide, the Slipstream slide, was located. A grid of 7 ocean bottom seismometers (OBS's) was deployed on the ridge, mostly near its crest. These recorded wide-angle reflections and refractions from a 120 cu-in airgun. The presence of gas hydrate is indicated by a prominent bottom-simulating reflector (BSR) observed on a vertical incidence reflection line beneath the ridge crest. To complement the vertical-incidence data, the sub-seafloor structure was imaged by migrating water-layer multiples from the OBS data. Preliminary results indicate an improvement in the BSR image beneath the steep slopes on a line across the ridge. Gas hydrate is also indicated from analysis of velocities from the OBS data. The BSR is observed at ~ 260-270 m depth beneath the ridge crest. The velocity structure above the BSR shows anomalous high velocities of about 2.0 km/s at shallow depths of 90 m below the seafloor. The depth of the BSR and high velocity layer are consistent with the velocity structure determined previously in an OBS survey at an adjacent ridge, where the thickness of the high-velocity layer appeared to be about 20-30 m based on results of drilling by the Integrated Ocean Drilling Program. However, in the present study the glide plane is observed at a depth of 100 ± 10 m, in contrast to the adjacent ridge where

  15. Vertical Alveolar Ridge Augmentation by Distraction Osteogenesis

    PubMed Central

    Kumar, N. Nanda; Ravindran, C.

    2015-01-01

    Introduction Compromised alveolar ridge in vertical and horizontal dimension is a common finding in patients visiting practitioners for dental prosthesis. Various treatment modalities are available for correction of deficient ridges among which alveolar distraction osteogenesis is one. Aim To study the efficacy of alveolar distraction osteogenesis in augmentation of alveolar ridges deficient in vertical dimension. Materials and Methods Ten patients aged 16 to 46 years with deficient alveolar ridge underwent ridge augmentation in 11 alveolar segments using the distraction osteogenesis method. For each patient a custom made distraction device was fabricated. The device was indigenously manufactured with SS-316 (ISO 3506). Results The vertical bone gain reached more than 10mm without the use of bone transplantation. Certain complications like incorrect vector of distraction, paresthesia, pain and loss of transport segment were encountered during the course of the study. Conclusion Alveolar vertical distraction osteogenesis is a reliable and predictable technique for both hard and soft tissue genesis. Implant placement is feasible with primary stability in neogenerated bone at the level of the distracted areas. PMID:26816991

  16. Compressive strain in Lunae Planum-shortening across wrinkle ridges

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.

    1991-01-01

    Wrinkle ridges have long been considered to be structural or structurally controlled features. Most, but not all, recent studies have converged on a model in which wrinkle ridges are structural features formed under compressive stress; the deformation being accommodated by faulting and folding. Given that wrinkle ridges are compressive tectonic features, an analysis of the associated shortening and strain provides important quantitative information about local and regional deformation. Lunae Planum is dominated by north-south trending ridges extending from Kasei Valles in the north to Valles Marineris in the south. To quantify the morphometric character, a photoclinometric study was undertaken for ridges on Lunae Planum using the Davis and Soderblom. More than 25 ridges were examined between long. 57 and 80 deg, lat. 5 to 25 deg N. For each ridge, several profiles were obtained along its length. Ridge width, total relief, and elevation offset were measured for each ridge. Analyses are given.

  17. Request for closure, underground storage tank 2130-U: Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, Facility ID {number_sign}0-010117

    SciTech Connect

    Not Available

    1993-12-01

    This document presents a summary of the activities and analytical data related to the removal of underground storage tank (UST) 2130-U, previously located at the Oak Ridge Y-12 Plant. Removal of this tank was conducted in accordance with Tennessee Department of Environment and Conservation (TDEC) regulation 1200-1-15 (1992). A completed copy of the State of Tennessee, Division of Underground Storage Tanks, Permanent Closure Report Form is included as Appendix A of this document Based on the information and data presented herein, the Oak Ridge Y-12 Plant requests permanent closure for the tank 2130-U site.

  18. Implementation plan for liquid low-level radioactive waste systems under the FFA for fiscal years 1996 and 1997 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-06-01

    This document is the fourth annual revision of the plans and schedules for implementing the Federal Facility Agreement (FFA) compliance program, originally submitted in 1992 as ES/ER-17&D1, Federal Facility Agreement Plans and Schedules for Liquid Low-Level Radioactive Waste Tank Systems at Oak Ridge National Laboratory, Oak Ridge, Tennessee. This document summarizes the progress that has been made to date implementing the plans and schedules for meeting the FFA commitments for the Liquid Low-Level Waste (LLLW) System at Oak Ridge National Laboratory (ORNL). In addition, this document lists FFA activities planned for FY 1997. Information presented in this document provides a comprehensive summary to facilitate understanding of the FFA compliance program for LLLW tank systems and to present plans and schedules associated with remediation, through the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process, of LLLW tank systems that have been removed from service.

  19. Biomedical and environmental sciences programs at the Oak Ridge National Laboratory

    SciTech Connect

    Richmond, C.R.; Johnson, C.A.

    1988-02-01

    This progress report summarizes the research and development activities conducted in the Biomedical and Environmental Sciences Programs of Oak Ridge National Laboratory. The report is structured to provide descriptions of current activities and accomplishments in each of the major organizational units. Following the accounts of research programs, is a list of publications and awards to its members. 6 figs., 14 tabs.

  20. Structure and development of an axial volcanic ridge: Mid-Atlantic Ridge, 45°N

    NASA Astrophysics Data System (ADS)

    Searle, R. C.; Murton, B. J.; Achenbach, K.; LeBas, T.; Tivey, M.; Yeo, I.; Cormier, M. H.; Carlut, J.; Ferreira, P.; Mallows, C.; Morris, K.; Schroth, N.; van Calsteren, P.; Waters, C.

    2010-10-01

    We describe the most comprehensive and detailed high resolution survey of an axial volcanic ridge (AVR) ever conducted, at 45°N on the Mid-Atlantic Ridge. We use 3 m resolution sidescan sonar, deep-towed magnetic field measurements, video observations from eleven ROV dives, and two very-high-resolution bathymetry and magnetic surveys. The most recently active AVR has high topographic relief, high acoustic backscatter, high crustal magnetization and little faulting. It is sharp-crested, 25 × 4 km in extent and 500 m high, and is covered by approximately 8000 volcanic "hummocks" whose detailed nature is revealed for the first time. Each is an individual volcano ≤ 450 m in diameter and ≤ 200 m high, ranging from steep-sided (45°) cones to low domes. Many have suffered significant flank collapse. Hummocks tend to align in rows parallel to the AVR axis, parallel to its NE-trending spurs or, on its lower flanks, sub-normal to the AVR trend. These latter are spaced 1-2 km apart and comprise 1-2 km-long rows of single volcanoes. We infer that their emplacement is controlled by down-flank magma transport, possibly via lava tubes. The AVR contains only one large flat-topped seamount. The flanking median valley floor consists of either older hummocky volcanic terrain or flat-lying, mostly sediment-covered lavas. These typically have low-relief lobate surfaces, inflation and collapse structures, and occasional lava tubes and tumuli. The AVR displays open fissures, mostly along its crest. There is direct evidence for only a few small faults on the AVR, though steep, outward-facing slopes draped by elongate pillows may be small normal faults covered by lava. The surrounding median valley floor is heavily fissured. Normal faults cut it and an older AVR, the latter displaying significant outward facing faults. High crustal magnetization, an approximate proxy for crustal age within the Brunhes, is confined to the active AVR. Magnetic palaeointensity measurements are

  1. Seismostratigraphy, tectonics and geological history of the Ninetyeast Ridge

    NASA Astrophysics Data System (ADS)

    Marinova, Yulia; Levchenko, Oleg; Sborshchikov, Igor

    2016-04-01

    The Ninetyeast Ridge (NER) is a ~5000 km-long, aseismic volcanic ridge trending N-S in the Central Indian Ocean Basin. It is widely accepted that NER formed as a hotspot track created by northward migration of the Indian plate over the Kerguelen hotspot during the Late Cretaceous and Early Cenozoic. High-resolution multibeam bathymetry data and multichannel seismic profiles collected over the NER at seven sites between 5.5° N and 26.1° S during cruise KNOX06RR of RV Roger Revelle with the participation of P.P. Shirshov Institute of Oceanology supplemented ideas about its seismostratigraphy and tectonics to clarify geological history [Sager et al.,2007]. High-resolution multibeam bathymetry data and 2D multichannel seismic data clearly show active faulting along the entire length of the NER. Bathymetry data collected in cruise show significant changes of NER's morphology varies with latitude - from large, individual seamounts in the north segment to smaller, linear, narrow seamounts and ridges in the central segment to high, nearly continuous, and often highly asymmetric with a steep eastern slope and low western slope ridge in the south. Three its distinct morphological segments are characterized also by different internal tectonic structure (faults geometry). The faults have different directions for each segment of NER - they trend to NW-SE less NE-SW in the northern segment, E-W in the central segment and NE-SW in the south. Large near E-W grabens mostly filled by intensively deformed sediments are widespread along the ridge. All three identified types of the faults are extension structures and no compression structures, predictable from the regional stress field, is not observed yet. Additional features were traced within the sedimentary cover of NER as a result of seismic stratigraphy analysis of the multichannel seismic data collected in proximity to DSDP and ODP drill holes (Sites 758, 216, 214, and 253) - eight reflectors: 0, 0A, 1, 1A, 2, 3, 4 and 5 and

  2. Modern therapy for severe alveolar ridge atrophy.

    PubMed

    Chen, Yu-Feng; Pan, Chin-Yun; Wang, Wen-Chen; Lan, Ting-Hsun

    2013-01-01

    This clinical report illustrates a modern method for oral rehabilitation of severe edentulous atrophic ridge. Shallow vestibule and small denture-bearing area of the maxilla provide insufficient retention, and only the symphyseal region of the mandible has obvious alveolar ridge. The surgery of deepening vestibule of the maxilla ridge was done by using tentative miniscrew combined with old denture and soft liner. The osseointegrated dental implants were installed over symphyseal region of the mandible to act as retentive devices for prostheses. In addition, functional reline with rebase material to build buccal-tongue contact over the retromolar area after denture delivery obtained high satisfaction from the patient. Many clinical conditions cannot be managed solely with implants or preprosthetic surgery alone, whereas a combination of the 2 can achieve successful outcome. PMID:24036818

  3. Oxygen Fugacity of Abyssal Peridotites Along the Gakkel Ridge

    NASA Astrophysics Data System (ADS)

    Said, M.; Birner, S.; Cottrell, E.

    2015-12-01

    The oxygen budget of the Earth's mantle is important in understanding how our planet evolves chemically over time. The Gakkel Ridge is the world's slowest spreading ridge [1], and exposes peridotites along its axis that record the activity of oxygen in the upper mantle. Our samples comprise relatively fertile lherzolites and harzburgites (Cr#=0.13-0.17, 3.1-8.3% modal cpx [2]) as well as refractory harzburgites (Cr#=0.43-0.55, 0.2-1.0% modal cpx [2]). Using spinel peridotite oxygen barometry [3], we calculated the oxygen fugacity (fO2) of a suite of 10 peridotites from the Gakkel Ridge in order to investigate how melt processes affect the oxygen budget of the Earth's interior. We show that the low-Cr# lherzolites and harzburgites range from -0.1 to +0.6 log units relative to the QFM buffer, consistent with the global abyssal peridotite array, whereas high-Cr# refractory harzburgites have low fO2 values, ranging from -0.7 to -2.7 log units below QFM, with the most refractory samples falling significantly lower than the global array. Because D'Errico et al. (submitted) interprets the refractory samples as recording ancient melt extraction, the low fO2 recorded by these samples may originate in the geologic past, perhaps even in a different tectonic setting. While LREE enrichment in the refractory harzburgites [2] provides evidence for refertilization by an infiltrating melt that could have recently imprinted reducing conditions, we see no corresponding increase in TiO2 content in the spinels, which weakens this hypothesis. Further research on additional refractory harzburgites is needed to constrain whether the reduced nature of these samples is telling us something about the effect of extreme melt extraction on fO2 at ridges, or whether these samples record a unique history that obscures processes operating at ridges today. [1] Coakley and Cochran, EPSL (1998), [2] D'Errico et al., submitted, [3] Bryndzia and Wood, American Journal of Science (1990)

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  6. The influence of ridge migration on the magmatic segmentation of mid-ocean ridges.

    PubMed

    Carbotte, S M; Small, C; Donnelly, K

    2004-06-17

    The Earth's mid-ocean ridges display systematic changes in depth and shape, which subdivide the ridges into discrete spreading segments bounded by transform faults and smaller non-transform offsets of the axis. These morphological changes have been attributed to spatial variations in the supply of magma from the mantle, although the origin of the variations is poorly understood. Here we show that magmatic segmentation of ridges with fast and intermediate spreading rates is directly related to the migration velocity of the spreading axis over the mantle. For over 9,500 km of mid-ocean ridge examined, leading ridge segments in the 'hotspot' reference frame coincide with the shallow magmatically robust segments across 86 per cent of all transform faults and 73 per cent of all second-order discontinuities. We attribute this relationship to asymmetric mantle upwelling and melt production due to ridge migration, with focusing of melt towards ridge segments across discontinuities. The model is consistent with variations in crustal structure across discontinuities of the East Pacific Rise, and may explain variations in depth of melting and the distribution of enriched lavas. PMID:15201906

  7. Environmental restoration and waste management Site-Specific Plan for the Oak Ridge Reservation. FY 1993

    SciTech Connect

    Not Available

    1993-01-15

    The United States Department of Energy (DOE) is committed to achieving and maintaining environmental regulatory compliance while responding to public concerns and emphasizing waste minimization. DOE publishes the Environmental Restoration and Waste Management Five-Year Plan (FYP) annually to document its progress towards these goals. The purpose of this Site-Specific Plan (SSP) is to describe the activities undertaken to implement the FYP goals at the DOE Oak Ridge Field Office (DOE/OR) installations and programs specifically for the Oak Ridge Reservation (ORR) and surrounding areas. This SSP addresses activities and goals to be accomplished during FY93 even through the FYP focuses on FY94.

  8. New data about small-magnitude earthquakes of the ultraslow-spreading Gakkel Ridge, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Morozov, Alexey N.; Vaganova, Natalya V.; Ivanova, Ekaterina V.; Konechnaya, Yana V.; Fedorenko, Irina V.; Mikhaylova, Yana A.

    2016-01-01

    At the present time there is available detailed bathymetry, gravimetric, magnetometer, petrological, and seismic (mb > 4) data for the Gakkel Ridge. However, so far not enough information has been obtained on the distribution of small-magnitude earthquakes (or microearthquakes) within the ridge area due to the absence of a suitable observation system. With the ZFI seismic station (80.8° N, 47.7° E), operating since 2011 at the Frantz Josef Land Archipelago, we can now register small-magnitude earthquakes down to 1.5 ML within the Gakkel Ridge area. This article elaborates on the results and analysis of the ZFI station seismic monitoring obtained for the period from December 2011 to January 2015. In order to improve the accuracy of the earthquakes epicenter locations, velocity models and regional seismic phase travel-times for spreading ridges in areas within the Euro-Arctic Region have been calculated. The Gakkel Ridge is seismically active, regardless of having the lowest spreading velocity among global mid-ocean ridges. Quiet periods alternate with periods of higher seismic activity. Earthquakes epicenters are unevenly spread across the area. Most of the epicenters are assigned to the Sparsely Magmatic Zone, more specifically, to the area between 1.5° E and 19.0° E. We hypothesize that assignment of most earthquakes to the SMZ segment can be explained by the amagmatic character of the spreading of this segment. The structuring of this part of the ridge is characterized by the prevalence of tectonic processes, not magmatic or metamorphic ones.

  9. Mantle exhumation at the Southwest Indian Ridge; preliminary results of the SMOOTHSEAFLOOR cruise

    NASA Astrophysics Data System (ADS)

    Sauter, D.; Cannat, M.; Andreani, M.; Birot, D.; Bronner, A.; Brunelli, D.; Carlut, J. H.; Delacour, A.; Guyader, V.; Mendel, V.; Ménez, B.; MacLeod, C. J.; Pasini, V.; Rouméjon, S.; Ruellan, E.; Searle, R. C.

    2011-12-01

    The eastern Southwest Indian Ridge (SWIR) is among the deepest part of the oceanic ridge system, and it is thus inferred to represent a melt-poor end-member for this system. It displays the widest expanses known to date of seafloor with no evidence for a volcanic upper crustal layer. This nonvolcanic ocean floor has no equivalent at faster spreading ridges and has been called "smooth seafloor" because it occurs in the form of broad ridges up to 2000 m high with a smooth, rounded topography with no resolvable volcanic cones on bathymetric data (Cannat et al., 2006). On R/V Marion Dufresne cruise "SMOOTHSEAFLOOR" in October 2010, we conducted a detailed geological-geophysical survey of such smooth seafloor areas, determining the rock types exposed at these ridges, searching for hydrothermal activity and mapping the volcanic, tectonic and sedimentary structures. 35 dredges and 15 CTDs have been realized and more than 1000 km long TOBI sidescan sonar images and deep towed magnetometer profiles have been collected over two contrasting survey areas up to magnetic anomaly C5n (10 Ma). The main result of our cruise is that serpentinized mantle-derived peridotites were dredged widely throughout the smooth seafloor areas while gabbros and basalts were rare. Mantle rocks were found on moderate slopes (20-35°), facing toward and away from the axial valley, at ridges with symmetric shape, as well as on gentle slopes (<15°) facing the axis at asymmetric ridges whose outward facing steeper slopes may be covered with volcanics. TOBI sidescan sonar images show that these hillsides are ancient large low angle normal faults which were covered locally by small amount of volcanics and dismembered by landslide activity. These results show that mantle exhumation has been the main process which shaped the smooth seafloor areas of the eastern SWIR for the last 10 Myrs.

  10. Environmental monitoring plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-09-01

    This document presents an Environmental Monitoring Plan (EMP) for Waste Area Grouping (WAG 6) at Oak Ridge National Laboratory (ORNL). This document updates a draft monitoring plan developed in 1993. The draft plan was never finalized awaiting resolution of the mechanisms for addressing RCRA concerns at a site where the CERCLA process resulted in a decision to defer action, i.e., postpone closure indefinitely. Over the past two years the Tennessee Department of Environment and Conservation (TDEC), US Department of Energy (DOE), and US Environmental Protection Agency (EPA) Region IV, have agreed that RCRA authority at the site will be maintained through a post- closure permit; ``closure`` in this case referring to deferred action. Both a Revised Closure Plan (DOE 1995a) and a Post-Closure Permit Application (DOE 1995b) have been developed to document this agreement; relevant portions of the EMP will be included in the RCRA Post-Closure Permit Application. As the RCRA issues were being negotiated, DOE initiated monitoring at WAG 6. The purpose of the monitoring activities was to (1) continue to comply with RCRA groundwater quality assessment requirements, (2) install new monitoring equipment, and (3) establish the baseline conditions at WAG 6 against which changes in contaminant releases could be measured. Baseline monitoring is scheduled to end September 30, 1995. Activities that have taken place over the past two years are summarized in this document.

  11. Agulhas Ridge, South Atlantic: the peculiar structure of a transform fault

    NASA Astrophysics Data System (ADS)

    Uenzelmann-Neben, G.; Gohl, K.

    2003-04-01

    Transform faults constitute conservative plate boundaries, where adjacent plates are in tangential contact. Transform faults in the ocean are marked by fracture zones, which are long, linear, bathymetric depressions. One of the largest transform offsets on Earth can be found in the South Atlantic. The 1200 km long Agulhas Falkland Fracture Zone (AFFZ), form by this, developed during the Early Cretaceous break-up of West Gondwana. Between approx. 41°S, 16°E and 43°S, 9°E the Agulhas Falkland Fracture Zone is characterised by a pronounced topographic anomaly, the Agulhas Ridge. The Agulhas Ridge rises more than 2 km above the surrounding seafloor. The only equivalent to this kind of topographic high, as part of the AFFZ, is found in form of marginal ridges along the continental parts of the fracture zone, namely the Falkland Escarpment at the South American continent and the Diaz Ridge adjacent to South Africa. But the Agulhas Ridge differs from both the Falkland Escarpment and the Diaz Ridge in the facts (1) that it was not formed during the early rift-drift phase, and (2) that it separates oceanic crust of different age and not continental from oceanic crust. A set of high-resolution seismic reflection data (total length 2000 km) and a seismic refraction line across the Agulhas Ridge give new information on the crustal and basement structure of this tectonic feature. We have observed that within the Cape Basin, to the North, the basement and sedimentary layers are in parts strongly deformed. We observe basement highs, which point towards intrusions. Both the basement and the sedimentary sequence show strong faulting. This points towards a combined tectono-magmatic activity, which led to the formation of basement ridges parallel to the Agulhas Ridge. Since at least the pre-Oligocene parts and, locally, the whole sedimentary column are affected we infer that the renewed activity began in the Middle Oligocene and may have lasted into the Quaternary. As an origin

  12. Cold test plan for the Old Hydrofracture Facility tank contents removal project, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1997-11-01

    This Old Hydrofracture Facility (OHF) Tanks Contents Removal Project Cold Test Plan describes the activities to be conducted during the cold test of the OHF sluicing and pumping system at the Tank Technology Cold Test Facility (TTCTF). The TTCTF is located at the Robotics and Process Systems Complex at the Oak Ridge National Laboratory (ORNL). The cold test will demonstrate performance of the pumping and sluicing system, fine-tune operating instructions, and train the personnel in the actual work to be performed. After completion of the cold test a Technical Memorandum will be prepared documenting completion of the cold test, and the equipment will be relocated to the OHF site.

  13. Oak Ridge Reservation annual site environmental report for 1997: Color your tomorrow

    SciTech Connect

    Hamilton, L.V.

    1998-10-01

    The U.S. Department of Energy currently oversees activities on the Oak Ridge Reservation (ORR), a government-owned, contractor-operated facility. The reservation contains three major operating sites: the Oak Ridge Y-12 Plant, Oak Ridge National Laboratory, and East Tennessee Technology Park (formerly the K-25 Site). The ORR was established in the early 1940s as part of the Manhattan Project, a secret undertaking that produced the materials for the first atomic bombs. The reservation's role has evolved over the years, and it continues to adapt to meet the changing defense, energy, and research needs of the United States. Both the work carried out for the war effort and subsequent research, development, and production activities have involved (and continue to involve) radiological and hazardous materials.

  14. Earthquake swarms on the Mid-Atlantic Ridge - Products of magmatism or extensional tectonics?

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1990-01-01

    The spatial and temporal patterns and other characteristics of earthquakes in 34 earthquake swarms on the Mid-Atlantic Ridge were compared with those of well-studied earthquake swarms which accompany terrestrial volcanic eruptions, to test the assumption that the teleseismically observed earthquake swarms along mid-ocean ridges are indicators of volcanism. Improved resolution of these patterns for the mid-ocean ridge events was achieved by a multiple-event relocation technique. It was found that the teleseismically located earthquake swarms on the mid-ocean ridge system have few features in common with swarms directly associated with active magmatism in terrestrial volcanic rift zones such as Hawaii and Iceland. While the possibility that some of the mid-ocean earthquake swarms might be directly associated with a current episode of eruptive activity on the Mid-Atlantic Ridge cannot be excluded, none of the 34 swarms studied in this work was found to be a conspicuously attractive candidate for such a role.

  15. Ridge Subduction Beneath the Americas: Synthesis and New Research on Anomalous Tectonism and Magmatism

    NASA Astrophysics Data System (ADS)

    Thorkelson, D. J.; Madsen, J. K.; Breitsprecher, K.; Groome, W. G.; Sluggett, C.

    2006-12-01

    The west coast of the Americas has been repeatedly affected by ridge-trench interactions from Mesozoic to Recent time. Beneath North America, subduction of the Kula-Farallon, Kula-Resurrection and Farallon- Resurrection spreading ridges resulted in anomalous and time-transgressive forearc to backarc magmatism and related tectonism from the Late Cretaceous to the Eocene. Following consumption and redistribution of the Kula and Resurrection plates, the Neogene Farallon-Pacific ridge system intersected the North American trench in two locations - western Canada and northwestern Mexico / southwestern United States - causing pronounced magmatic and tectonic effects that continue to the present. Beneath Central America, divergent subduction of the Nazca and Cocos plates led to development of a slab window, with a present location beneath Panama and a probable pre-Pliocene position beneath Columbia or Ecuador. Patagonia has been the site of localized ridge subduction from the Eocene to the Recent, with the Phoenix-Farallon ridge subducting from the Eocene to the early Miocene, and the Nazca-Antarctic ridge from the Miocene to the present. Antarctica experienced diverging Antarctic-Phoenix plate subduction from the Eocene to the Pliocene. In all cases, normal arc magmatism was interrupted or eliminated by anomalous igneous activity ranging in signature from adakitic to intraplate. Our current research involves geochemical, tectonic, and thermal modeling of slab window environments. A new geochemical analysis on the effects of Miocene to Recent subduction of the northern segment of the Farallon (Juan de Fuca)-Pacific ridge is underway. A symmetrical arc-intraplate-arc geochemical pattern is evident in a transect from the northern Cascade Arc, through the volcanic fields of British Columbia, Yukon and eastern Alaska, and into the Aleutian Arc. This pattern can be explained by Neogene displacement of the arc-metasomatized mantle wedge caused by upwelling oceanic

  16. Caught in the Act: A Hot Mantle Pulse beneath the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Parnell-Turner, R. E.; White, N. J.; Maclennan, J.; Henstock, T.; Murton, B. J.; Jones, S. M.

    2012-12-01

    The intersection of the Icelandic plume with the Reykjanes Ridge provides us with a useful window into aspects of mantle convective processes. This spreading ridge acts as a linear sampler, recording transient plume activity as a series of V-shaped ridges and troughs within the oceanic basin. The geometry of these ridges and troughs shows how plume flux varies with time, and how the shape and size of the plume head has evolved. Here, we present the results of a detailed study of the morphology of the Reykjanes Ridge between 57° and 63°N, where the youngest V-shaped ridge forms thickened crust. This study is a synthesis of newly acquired and legacy data. A combination of high-resolution and multibeam bathymetric and 2D seismic reflection surveys acquired at the ridge axis reveals the detailed pattern of volcanism and normal faulting. The density of seamounts varies significantly along the ridge, increasing by a factor of two between 59° and 62°N. Within this zone, mean fault length decreases from ~11 to 6 km and the cumulative moment release of earthquakes decreases by about two orders of magnitude. Recently acquired seismic profiles show enhanced acoustic scattering at the seabed and a change in the character of Layer 2A. A steady-state thermal model is used to show that a combination of increased crustal thickness and decreased hydrothermal circulation accounts for the range of observations within this ~200 km long portion of ridge. The increase in temperature required to effectively shut off brittle deformation is consistent with geochemical modeling of major, trace and rare earth elemental compositions which require horizontal advection of hotter asthenospheric material beneath the ridge axis. The existence of a ~200 km long transient mantle pulse within a ~100-200 km thick low velocity channel, horizontally advecting away from the Icelandic plume at a velocity of ~40 cm/yr, has important implications for the relationship between mantle convection, crustal

  17. Wrinkle Ridges in Aeolis Dorsa, Mars: Preliminary Mapping

    NASA Astrophysics Data System (ADS)

    Borden, R. M.; Burr, D. M.

    2016-06-01

    Previous work has interpreted wrinkle ridges as compressional landforms caused by movement along blind thrust faults. Our preliminary mapping in the Aeolis Dorsa, Mars has identified widely distributed wrinkle ridges, suggesting episodic contraction.

  18. Martian Wrinkle Ridge Topography: Evidence for Subsurface Faults from MOLA

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Anderson, F. S.; Zuber, M. T.

    2000-01-01

    Mars Orbiter Laser Altimeter (MOLA) profiles across wrinkle ridges are characterized by plains surfaces at different elevations on either side that appear best explained by subsurface thrust faults that underlie the ridges and produce the offset.

  19. Final deactivation project report on the Integrated Process Demonstration Facility, Building 7602 Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1997-09-01

    The purpose of this report is to document the condition of the Integrated Process Demonstration Facility (Building 7602) at Oak Ridge National Laboratory (ORNL) after completion of deactivation activities by the High Ranking Facilities Deactivation Project (HRFDP). This report identifies the activities conducted to place the facility in a safe and environmentally sound condition prior to transfer to the U.S. Department of Energy (DOE) Environmental Restoration EM-40 Program. This report provides a history and description of the facility prior to commencing deactivation activities and documents the condition of the building after completion of all deactivation activities. Turnover items, such as the Post-Deactivation Surveillance and Maintenance (S&M) Plan, remaining hazardous and radioactive materials inventory, radiological controls, Safeguards and Security, and supporting documentation provided in the Office of Nuclear Material and Facility Stabilization Program (EM-60) Turnover package are discussed.

  20. Oak Ridge reservation land-use plan

    SciTech Connect

    Bibb, W. R.; Hardin, T. H.; Hawkins, C. C.; Johnson, W. A.; Peitzsch, F. C.; Scott, T. H.; Theisen, M. R.; Tuck, S. C.

    1980-03-01

    This study establishes a basis for long-range land-use planning to accommodate both present and projected DOE program requirements in Oak Ridge. In addition to technological requirements, this land-use plan incorporates in-depth ecological concepts that recognize multiple uses of land as a viable option. Neither environmental research nor technological operations need to be mutually exclusive in all instances. Unique biological areas, as well as rare and endangered species, need to be protected, and human and environmental health and safety must be maintained. The plan is based on the concept that the primary use of DOE land resources must be to implement the overall DOE mission in Oak Ridge. This document, along with the base map and overlay maps, provides a reasonably detailed description of the DOE Oak Ridge land resources and of the current and potential uses of the land. A description of the land characteristics, including geomorphology, agricultural productivity and soils, water courses, vegetation, and terrestrial and aquatic animal habitats, is presented to serve as a resource document. Essentially all DOE land in the Oak Ridge area is being fully used for ongoing DOE programs or has been set aside as protected areas.

  1. 25 MV tandem accelerator at Oak Ridge

    SciTech Connect

    Jones, C.M.

    1980-01-01

    A new heavy-ion accelerator facility is under construction at the Oak Ridge National Laboratory. A brief description of the scope and status of this project is presented with emphasis on the first operational experience with the 25 MV tandem accelerator.

  2. Oak Ridge Reservation Waste Management Plan

    SciTech Connect

    Turner, J.W.

    1995-02-01

    This report presents the waste management plan for the Oak Ridge Reservation facilities. The primary purpose is to convey what facilities are being used to manage wastes, what forces are acting to change current waste management systems, and what plans are in store for the coming fiscal year.

  3. SUSTAINABLE HOUSING AT PINE RIDGE RESERVATION

    EPA Science Inventory

    The Pine Ridge Reservation, located in rural South Dakota is plagued with deteriorating infrastructure, poverty, lack of local employment, and high utility bills. Many of the residents, the Oglala Lakota Nation, live in mobile homes or substandard housing and spend nearly 25% of...

  4. Pulse granuloma of the alveolar ridge.

    PubMed

    Mincer, H H; McCoy, J M; Turner, J E

    1979-08-01

    Six examples of pulse granulomas of the alveolar ridge are presented. The lesion consists of a foreign-body granuloma containing identifiable particles of leguminous foods. The vegetable matter is introduced through an alveolar defect, usually a postextraction socket. Simple curettage is apparently adequate treatment to effect cure. PMID:382018

  5. Groundwater quality monitoring well installation for Waste Area Grouping at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Environmental Restoration Program

    SciTech Connect

    Mortimore, J.A.; Lee, T.A.

    1994-09-01

    This report documents the drilling and installation of 18 groundwater quality monitoring (GQM) wells on the perimeter of Waste Area Grouping (WAG) 11. WAG 11 (White Wing Scrap Yard) is located on the west end of East Fork Ridge between White Wing Road and the Oak Ridge Turnpike. The scrap yard is approximately 25 acres in size. The wells at WAG 11 were drilled and developed between January 1990 and October 1990. These wells were installed to characterize and assess the WAG in accordance with applicable Department of Energy, state, and Environmental Protection Agency regulatory requirements. The wells at WAG 11 were drilled with auger or air rotary rigs. Depending on the hydrogeologic conditions present at each proposed well location, one of four basic installation methods was utilized. Detailed procedures for well construction were specified by the Engineering Division to ensure that the wells would provide water samples representative of the aquifer. To ensure conformance with the specifications, Energy Systems Construction Engineering and ERCE provided continuous oversight of field activities. The purpose of the well installation program was to install GQM wells for groundwater characterization at WAG 11. Data packages produced during installation activities by the ERCE hydrogeologists are an important product of the program. These packages document the well drilling, installation, and development activities and provide valuable data for well sampling and WAG characterization. The forms contained in the packages include predrilling and postdrilling checklists, drilling and construction logs, development and hydraulic conductivity records, and quality control-related documents.

  6. A radiological and chemical investigation of the 7500 Area Contamination Site at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Williams, J.K.; Foley, R.D.; Tiner, P.F.; Hatmaker, T.L.; Uziel, M.S.; Swaja, R.E.

    1993-05-01

    A radiological and chemical investigation of the 7500 Area Contamination Site at Oak Ridge National Laboratory (ORNL) was conducted intermittently from February 1992 through May 1992. The investigation was performed by the Measurement Applications and Development Group of the Health and Safety Research Division of ORNL at the request of the US Department of Energy`s Oak Ridge Operations Office and the ORNL Environmental Restoration Program. Results of this investigation indicate that the source of radioactive contamination at the point of the contamination incident is from one of the underground abandoned lines. The contamination in soil is likely the result of residual contamination from years of waste transport and maintenance operations (e.g., replacement of degraded joints, upgrading or replacement of entire pipelines, and associated landscaping activities). However, because (1) there is currently an active LLW line positioned in the same subsurface trench with the abandoned lines and (2) the physical condition of the abandoned lines may be brittle, this inquiry could not determine which abandoned line was responsible for the subsurface contamination. Soil sampling at the location of the contamination incident and along the pipeline route was performed in a manner so as not to damage the active LLW line and abandoned lines. Recommendations for corrective actions are included.

  7. Fluid and chemical fluxes along a buried-basement ridge in the eastern Juan de Fuca Ridge flank

    NASA Astrophysics Data System (ADS)

    Hulme, S.; Wheat, C. G.

    2010-12-01

    Hydrothermal fluid circulation within oceanic crust at low temperatures affects global biogeochemical cycles, with the volume of fluid circulation rivaling that of the world’s water flux to the oceans from rivers. Our work focuses on the best studied low temperature hydrothermal system on the eastern flank of the Juan de Fuca Ridge where a buried basement ridge 100 km from the active spreading axis has been sampled with a variety of mediums. We use data from deep sea drilling, gravity coring, and submersible operations from five sites along-strike of the buried ridge to better constrain the chemical and fluid fluxes along this transect. A transport (advection-diffusion) model is applied to the data, constraining the volumetric fluid flux per unit length within the oceanic crust from 0.05 and 0.2 m3 y-1 cm-1 and identifying conservative elements within this system. Using an average fluid flux, reactive fluxes are determined for non-conservative elements within basaltic crust for twenty-four chemical species. Conservative species include K, Cl, SO4, Ba, Sr, Cs, Mo, and Y. Only Ca and the rare earth elements Ce and Gd are produced by basaltic basement. The remaining chemical species Mg, Na, ammonium, Li, Rb, Mn, Fe, Co, Zn, Cd, U, La and Yb are all consumed within upper basaltic basement. Fluxes of potentially-bioavailable redox species ammonium, Fe, and Mn into the upper basaltic basement are 3 to 20 nmol y-1cm-2. Possible mechanisms of removal are suggested, placing constraints on microbial metabolic activity and biomineralization.

  8. Bowers Swell: Evidence for a zone of compressive deformation concentric with Bowers Ridge, Bering Sea

    USGS Publications Warehouse

    Marlow, M. S.; Cooper, A. K.; Dadisman, S.V.; Geist, E.L.; Carlson, P.R.

    1990-01-01

    Bowers Swell is a newly discovered bathymetric feature which is up to 90 m high, between 12 and 20 km wide, and which extends arcuately about 400 km along the northern and eastern sides of Bowers Ridge. The swell was first revealed on GLORIA sonographs and subsequently mapped on seismic reflection and 3.5 kHz bathymetric profiles. These geophysical data show that the swell caps an arcuate anticlinal ridge, which is composed of deformed strata in an ancient trench on the northern and eastern sides of Bowers Ridge. The trench fill beneath the swell is actively deforming, as shown by faulting of the sea floor and by thinning of the strata across the crest of the swell. Thinning and faulting of the trench strata preclude an origin for the swell by simple sediment draping over an older basement high. We considered several models for the origin of Bowers Swell, including folding and uplift of the underlying trench sediment during the interaction between the Pacific plate beneath the Aleutian Ridge and a remnant oceanic slab beneath Bowers Ridge. However, such plate motions should generate extensive seismicity beneath Bowers Ridge, which is aseismic, and refraction data do not show any remnant slab beneath Bowers Ridge. Another origin considered for Bowers Swell invokes sediment deformation resulting from differential loading and diapirism in the trench fill. However, diapirism is not evident on seismic reflection profiles across the swell. We favour a model in which sediment deformation and swell formation resulted from a few tens of kilometers of low seismicity motion by intraplate crustal blocks beneath the Aleutian Basin. This motion may result from the translation of blocks in western Alaska to the south-west, forcing the movement of the Bering Sea margin west of Alaska into the abyssal Aleutian Basin. ?? 1990.

  9. Design assessment for the Bethel Valley FFA Upgrades at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-09-01

    This report describes the proposed upgrades to Building 3025 and the Evaporator Area at Oak Ridge National Laboratory. Design assessments, specifications and drawings are provided. Building 3025 is a general purpose research facility utilized by the Materials and Ceramics Division to conduct research on irradiated materials. The Evaporator Area, building 2531, serves as the collection point for all low-level liquid wastes generated at the Oak Ridge National Laboratory.

  10. Geophysical survey work plan for White Wing Scrap Yard (Waste Area Grouping 11) at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-02-01

    The White Wing Scrap Yard, located on the U.S. Department of Energy`s Oak Ridge Reservation, served as an aboveground storage and disposal area for contaminated debris and scrap from the Oak Ridge K-25 Site, the Oak Ridge Y-12 Plant, and the Oak Ridge National laboratory. The site is believed to have been active from the early 1950s until the mid-1960s. A variety of materials were disposed of at the site, including contaminated steel tanks and vehicles. As an interim corrective action, a surface debris removal effort was initiated in November 1993 to reduce the potential threat to human health and the environment from the radionuclide-contaminated debris. Following this removal effort, a geophysical survey will be conducted across the site to locate and determine the lateral extent of buried nonindigenous materials. This survey will provide the data necessary to prepare a map showing areas of conductivity and magnetic intensity that vary from measured background values. These anomalies represent potential buried materials and therefore can be targeted for further evaluation. This work plan outlines the activities necessary to conduct the geophysical survey.

  11. 76 FR 35909 - Temporary Concession Contract for Blue Ridge Parkway

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ... National Park Service Temporary Concession Contract for Blue Ridge Parkway AGENCY: National Park Service, Interior. ACTION: Notice of proposed award of temporary concession contracts for Blue Ridge Parkway, NC/VA... Blue Ridge Parkway, North Carolina and Virginia, for a term not to exceed 3 years. The visitor...

  12. Photoclinometric analysis of wrinkle ridges on Lunae Planum, Mars

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.

    1990-01-01

    Wrinkle ridges are common morphologic features on Mars. Both volcanic and tectonic mechanisms were suggested to explain their origin; recent work has focused on a compressional origin. Analysis of terrestrial analogs has greatly influenced and aided the understanding of wrinkle ridge formation. An important aspect necessary to intrepret structure is topography. Topographic profiles across ridges can provide important constraints for models of internal structure and analyzing deformation associated with ridges. Topographic maps of Mars are too coarse to resolve the topography of individual ridges; therefore, monoscopic photoclinometry was used to derive topographic profiles for the ridges. Profiles spaced a few kilometers apart were obtained for each ridge, the number depended on ridge length, morphology, and albedo variation. Photoclinometry relies on pixel brightness variations which results from topography, albedo, or both. Because of the albedo variations, photoclimometric profiles can not be extended across large distances, such as between adjacent ridges (about 20 to 80 km). However, the technique is applicable to shorter distances, such as the distance across typical ridges. Profiles were measured across the ridge and extended a few kilometers on either side, including all visible components of the ridge. The results of these measurements and the use of internal structure and topographic profile models for estimating the shortening due to folding and faulting are discussed.

  13. Waste Reduction plan for Oak Ridge National Laboratory

    SciTech Connect

    Not Available

    1991-12-01

    Oak Ridge National Laboratory (ORNL) is a multipurpose research and development (R D) facility owned and operated by the Department of Energy (DOE) and managed under subcontract by Martin Marietta Energy Systems (Energy Systems), Inc. ORNL R D activities generate numerous small waste streams. In the hazardous waste category alone, over 300 streams of a diverse nature exist. Generation avoidance, reduction or recycling of wastes is an important goal in maintaining efficiency of ORNL R D activities and protection of workers, the public, and the environment. Waste minimization is defined as any action that minimizes or eliminates the volume or toxicity of waste by avoiding its generation or recycling. This is accomplished by material substitution and inventory management, process modification, or recycling wastes for reuse. Waste reduction is defined as waste minimization plus treatment which results in volume or toxicity reduction. The ORNL Waste Reduction Program will include both waste minimization and waste reduction activities.

  14. Waste Reduction plan for Oak Ridge National Laboratory

    SciTech Connect

    Not Available

    1991-12-01

    Oak Ridge National Laboratory (ORNL) is a multipurpose research and development (R&D) facility owned and operated by the Department of Energy (DOE) and managed under subcontract by Martin Marietta Energy Systems (Energy Systems), Inc. ORNL R&D activities generate numerous small waste streams. In the hazardous waste category alone, over 300 streams of a diverse nature exist. Generation avoidance, reduction or recycling of wastes is an important goal in maintaining efficiency of ORNL R&D activities and protection of workers, the public, and the environment. Waste minimization is defined as any action that minimizes or eliminates the volume or toxicity of waste by avoiding its generation or recycling. This is accomplished by material substitution and inventory management, process modification, or recycling wastes for reuse. Waste reduction is defined as waste minimization plus treatment which results in volume or toxicity reduction. The ORNL Waste Reduction Program will include both waste minimization and waste reduction activities.

  15. An interdisciplinary management of severely resorbed maxillary anterior ridge complicated by traumatic bite using a ridge splitting technique

    PubMed Central

    Gupta, Narender Dev; Maheshwari, Sandhya; Chaudhari, Prabhat Kumar; Rathi, Shraddha

    2015-01-01

    Injury to the teeth and alveolar ridge of the maxillary anterior region due to trauma can cause severe alveolar ridge deficiency. Ridge augmentation is a valuable periodontal plastic surgical method for the correction of ridge defects for esthetic purpose. Although ridge augmentation can help to restore the ridge volume, the grafting procedures can significantly increase the patient morbidity, treatment time, and the cost. Among the ridge augmentation techniques, the ridge split procedure demonstrates many benefits such as no need for donor site, the rare risk of damage to underlying anatomical structures, less pain, and swelling. This case report presents a vertical split technique for increasing the bone volume. There was a remarkable healing and significant increase in bone volume. We have followed the case for 6 months. PMID:25810602

  16. Hydrothermal plumes at the Rodriguez triple junction, Indian ridge

    NASA Astrophysics Data System (ADS)

    Gamo, Toshitaka; Nakayama, Eiichiro; Shitashima, Kiminori; Isshiki, Kenji; Obata, Hajime; Okamura, Kei; Kanayama, Shinji; Oomori, Tamotsu; Koizumi, Takayuki; Matsumoto, Satoshi; Hasumoto, Hiroshi

    1996-07-01

    Water column anomalies of light transmission, Mn, Fe, Al and CH 4 concentrations were searched in the central, southeastern and southwestern Indian Ridge segments centered on the Rodriguez Triple Junction (RTJ) (˜25°32'S, ˜70°02'E), for the purpose of locating hydrothermally active areas, in July to August 1993. We found an active zone in the central Indian Ridge segment (25°18-20'S) approximately 12 miles north of the RTJ, where significant hydrothermal plumes were observed at 2,200-2,400 m depth. Intensive tow-yo observations using a CTD rosette multi-sampling system equipped with a transmissometer revealed that the plumes show temporal as well as spatial variations. Discrete water samples within the plumes were enriched in Mn, Fe, and CH 4, with maximum concentrations of 9.8 n M, 40.2 n M and 3.3 n M, respectively. Judging from the spatial and chemical characteristics of the plumes, especially from transmission anomalies and C/H 4Mn ratios, we speculate that the hydrothermal venting site might be not in the rift valley but on the eastern off-axis zone, several miles distant from the rift valley.

  17. Oak Ridge National Laboratory Waste Management Plan. Revision 1

    SciTech Connect

    Forgy, Jr., J. R.

    1991-12-01

    The goal of the Oak Ridge National Laboratory (ORNL) Waste Management Program is the protection of workers, the public, and the environment. A vital aspect of this goal is to comply with all applicable state, federal, and DOE requirements. Waste management requirements for DOE radioactive wastes are detailed in DOE Order 5820.2A, and the ORNL Waste Management Program encompasses all elements of this order. The requirements of this DOE order and other appropriate DOE orders, along with applicable Tennessee Department of Environment and Conservation (TDEC) and US Environmental Protection Agency (EPA) rules and regulations, provide the principal source of regulatory guidance for waste management operations at ORNL. The objective of the Oak Ridge National Laboratory Waste Management Plan is to compile and to consolidate information annually on how the ORNL Waste Management is to compile and to consolidate information annually on how the ORNL Waste Management Program is conducted, which waste management facilities are being used to manage wastes, what forces are acting to change current waste management systems, what activities are planned for the forthcoming fiscal year (FY), and how all of the activities are documented.

  18. Status Report: A Hydrologic Framework for the Oak Ridge Reservation

    SciTech Connect

    Solomon, D.K.

    1992-01-01

    The Oak Ridge Reservation Hydrology and Geology Study (ORRHAGS) was established in 1989 as an integrated study of the hydrology, geology, and soils of the reservation in support of the extensive activities in environmental monitoring, environmental restoration, waste management, and regulatory compliance on the Oak Ridge Reservation (ORR) of the US Department of Energy (DOE). The Hydrologic Studies Task of ORRHAGS is designed to provide essential information about the hydrologic environment of the ORR to those responsible for dealing with environmental issues, including restoration, environmental monitoring, and waste management, compliance, and enforcement. In order to ensure optimum environmental protection, these systems and their elements must be better understood and quantified. Additionally, in light of the enormous costs attached to environmental protection, restoration, monitoring, and waste management, these activities must be planned and implemented as efficiently as possible. A practical understanding of the hydrologic systems is required for all the objectives associated with contaminants in the hydrologic environment of the ORR. This report describes the current status of the development of a workable framework for the hydrology of the ORR. The framework is based mostly on data and information available from previous investigations.

  19. Oak Ridge K-25 Site Technology Logic Diagram

    SciTech Connect

    Fellows, R.L.

    1993-02-26

    The Oak Ridge K-25 Technology Logic Diagram (TLD), a decision support tool for the K-25 Site, was developed to provide a planning document that relates environmental restoration and waste management problems at the Oak Ridge K-25 Site to potential technologies that can remediate these problems. The TLD technique identifies the research necessary to develop these technologies to a state that allows for technology transfer and application to waste management, remedial action, and decontamination and decommissioning activities. The TLD consists of four separate volumes-Vol. 1, Vol. 2, Vol. 3A, and Vol. 3B. This Volume, Volume 1 provides introductory and overview information about the TLD. Volume 2 contains logic diagrams. Volume 3 has been divided into two separate volumes to facilitate handling and use. This volume is divided into ten chapters. The first chapter is a brief introduction, and the second chapter details the technical approach of the TLD. These categories are the work activities necessary for successful decontamination and decommissioning, waste management, and remedial action of the K-25 Site. The categories are characterization, decontamination, dismantlement, robotics and automation, remedial action, and waste management. Materials disposition is addressed in Chap. 9. The final chapter contains regulatory compliance information concerning waste management, remedial action, and decontamination and decommissioning.

  20. Oak Ridge reservation, annual site environmental report summary for 1993

    SciTech Connect

    Not Available

    1994-11-01

    The U.S. Department of Energy requires annual site environmental reports from facilities that operate under its auspices. To fulfill that requirement, such an annual report is published for the Oak Ridge Reservation, which comprises three major sites, each of which has unique monitoring requirements in addition to many shared obligations. As a result, the report is complex and highly detailed. Annual site environmental reports are public documents that are read by government regulators, scientists, engineers, business people, special interest groups, and members of the public at large. For that reason, the reports need to be accessible to a variety of audiences in addition to being accurate and complete. This pamphlet summarizes environmental activities on the reservation, which for some readers may be adequate; for those who seek more detail, it will lend coherence to their approach to the report itself. The content of this summary was taken from Oak Ridge Reservation Annual Site Environmental Report for 1993. Results of the many environmental monitoring and surveillance activities are detailed in this report.

  1. Oak Ridge National Laboratory Waste Management Plan. Rev. 1

    SciTech Connect

    1991-12-01

    The goal of the Oak Ridge National Laboratory (ORNL) Waste Management Program is the protection of workers, the public, and the environment. A vital aspect of this goal is to comply with all applicable state, federal, and DOE requirements. Waste management requirements for DOE radioactive wastes are detailed in DOE Order 5820.2A, and the ORNL Waste Management Program encompasses all elements of this order. The requirements of this DOE order and other appropriate DOE orders, along with applicable Tennessee Department of Environment and Conservation (TDEC) and US Environmental Protection Agency (EPA) rules and regulations, provide the principal source of regulatory guidance for waste management operations at ORNL. The objective of the Oak Ridge National Laboratory Waste Management Plan is to compile and to consolidate information annually on how the ORNL Waste Management is to compile and to consolidate information annually on how the ORNL Waste Management Program is conducted, which waste management facilities are being used to manage wastes, what forces are acting to change current waste management systems, what activities are planned for the forthcoming fiscal year (FY), and how all of the activities are documented.

  2. Oak Ridge K-25 Site Technology Logic Diagram

    SciTech Connect

    Fellows, R.L.

    1993-02-26

    The Oak Ridge K-25 Technology Logic Diagram (TLD), a decision support tool for the K-25 Site, was developed to provide a planning document that relates environmental restoration (ER) and waste management (WN) problems at the Oak Ridge K-25 Site. The TLD technique identifies the research necessary to develop these technologies to a state that allows for technology transfer and application to waste management, remediation, decontamination, and decommissioning activities. The TLD consists of four separate volumes-Vol. 1, Vol. 2, Vol. 3A, and Vol. 3B. Volume 1 provides introductory and overview information about the TLD. Volume 2 contains logic diagrams. Volume 3 has been divided into two separate volumes to facilitate handling and use. This volume 3 B provides the Technology Evaluation Data Sheets (TEDS) for ER/WM activities (Remedial Action Robotics and Automation, Waste Management) that are referenced by a TEDS code number in Vol. 2 of the TLD. Each of these sheets represents a single logic trace across the TLD. These sheets contain more detail than each technology in Vol. 2. The TEDS are arranged alphanumerically by the TEDS code number in the upper right corner of each data sheet. Volume 3 can be used in two ways: (1) technologies that are identified from Vol. 2 can be referenced directly in Vol. 3 by using the TEDS codes, and (2) technologies and general technology areas (alternatives) can be located in the index in the front of this volume.

  3. Seismic hazard evaluation for Department of Energy Oak Ridge Reservations, Oak Ridge, Tennessee

    SciTech Connect

    McGuire, R.K.; Toro, G.F.; Hunt, R.J.

    1992-09-30

    This study presents the results of an investigation of seismic hazard at the Department of Energy Oak Ridge Reservations (K-25 Site, Oak Ridge National Laboratories, and Oak Ridge Y-12 Plant), located in Oak Ridge, Tennessee. Oak Ridge is located in eastern Tennessee, in an area of moderate to high historical seismicity. Results from two separate seismic hazard analyses are presented. The EPRI/SOG analysis uses the input data and methodology developed by the Electric Power Research Institute, under the sponsorship of several electric utilities, for the evaluation of seismic hazard in the central and eastern United States. The LLNL analysis uses the input data and methodology developed by the Lawrence Livermore National Laboratory for the Nuclear Regulatory Commission. Both the EPRI/SOG and LLNL studies characterize earth-science uncertainty on the causes and characteristics of earthquakes in the central and eastern United States. This is accomplished by considering multiple hypotheses on the locations and parameters of seismic source zones and by considering multiple attenuation functions for the prediction of ground shaking given earthquake size and location. These hypotheses were generated by multiple expert teams and experts. Furthermore, each team and expert was asked to generate multiple hypotheses in order to characterize his own internal uncertainty. The seismic-hazard calculations are performed for all hypotheses. Combining the results from each hypothesis with the weight associated to that hypothesis, one obtains an overall representation of the seismic hazard at the Oak Ridge site and its uncertainty.

  4. Removal site evaluation report on Building 7602 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-09-01

    This removal site evaluation report for Building 7602 at Oak Ridge National Laboratory was prepared to provide the Environmental Restoration Program with information necessary to evaluate whether hazardous and/or radiological contaminants in and around the facility pose a substantial risk to human health or the environment (i.e., a high probability of adverse effects) and whether remedial site evaluations or removal actions are, therefore, required. The scope of the project included (1) a search for, and review of, readily available historical records regarding operations and use of the facility (including hazardous substance usage and existing contamination); (2) interviews with facility personnel concerning current and past practices; and (3) a brief walk-through to visually inspect the facility and identify existing hazard areas requiring maintenance actions, removal actions, or remedial evaluation. The results of the removal site evaluation indicate that areas associated with Building 7602 pose no imminent hazards requiring maintenance actions. Adequate engineering and administrative controls are in place and enforced within the facility to ensure worker and environmental protection. Current actions that are being taken to prevent further release of contamination and ensure worker safety within Building 7602 are considered adequate until decontamination and decommissioning activities begin. Given the current status and condition of Building 7602, this removal site evaluation is considered complete and terminated.

  5. Environmental Monitoring Plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-09-01

    This document presents the Environmental Monitoring Plan (EMP) for Waste Area Grouping (WAG) 6 at the Oak Ridge National Laboratory (ORNL). Based on the results of the Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) and on subsequent discussions with regulators, a decision was made to defer implementing source control remedial measures at the WAG. The alternative selected to address the risks associated with WAG 6 involves maintenance of site access controls prevent public exposure to on-site contaminants, continued monitoring of contaminant releases determine if source control measures are required, and development of technologies that could support the final remediation of WAG 6. Although active source control measures are not being implemented at WAG 6, environmental monitoring is necessary to ensure that any potential changes in contaminant release from the WAG are identified early enough to take appropriate action. Two types of environmental monitoring will be conducted: baseline monitoring and annual routine monitoring. The baseline monitoring will be conducted to establish the baseline contaminant release conditions at the WAG, confirm the site-related chemicals of concern (COCs), and gather data to confirm the site hydrologic model. The baseline monitoring is expected to begin in 1994 and last for 12--18 months. The annual routine monitoring will consist of continued sampling and analyses of COCs to determine off-WAG contaminant flux and risk, identify mills in releases, and confirm the primary contributors to risk. The annual routine monitoring will continue for {approximately} 4 years after completion of the baseline monitoring.

  6. Environmental Survey preliminary report, Oak Ridge Gaseous Diffusion Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1989-02-01

    This report presents the preliminary findings from the first phase of the Environmental Survey of the US Department of Energy's (DOE) Oak Ridge Gaseous Diffusion Plant (ORGDP) conducted March 14 through 25, 1988. The Survey is being conducted by an interdisciplinary team of environmental specialists, led and managed by the Office of Environment, Safety and Health's Office of Environmental Audit. Individual team components are being supplied by a private contractor. The objective of the Survey is to identify environmental risk associated with ORGDP. The Survey covers all environmental media and all areas of environmental regulation. It is being performed in accordance with the DOE Environmental Survey Manual. This phase of the Survey involves the review of existing site environmental data, observations of the operations carried on at ORGDP, and interviews with site personnel. The Survey team developed a Sampling and Analysis Plan to assist in further assessing certain of the environmental problems identified during is on-site activities. The Sampling and Analysis Plan will be executed by Idaho National Engineering Laboratory (INEL). When completed, the results will be incorporated into the ORGDP Survey findings for in inclusion into the Environmental Survey Summary Report. 120 refs., 41 figs., 74 tabs.

  7. Site characterization report for the Old Hydrofracture Facility at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-01-01

    Several Old Hydrofracture Facility (OHF) structures (i.e., Building 7852, the bulk storage bins, the pump house, water tank T-5, and pump P-3) are surplus facilities at Oak Ridge National Laboratory (ORNL) slated for decontamination and decommissioning (D and D). OHF was constructed in 1963 to allow experimentation and operations with an integrated solids storage, handling, mixing, and grout injection facility. It was shut down in 1980 and transferred to ORNL`s Surveillance and Maintenance Program. The hydrofracture process was a unique disposal method that involved injecting waste materials mixed with grout and additives under pumping pressures of 2,000 psi or greater into a deep, low-permeability shale formation. The injected slurry spread along fractures and bedding planes for hundreds of feet from the injection points, forming thin grout sheets (often less than 1/8 in. thick). The grout ostensibly immobilized and solidified the liquid wastes. Site characterization activities were conducted in the winter and spring of 1994 to collect information necessary to plan the D and D of OHF structures. This site characterization report documents the results of the investigation of OHF D and D structures, presenting data from the field investigation and laboratory analyses in the form of a site description, as-built drawings, summary tables of radiological and chemical contaminant concentrations, and a waste volume estimate. 25 refs., 54 figs., 17 tabs.

  8. Environmental Survey preliminary report, Oak Ridge National Laboratory (X-10), Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1988-07-01

    This report presents the preliminary findings from the first phase of the Environmental Survey of the US Department of Energy (DOE) Oak Ridge National Laboratory (ORNL), X-10 site, conducted August 17 through September 4, 1987. The Survey is being conducted by an interdisciplinary team of environmental specialists, led and managed by the Office of Environment, Safety and Health's Office of Environmental Audit. Individual team specialists are outside experts supplied by a private contractor. The objective of the Survey is to identify environmental problems and areas of environmental risk associated with ORNL. The Survey covers all environmental media and all areas of environmental regulation. It is being performed in accordance with the DOE Environmental Survey Manual. The on-site phase of the Survey involves the review of existing site environmental data, observations of the operations carried on at ORNL, and interviews with site personnel. The Survey team developed a Sampling and Analysis Plan to assist in further assessing certain of the environmental problems identified during its on-site activities. The Sampling and Analysis Plan will be executed by a DOE National Laboratory or a support contractor. When completed, the results will be incorporated into the Environmental Survey Interim Report for ORNL. The Interim Report will reflect the final determinations of the ORNL Survey. 120 refs., 68 figs., 71 tabs.

  9. Post-Messinian evolution of the Florence Ridge area (Western Cyprus Arc), Part I: Morphostructural analysis

    NASA Astrophysics Data System (ADS)

    Sellier, N. C.; Loncke, L.; Vendeville, B. C.; Mascle, J.; Zitter, T.; Woodside, J.; Loubrieu, B.

    2013-04-01

    The Florence Ridge, part of the western Cyprus arc, is a compressional relief that was eroded during the Messinian salinity crisis while deposition of salt occurred North (Antalya basin) and South (Herodotus abyssal plain). In order to better assess the impact of salt-tectonics in the Florence Ridge region deformations, we conducted a morpho-structural analysis of available multibeam and seismic data (Simed and Prismed II campaigns). It is indeed a crucial issue to distinguish crustal and gravity driven structures in the compressional to strike-slip belts of the eastern Mediterranean. Along the Antalya basin, we mainly observed multi-directional tectonic rafts typical of gravity gliding above salt. On the Florence Ridge itself, the base of salt evolves laterally to a Messinian erosional surface that erodes a series of stacked nappes. This surface is involved in recent faulting. South of the Florence Ridge, a nearly 100 km wide fold belt characterizes the Herodotus abyssal plain. Three different zones parallel to the Florence Ridge appear within this fold belt. Those are respectively from North to South zones A, B and C. Zone A is characterized mainly by small-wavelength folding and faulting. Approaching Zone B, a long extensional graben deforms the seafloor. Zone B stands ~ 100 to 200 m higher than zones A and C. There, salt welding seems common. In the easternmost zone B deep sub-circular bathymetric depressions are associated with extremely thick and fan-shaped depocenters probably emplaced in relation with active sub-salt thrusts. Many evidences suggest post-Messinian uplift in this zone. Zone C shows medium to high wavelength salt-cored folds. Wavelength of those folds increase approaching the distal Nile deep-sea fan. Within zone C, a nearly undeformed domain exists approaching the Eratosthenes seamount. 'En echelon' folds bound this flat domain suggesting lateral salt extrusion at the junction between zone C and the distal Nile deep-sea fan. To conclude

  10. INDEPENDENT VERIFICATION SURVEY REPORT FOR ZONE 1 OF THE EAST TENNESSEE TECHNOLOGY PARK IN OAK RIDGE, TENNESSEE

    SciTech Connect

    King, David A.

    2012-08-16

    Oak Ridge Associated Universities (ORAU) conducted in-process inspections and independent verification (IV) surveys in support of DOE's remedial efforts in Zone 1 of East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. Inspections concluded that the remediation contractor's soil removal and survey objectives were satisfied and the dynamic verification strategy (DVS) was implemented as designed. Independent verification (IV) activities included gamma walkover surveys and soil sample collection/analysis over multiple exposure units (EUs).

  11. Morphostructure at the junction between the Beata ridge and the Greater Antilles island arc (offshore Hispaniola southern slope)

    NASA Astrophysics Data System (ADS)

    Granja Bruña, J. L.; Carbó-Gorosabel, A.; Llanes Estrada, P.; Muñoz-Martín, A.; ten Brink, U. S.; Gómez Ballesteros, M.; Druet, M.; Pazos, A.

    2014-03-01

    Oblique convergence between the Caribbean plate's interior and the inactive Greater Antilles island arc has resulted in the collision and impingement of the thickened crust of the Beata ridge into southern Hispaniola Island. Deformation resulting from this convergence changes from a low-angle southward-verging thrust south of eastern Hispaniola, to collision and uplift in south-central Hispaniola, and to left-lateral transpression along the Southern peninsula of Haiti in western Hispaniola. Using new swath bathymetry and a dense seismic reflection grid, we mapped the morphological, structural and sedimentological elements of offshore southern Hispaniola. We have identified four morphotectonic provinces: the Dominican sub-basin, the Muertos margin, the Beata ridge and the Haiti sub-basin. The lower slope of the Muertos margin is occupied by the active Muertos thrust belt, which includes several active out-of-sequence thrust faults that, were they to rupture along their entire length, could generate large-magnitude earthquakes. The interaction of the thrust belt with the Beata ridge yields a huge recess and the imbricate system disappears. The upper slope of the Muertos margin shows thick slope deposits where the extensional tectonics and slumping processes predominate. The northern Beata ridge consists of an asymmetrically uplifted and faulted block of oceanic crust. Our results suggest that the shallower structure and morphology of the northern Beata ridge can be mainly explained by a mechanism of extensional unloading from the Upper Cretaceous onward that is still active residually along the summit of the ridge. The tectonic models for the northern Beata ridge involving active reverse strike-slip faults and transpression caused by the oblique convergence between the Beata ridge and the island arc are not supported by the structural interpretation. The eastern Bahoruco slope an old normal fault that acts as a passive tear fault accommodating the sharp along

  12. Plume- Ridge Lithospheric Interactions: Cases of Afar (Africa)

    NASA Astrophysics Data System (ADS)

    Montagner, J. P.; Stutzmann, E.; Sicilia, D.; Sebai, A.; Beucler, E.; Silveira, G.; Cara, M.; Debayle, E.; Leveque, J. J.

    2003-04-01

    Detection of mantle plumes in geophysical and geochemical data is controversial and trigger vigorous debates. It remains unclear how plumes are formed, their origin at depth, and whether they act independently from plate tectonics. We may learn about the role of plumes in mantle dynamics by studying their interactions with lithosphere and crust below ridges and the way in which they perturb the flow pattern in the uppermost mantle. Several regional tomographic studies of seismic velocity and anisotropy around several hotspots were obtained during the last 2 years. Their lateral resolution is smaller than 1000km and they enable to make qualitative intercomparison between Afar (Horn of Africa Program), Azores (COSEA project) in the Atlantic, La Reunion in the Indian Ocean and Pacific provinces hotspots. These models demonstrate that there is not only one family of plumes but several ones. Some plumes are confined in the uppermost 200km but a few can originate in the transition zone and even at the Core-mantle Boundary for superplumes. Seismic anisotropy which is a good marker of deformation processes and mantle flow pattern, shows that the interaction between a plume and a ridge below the lithosphere can occur over distances larger than 1000km, via sublithospheric channels. The existence of LACs (Low Anisotropy Channels) below the Pacific plate seems to be intimately related to the active hotspots in Central Pacific and indicate a future reorganization of plate boundaries. Another important consequence of the interaction between plume and ridge is the triggering of secondary convection in the asthenosphere, which will be discussed during the presentation.

  13. Chestnut Ridge Borrow Area Waste Pile work plan

    SciTech Connect

    Johnson, R. )

    1991-08-01

    The US Department of Energy (DOE), through its contractor Martin Marietta Energy Systems, Inc., has constructed a storage facility, the Chestnut Ridge Borrow Area Waste Pile (CRBAWP), for mercury-contaminated soil excavated from the Oak Ridge Civic Center properties and the Oak Ridge Sewer Line Beltway. Excavation of the soil from the Civic Center began in September 1984 and was completed in early 1985. Similar soils from other areas of the city were added to the pile until 1987. Approximately 3000 yd{sup 3} are stored at the present time. An Interim Status RCRA permit was initially sought for this facility. Samples from the waste pile passed the Extraction Procedure Toxicity Test (EP Tox). The Tennessee Department of Health and Environment (now the Tennessee Department of Conservation-TDC) denied the permit based on their conclusion that the waste was not a RCRA-regulated waste. On September 25, 1990 the Toxicity Characteristic Leaching Procedure (TCLP) superseded the EP Tox test. TCLP tests are not proposed to satisfy a request by TDC and to make a final determination of the nature of the soils in order to close the CRBAWP as a solid waste disposal facility under Tennessee State rule 1200-1-7-.04. The objectives of this work are to summarize existing site information and detail actions necessary to sample and characterize soils from the waste pile as hazardous or nonhazardous per the Toxicity Characteristic Leaching Procedure (TCLP). Within the scope of this plan, a site investigation will be discussed; a field sampling plan will be described in terms of sampling locations, procedures, and quality assurance; and ancillary activities such as waste management, data management, and health and safety will be outlines. 15 refs., 7 figs., 2 tabs.

  14. Initiation of Ridges and Transform Faults

    NASA Astrophysics Data System (ADS)

    Nyst, M.; Thompson, G. A.; Parsons, T.

    2004-12-01

    No clear consensus has emerged to explain initiation of the strikingly regular pattern of ocean ridges and transform faults. The question is important on the continents also, because a less regular pattern of step-overs on faults such as the San Andreas influences the sources of earthquakes. We explore the question by finite element modeling and a study of observational data on ridges and transforms. We focus on the simplest case, where ridges and transforms seem to self-organize at new plate boundaries as soon as new oceanic (magmatic) crust forms. The South Atlantic supplies a clear example. Continental South America and Africa separated along an irregular break, whose general shape is still preserved in the Mid-Atlantic Ridge. In detail, however, the sea floor magnetic anomalies and satellite gravity show that traces of the ridges and transforms extend to the base of the continental slope, i.e. they formed quickly in the new oceanic crust. The Gulf of California provides another clear example and is notable because of its northward transition into the continental San Andreas fault system. In continental crust, dike segments connected by transform faults provide the clearest analogues of oceanic ridges and transforms. Remarkably, the ridge-transform pattern has been simulated by pulling the crust on molten wax [Oldenburg and Brune, JGR, 80, 1975] and also observed in the crust of a molten lava lake [Duffield, JGR, 77, 1972]. In neither of these models, however, do the spatial and temporal scales permit investigation of the dikes whose repeated emplacement and inflation builds layer 3 of the ocean crust. It is well established that, under a buoyant head of magma, dikes tend to fracture and intrude the crust in planes perpendicular to the least horizontal stress, and they relieve the stress difference as they inflate [e.g. Parsons and Thompson, Science, 253, 1991]. Dikes are commonly used as stress-direction indicators analogous to artificial hydraulic fractures

  15. Three-dimensional estimate of the lithospheric effective elastic thickness of the Line ridge

    NASA Astrophysics Data System (ADS)

    Hu, Minzhang; Li, Jiancheng; Jin, Taoyong; Xu, Xinyu; Xing, Lelin; Shen, Chongyang; Li, Hui

    2015-09-01

    Using a new bathymetry grid formed with vertical gravity gradient anomalies and ship soundings (BAT_VGG), a 1° × 1° lithospheric effective elastic thickness (Te) grid of the Line ridge was calculated with the moving window admittance technique. As a comparison, both the GEBCO_08 and SIO V15.1 bathymetry datasets were used to calculate Te as well. The results show that BAT_VGG is suitable for the calculation of lithospheric effective elastic thickness. The lithospheric effective elastic thickness of the Line ridge is shown to be low, in the range of 5.5-13 km, with an average of 8 km and a standard deviation of 1.3 km. Using the plate cooling model as a reference, most of the effective elastic thicknesses are controlled by the 150-300 °C isotherm. Seamounts are primarily present in two zones, with lithospheric ages of 20-35 Ma and 40-60 Ma, at the time of loading. Unlike the Hawaiian-Emperor chain, the lithospheric effective elastic thickness of the Line ridge does not change monotonously. The tectonic setting of the Line ridge is discussed in detail based on our Te results and the seamount ages collected from the literature. The results show that thermal and fracture activities must have played an important role in the origin and evolution of the ridge.

  16. Remedial investigation work plan for the Groundwater Operable Unit at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-03-01

    This Remedial Investigation (RI) Work Plan has been developed as part of the US Department of Energy`s (DOE`s) investigation of the Groundwater Operable Unit (GWOU) at Oak Ridge National Laboratory (ORNL) located near Oak Ridge, Tennessee. The first iteration of the GWOU RI Work Plan is intended to serve as a strategy document to guide the ORNL GWOU RI. The Work Plan provides a rationale and organization for groundwater data acquisition, monitoring, and remedial actions to be performed during implementation of environmental restoration activities associated with the ORNL GWOU. It Is important to note that the RI Work Plan for the ORNL GWOU is not a prototypical work plan. The RI will be conducted using annual work plans to manage the work activities, and task reports will be used to document the results of the investigations. Sampling and analysis results will be compiled and reported annually with a review of data relative to risk (screening level risk assessment review) for groundwater. This Work Plan outlines the overall strategy for the RI and defines tasks which are to be conducted during the initial phase of investigation. This plan is presented with the understanding that more specific addenda to the plan will follow.

  17. Phase 1 report on the Bear Creek Valley treatability study, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1997-04-01

    Bear Creek Valley (BCV) is located within the US Department of Energy (DOE) Oak Ridge Reservation and encompasses multiple waste units containing hazardous and radioactive wastes associated with past operations at the adjacent Oak Ridge Y-12 Plant. The BCV Remedial Investigation determined that disposal of wastes at the S-3 Site, Boneyard/Burnyard (BYBY), and Bear Creek Burial Grounds (BCBG) has caused contamination of both deep and shallow groundwater. The primary contaminants include uranium, nitrate, and VOCs, although other metals such as aluminum, magnesium, and cadmium persist. The BCV feasibility study will describe several remedial options for this area, including both in situ and ex situ treatment of groundwater. This Treatability Study Phase 1 Report describes the results of preliminary screening of treatment technologies that may be applied within BCV. Four activities were undertaken in Phase 1: field characterization, laboratory screening of potential sorbents, laboratory testing of zero valent iron products, and field screening of three biological treatment systems. Each of these activities is described fully in technical memos attached in Appendices A through G.

  18. Data base management plan for the remedial investigation/feasibility study at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1993-11-01

    This Data Base Management (DBM) Plan has been prepared for use by Bechtel National, Inc. (Bechtel) and its subcontractors in the performance of the Oak Ridge National Laboratory (ORNL) Remedial Investigation/Feasibility Study (RI/FS) program activities. The RI/FS program is being performed under subcontract to Martin Marietta Energy Systems, Inc. (Energy Systems), the contractor operating ORNL for the Department of Energy. This DBM Plan defines the procedures and protocol to be followed in developing and maintaining the data base used by Bechtel and its subcontractors for RI/FS activities at ORNL; describes the management controls, policies, and guidelines to be followed; and identifies responsible positions and their Energy Systems functions. The Bechtel RI/FS data base will be compatible with the Oak Ridge Environmental Information System and will include data obtained from field measurements and laboratory and engineering analyses. Personnel health and safety information, document control, and project management data will also be maintained as part of the data base. The computerized data management system is being used to organize the data according to application and is capable of treating data from any given site as a variable entity. The procedures required to implement the DBM Plan are cross-referenced to specific sections of the plan.

  19. Fiscal year 1996 well installation program summary, Y-12 Plant Oak Ridge, Tennessee

    SciTech Connect

    1997-04-01

    This report summarizes the well installation activities conducted during the federal fiscal year (FY) 1996 drilling program at the Oak Ridge Y-12 Plant, Oak Ridge Tennessee. Synopses of monitoring well construction/well development data, well location rationale, geological/hydrological observations, quality assurance/quality control methods, and health and safety monitoring are included. Two groundwater monitoring wells were installed during the FY 1996 drilling program. One of the groundwater monitoring wells was installed in the Lake Reality area and was of polyvinyl chloride screened construction. The other well, installed near the Ash Disposal Basin, was of stainless steel construction.

  20. Topographically Enhanced Subinertial Currents at Endeavour Ridge

    NASA Astrophysics Data System (ADS)

    Thomson, R. E.; Rabinovich, A. B.; Mihaly, S. F.; Veirs, S.; Stahr, F. R.; McDuff, R. E.; Subbotina, M. M.

    2001-12-01

    We use velocity records collected from moored current meters to examine the effects of seafloor topography and hydrothermal venting on near-bottom (\\~ 2000 m depth) currents flowing over the Endeavour Segment of Juan de Fuca Ridge. Focus is on the 50-m vertical resolution records collected from July-October 2000 near the main Endeavour vent field and on the 2-km lateral resolution records collected from July-October 2001 at three sites within the 100 m deep axial valley. Semidiurnal currents are found to be marginally more energetic than diurnal currents, and flow above the ridge crest is often dominated by wind-generated inertial events (periods \\~ 16 hrs at 48N) and low-frequency (O(10 day) period) clockwise rotary motions. Observations, supported by numerical modeling, reveal marked topographic amplification of subinertial motions within 100 m of the ridge crest. Motions within the diurnal, inertial, and wind-forced frequency bands undergo especially pronounced above-ridge amplification but attenuate equally rapidly within the confines of the narrow (\\~ 1 km) axial valley. Semidiurnal currents are much less affected by the ridge topography and have approximately uniform amplitudes with depth within the first 250 m of the bottom. Within a few tens of meters of the valley floor, the flow is dominated by \\~ 5 cm/s along-axis semidiurnal oscillations and a surprisingly strong (2 to 4 cm/s), persistently northward up-valley flow. The up-valley flow appears to be independent of, and generally counter to, the prevailing flow in the overlying water column. Initial findings suggest that the enhanced near-bottom flow is maintained by an along-valley pressure gradient created by turbulent entrainment of cold (\\~ 2 C) ambient water by the superheated (\\~ 350 C) hydrothermal plumes and low-temperature diffuse flow. If so, the mean-flow dynamics may be analogous to the summer sea-breeze in coastal fjords, with hydrothermal convection playing the role of summertime

  1. Growth of a tectonic ridge during the Landers earthquake

    SciTech Connect

    Fleming, R.W.; Johnson, A.M.

    1997-04-01

    The formation of tectonic ridges by localized vertical uplift along strike-slip faults has long been suspected, but the actual growth of a tectonic ridge during an earthquake has never been documented. During the 1992 Landers, California, earthquake sequence, an awl-shaped, dome-like topographic ridge along the Emerson fault zone increased its height at least 1 m concurrently with 3 m of right-lateral shift across the fault zone containing the ridge. Five deformation vectors within the ridge reveal dilatant behavior in addition to the uplift and shift on boundary faults. 10 refs., 5 figs.

  2. Growth of a tectonic ridge during the Landers earthquake

    USGS Publications Warehouse

    Fleming, R.W.; Johnson, A.M.

    1997-01-01

    The formation of tectonic ridges by localized vertical uplift along strike-slip faults has long been suspected, but the actual growth of a tectonic ridge during an earthquake has never been documented. During the 1992 Landers, California, earthquake sequence, an awl-shaped, dome-like topographic ridge along the Emerson fault zone increased its height at least 1 m concurrently with 3 m of right-lateral shift across the fault zone containing the ridge. Five deformation vectors within the ridge reveal dilatant behavior in addition to the uplift and shift on boundary faults.

  3. Waste Area Grouping 4 Site Investigation Sampling and Analysis Plan, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1994-12-01

    Waste Area Grouping (WAG) 4 is one of 17 WAGs within and associated with Oak Ridge National Laboratory (ORNL), on the Oak Ridge Reservation in Oak Ridge, Tennessee. WAG 4 is located along Lagoon Road south of the main facility at ORNL. WAG 4 is a shallow-waste burial site consisting of three separate areas: (1) Solid Waste Storage Area (SWSA) 4, a shallow-land burial ground containing radioactive and potentially hazardous wastes; (2) an experimental Pilot Pit Area, including a pilot-scale testing pit; and (3) sections of two abandoned underground pipelines formerly used for transporting liquid, low-level radioactive waste. In the 1950s, SWSA 4 received a variety of low-and high-activity wastes, including transuranic wastes, all buried in trenches and auger holes. Recent surface water data indicate that a significant amount of {sup 90}Sr is being released from the old burial trenches in SWSA 4. This release represents a significant portion of the ORNL off-site risk. In an effort to control the sources of the {sup 90}Sr release and to reduce the off-site risk, a site investigation is being implemented to locate the trenches containing the most prominent {sup 90}Sr sources. This investigation has been designed to gather site-specific data to confirm the locations of {sup 90}Sr sources responsible for most off-site releases, and to provide data to be used in evaluating potential interim remedial alternatives prepared to direct the site investigation of the SWSA 4 area at WAG 4.

  4. Status Report on the Geology of the Oak Ridge Reservation

    SciTech Connect

    Hatcher, R.D., Jr.

    1992-01-01

    This report provides an introduction to the present state of knowledge of the geology of the Oak Ridge Reservation (ORR) and a cursory introduction to the hydrogeology. A detailed reported on hydrogeology is being produced in parallel to this one. An important element of this work is the construction of a modern detailed geologic map of the ORR containing subdivisions of all mappable rock units and displaying mesoscopic structural data. Understanding the geologic framework of the ORR is essential to many current and proposed activities related to land-use planning, waste management, environmental restoration, and waste remediation. This interim report is the result of cooperation between geologists in two Oak Ridge National Laboratory (ORNL) divisions, Environmental Sciences and Energy, and is a major part of one doctoral dissertation in the Department of Geological Sciences at The University of Tennessee--Knoxville. Major long-term goals of geologic investigations in the ORR are to determine what interrelationships exist between fractures systems in individual rock or tectonic units and the fluid flow regimes, to understand how regional and local geology can be used to help predict groundwater movement, and to formulate a structural-hydrologic model that for the first time would enable prediction of the movement of groundwater and other subsurface fluids in the ORR. Understanding the stratigraphic and structural framework and how it controls fluid flow at depth should be the first step in developing a model for groundwater movement. Development of a state-of-the-art geologic and geophysical framework for the ORR is therefore essential for formulating an integrated structural-hydrologic model. This report is also intended to convey the present state of knowledge of the geologic and geohydrologic framework of the ORR and vicinity and to present some of the data that establish the need for additional geologic mapping and geohydrologic studies. An additional intended

  5. An ultraslow-spreading class of ocean ridge.

    PubMed

    Dick, Henry J B; Lin, Jian; Schouten, Hans

    2003-11-27

    New investigations of the Southwest Indian and Arctic ridges reveal an ultraslow-spreading class of ocean ridge that is characterized by intermittent volcanism and a lack of transform faults. We find that the mantle beneath such ridges is emplaced continuously to the seafloor over large regions. The differences between ultraslow- and slow-spreading ridges are as great as those between slow- and fast-spreading ridges. The ultraslow-spreading ridges usually form at full spreading rates less than about 12 mm yr(-1), though their characteristics are commonly found at rates up to approximately 20 mm yr(-1). The ultraslow-spreading ridges consist of linked magmatic and amagmatic accretionary ridge segments. The amagmatic segments are a previously unrecognized class of accretionary plate boundary structure and can assume any orientation, with angles relative to the spreading direction ranging from orthogonal to acute. These amagmatic segments sometimes coexist with magmatic ridge segments for millions of years to form stable plate boundaries, or may displace or be displaced by transforms and magmatic ridge segments as spreading rate, mantle thermal structure and ridge geometry change. PMID:14647373

  6. Faulting and folding in the formation of planetary wrinkle ridges

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Plescia, J. B.; Franklin, B. J.

    1991-01-01

    Topographic profiles for planetary wrinkle ridges compiled from high-resolution Lunar Topographic Orthophoto maps for the moon and from monoscopic photoclinometry data for Mars reveal that many of these ridges are characterized by an elevation offset between one side of a ridge and the other. To investigate the relative importance of faulting and folding in the formation of planetary wrinkle ridges, this paper develops a model of subsurface structure, based on observations and measurements of surface physiography and topography by Golombek and Franklin (1987) and Plescia (1990), and assumptions of subsurface structure, which makes it possible to estimate shortening across wrinkle ridges on Moon and Mars. According to this model, total ridge shortening is on the order of 100 m; shortening due to faulting exceeds shortening due to folding for fault dips up to 60-80 deg, implying that faults beneath many wrinkle ridges break the surface to accomodate the greater displacement along the fault than is accomodated in the fold.

  7. Calendar year 1994 groundwater quality report for the Chestnut Ridge Hydrogeologic Regime, Y-12 Plant, Oak Ridge, Tennessee. 1994 groundwater quality data and calculated rate of contaminant migration

    SciTech Connect

    1995-02-01

    This annual groundwater quality report (GWQR) contains groundwater quality data obtained during the 1994 calendar year (CY) at several hazardous and non-hazardous waste-management facilities associated with the US Department of Energy (DOE) Y-12 Plant located on the DOE Oak Ridge Reservation (ORR) southeast of Oak Ridge, Tennessee (Figure 1). These sites are located south of the Y-12 Plant in the Chestnut Ridge Hydrogeologic Regime (Chestnut Ridge Regime), which is one of three regimes defined for the purposes of groundwater quality monitoring at the Y- 12 Plant. The Environmental Management Department of the Y-12 Plant Health, Safety, Environment, and Accountability (HSEA) Organization manages the groundwater monitoring activities in each regime as part of the Y-12 Plant Groundwater Protection Program (GWPP). The GWQR for the Chestnut Ridge Regime is completed in two-parts: Part 1 (this report) containing the groundwater quality data and Part 2 containing a detailed evaluation of the data. The primary purpose of this report is to serve as a reference containing the groundwater quality data obtained each year under the lead of the Y-12 Plant GWPP. However, because it contains information needed to comply with Resource Conservation and Recovery Act (RCRA) interim status assessment monitoring and reporting requirements, this report is submitted to the Tennessee Department of Environment and Conservation (TDEC) by the RCRA reporting deadline (March 1 of the following CY). Part 2 of the annual groundwater report, to be issued mid-year, will contain a regime-wide evaluation of groundwater quality, present the findings and status of ongoing hydrogeologic studies, describe changes in monitoring priorities, and present planned modifications to the groundwater sampling and analysis activities.

  8. The mean composition of ocean ridge basalts

    NASA Astrophysics Data System (ADS)

    Gale, Allison; Dalton, Colleen A.; Langmuir, Charles H.; Su, Yongjun; Schilling, Jean-Guy

    2013-03-01

    mean composition of mid-ocean ridge basalts (MORB) is determined using a global data set of major elements, trace elements, and isotopes compiled from new and previously published data. A global catalog of 771 ridge segments, including their mean depth, length, and spreading rate enables calculation of average compositions for each segment. Segment averages allow weighting by segment length and spreading rate and reduce the bias introduced by uneven sampling. A bootstrapping statistical technique provides rigorous error estimates. Based on the characteristics of the data, we suggest a revised nomenclature for MORB. "ALL MORB" is the total composition of the crust apart from back-arc basins, N-MORB the most likely basalt composition encountered along the ridge >500 km from hot spots, and D-MORB the depleted end-member. ALL MORB and N-MORB are substantially more enriched than early estimates of normal ridge basalts. The mean composition of back-arc spreading centers requires higher extents of melting and greater concentrations of fluid-mobile elements, reflecting the influence of water on back-arc petrogenesis. The average data permit a re-evaluation of several problems of global geochemistry. The K/U ratio reported here (12,340 ± 840) is in accord with previous estimates, much lower than the estimate of Arevalo et al. (2009). The low Sm/Nd and 143Nd/144Nd ratio of ALL MORB and N-MORB provide constraints on the hypothesis that Earth has a non-chondritic primitive mantle. Either Earth is chondritic in Sm/Nd and the hypothesis is incorrect or MORB preferentially sample an enriched reservoir, requiring a large depleted reservoir in the deep mantle.

  9. ORNL (Oak Ridge National Laboratory) 89

    SciTech Connect

    Anderson, T.D.; Appleton, B.R.; Jefferson, J.W.; Merriman, J.R.; Mynatt, F.R.; Richmond, C.R.; Rosenthal, M.W.

    1989-01-01

    This is the inaugural issues of an annual publication about the Oak Ridge National Laboratory. Here you will find a brief overview of ORNL, a sampling of our recent research achievements, and a glimpse of the directions we want to take over the next 15 years. A major purpose of ornl 89 is to provide the staff with a sketch of the character and dynamics of the Laboratory.

  10. Segmentation of mid-ocean ridges

    USGS Publications Warehouse

    Schouten, Hans; Klitgord, Kim D.; Whitehead, J.A.

    1985-01-01

    Studies of mid-ocean ridges in the Pacific and Atlantic oceans show that the volcanism that forms the oceanic crust along the spreading-plate boundaries is concentrated at regular intervals related to spreading rate. This observation and a new calculation for a Rayleigh-Taylor type of gravitational instability of a partially molten mantle region growing under spreading centres yield reasonable estimates of upper mantle viscosities. ?? 1985 Nature Publishing Group.

  11. Jurassic zircons from the Southwest Indian Ridge

    PubMed Central

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-01-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U–Pb and Lu–Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7–+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from−2.3 to−4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins. PMID:27185575

  12. Jurassic zircons from the Southwest Indian Ridge.

    PubMed

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-01-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U-Pb and Lu-Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7-+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from-2.3 to-4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins. PMID:27185575

  13. Jurassic zircons from the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-05-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U–Pb and Lu–Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7–+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from‑2.3 to‑4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins.

  14. Treatment of Organic-Contaminated Mixed Waste Utilizing the Oak Ridge Broad Spectrum Contracts

    SciTech Connect

    Estes, C. H.; Heacker, F. K.; Cunningham, J.; Westich, B.

    2003-02-25

    To meet the requirements of the State of Tennessee's Department of Environment and Conservation Commissioner's Order for treatment of mixed low level wastes, Oak Ridge has utilized commercial treatment companies to treat and dispose mixed waste. Over the past year, Oak Ridge has shipped organic-contaminated mixed waste for treatment to meet milestones under the Site Treatment Plan. Oak Ridge has established contracts with commercial treatment companies accessible by all DOE sites for treatment of a wide range of mixed wastes. The paper will describe and summarize the activities involved in treating and disposing of organic-contaminated mixed waste utilizing DOE complex-wide contracts and the treatment and disposal activities required. This paper will describe the case history of treatment of several organic-contaminated mixed wastes from the Oak Ridge Reservation requiring treatment prior to disposal. The paper will include waste category information, implementation activities, and contract access. The paper will discuss the specifics of the mixed waste treatment including waste characteristics, treatment process and equipment utilized, and treatment results. Additional information will be provided on task order development, waste profiling, treatment pricing, and the disposal process.

  15. Removal action report on Waste Area Grouping 4 seeps 4 and 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-12-01

    This report documents removal action activities for a Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) non-time-critical removal action as described in the Action Memorandum prepared in 1996. The technical objective of this removal action was to reduce the release of strontium 90 ({sup 90}Sr) into an ephemeral tributary to White Oak Creek from Waste Area Grouping 4 (WAG 4) seeps, as measured at Monitoring Station (MS) 1 at ORNL, Oak Ridge, TN. Design was initiated in early January 1996 and grouting activities were completed in late October 9996. Portions of four waste disposal trenches were injected using low-temperature permeation grouting technology with multiple formulations of grouts to reduce the in situ hydraulic conductivity of the waste materials and ultimately reduce the off-site transport of {sup 90}Sr.

  16. Opportunities for Cost Effective Disposal of Radioactively Contaminated Solid Waste on the Oak Ridge Reservation, Oak Ridge, TN - 13045

    SciTech Connect

    DeMonia, Brian; Dunning, Don; Hampshire John

    2013-07-01

    Department of Energy (DOE) requirements for the release of non-real property, including solid waste, containing low levels of residual radioactive materials are specified in DOE Order 458.1 and associated guidance. Authorized limits have been approved under the requirements of DOE Order 5400.5, predecessor to DOE Order 458.1, to permit disposal of solid waste containing low levels of residual radioactive materials at solid waste landfills located within the DOE Oak Ridge Reservation (ORR). Specifically, volumetric concentration limits for disposal of solid waste at Industrial Landfill V and at Construction/Demolition Landfill VII were established in 2003 and 2007, respectively, based on the requirements in effect at that time, which included: an evaluation to ensure that radiation doses to the public would not exceed 25 mrem/year and would be as low as reasonably achievable (ALARA), with a goal of a few mrem/year or less (in fact, these authorized limits actually were derived to meet a dose constraint of 1 mrem/year); an evaluation of compliance with groundwater protection requirements; and reasonable assurance that the proposed disposal is not likely to result in a future requirement for remediation of the landfill. Prior to approval as DOE authorized limits, these volumetric concentration limits were coordinated with the Tennessee Department of Environment and Conservation (TDEC) and documented in a Memorandum of Understanding (MOU) between the TDEC Division of Radiological Health and the TDEC Division of Solid Waste Management. These limits apply to the disposal of soil and debris waste generated from construction, maintenance, environmental restoration, and decontamination and decommissioning (D and D) activities on the DOE Oak Ridge Reservation. The approved site-specific authorized limits were incorporated in the URS/CH2M Oak Ridge LLC (UCOR) waste profile system that authorizes disposal of special wastes at either of the RCRA Subtitle D landfills. However, a

  17. Crustal manifestations of a hot transient pulse at 60°N beneath the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Parnell-Turner, R. E.; White, N. J.; Maclennan, J.; Henstock, T. J.; Murton, B. J.; Jones, S. M.

    2013-02-01

    Since its inception at 62 Ma, mantle convective upwelling beneath Iceland has had a significant influence on Cenozoic vertical motions, magmatism and paleoceanography in the North Atlantic Ocean. Crucially, intersection of the Reykjanes Ridge with the Icelandic Plume provides us with a useful window into the transient activity of this plume. Here, the spreading ridge acts as a linear sampler of plume activity, which is recorded as a series of time-transgressive V-shaped ridges and troughs. We present the results of a detailed study of the spreading ridge close to 60°N, where the youngest V-shaped ridge of thickened oceanic crust is forming today. A combination of multibeam bathymetry and seismic reflection profiles, acquired along and across the ridge axis, is used to map the detailed pattern of volcanism and normal faulting. Along the ridge axis, the density of volcanic seamounts varies markedly, increasing by a factor of two between 59°N and 62°N. Within this zone, seismic imaging shows that there is enhanced acoustic scattering at the seabed. These observations are accompanied by a decrease in mean fault length from ∼12 km to ∼6 km. A 1960-2009 catalog of relocated teleseismic earthquake hypocenters indicates that there is a pronounced gap in seismicity between 59°N and 62°N where the cumulative moment release is two orders of magnitude smaller than that along adjacent ridge segments. A steady-state thermal model is used to show that a combination of increased melt generation and decreased hydrothermal circulation accounts for this suite of observations. The predicted decrease in the thickness of the brittle seismogenic layer is consistent with geochemical modeling of dredged basaltic samples, which require hotter asthenospheric material beneath the spreading axis. Thus, along-axis variation in melt supply caused by passage of a pulse of hot material modulates crustal accretion processes and rheological properties.

  18. Surveillance Plan for environmental monitoring in Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-12-01

    This Surveillance Plan has been developed as part of the Environmental Monitoring Plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Environmental monitoring will be conducted in two phases: the baseline monitoring phase and the routine annual monitoring phase. The baseline monitoring phase will be conducted to establish the baseline contaminant release conditions at the Waste Area Grouping (WAG), to confirm the site-related chemicals of concern (COC), and to gather data to confirm the site hydrologic model The baseline monitoring phase is expected to begin in 1994 and continue for 12--18 months. The routine annual monitoring phase will consist of continued sampling and analyses of COC to determine off-WAG contaminant flux, to identify trends in releases, and to confirm the COC The routine annual monitoring phase will continue for {approximately}4 years after completion of the baseline monitoring phase. This Surveillance Plan presents the technical and quality assurance surveillance activities for the various WAG 6 environmental monitoring and data evaluation plans and implementing procedures.

  19. RCRA Facility investigation report for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Kannard, J. R.; Wilson, R. C.; Zondlo, T. F.

    1991-09-01

    This report describes the borehole geophysical logging performed at selected monitoring wells at waste area grouping (WAG) 6 of Oak Ridge National Laboratory in support of the WAG 6 Resource Conservation and Recovery Act Facility Investigation (RFI). It identifies the locations and describes the methods, equipment used in the effort, and the results of the activity. The actual logs for each well logged are presented in Attachment 1 through 4 of the TM. Attachment 5 provide logging contractor service literature and Attachment 6 is the Oak Ridge National Laboratory (ORNL) Procedure for Control of a Nuclear Source Utilized in Geophysical logging. The primary objectives of the borehole geophysical logging program were to (1) identify water-bearing fractured bedrock zones to determine the placement of the screen and sealed intervals for subsequent installation, and (2) further characterize local bedrock geology and hydrogeology and gain insight about the deeper component of the shallow bedrock aquifer flow system. A secondary objective was to provide stratigraphic and structural correlations with existing logs for Hydraulic Head Monitoring Station (HHMS) wells, which display evidence of faulting.

  20. Contingency plan for the Old Hydrofracture Facility tanks sluicing project at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-10-01

    Lockheed Martin Energy Systems, Inc. (Energy Systems), plans to begin a sluicing (flushing) and pumping project to remove the contents from five inactive, underground storage tanks at the Old Hydrofracture Facility (OHF) at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The tank contents will be transferred to the Melton Valley Storage Tanks, which are part of the active waste treatment system at ORNL. The purpose of the project is to minimize the risk of leaking the highly radioactive material to the environment. The five OHF tanks each contain a layer of sludge and a layer of supernatant. Based on a sampling project undertaken in 1995, the sludge in the tanks has been characterized as transuranic and mixed waste and the supernatants have been characterized as mixed waste. The combined radioactivity of the contents of the five tanks is approximately 29,500 Ci. This contingency plan is based on the preliminary design for the project and describes a series of potential accident/release scenarios for the project. It outlines Energy Systems` preliminary plans for prevention, detection, and mitigation. Prevention/detection methods range from using doubly contained pipelines to alarmed sensors and automatic pump cutoff systems. Plans for mitigation range from pumping leaked fluids from the built-in tank drainage systems and cleaning up spilled liquids to personnel evacuation.

  1. Geospatializing The Klang Gate Quartz Ridge in Malaysia: A Technological Perspective

    NASA Astrophysics Data System (ADS)

    Azahari Razak, Khamarrul; Mohamad, Zakaria; Zaki Ibrahim, Mohd; Azad Rosle, Qalam; Hattanajmie Abd Wahab, Mohd; Abu Bakar, Rabieahtul; Mohd Akib, Wan Abdul Aziz Wan

    2015-04-01

    Establishment of inventories on geological heritage, or geoheritage resources is a step forward for a comprehensive geoheritage management leading to a better conservation at national and global levels. Compiling and updating inventory of geoheritage is a tedious process and even so in a tropical environment. Malaysia has a tremendous list of geodiversity and generating its national database is a multi-institutional effort and worthwhile investment. However, producing accurate and reliable characteristics of such landform and spectacular geological features remained elusive. The advanced and modern mapping techniques have revolutionized the mapping, monitoring and modelling of the earth surface processes and landforms. Yet the methods for quantification of geodiversity physical features are not fully utilized in Malaysia for a better understanding its processes and activity. This study provides a better insight into the use of advanced active remote sensing technology for characterizing the forested Quartz Ridge in Malaysia. We have developed the novel method and tested in the Klang Gates Quartz Ridge, Selangor. The granitic country rock made up by quartz mineral is known as the longest quartz ridge in Malaysia and characterized by rugged topography, steep slopes, densely vegetated terrain and also rich-biodiversity area. This study presents an integrated field methodological framework and processing scheme by taking into account the climatic, topographic, geologic, and anthropogenic challenges in an equatorial region. Advanced terrestrial laser scanning system was used to accurately capture, map and model the ridge carried out within a relatively stringent time period. The high frequency Global Navigation Satellite System and modern Total Station coupled with the optical satellite and radar imageries and also advanced spatial analysis were fully utilized in the field campaign and data assessment performed during the recent monsoon season. As a result, the mapping

  2. Rediscovery and Exploration of Magic Mountain, Explorer Ridge, NE Pacific

    NASA Astrophysics Data System (ADS)

    Embley, R. W.

    2002-12-01

    either centered within the neovolcanic zone or associated with a boundary fault. The active venting occurs over at least 400 m along axis and is mostly concentrated in clusters of high temperature chimneys, each about 50 m in diameter. Two of these clusters have a basal sulfide mound. There is obvious structural control of many of the vents - many lie along or in line with distinct fissures or small faults and the entire field appears to have developed within a shallow graben formed on the ridge flank. Most of the chimneys consist of relatively friable sulfates (barite/anhydrite) that vent clear fluid at up to about 290°C. Several larger active chimneys consist primarily of sulfide minerals that emit gray smoke with temperatures as high as 312§ C. Biologic communities were primarily associated with the more stable sulfide structures. The mixture of proven technology used from a capable surface vessel during the 2002 Explorer Ridge program, including a cutting edge deep AUV and a large ROV, provided the tools to explore a little-known site at a full range of scales in a short amount of time and collect invaluable samples for research. These initial data sets from the 2002 exploration program set the stage for more detailed studies of this unique hydrothermal system in the future.

  3. Summary of available waste forecast data for the Environmental Restoration Program at the Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-08-01

    This report identifies patterns of Oak Ridge National Laboratory (ORNL) Environmental Restoration (ER) waste generation that are predicted by the current ER Waste Generation Forecast data base. It compares the waste volumes to be generated with the waste management capabilities of current and proposed treatment, storage, or disposal (TSD) facilities. The scope of this report is limited to wastes generated during activities funded by the Office of the Deputy Assistant Secretary for Environmental Restoration (EM-40) and excludes wastes from the decontamination and decommissioning of facilities. Significant quantities of these wastes are expected to be generated during ER activities. This report has been developed as a management tool supporting communication and coordination of waste management activities at ORNL. It summarizes the available data for waste that will be generated as a result of remediation activities under the direction of the U.S. Department of Energy Oak Ridge Operations Office and identifies areas requiring continued waste management planning and coordination. Based on the available data, it is evident that most remedial action wastes leaving the area of contamination can be managed adequately with existing and planned ORR waste management facilities if attention is given to waste generation scheduling and the physical limitations of particular TSD facilities. Limited use of off-site commercial TSD facilities is anticipated, provided the affected waste streams can be shown to satisfy the requirements of the performance objective for certification of non-radioactive hazardous waste and the waste acceptance criteria of the off-site facilities. Ongoing waste characterization will be required to determine the most appropriate TSD facility for each waste stream.

  4. Level 3 baseline risk evaluation for Building 3506 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Golden, K.M.; Robers, S.K.; Cretella, F.M.

    1994-12-01

    This report presents the results of the Level 3 Baseline Risk Evaluation (BRE) performed on Building 3506 located at the Oak Ridge National Laboratory (ORNL). This BRE is intended to provide an analysis of the potential for adverse health effects (current or future) posed by contaminants at the facility. The decision was made to conduct a Level 3 (least rigorous) BRE because only residual contamination exists in the building. Future plans for the facility (demolition) also preclude a rigorous analysis. Site characterization activities for Building 3506 were conducted in fall of 1993. Concrete core samples were taken from the floors and walls of both the cell and the east gallery. These cores were analyzed for radionuclides and organic and inorganic chemicals. Smear samples and direct radiation measurements were also collected. Sediment exists on the floor of the cell and was also analyzed. To adequately characterize the risks posed by the facility, receptors for both current and potential future land uses were evaluated. For the current land use conditions, two receptors were evaluated. The first receptor is a hypothetical maintenance worker who spends 250 days (8 hours/day) for 25 years working in the facility. The remaining receptor evaluated is a hypothetical S and M worker who spends 2 days (8 hours/day) per year for 25 years working within the facility. This particular receptor best exemplifies the current worker scenario for the facility. The two current exposure scenarios and parameters of exposure (e.g., inhalation and ingestion rates) have been developed to provide a conservative (i.e. health protective) estimate of potential exposure.

  5. Work plan for the Isotopes Facilities Deactivation Project at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-08-01

    The purpose of the Isotopes Facilities Deactivation Project (IFDP) is to place former isotopes production facilities at the Oak Ridge National Laboratory in a safe, stable, and environmentally sound condition; suitable for an extended period of minimum surveillance and maintenance (S and M) and as quickly and economical as possible. Implementation and completion of the deactivation project will further reduce the risks to the environment and to public safety and health. Furthermore, completion of the project will result in significant S and M cost savings in future years. The IFDP work plan defines the project schedule, the cost estimate, and the technical approach for the project. A companion document, the EFDP management plan, has been prepared to document the project objectives, define organizational relationships and responsibilities, and outline the management control systems to be employed in the management of the project. The project has adopted the strategy of deactivating the simple facilities first, to reduce the scope of the project and to gain experience before addressing more difficult facilities. A decision support system is being developed to identify the activities that best promote the project mission and result in the largest cost savings. This work plan will be reviewed and revised annually. Deactivation of EFDP Facilities was initiated in FY 1994 and will be completed in FY 2000. The schedule for deactivation of facilities is shown. The total cost of the project is estimated to be $51M. The costs are summarized. Upon completion of deactivation, annual S and M costs of these facilities will be reduced from the current level of $5M per year to less than $1M per year.

  6. Effect of B(sub y) on neutral line ridges and dynamical source ordering

    NASA Technical Reports Server (NTRS)

    Martin, R. F., Jr.; Speiser, T. W.; Klamczynski, K.

    1994-01-01

    In this paper we study the effect of a uniform magnetic field B(sub y) in the cross-tail y direction on the dynamics and distribution of energetic ions in a current sheet model including a neutral line. Martin and Speiser (1988) have previously shown that a 'ridge' in the velocity space distribution function is a remote neutral line signature in a two-dimensional field without B(sub y). Our results show that as B(sub y) is increased, using nominal tail parameters, there is very little change in the ridge signature for small B(sub y) (up to about 4 times B(sub z)). For intermediate values (up to about 10 times times B(sub Y)) the ridge becomes observable further from the neutral line, while close to the X line the ridge is strongly modified. For large B(sub y) (of the order of B(sub x)) the ridge evolves into the new neutral line signatures which depend strongly on whether the observations point is above or below the current sheet. These results are used to estimate B(sub y) less than 2 nT in the Active Magentospheric Particle Traces Explorers/Ion Release Module (AMPTE/IRM) event modeled by Speiser and Martin (1994), which is consistent with onboard magnetometer measurements. We further show that the cause of the new structures appearing at large B(sub Y) is the same source seperation effect that produced the original ridge and that all these signatures are relatively insensitive to a small parallel electric field. Finally, we point our a dynamical ordering which occurs at large B(sub y): Using high-resolution simulations, we find a common boundary separating regions of positive and negative initial x, y, and z position, as well as initial pitch angle. This boundary is purely dynamical in nature and is independent of modeled source distributions.

  7. Comparison of results of two dye-tracer tests at the Chestnut Ridge Security Pits, Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Goldstrand, P.M.; Haas, J.

    1994-01-01

    Personnel from Martin Marietta Energy Systems, Inc. (Energy Systems) manage a closed hazardous waste disposal unit the Chestnut Ridge Security Pits (CRSP), located on the crest of Chestnut Ridge near the Y-12 Plant, Oak Ridge, Tennessee. To investigate the discharge of groundwater from CRSP to springs and streams located along the flanks and base of Chestnut Ridge, an initial dye-tracer study was conducted during 1990. A hydraulic connection was inferred to exist between the injection well (GW-178) on Chestnut Ridge and several sites to the east-northeast, east, and southeast of CRSP. A second dye-tracer study was conducted in 1992 to verify the results of the initial test and identify additional discharge points that are active during wet-weather conditions. No definitive evidence for the presence of dye was identified at any of the 35 locations monitored during the second dye study. Although interpretations of the initial dye test suggest a hydraulic connection with several sites and CRSP, reevaluation of the spectrofluorescence data from this test suggests that dye may not have been detected during the initial test. A combination of relatively high analytical detection limits during the initial test, and high natural background interference spectral peaks observed during the second test, suggest that high natural background emission spectra near the wavelength of the dye used during the initial test may have caused the apparently high reported concentrations. The results of these two tests do not preclude that a hydraulic connection exists; dye may be present in concentrations below the analytical detection limits or has yet to emerge from the groundwater system. The dye injection well is not completed within any significant karst features. Dye migration therefore, may be within a diffuse, slow-flow portion of the aquifer, at least in the immediate vicinity of the source well.

  8. Geophysical signatures over and around the northern segment of the 85°E Ridge, Mahanadi offshore, Eastern Continental Margin of India: Tectonic implications

    NASA Astrophysics Data System (ADS)

    Desa, Maria Ana; Ramana, M. V.; Ramprasad, T.; Anuradha, M.; Lall, M. V.; Kumar, B. J. P.

    2013-09-01

    The nature and origin of the subsurface 85°E Ridge in the Bay of Bengal has remained enigmatic till date despite several theories proposed by earlier researchers. We reinterpreted the recently acquired high quality multichannel seismic reflection data over the northern segment of the ridge that traverses through the Mahanadi offshore, Eastern Continental Margin of India and mapped the ridge boundary and its northward continuity. The ridge is characterized by complex topography, multilayer composition, intrusive bodies and discrete nature of underlying crust. The ridge is associated with large amplitude negative magnetic and gravity anomalies. The negative gravity response across the ridge is probably due to emplacement of relatively low density material as well as ∼2-3 km flexure of the Moho. The observed broad shelf margin basin gravity anomaly in the northern Mahanadi offshore is due to the amalgamation of the 85°E Ridge material with that of continental and oceanic crust. The negative magnetic anomaly signature over the ridge indicates its evolution in the southern hemisphere when the Earth's magnetic field was normally polarized. The presence of ∼5 s TWT thick sediments over the acoustic basement west of the ridge indicates that the underlying crust is relatively old, Early Cretaceous age. The present study indicates that the probable palaeo-location of Elan Bank is not between the Krishna-Godavari and Mahanadi offshores, but north of Mahanadi. Further, the study suggests that the northern segment of the 85°E Ridge may have emplaced along a pseudo fault during the Mid Cretaceous due to Kerguelen mantle plume activity. The shallow basement east of the ridge may have formed due to the later movement of the microcontinents Elan Bank and Southern Kerguelen Plateau along with the Antarctica plate.

  9. Dynamic plumbing systems along the 100 km long Arctic Vestnesa Ridge

    NASA Astrophysics Data System (ADS)

    Plaza-Faverola, Andreia; Buenz, Stefan; Vadakkepuliyambatta, Sunil; Mienert, Jurgen; Chand, Shyam; Johnson, Joel; Greinert, Jens

    2014-05-01

    Vestnesa is a ridge-like contour-current controlled sediment succession that lies above young oceanic crust created during the tectonic opening of Fram Strait. It is surrounded by the Molloy transform fault to the southwest, the Molloy deep to the north-west, the Knipovich oceanic ridge to the south-east, and the continental margin of Svalbard to the northeast. Although interrupted in places, a mostly continuous bottom simulating reflector (BSR), the seismic indicator for the base of the gas hydrate stability zone (GHSZ), extends for tens of kilometers from the crest of the ridge towards its northern and southern flanks. High-resolution P-Cable 2D seismic data show vertical fluid migration pathways, distributed in clusters along the 100 km long ridge, connecting the free gas system beneath the GHSZ through a 160-180 m thick hydrate stability zone to seabed pockmarks at the crest of the ridge. Among these clusters only those lying towards the easternmost end of the ridge have been documented to be periodically active in terms of present-day seafloor gas seepage. The methane release activity shows particularly well on 18 kHz echosounder data over a time period from 2008 to 2013. Gas hydrates have been recovered in shallow sediment cores (<6 mbsf) at the active seafloor seepage site. Gas analyses show heavier gases in addition to methane, as a hydrate-forming gas. Within the framework of CAGE - Center for Arctic Gas Hydrate, Environment and Climate, we are investigating the development of the plumbing systems of the Arctic Vestnesa Ridge in space and time domains. We compare the modeled base of the GHSZ for different gas compositions against the depth of the BSR in the region and discuss the elements of fluid migration systems that could explain observed lateral changes in BSR depths and the switching between active and inactive plumbing systems. The Centre of Excellence is funded by the Norwegian Research Council (grant No. 223259) over a period of ten years.

  10. The Influence of Ridge Geometry at Ultraslow Spreading Rates

    NASA Astrophysics Data System (ADS)

    Dick, H. J.; Standish, J.

    2004-12-01

    Ridges spreading at ultraslow rate less than 20 mm/yr have been identified as a unique class of ocean ridge as different from slow spreading as slow spreading are from fast 1. Ridge characteristics, such as the presence or absence of amagmatic accretionary segments, transform faults, axial valleys or axial rises, however, are not a simple function of spreading rate, and it is therefore difficult to define precisely ridge classes simply on this criterion. Ridge morphology, tectonics, and geochemistry are also largely a function of mantle thermal structure, upwelling rate, fertility, and ridge geometry. However, examination of ridge crustal structure with spreading rate clearly shows a sharp break, with seismic measurements of crustal thickness indicating highly variable, generally thin crust associated with spreading rates below 20 mm/yr. In contrast, crust formed at spreading rates greater than 20 mm/yr is generally thicker and less variable thickness, averaging between 6 and 7 km, without a clear relationship to spreading rate. The generally accepted explanation is the influence of conductive heat loss and the formation of a thick axial lithosphere due to slow mantle upwelling rates, thereby limiting melt production at ultraslow spreading rates 2. Comparatively, the influence of conductive heat loss at spreading rates greater than 20 mm/yr is likely negligible except near major large offset transforms. The latter effect is predicted by modeling to increase sharply with decreasing spreading rate below 20 mm/yr. Thus perturbations in ridge geometry that would otherwise have a negligible effect, can dramatically influence melt production and ridge tectonics at ultraslow spreading rates. Investigation of the SW Indian Ridge and along the Gakkel Ridge, for example, shows that where the effective spreading rate for mantle upwelling, which ridge obliquity, falls below ~12 mm/yr, long amagmatic accretionary ridge segments form and replace both magmatic accretionary ridge

  11. Slow-Spreading Oceanic Crust Formed By Steady-State Axial Volcanic Ridges

    NASA Astrophysics Data System (ADS)

    Murton, B. J.; Schroth, N.; LeBas, T.; Van Calsteren, P. W.; Yeo, I. A.; Achenbach, K. L.; Searle, R. C.

    2012-12-01

    Oceanic crust originates at mid-ocean spreading ridges (MORs), covers almost three quarters of the earth's surface and dominates the global magmatic flux. Axial volcanic ridges (AVRs) are almost ubiquitous features of orthogonal slow-spreading ridges, which account for three quarters of the global mid-ocean spreading ridge system today. Typically 3-6 km wide, 200-500 m high and 10-20 km long, AVRs are the loci of recent volcanic activity and form the most prominent topography rising above the otherwise flat-lying Median Valley floor. Previous studies indicate that AVRs, and their related crustal magma reservoirs are episodic, on a time scale of 150-300 ka. Yet their near ubiquitous occurrence at slow-spreading ridge segments provides us with a paradox: if AVRs have a life cycle of formation and degradation, does their near ubiquitous presence at slow spreading ridges imply their life-cycles are synchronised? In this contribution, we report the findings from a high-resolution study of a well-developed axial volcanic ridge (AVR) at 45°N on the Mid-Atlantic Ridge (MAR). Here, the MAR is typical of most slow-spreading ridges: it spreads generally symmetrically and orthogonally, at a full rate of 23.6 mm per year, has second and third-order segmentation, and contains a typical AVR. Using a combination of detailed micro-bathymetry, sidescan sonar, visual surveying and petrology, we suggest that the AVR is the product of quasi-steady state volcanotectonic processes. Small volume lava flows, originating at or near the crest and with short run-out lengths, form ~60 m high hummocky pillow-lava mounds that dominate the construction of the AVR. The lavas are the product of moderate degrees of mantle melting that are typical for normal mid-ocean ridge basalt. Synchronous with these eruptions the flanks of the AVR subside forming a structural horst. Subsidence is partially accommodated by a series of outward-facing volcanic growth faults that step-down and away from the AVR

  12. Age, geochemistry and melt flux variations for the Hawaiian Ridge

    NASA Astrophysics Data System (ADS)

    Garcia, M. O.; Weis, D. A.; Greene, A. R.; Wessel, P.; Harrison, L.; Tree, J.

    2012-12-01

    The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantle plume produced linear island chain, is 6000 km in length, active for 80+ Myr, and tectonically simple. Despite its importance to our understanding of mantle plumes and Cenozoic plate motion, there are large data gaps for the age and geochemistry of lavas from volcanoes along the Hawaiian Ridge (HR) portion of the Chain. Ages: Only volcanoes near the Hawaiian-Emperor bend and in the Hawaiian Islands have modern Ar-Ar ages, leaving a gap of 2000 km where existing K-Ar ages suggest synchronous volcanism over a 1000 km section. Geochemistry: There is a 2900 km gap in high precision geochemical data for the HR. The Emperor Seamounts (>45 Ma) have better regional coverage of recent isotopic data and show a correlation of Sr isotope composition with age of the underlying oceanic lithosphere (Regelous et al. 2003). The HR has an unexplained, exponential increase in magma flux over the last 30 Myr (Vidal & Bonneville 2004). Potential explanations for the increase in magma flux include: changes in melting conditions (temperature and/or pressure), change in source fertility related to rock type (pyroxenite vs. peridotite) or previous melting history, and/or changes in plate stresses resulting from reconfigurations of plate motion. Our new multi-disciplinary project will: 1) Determine 40Ar/39Ar ages, and whole-rock major, trace element, and Pb, Sr, Nd and Hf isotopic geochemistry for lavas from 20 volcanoes spanning ~2150 km of the HR (NW of the Hawaiian Islands). 2) Use the geochemical data to determine the long-term evolution of the Hawaiian mantle plume source components and to evaluate whether there have been systematic variations in mantle potential temperature, melting pressure, and/or source lithology during the creation of the HR. If so, are they responsible for the 300% variation in melt production along the Ridge? Also, we will assess when the more fertile Loa source component

  13. Transverse Aeolian Ridges on Mars: Sediment sources, volumes, and ages.

    NASA Astrophysics Data System (ADS)

    Berman, D. C.; Balme, M. R.

    2014-12-01

    Transverse Aeolian Ridges (TARs) are aeolian bedforms that are morphologically and dimensionally distinct from Large Dark Dune (LDD) fields, being generally brighter than, or of similar albedo to, the surrounding terrain. These features are significantly smaller than the LDDs, appear to form normal to local winds, and tend to have simple, transverse, ripple-like morphologies. Whether these small martian bedforms represent large granule ripples, small transverse dunes, or something else entirely is currently under debate. The spatial distribution of TARs provides important information about where on Mars aeolian sediments are concentrated, and determining their volume can help us constrain the sediment transport regime on Mars. Also, if we can determine if TARs were active only in the past, or whether TARs are mobile under today's wind conditions, then we can begin to assess when and where TARs are/were active over Mars' recent geological history. Thus TARs have the potential for being indicators/records of climate change on Mars. In this work we build on previous work [1,2] and focus on the local/regional scale. We have identified six regional study areas, each 5° by 5°, to investigate the behavior of TARs in detail; one in the northern hemisphere, three in the equatorial band, and two in the southern hemisphere. We have systematically mapped TAR and LDD deposits in each study area to constrain sediment transport pathways and identify sediment sources. In general, TAR sediments appear to be tied to local sources such as LDDs or layered terrains. HiRISE DTMs were utilized to measure TAR heights, widths, wavelengths, and lengths to calculate sediment volumes and estimate volumes over entire study areas based on mapping. Crater count analyses on contiguous TAR fields in the equatorial regions, where the bedforms appear more lithified, reveal ages of several million years. Mid-latitude TAR fields do not show any superposed craters, suggesting much younger deposits

  14. Mid-ocean ridge eruptions as a climate valve

    NASA Astrophysics Data System (ADS)

    Tolstoy, Maya

    2015-03-01

    Seafloor eruption rates and mantle melting fueling eruptions may be influenced by sea level and crustal loading cycles at scales from fortnightly to 100 kyr. Recent mid-ocean ridge eruptions occur primarily during neap tides and the first 6 months of the year, suggesting sensitivity to minor changes in tidal forcing and orbital eccentricity. An ~100 kyr periodicity in fast-spreading seafloor bathymetry and relatively low present-day eruption rates at a time of high sea level and decreasing orbital eccentricity suggest a longer-term sensitivity to sea level and orbital variations associated with Milankovitch cycles. Seafloor spreading is considered a small but steady contributor of CO2 to climate cycles on the 100 kyr time scale; however, this assumes a consistent short-term eruption rate. Pulsing of seafloor volcanic activity may feed back into climate cycles, possibly contributing to glacial/interglacial cycles, the abrupt end of ice ages, and dominance of the 100 kyr cycle.

  15. Degenerate band edge resonances in periodic silicon ridge waveguides.

    PubMed

    Wood, Michael G; Burr, Justin R; Reano, Ronald M

    2015-06-01

    We experimentally demonstrate degenerate band edge resonances in periodic Si ridge waveguides that are compatible with carrier injection modulation for active electro-optical devices. The resonant cavities are designed using a combination of the plane-wave expansion method and the finite difference time domain technique. Measured and simulated quality factors of the first band edge resonances scale to the fifth power of the number of periods. Quality factor scaling is determined to be limited by fabrication imperfections. Compared to resonators based on a regular transmission band edge, degenerate band edge devices can achieve significantly larger quality factors in the same number of periods. Applications include compact electro-optical switches, modulators, and sensors that benefit from high-quality factors and large distributed electric fields. PMID:26030540

  16. Waste certification program plan for Oak Ridge National Laboratory

    SciTech Connect

    Kornegay, F.C.

    1996-09-01

    This document defines the waste certification program being developed for implementation at Oak Ridge National Laboratory (ORNL). The document describes the program structure, logic, and methodology for certification of ORNL wastes. The purpose of the waste certification program is to provide assurance that wastes are properly characterized and that the Waste Acceptance Criteria (WAC) for receiving facilities are met. The program meets the waste certification requirements outlined in U.S. Department of Energy (DOE) Order 5820.2A, Radioactive Waste Management, and ensures that 40 CFR documentation requirements for waste characterization are met for mixed (both radioactive and hazardous) and hazardous (including polychlorinated biphenyls) waste. Program activities will be conducted according to ORNL Level 1 document requirements.

  17. Science and technology for a sustainable energy future: Accomplishments of the Energy Efficiency and Renewable Energy Program at Oak Ridge National Laboratory

    SciTech Connect

    Brown, M.A.; Vaughan, K.H.

    1995-03-01

    Accomplishments of the Energy Efficiency and Renewable Energy Program at the Oak Ridge National Laboratory are presented. Included are activities performed in the utilities, transportation, industrial, and buildings technology areas.

  18. The influence of isotropic and anisotropic crustal permeability on hydrothermal flow at fast spreading ridges

    NASA Astrophysics Data System (ADS)

    Hasenclever, Jörg; Rüpke, Lars; Theissen-Krah, Sonja; Morgan, Jason

    2016-04-01

    activity. We also explore the effect of anisotropic permeability that is likely to be a feature of the diking region above the melt lens where the repeated emplacement of meter-size dikes should lead to higher permeability in vertical and along-ridge direction and to lower permeability across the ridge. We further study the effect of along-ridge depth-variations of the axial melt lens on the distribution of hydrothermal vent sites.

  19. Simple bone augmentation for alveolar ridge defects.

    PubMed

    Haggerty, Christopher J; Vogel, Christopher T; Fisher, G Rawleigh

    2015-05-01

    Dental implant procedures, both surgical placement and preimplant bone augmentation, have become an integral aspect of the oral and maxillofacial surgeon's practice. The number of dental implants placed each year continues to increase as a result of increasing patient exposure and awareness of dental implants, the increased functional and esthetic dental demands of general practitioners and patients, the overall increase in age of the US patient population, and expanded insurance coverage of dental implant-related procedures. This article outlines relevant surgical procedures aimed toward reconstructing alveolar ridge defects to restore intra-arch alveolar discrepancies before restoration-driven dental implant placement. PMID:25951957

  20. Oak Ridge Leadership Computing Facility Position Paper

    SciTech Connect

    Oral, H Sarp; Hill, Jason J; Thach, Kevin G; Podhorszki, Norbert; Klasky, Scott A; Rogers, James H; Shipman, Galen M

    2011-01-01

    This paper discusses the business, administration, reliability, and usability aspects of storage systems at the Oak Ridge Leadership Computing Facility (OLCF). The OLCF has developed key competencies in architecting and administration of large-scale Lustre deployments as well as HPSS archival systems. Additionally as these systems are architected, deployed, and expanded over time reliability and availability factors are a primary driver. This paper focuses on the implementation of the Spider parallel Lustre file system as well as the implementation of the HPSS archive at the OLCF.

  1. Oak Ridge Mobile Agent Community (ORMAC)

    2003-06-30

    The Oak Ridge Mobile Agent Community (ORMAC) framework software facilitates the execution of a collection of mobile software agents across a heterogeneous collection of computer systems. ORMAC provides the software agents with the ability to communicate with each other in a synchronous and asynchronous manner. Also, ORMAC allows the software agents to move to any computer system in the community and continue execution there. ORMAC is intended to aid programmers in solving a very generalmore » set of distributed software problems.« less

  2. Environmental baseline survey report for West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge and parcel 21D in the vicinity of the East Technology Park, Oak Ridge, Tennessee

    SciTech Connect

    King, David A.

    2012-11-29

    This environmental baseline survey (EBS) report documents the baseline environmental conditions of five land parcels located near the U.S. Department of Energy?s (DOE?s) East Tennessee Technology Park (ETTP), including West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge, and Parcel 21d. Preparation of this report included the detailed search of federal government records, title documents, aerial photos that may reflect prior uses, and visual inspections of the property and adjacent properties. Interviews with current employees involved in, or familiar with, operations on the real property were also conducted to identify any areas on the property where hazardous substances and petroleum products, or their derivatives, and acutely hazardous wastes may have been released or disposed. In addition, a search was made of reasonably obtainable federal, state, and local government records of each adjacent facility where there has been a release of any hazardous substance or any petroleum product or their derivatives, including aviation fuel and motor oil, and which is likely to cause or contribute to a release of any hazardous substance or any petroleum product or its derivatives, including aviation fuel or motor oil, on the real property. A radiological survey and soil/sediment sampling was conducted to assess baseline conditions of Parcel 21d that were not addressed by the soils-only no-further-investigation (NFI) reports. Groundwater sampling was also conducted to support a Parcel 21d decision. Based on available data West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, and West Pine Ridge are not impacted by site operations and are not subject to actions per the Federal Facility Agreement (FFA). This determination is supported by visual inspections, records searches and interviews, groundwater conceptual modeling, approved NFI reports, analytical data, and risk analysis results. Parcel 21d data, however, demonstrate impacts from site

  3. Magnetostratigraphy of cave sediments, Wyandotte Ridge, Crawford County, southern Indiana

    SciTech Connect

    Pease, P.P.; Gomez, B. . Dept. of Geography and Geology); Schmidt, V.A. . Dept. of Geology and Planetary Science)

    1992-01-01

    The field polarities of 42 sediment samples obtained from 21 sites in Wyandotte Cave, and five smaller satellite caves in Wyandotte Ridge, southern Indiana, have been determined and correlated with magnetostratigraphic data from Mammoth Cave, Kentucky. In Wyandotte Cave sediment samples obtained between 137 m and 162 m in elevation possessed a normal field polarity, while samples obtained between 168 m and 171 m exhibited a field reversal. The reversal was interpreted to represent the most recent polarity change, dating the sediment fill and the end of the active period of the upper level of Wyandotte Cave at ca 0.788 Ma. There is a temporal correlation between the active period of the upper level in Wyandotte Cave and the C-level in Mammoth Cave, which lies at a similar elevation. Such a correlation is most likely a consequence of the contemporaneous abandonment of passages in the two cave systems during the early Pleistocene reconstruction of the Ohio River system, which acts as the base level control in both caves. Samples from two caves near the top of Wyandotte Ridge, located between elevations of 236 m and 241 m, exhibited a normal polarity. These caves are located at a higher elevation than any of the sample sites in Mammoth Cave and their location suggests that the fill predates sediments from that system. It appears most likely that the fill in these caves is a minimum of ca 2.48 Ma. old and correlates with the residuum of the upper Mitchell Plain surface, not with the fill in the upper (A- or B-levels) in Mammoth Cave.

  4. Soils and geomorphology of the East Chestnut Ridge site

    SciTech Connect

    Lietzke, D.A.; Ketelle, R.H.; Lee, R.R. , Rutledge, TN; Oak Ridge National Lab., TN )

    1989-10-01

    Soil mapping of the East Chestnut Ridge site in conjunction with subsurface soil and rock coring provides an in-depth evaluation of the site and its suitability for disposal of wastes. Landforms and surface and subsurface hydrology, the natural, undisturbed, soil-saprolite-geohydrology system beneath the zone of engineering modifications provides for the ultimate containment of wastes and a means for the filtration and purification of any leachate before it reaches the aquifer. The surface location and extent of each geologic formation on the site were mapped. These locations correlated well with projections of subsurface contacts to the surface even through the criteria used by the pedologist and geologist to identify soil and rock from the same formation may be different. Soil thickness over bedrock of the Copper Ridge, Chepultepec, Longview, and Kingsport Formations is sufficient to provide considerable buffering between trench bottoms and groundwater or rock. Soil thickness over the Mascot Formation is comparatively thin, and pinnacles and ledges exposed on steeper sideslopes are common. Soil underlain by the Mascot Formation is not suited for a trench landfill. According to soil coring and active borrow pit observations, chert beds in the soil and saprolite are preferred zones of water flow. Construction of adequate clay liners beneath disposal units sited on the Longview dolomite may require placement and compaction of other native soils to achieve sufficiently low soil permeabilities. Karst geomorphic processes that initiated the formation of dolines evidently started several million years ago. Doline formation and enlargement is episodic, with short periods of activity followed by long periods of stability. Analysis of doline soil stratigraphy suggests that most of the large dolines on the site have been stable for most of the past 10,000 to 1000,000 years. 8 refs., 9 figs.

  5. A seismic anisotropy study of the Dragon Flag hydrothermal field (49°39'E ) on the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Zhao, M.; Tong, V. C. H.; Qiu, X.

    2015-12-01

    Dragon Flag hydrothermal field located at 49°39'E on the Southwest Indian Ridge contains the active hydrothermal vents firstly discovered on the ultraslow spreading ridge (Tao et al, 2012). Anisotropic study in this area will provide important information tectonic activities. 65634 traveltime residuals from the three-dimensional isotropic inversion (Zhao et al., 2013), were divided into three groups, which correspond to quasi ocean crustal Layer 2 (qL2), quasi ocean crustal Layer 3 (qL3) and quasi uppermost mantle (qUM), respectively. Traveltime residuals at different depths show that there are obvious cosine relationships between traveltime residuals and azimuth of qL2, qL3 and qUM, indicating anisotropy existed in both crust and mantle beneath Dragon Flag hydrothermal field. The best fitted cosine curves indicate that the fast directions (negative traveltime residuals) corresponding to the general trend of ridge axis of N104°E. According to these results, we propose that there may be prevalent cracks penetrating into lower crust or even uppermost mantle. We argue that the hydrothermal convection of Dragon Flag hydrothermal field not only occurs perpendicular to ridge axis, but also occurs parallel to ridge axis. We reveal for the first time anisotropic characteristics of the ultraslow spreading ridge, which has profound scientific significance for the future research on global ocean lithospheric anisotropy. This research was granted by the Natural Science Foundation of China (91028002, 41176053, 91428204). Keywords: ultraslow spreading ridge, Southwest Indian Ridge, Dragon Flag hydrothermal field, P wave traveltime residuals, anisotropy References: Tao C H, Lin J, Guo S, et al. First active hydrothermal vents on an ultraslow-spreading center: Southwest Indian Ridge. Geology, 2012, 40(1): 47~50. Zhao M H, Qiu X L, Li J B, et al. Three-dimensional seismic structure of the Dragon Flag oceanic core complex at the ultraslow spreading Southwest Indian Ridge (49°39

  6. Comprehensive integrated planning: A process for the Oak Ridge Reservation, Oak Ridge, Tennessee

    SciTech Connect

    1998-05-01

    The Oak Ridge Comprehensive Integrated Plan is intended to assist the US Department of Energy (DOE) and contractor personnel in implementing a comprehensive integrated planning process consistent with DOE Order 430.1, Life Cycle Asset Management and Oak Ridge Operations Order 430. DOE contractors are charged with developing and producing the Comprehensive Integrated Plan, which serves as a summary document, providing information from other planning efforts regarding vision statements, missions, contextual conditions, resources and facilities, decision processes, and stakeholder involvement. The Comprehensive Integrated Plan is a planning reference that identifies primary issues regarding major changes in land and facility use and serves all programs and functions on-site as well as the Oak Ridge Operations Office and DOE Headquarters. The Oak Ridge Reservation is a valuable national resource and is managed on the basis of the principles of ecosystem management and sustainable development and how mission, economic, ecological, social, and cultural factors are used to guide land- and facility-use decisions. The long-term goals of the comprehensive integrated planning process, in priority order, are to support DOE critical missions and to stimulate the economy while maintaining a quality environment.

  7. Custom Titanium Ridge Augmentation Matrix (CTRAM): A Case Report.

    PubMed

    Connors, Christopher A; Liacouras, Peter C; Grant, Gerald T

    2016-01-01

    This is a case report of a custom titanium ridge augmentation matrix (CTRAM). Using cone beam computed tomography (CBCT), a custom titanium space-maintaining device was developed. Alveolar ridges were virtually augmented, a matrix was virtually designed, and the CTRAM was additively manufactured with titanium (Ti6Al4V). Two cases are presented that resulted in sufficient increased horizontal bone volume with successful dental implant placement. The CTRAM design allows for preoperative planning for increasing alveolar ridge dimensions to support dental implants, reduces surgical time, and prevents the need for a second surgical site to gain sufficient alveolar ridge bone volume for dental implant therapy. PMID:27560675

  8. An analysis of ridge axis gravity roughness and spreading rate

    NASA Technical Reports Server (NTRS)

    Small, Christopher; Sandwell, David T.

    1992-01-01

    Fast and slow spreading ridges have radically different morphologic and gravimetric characteristics. In this study, altimeter measurements from the Geosat Exact Repeat Mission are used to investigate spreading rate dependence of the ridge axis gravity field. Gravity roughness provides an estimate of the amplitude of the gravity anomaly and is robust to small errors in the location of the ridge axis. Gravity roughness as a weighted root mean square of the vertical deflection at 438 ridge crossings on the mid-ocean ridge system is computed. Ridge axis gravity anomalies show a decrease in amplitude with increasing spreading rate up to an intermediate rate of about 60-80 mm/yr and almost no change at higher rates; overall the roughness decreases by a factor of 10 between the lowest and highest rates. In addition to the amplitude decrease, the range of roughness values observed at a given spreading rate shows a similar order of magnitude decrease with transition between 60 and 80 mm/yr. The transition of ridge axis gravity is most apparent at three relatively unexplored locations on the Southeast Indian Ridge and the Pacific-Antarctic Rise; on these intermediate rate ridges the transition occurs abruptly across transform faults.

  9. Segmentation and a nontransform ridge offset of the Reykjanes Ridge near 58 deg N

    NASA Astrophysics Data System (ADS)

    Searle, R. C.; Field, P. R.; Owens, R. B.

    1994-12-01

    Multibeam bathymetry, deep-towed side scan sonar, gravity, and magnetic data over a 50 km square area all suggest the presence of a second-order, nontransform offset on the obliquely spreading Reykjanes Ridge (North Atlantic ocean) near 58 deg N latitude. It is the first such offset to be recognized on the Reykjanes Ridge. This region is characterized by a shallow median valley containing en echelon axial volcanic ridges (AVRs) similar to those found on more northerly parts of the Reykjanes Ridge. The side scan sonar shows that all the AVRs are constructional in nature. The one immediately south of the offset basin backscatters strongly, is unmarked by faulting, and so appears extremely young. Other AVRs appear older, having lower backscatter and, off axis, being cut by faults and fissures. At 57 deg 55 min N the progression of AVRs is interrupted by a 600-m-deep, 20 km x 10 km basin. Residual mantle Bouguer anomalies, corrected for two-dimensional lithospheric cooling, display a high of at least 8 mGal over the basin. Two small, off axis basins occur roughly along the flow line from this basin and are also characterized by gravity highs. The basins are interpreted as regions of crustal thinning and are believed to represent the discontinuous trace of the ridge offset, which has thus been in existence for at least 2 m.y. and has been slowly propagating south. Inversion of the magnetic field shows a very low magnetization (approximately 3-4 A/m) associated with the offset basin, which is interpreted as indicating a reduced magnetic layer thickness due to poor magma supply to the offset area. The Brunhes-Matuyama reversal boundary and Anomaly 2 traces are offset about 3 km dextrally across the proposed offset trace. The AVR immediately north of the offset displays high amplitudes of magnetization which steadily increase southward toward its tip adjacent to the offset, suggesting the presence of increasingly highly fractionated basalts toward the AVR tip. Polarity

  10. DATA SHARING REPORT CHARACTERIZATION OF THE SURVEILLANCE AND MAINTENANCE PROJECT MISCELLANEOUS PROCESS INVENTORY WASTE ITEMS OAK RIDGE NATIONAL LABORATORY, Oak Ridge TN

    SciTech Connect

    Weaver, Phyllis C

    2013-12-12

    The U.S. Department of Energy (DOE) Oak Ridge Office of Environmental Management (EM-OR) requested Oak Ridge Associated Universities (ORAU), working under the Oak Ridge Institute for Science and Education (ORISE) contract, to provide technical and independent waste management planning support under the American Recovery and Reinvestment Act (ARRA). Specifically, DOE EM-OR requested ORAU to plan and implement a sampling and analysis campaign to target certain items associated with URS|CH2M Oak Ridge, LLC (UCOR) surveillance and maintenance (S&M) process inventory waste. Eight populations of historical and reoccurring S&M waste at the Oak Ridge National Laboratory (ORNL) have been identified in the Waste Handling Plan for Surveillance and Maintenance Activities at the Oak Ridge National Laboratory, DOE/OR/01-2565&D2 (WHP) (DOE 2012) for evaluation and processing for final disposal. This waste was generated during processing, surveillance, and maintenance activities associated with the facilities identified in the process knowledge (PK) provided in Appendix A. A list of items for sampling and analysis were generated from a subset of materials identified in the WHP populations (POPs) 4, 5, 6, 7, and 8, plus a small number of items not explicitly addressed by the WHP. Specifically, UCOR S&M project personnel identified 62 miscellaneous waste items that would require some level of evaluation to identify the appropriate pathway for disposal. These items are highly diverse, relative to origin; composition; physical description; contamination level; data requirements; and the presumed treatment, storage, and disposal facility (TSDF). Because of this diversity, ORAU developed a structured approach to address item-specific data requirements necessary for acceptance in a presumed TSDF that includes the Environmental Management Waste Management Facility (EMWMF)—using the approved Waste Lot (WL) 108.1 profile—the Y-12 Sanitary Landfill (SLF) if appropriate; Energy

  11. Field Operations Procedures Manual for environmental monitoring in Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-12-01

    This Sampling and Analysis Plan addresses meteorological monitoring activities that will be conducted in support of the Environmental Monitoring Plan for Waste Area Grouping (WAG) 6. WAG 6 is a shallow-burial land disposal facility for low-level radioactive waste at the Oak Ridge National Laboratory, a research facility owned by the US Department of Energy and managed by Martin Marietta Energy Systems, Inc. Meteorological monitoring of various climatological parameters (e.g., temperature, wind speed, humidity) will be collected by instruments installed at WAG 6. Data will be recorded electronically at frequencies varying from 5-min intervals to 1-h intervals, dependent upon parameter. The data will be downloaded every 2 weeks, evaluated, compressed, and uploaded into a WAG 6 data base for subsequent use. The meteorological data will be used in water balance calculations in support of the WAG 6 hydrogeological model.

  12. Sampling and Analysis Plan for White Oak Creek Watershed Remedial Investigation supplemental sampling, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-05-01

    This Sampling and Analysis (SAP) presents the project requirements for proposed soil sampling to support the White Oak Creek Remedial Investigation/Feasibility Study at Oak Ridge National Laboratory. During the Data Quality Objectives process for the project, it was determined that limited surface soils sampling is need to supplement the historical environmental characterization database. The primary driver for the additional sampling is the need to identify potential human health and ecological risks at various sites that have not yet proceeded through a remedial investigation. These sites include Waste Area Grouping (WAG)3, WAG 4, WAG 7, and WAG 9. WAG 4 efforts are limited to nonradiological characterization since recent seep characterization activities at the WAG have defined the radiological problem there.

  13. Ridge Orientations of the Ridge-Forming Unit, Sinus Meridiani, Mars-A Fluvial Explanation

    NASA Technical Reports Server (NTRS)

    Wilkinson, M. Justin; Herridge, A.

    2013-01-01

    Imagery and MOLA data were used in an analysis of the ridge-forming rock unit (RFU) exposed in Sinus Meridiani (SM). This unit shows parallels at different scales with fluvial sedimentary bodies. We propose the terrestrial megafan as the prime analog for the RFU, and likely for other members of the layered units. Megafans are partial cones of fluvial sediment, with radii up to hundreds of km. Although recent reviews of hypotheses for the RFU units exclude fluvial hypotheses [1], inverted ridges in the deserts of Oman have been suggested as putative analogs for some ridges [2], apparently without appreciating The wider context in which these ridges have formed is a series of megafans [3], a relatively unappreciated geomorphic feature. It has been argued that these units conform to the megafan model at the regional, subregional and local scales [4]. At the regional scale suites of terrestrial megafans are known to cover large areas at the foot of uplands on all continents - a close parallel with the setting of the Meridiani sediments at the foot of the southern uplands of Mars, with its incised fluvial systems leading down the regional NW slope [2, 3] towards the sedimentary units. At the subregional scale the layering and internal discontinuities of the Meridiani rocks are consistent, inter alia, with stacked fluvial units [4]. Although poorly recognized as such, the prime geomorphic environment in which stream channel networks cover large areas, without intervening hillslopes, is the megafan [see e.g. 4]. Single megafans can reach 200,000 km2 [5]. Megafans thus supply an analog for areas where channel-like ridges (as a palimpsest of a prior landscape) cover the intercrater plains of Meridiani [6]. At the local, or river-reach scale, the numerous sinuous features of the RFU are suggestive of fluvial channels. Cross-cutting relationships, a common feature of channels on terrestrial megafans, are ubiquitous. Desert megafans show cemented paleo-channels as inverted

  14. Comparison of buried sand ridges and regressive sand ridges on the outer shelf of the East China Sea

    NASA Astrophysics Data System (ADS)

    Wu, Ziyin; Jin, Xianglong; Zhou, Jieqiong; Zhao, Dineng; Shang, Jihong; Li, Shoujun; Cao, Zhenyi; Liang, Yuyang

    2016-06-01

    Based on multi-beam echo soundings and high-resolution single-channel seismic profiles, linear sand ridges in U14 and U2 on the East China Sea (ECS) shelf are identified and compared in detail. Linear sand ridges in U14 are buried sand ridges, which are 90 m below the seafloor. It is presumed that these buried sand ridges belong to the transgressive systems tract (TST) formed 320-200 ka ago and that their top interface is the maximal flooding surface (MFS). Linear sand ridges in U2 are regressive sand ridges. It is presumed that these buried sand ridges belong to the TST of the last glacial maximum (LGM) and that their top interface is the MFS of the LGM. Four sub-stage sand ridges of U2 are discerned from the high-resolution single-channel seismic profile and four strikes of regressive sand ridges are distinguished from the submarine topographic map based on the multi-beam echo soundings. These multi-stage and multi-strike linear sand ridges are the response of, and evidence for, the evolution of submarine topography with respect to sea-level fluctuations since the LGM. Although the difference in the age of formation between U14 and U2 is 200 ka and their sequences are 90 m apart, the general strikes of the sand ridges are similar. This indicates that the basic configuration of tidal waves on the ECS shelf has been stable for the last 200 ka. A basic evolutionary model of the strata of the ECS shelf is proposed, in which sea-level change is the controlling factor. During the sea-level change of about 100 ka, five to six strata are developed and the sand ridges develop in the TST. A similar story of the evolution of paleo-topography on the ECS shelf has been repeated during the last 300 ka.

  15. Comparison of buried sand ridges and regressive sand ridges on the outer shelf of the East China Sea

    NASA Astrophysics Data System (ADS)

    Wu, Ziyin; Jin, Xianglong; Zhou, Jieqiong; Zhao, Dineng; Shang, Jihong; Li, Shoujun; Cao, Zhenyi; Liang, Yuyang

    2016-07-01

    Based on multi-beam echo soundings and high-resolution single-channel seismic profiles, linear sand ridges in U14 and U2 on the East China Sea (ECS) shelf are identified and compared in detail. Linear sand ridges in U14 are buried sand ridges, which are 90 m below the seafloor. It is presumed that these buried sand ridges belong to the transgressive systems tract (TST) formed 320-200 ka ago and that their top interface is the maximal flooding surface (MFS). Linear sand ridges in U2 are regressive sand ridges. It is presumed that these buried sand ridges belong to the TST of the last glacial maximum (LGM) and that their top interface is the MFS of the LGM. Four sub-stage sand ridges of U2 are discerned from the high-resolution single-channel seismic profile and four strikes of regressive sand ridges are distinguished from the submarine topographic map based on the multi-beam echo soundings. These multi-stage and multi-strike linear sand ridges are the response of, and evidence for, the evolution of submarine topography with respect to sea-level fluctuations since the LGM. Although the difference in the age of formation between U14 and U2 is 200 ka and their sequences are 90 m apart, the general strikes of the sand ridges are similar. This indicates that the basic configuration of tidal waves on the ECS shelf has been stable for the last 200 ka. A basic evolutionary model of the strata of the ECS shelf is proposed, in which sea-level change is the controlling factor. During the sea-level change of about 100 ka, five to six strata are developed and the sand ridges develop in the TST. A similar story of the evolution of paleo-topography on the ECS shelf has been repeated during the last 300 ka.

  16. Land Use Manager Application Ensures Protectiveness Following Remediation on the Oak Ridge Reservation - 13355

    SciTech Connect

    Garland, Sid; Brown, Sally; Sims, Lynn; Darby, Jason

    2013-07-01

    Long-term stewardship is the set of activities necessary to return contaminated land to safe and beneficial use. The activities include physical and legal controls to prevent inappropriate exposure to contamination left in place at a site. It is the longest phase of the Department of Energy's Environmental Management Program and ensures the protection of human health and the environment for varied end uses. At the Department of Energy's Oak Ridge Reservation an automated program has been developed and implemented that tracks the multitude of long-term stewardship activities. The Oak Ridge Reservation is a large site that currently has over 50 actions requiring long-term stewardship activities. The Oak Ridge Reservation consists primarily of three plant sites, and long-term stewardship will enable these sites to be leased to private entities (East Tennessee Technology Park), modernized for an evolving national security mission (Y-12 National Security Complex), and revitalized to continue multi-disciplinary research (Oak Ridge National Laboratory). The varied site end uses of the individual plant sites coupled with the multitude of controls required by leaving waste in place presents challenges. A single remedial action may include surveillance and maintenance activities, media monitoring, property record notices as well as physical controls such as fences and signs. Thus, the array of long-term stewardship activities is complex and intermingled (over 200 inspections each year at various frequencies are required currently) and requires an effective tracking program, termed the Land Use Manager. The Land Use Manager is a web-based data management application for use by personnel responsible for implementing, maintaining, and verifying engineering and land use controls on the Oak Ridge Reservation. The program is a data entry and tracking tool, as well as a notification tool. The status and performance of engineering and land use controls are checked annually for

  17. VERITAS Observations of The Galactic Center Ridge

    NASA Astrophysics Data System (ADS)

    Smith, Andrew; Veritas

    2015-01-01

    The Galactic Center Ridge is perhaps the most local, busy environment for high energy particle acceleration; home to many relativistic particle accelerators such as pulsar wind nebulae, supernova remnants, and the central supermassive black hole SgrA*. Observations with VHE (>100 GeV) gamma-ray telescopes of the region have revealed multiple point sources associated with well known objects, as well as regions of extended emission not directly associated with targets at other wavelengths. More importantly, the detection of a large, diffuse component of >300 GeV gamma-ray emission by the HESS collaboration is strongly believed to be the result of accelerated cosmic rays interacting with molecular cloud regions, thus providing a window into high energy cosmic ray acceleration. Here we present the VERITAS observations of the Galactic Center Ridge taken from 2008-2014 in the >2 TeV regime. We will focus on the VERITAS results on the known HESS sources in the region, as well as the diffuse component of TeV emission along the plane. Due to the much higher energy threshold of the VERITAS observations, our data provide a new window into some of the highest energy particle acceleration occurring in the center of our galaxy.

  18. Ridges and Troughs in Sippar Sulcus, Ganymede

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Embayment of ridges and troughs in a portion of the Sippar Sulcus area of Jupiter's moon Ganymede in this image from NASA's Galileo spacecraft is interpreted as evidence that the low-lying area was filled in by flooding with low-viscosity material, such as water or water-ice slush lavas. Bays of the material appeared to have formed in troughs (indicated by arrows) between the ridges.

    The smallest features visible are about 180 meters (590 feet) across. Analysis of such high-resolution images in combination with estimates of the features' relative elevations is helping scientists interpret the roles of volcanism and tectonics in creating the bright terrain on Ganymede.

    This image was prepared by the Lunar and Planetary Institute, Houston, and included in a report by Dr. Paul Schenk et al. in the March 1, 2001, edition of the journal Nature.

    The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.

    Images and data received from Galileo are posted on the Galileo mission home page at http://www.jpl.nasa.gov/galileo. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo .

  19. The Oak Ridge Isochronous Cyclotron Refurbishment Project

    SciTech Connect

    Mendez, II, Anthony J; Ball, James B; Dowling, Darryl T; Mosko, Sigmund W; Tatum, B Alan

    2011-01-01

    The Oak Ridge Isochronous Cyclotron (ORIC) has been in operation for nearly fifty years at the Oak Ridge National Laboratory (ORNL). Presently, it serves as the driver accelerator for the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), where radioactive ion beams are produced using the Isotope Separation Online (ISOL) technique for post-acceleration by the 25URC tandem electrostatic accelerator. Operability and reliability of ORIC are critical issues for the success of HRIBF and have presented increasingly difficult operational challenges for the facility in recent years. In February 2010, a trim coil failure rendered ORIC inoperable for several months. This presented HRIBF with the opportunity to undertake various repairs and maintenance upgrades aimed at restoring the full functionality of ORIC and improving the reliability to a level better than what had been typical over the previous decade. In this paper, we present details of these efforts, including the replacement of the entire trim coil set and measurements of their radial field profile. Comparison of measurements and operating tune parameters with setup code predictions will also be presented.

  20. Phase I remedial investigation report of Waste Area Grouping 2 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Miller, D.E.

    1995-07-01

    This report presents the activities and findings of the first phase of a three-phase remedial investigation (RI) of Waste Area Grouping (WAG) 2 at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, and updates the scope and strategy for WAG-2-related efforts. WAG 2 contains White Oak Creek (WOC) and its tributaries downstream of the ORNL main plant area, White Oak Lake, White Oak Creek Embayment on the Clinch River, and the associated floodplain and subsurface environment. Water, sediment, soil, and biota in WAG 2 are contaminated and continue to receive contaminants from upgradient WAGs. This report includes field activities completed through October 1992. The remediation of WAG 2 is scheduled to follow the cessation of contaminant input from hydrologically upgradient WAGs. While upgradient areas are being remediated, the strategy for WAG 2 is to conduct a long-term monitoring and investigation program that takes full advantage of WAG 2`s role as an integrator of contaminant fluxes from other ORNL WAGs and focuses on four key goals: (1) Implement, in concert with other programs, long-term, multimedia environmental monitoring and tracking of contaminants leaving other WAGs, entering WAG 2, and being transported off-site. (2) Provide a conceptual framework to integrate and develop information at the watershed-level for pathways and processes that are key to contaminant movement, and so support remedial efforts at ORNL. (3) Provide periodic updates of estimates of potential risk (both human health and ecological) associated with contaminants accumulating in and moving through WAG 2 to off-site areas. (4) Support the ORNL Environmental Restoration Program efforts to prioritize, remediate, and verify remedial effectiveness for contaminated sites at ORNL, through long-term monitoring and continually updated risk assessments.

  1. Improved Digitization of Lunar Mare Ridges with LROC Derived Products

    NASA Astrophysics Data System (ADS)

    Crowell, J. M.; Robinson, M. S.; Watters, T. R.; Bowman-Cisneros, E.; Enns, A. C.; Lawrence, S.

    2011-12-01

    Lunar wrinkle ridges (mare ridges) are positive-relief structures formed from compressional stress in basin-filling flood basalt deposits [1]. Previous workers have measured wrinkle ridge orientations and lengths to investigate their spatial distribution and infer basin-localized stress fields [2,3]. Although these plots include the most prominent mare ridges and their general trends, they may not have fully captured all of the ridges, particularly the smaller-scale ridges. Using Lunar Reconnaissance Orbiter Wide Angle Camera (WAC) global mosaics and derived topography (100m pixel scale) [4], we systematically remapped wrinkle ridges in Mare Serenitatis. By comparing two WAC mosaics with different lighting geometry, and shaded relief maps made from a WAC digital elevation model (DEM) [5], we observed that some ridge segments and some smaller ridges are not visible in previous structure maps [2,3]. In the past, mapping efforts were limited by a fixed Sun direction [6,7]. For systematic mapping we created three shaded relief maps from the WAC DEM with solar azimuth angles of 0°, 45°, and 90°, and a fourth map was created by combining the three shaded reliefs into one, using a simple averaging scheme. Along with the original WAC mosaic and the WAC DEM, these four datasets were imported into ArcGIS, and the mare ridges of Imbrium, Serenitatis, and Tranquillitatis were digitized from each of the six maps. Since the mare ridges are often divided into many ridge segments [8], each major component was digitized separately, as opposed to the ridge as a whole. This strategy enhanced our ability to analyze the lengths, orientations, and abundances of these ridges. After the initial mapping was completed, the six products were viewed together to identify and resolve discrepancies in order to produce a final wrinkle ridge map. Comparing this new mare ridge map with past lunar tectonic maps, we found that many mare ridges were not recorded in the previous works. It was noted

  2. Project management plan for Waste Area Grouping 5 Old Hydrofracture Facility tanks contents removal at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1998-06-01

    On January 1, 1992, the US Department of Energy (DOE), the US Environmental Protection Agency (EPA) Region IV, and the Tennessee Department of Environment and Conservation (TDEC) signed a Federal Facility Agreement (FFA) concerning the Oak Ridge Reservation. The FFA requires that inactive liquid low-level (radioactive) waste (LLLW) tanks at Oak Ridge National Laboratory (ORNL) be remediated in accordance with requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This revision is to update the schedule and designation of responsibilities for the Old Hydrofracture Facility (OHF) tanks contents removal project. The scope of this project is to transfer inventory from the five inactive LLLW tanks at the OHF into the active LLLW system.

  3. Are sinuous ridges in the equatorial Rahway Vallis region of Mars fluvioglacial in origin?

    NASA Astrophysics Data System (ADS)

    Ramsdale, Jason D.; Balme, Matt R.; Conway, Susan J.; Gallagher, Colman

    2013-04-01

    A suite of elongate, branching positive relief landforms has been observed around Rahway Vallis, south-west of Orcus Patera, Mars. They are typically 10 to 150 metres across, and several to tens of kilometres in length. We have observed that these forms occur both individually and as part of complex systems incorporating various cross-cutting, anastomosing and branching patterns. This study forms part of a larger debate as to whether fluvioglacial processes, as opposed to igneous activity, shaped the landscapes in the Elysium Planitia region. The similarity of some of these positive relief branching forms to inverted channels, or perhaps even relict sub-glacial fluvial systems (eskers) suggests an alternative fluvioglacial hypothesis to formation by volcanic processes. Interestingly, if these are esker-like forms then glacial activity in this region was "wet-based", so there should be other characteristic landforms visible. To address this idea, we are conducting a new mapping study of sinuous ridges in the region around Rahway Vallis to assess whether they are more consistent in morphology with formation by igneous or fluvioglacial processes. The survey is being performed using orbital images from the Context Camera (CTX) on the Mars Reconnaissance Orbiter and elevation data from the Mars Orbiter Laser Altimeter (MOLA). Our mapping has shown that many of the ridges form convergent, contributory networks. The ridges are spatially associated with kilometre-wide shallow channels and are found at a nearly constant elevation of -3000m above Mars Datum. Our preliminary interpretation is that these ridges are depositional landforms with multiple sources, and therefore could be sub-glacial (eskers), or inverted fluvial channels. The associated larger channels could be higher order fluvial channels, with the ridges and wide-channels together forming part of a larger drainage network.

  4. ­­­­Submarine Mass Wasting on Hovgaard Ridge, Fram Strait, European Arctic

    NASA Astrophysics Data System (ADS)

    Forwick, M.; Laberg, J. S.; Husum, K.; Gales, J. A.

    2015-12-01

    Hovgaard Ridge is an 1800 m high bathymetric high in the Fram Strait, the only deep-water gateway between the Arctic Ocean and the other World's oceans. The slopes of the ridge provide evidence of various types of sediment reworking, including 1) up to 12 km wide single and merged slide scars with maximum ~30 m high headwalls and some secondary escarpments; 2) maximum 3 km wide and 130 m deep slide scars with irregular internal morphology, partly narrowing towards the foot of the slope; 3) up to 130 m deep, 1.5 km wide and maximum 8 km long channels/gullies originating from areas of increasing slope angle at the margins of a plateau on top of the ridge. Most slide scars result presumably from retrogressive failure related to weak layers in contourites or ash. The most likely trigger mechanism is seismicity related to tectonic activity within the nearby mid-ocean fracture zone. Gully/channel formation is suggested to result from cascading water masses and/or from sediment gravity flows originating from failure at the slope break after winnowing on the plateau of the ridge.

  5. Structural and stratigraphic evolution of Aleutian convergent-margin basins - ridge crest to trench floor

    SciTech Connect

    Scholl, D.W.; Ryan, H.F.; Geist, E.L.; Vallier, T.L.; Stevenson, A.J.; Childs, J.R. )

    1988-02-01

    The Aleutian Ridge lies along nearly 2000 km of the north Pacific's obliquely converging plate boundary with North America. Since middle Eocene time, convergent-margin basins have repeatedly formed here, typically as summit basins along the ridge crest, and as forearc basins on the landward trench slope. Summit and forearc basins formed as a consequence of plate-boundary coupling and the application of compressional and right-lateral shear stresses to the arc massif. Basins typically evolved along shear zones in response to transtensional processes, and as trailing-edge grabens behind rotating blocks of arc massif. In the late Cenozoic, high rates of trench sedimentation led to the growth of an accretionary complex that underthrust forearc basement. Wedging and improved plate coupling elevated and laterally shifted blocks of outer forearc rocks, creating much of the structural framework of the regionally extensive Aleutian Terrace forearc basin. Changes in plate-boundary conditions that affected the ridge's volcanic activity and regional elevation importantly influenced basinal sedimentation. Changes of greatest significance were a major shift in convergence direction and rate about 42 Ma (reduced volcanism), ridge underthrusting by increasingly younger ocean crust in Oligocene and Miocene time (arc elevation), and the combination of more orthogonal underthrusting and the subduction of a dead spreading center 5-10 Ma (arc subsidence).

  6. Structural and stratigraphic evolution of Aleutian convergent-margin basins - Ridge crest to trench floor

    SciTech Connect

    Scholl, D.W.; Ryan, H.F.; Geist, E.L.; Vallier, T.L.

    1988-01-01

    The Aleutian Ridge lies along nearly 2,000 km of the north Pacific's obliquely converging plate boundary with North America. Since middle Eocene time, convergent-margin basins have repeatedly formed here, typically as summit basins along the ridge crest, and as forecarc basins on the landward trench slope. Thick (1-4 km) sequences of terrigenous, hemipelagic, and biogenic debris have accumulated in these depressions, which are mostly intra-arc structures floored by arc-basement rocks. Summit and forearc basins formed as a consequence of plate-boundary coupling and the application of compressional and right-lateral shear stresses to the arc massif. Basins typically evolved along shear zones in response to transtensional processes, and as trailing-edge grabens behind rotating blocks of arc massif. In the late Cenozoic, high rates of trench sedimentation led to the growth of an accretionary complex that underthrust forearc basement. Wedging and improved plate coupling elevated and laterally shifted blocks of outer forearc rocks, creating much of the structural framework of the regionally extensive Aleutian Terrace forearc basin. Changes in plate-boundary conditions that affected the ridge's volcanic activity and regional elevation importantly influenced basinal sedimentation. Changes of greatest significant were a major shift in convergence direction and rate about 42 Ma (reduced volcanism), ridge underthrusting by increasingly younger ocean crust in Oligocena and Miocene time (arc elevation), and the combination of more orthogonal underthrusting and the subduction of a dead spreading center 5-120 Ma (arc subsidence).

  7. G351.77-0.51: ridge formation caught in the act

    NASA Astrophysics Data System (ADS)

    Leurini, S.; Pillai, T.; Jones, P.; Csengeri, T.; König, C.; Stanke, T.; Wyrowski, F.; Menten, K. M.; Caselli, P.; Cunningham, M.; Testi, L.

    2016-05-01

    The initial steps of star formation are now believed to be tightly linked to the dynamical evolution of interstellar filaments. Mass accretion from large scales in the form of sub-filaments seems to play a key role for the formation of massive filaments with AV > 100 mag, a criterion satisfied by ridges. In this contribution, we discuss the very close-by ridge G351.77-0.51, identified as the closest dense filament in the ATLASGAL survey of the inner Galactic plane. G351.77-0.51 is actively forming massive stars in at least two positions and other dust clumps have the potential to form intermediate to high-mass young stellar objects. It also exhibits a remarkable large-scale network of filamentary structures seen in extinction at 8 μm which extend over the whole length of the ridge. The sub-filaments have the same velocity as the ridge. Their mass shows that mass-replenishment is probably still on-going in the source.

  8. Geochemistry of Axial seamount lavas: Magmatic relationship between the Cobb hotspot and the Juan de Fuca Ridge

    SciTech Connect

    Rhodes, J.M.; Morgan, C.; Lilas, R.A. )

    1990-08-10

    Axial seamount, located along the central portion of the Juan de Fuca Ridge axis and at the eastern end of the Cobb-Eickelberg seamount chain, is the current center of the Cobb hotspot. Lava chemistry and bathymetry indicate that Axial seamount is a discrete volcanic unit, with a more productive shallow magmatic plumbing system separate from the adjacent ridge segments. Despite this classic association of spreading center and hotspot volcanic activity, there is no evidence in the lavas for geochemical or isotopic enrichment typical of hotspot or mantle plume activity. The differences in composition between the Axial seamount lavas and the Juan de Fuca Ridge lavas are attributed to melting processes rather than to any fundamental differences in their mantle source compositions. The higher magma production rates, higher Sr, and lower silica saturation in the seamount lavas relative to the ridge lavas are thought to be a consequence of melt initiation at greater depths. The melting column producing the seamount lavas is thought to be initiated in the stability field of spinel peridotite, whereas the ridge lavas are produced from a melting column initiated at shallower levels, possibly within or close to the stability field of plagioclase peridotite. Implicit in this interpretation is the conclusion that the Juan de Fuca Ridge lavas, and by analogy most MORB, are generated at shallow mantle levels, mostly within the stability field of plagioclase peridotite. This interpretation also requires that for the upwelling mantle to intersect the solidus at different depths, the mantle supplying Axial seamount must be hotter than the rest of the Juan de Fuca Ridge. Axial seamount, therefore, reflects a thermal anomaly in the mantle, rather than a geochemically enriched ocean island basalt type mantle plume.

  9. Results from a 14-month hydroacoustic monitoring of the three mid-oceanic ridges in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Royer, J.-Y.; Dziak, R. P.; Delatre, M.; Chateau, R.; Brachet, C.; Haxel, J. H.; Matsumoto, H.; Goslin, J.; Brandon, V.; Bohnenstielh, D. R.

    2009-04-01

    From October 2006 to January 2008, an hydroacoustic experiment in the Indian Ocean was carried out by the CNRS/University of Brest and NOAA/Oregon State University to monitor the low-level seismic activity associated with the three contrasting spreading ridges and deforming zones in the Indian Ocean. Three autonomous hydrophones were moored in the SOFAR channel by R/V Marion Dufresne for 14 months in the Madagascar Basin, and northeast and southwest of Amsterdam Island, complementing the two permanent hydroacoustic stations of the Comprehensive nuclear-Test-Ban Treaty Organization (CTBTO) located near Diego Garcia Island and off Cape Leeuwin. The three instruments successfully collected 14 month of continuous acoustic records. Combined with the records from the permanent stations, the array detected 1780 acoustic events consisting mostly of earthquake generated T-waves, but also of iceberg tremors from Wilkes Land, Antarctica. Within the triangle defined by the temporary array, the three ridges exhibit contrasting seismicity patterns. Along the Southeast Indian ridge (SEIR), the 272 acoustic events (vs 24 events in the NEIC catalog) occur predominantly along the transform faults ; only one ridge segment (76˚E) displays a continuous activity for 10 months. Along the Central Indian Ridge (CIR), seismicity is distributed along fracture zones and ridge segments (269 events vs 45 NEIC events), with two clusters of events near the triple junction (24-25S) and south of Marie-Celeste FZ (18.5S). Along the Southwest Indian Ridge (SWIR), the 222 events (vs 31 NEIC events) are distributed along the ridge segments with a larger number of events west of Melville FZ and a cluster at 58E. The immediate vicinity of the Rodrigues triple junction shows periods of quiescence and of intense activity. Some large earthquakes (Mb>5) near the triple junction (SEIR and CIR) seem to be preceded by several acoustic events that may be precursors. Finally, off-ridge seismicity is mostly

  10. Effects of alveolar ridge preservation on delayed implant osseointegration

    PubMed Central

    Shao, Shan; Li, Bin; Xue, Hui-Min; Huang, Hai-Yun; Liu, Gang-Li

    2015-01-01

    To evaluate the effects of alveolar ridge preservation with Bio-Oss bone substitute (Geistlich Pharma) on delayed implant osseointegration. The 3rd and 4th left and right mandibular premolars were extracted from four adult healthy male and female dogs. For the experimental group, we randomly selected two extraction sockets in each dog to be filled with Bio-Oss bone substitute (Geistlich Pharma). The two remaining extraction sockets remained untreated and served as the control group. Three months after Bio-Oss placement, dental implants were inserted into the alveolar bone of the experimental group and the control group. The osteogenic activity of the bone around the implants was assessed by evaluating the histological morphology and by estimating histomorphometric parameters at 3 and 6 months after delayed implantation. At 3 months, Goldner’s trichrome staining analysis showed that the bone-implant contact rate and mineralised bone area around the implant were significantly higher in the experimental group (75.98% ± 8.97% and 69.52% ± 9.63%, respectively) than in the control group (56.13% ± 8.18% and 52.82% ± 7.25%, respectively; P < 0.05). However, at 6 months, the two groups showed no significant difference. Fluorescence microscopy analysis revealed that the average mineralisation apposition rate of the bone tissue around the dental implant in the experimental group at 3 and 6 months was 6.80 ± 0.43 μm and 8.38 ± 0.84 μm, respectively, which was significantly higher than the rate in the control group (P < 0.05). These data indicated that alveolar ridge preservation by using Bio-Oss placement can promote osseointegration of delayed implantation. This may be a promising option for clinical use. PMID:26379871

  11. Development of Leaky Wave Antennas for Layered Ridge Dielectric Waveguide

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Katehi, Linda P. B.

    1993-01-01

    The millimeter wave, especially above 100 GHz, and the submillimeter wave frequency spectrum offers the possibility for narrow-beam, high-resolution antennas which are critical for high definition radars required for space debris tracking, airport ground avoidance radars, and missile tracking. In addition, the frequency which most atmospheric constituents may be detected lie in this part of the frequency spectrum. Therefore, the development of electronic components for millimeter/submillimeter wave passive sensors is required for environmental monitoring of the Earth's atmosphere. Typical microwave transmission lines such as microstrip and coplanar waveguide rely on two or more electrical conductors to concentrate and guide the electromagnetic energy. Unfortunately, the surface resistance of the conductors increases as the square root of frequency. In addition, the circuit dimensions must be decreased with increasing frequency to maintain a single mode transmission line which further increases the conductor loss. An alternative family of transmission lines are formed from two or more insulating materials and rely on the differences in the permittivities between the two materials to guide the wave. No metal conductors are required although some dielectric waveguides do utilize a metallic ground plane to facilitate the interconnections of active electrical elements or to reduce the transmission line size. Examples of such transmission lines are image guides, insulated image guides, trapped image guides, ridge guide, and layered ridge dielectric waveguide (LRDW). Although most dielectric waveguides have dimensions on the order of lambda to provide sufficient field confinement, the LRDW has been shown to provide good field confinement for electrically small lines. This offers an advantage in circuit integration. It has been shown that a periodic array of metallic strips placed either along or on top of a dielectric waveguide forms an effective radiator. This antenna is

  12. Oak Ridge Reservation Public Warning Siren System Annual Test Report

    SciTech Connect

    R. F. Gee

    2000-10-01

    The full operational test of the Oak Ridge Reservation (ORR) Public Warning Siren System (PWSS) was successfully conducted on September 27, 2000. The annual test is a full-scale sounding of the individual siren systems around each of the three Department of Energy (DOE) sites in Oak Ridge, Tennessee. The purpose of the annual test is to demonstrate and validate the siren systems' ability to alert personnel outdoors in the Immediate Notification Zones (INZ) (approximately two miles) around each site. The success of this test is based on two critical functions of the siren system. The first function is system operability. The system is considered operable if 90% of the sirens are operational. System diagnostics and direct field observations were used to validate the operability of the siren systems. Based on the diagnostic results and field observations, greater than 90% of the sirens were considered operational. The second function is system audibility. The system is considered audible if the siren could be heard in the immediate notification zones around each of the three sites. Direct field observations, along with sound level measurements, were used to validate the audibility of the siren system. Based on the direct field observations and sound level measurements, the siren system was considered audible. The combination of field observations, system diagnostic status reports, and sound level measurements provided a high level of confidence that the system met and would meet operational requirements upon demand. As part of the overall system test, the Tennessee Emergency Management Agency (TEMA) activated the Emergency Alerting System (EAS), which utilized area radio stations to make announcements regarding the test and to remind residents of what to do in the event of an actual emergency.

  13. High Resolution Mosaic of Ridges, Plains, and Mountains on Europa

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This mosaic shows some of the highest resolution images obtained by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during its eleventh orbit around Jupiter. North is to the top of the image. The sun illuminates the scene from the left, showing hundreds of ridges that cut across each other, indicating multiple episodes of ridge formation either by volcanic or tectonic activity within the ice. Also visible in the image are numerous isolated mountains or 'massifs'. The highest of these, located in the upper right corner and lower center of the mosaic, are approximately 500 meters (1,640 feet) high. Irregularly shaped areas where the ice surface appears to be lower than the surrounding plains (e.g., in the left-center and lower left corner of the mosaic) may be related to the 'chaos' areas of iceberg-like features seen in earlier SSI images of Europa.

    The mosaic, centered at 35.4 degrees north latitude and 86.8 degrees west longitude, covers an area of 108 kilometers by 90 kilometers (66 miles by 55 miles). The smallest distinguishable features in the image are about 68 meters (223 feet) across. These images were obtained on November 6, 1997, when the Galileo spacecraft was approximately 3,250 kilometers (1,983 miles) from Europa.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of California Institute of Technology.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  14. Intraplate compressional deformation in West-Congo and the Congo basin: related to ridge-puch from the South Atlantic spreading ridge?

    NASA Astrophysics Data System (ADS)

    Delvaux, Damien; Everaerts, Michel; Kongota Isasi, Elvis; Ganza Bamulezi, Gloire

    2016-04-01

    After the break-up and separation of South America from Africa and the initiation of the South-Atlantic mid-oceanic ridge in the Albian, at about 120 Ma, ridge-push forces started to build-up in the oceanic lithosphere and were transmitted to the adjacent continental plates. This is particularly well expressed in the passive margin and continental interior of Central Africa. According to the relations of Wiens and Stein (1985) between ridge-push forces and basal drag in function of the lithospheric age of oceanic plates, the deviatoric stress reaches a compressional maximum between 50 and 100, Ma after the initiation of the spreading ridge, so broadly corresponding to the Paleocene in this case (~70-20 Ma). Earthquake focal mechanism data show that the West-Congo margin and a large part of the Congo basin are still currently under compressional stresses with an horizontal compression parallel to the direction of the active transform fracture zones. We studied the fracture network along the Congo River in Kinshasa and Brazzaville which affect Cambrian sandstones and probably also the late Cretaceous-Paleocene sediments. Their brittle tectonic evolution is compatible with the buildup of ridge-push forces related to the South-Atlantic opening. Further inland, low-angle reverse faults are found affecting Jurassic to Middle Cretaceous cores from the Samba borehole in the Congo basin and strike-slip movements are recorded as a second brittle phase in the Permian cores of the Dekese well, at the southern margin of the Congo basin. An analysis of the topography and river network of the Congo basin show the development of low-amplitude (50-100 m) long wavelengths (100-300 km) undulations that can be interpreted as lithospheric buckling in response to the compressional intraplate stress field generated by the Mid-Atlantic ridge-push. Wiens, D.A., Stein, S., 1985. Implications of oceanic intraplate seismicity for plate stresses, driving forces and theology. Tectonophysics

  15. The RAMESSES experiment-V. Crustal accretion at axial volcanic ridge segments-a gravity study at 57°45'N on the slow spreading Reykjanes Ridge

    NASA Astrophysics Data System (ADS)

    Peirce, Christine; Navin, Debbie A.

    2002-04-01

    Presented in this paper are the results of a two-stage analysis of gravity data acquired during a multidisciplinary geophysical survey of a magmatically active axial volcanic ridge (AVR) segment located at 57°45'N on the Reykjanes Ridge, part of the slow spreading Mid-Atlantic Ridge south of Iceland. Modelling of the free-air anomaly in 2-D shows that, across-axis, the observed anomaly results largely from density and layer thickness variation in the mid-lower crust. Although seismic control on crustal thickness along-axis is limited, modelling also suggests that both crustal density and thickness also vary towards AVR tips. Using the 2-D modelling results as crustal reference, the residual mantle Bouguer anomaly (RMBA) is calculated to assess whether magma-related density anomalies are present in the mantle and to investigate the structure of, and relationship between, adjacent AVRs along-axis. RMBA lows are associated with both an along-ridge trend encompassing a number of adjacent AVRs and with individual, more topographically robust AVRs. Modelling of the RMBA low associated with the 57°45'N AVR further suggests that along-axis density variation is confined to the central region of this AVR and that the anomaly can largely be accounted for by density variation within Layer 3 and a degree of crustal thinning towards AVR tips. The nature of the along-axis variation in crustal density further suggests that it may result from repeated phases of magma supply to the crustal system from the mantle. Within the resolution of the RMBA, modelling does not confirm or preclude the presence of a subcrustal density anomaly associated with retention of a small percentage of melt in the mantle. However, a melt-free model for at least the top 40 km of the mantle is preferred as this is consistent with the results of modelling a coincident magnetotelluric data set. The ridge-trend characteristics of the RMBA also suggest that magma delivery may take place along this trend, and

  16. Two contra-rotating eddies of the Mozambique Ridge Current

    NASA Astrophysics Data System (ADS)

    Gründlingh, Marten L.

    1989-01-01

    The combined existence of a cyclonic and anticyclonic eddy pair on the Mozambique Ridge tends to confirm the hypothesis that they are created by a westward-flowing Mozambique Ridge Current. The eddies are mutually comparable in size but smaller than cyclonic eddies previously observed in the region.

  17. Numerical Simulations of Conditionally Unstable Flows over a Mountain Ridge

    NASA Astrophysics Data System (ADS)

    Rotunno, R.

    2009-09-01

    This presentation describes numerical simulations of conditionally unstable flows impinging on an idealized mesoscale mountain ridge. These idealized simulations, which were performed with an explicitly resolving cloud model, allow the investigation of the solution precipitation characteristics as a function of the prescribed environment. The numerical solutions were first carried out for different uniform-wind profiles impinging on a bell-shaped ridge 2000 m high. In the experiments with weaker environmental wind speeds (2.5 m/s), the cold-air outflow, caused by the evaporative cooling of rain from precipitating convective cells, is the main mechanism for cell redevelopment and movement; this outflow produces new convective cells near the head of the up- and down-stream density currents, which rapidly propagate far from the ridge, so that no rainfall is produced close to the ridge at later times. For larger wind speeds (10, 20 m/s), there is less time for upwind, evaporation-induced, cold-pool formation before air parcels reach the ridge top and descend downwind and so the (statistically) steady rainfall tends to be concentrated near the ridge top. Further experiments with different ridge heights and half-widths were carried out in order to analyze their effect on the distribution and intensity of precipitation. Dimensional analysis reveals that the maximum (nondimensional) rainfall rate mainly depends on the ratio of mountain height to the level of free convection, the ridge aspect ratio and on a parameter that measures the ratio of advective to convective time scale.

  18. 27. OPEN DITCH ON SHAKE RIDGE ROAD ACROSS FROM THE ...

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

    27. OPEN DITCH ON SHAKE RIDGE ROAD ACROSS FROM THE AMADOR WATER AGENCY. DITCH LEADS TO PENSTOCK GIVING 500' HEAD OF WATER TO KNIGHT FOUNDRY. VIEW IS TOWARD NORTHWEST KNIGHT FOUNDRY IS AT THE BOTTOM OF THE HILL IN THE BACKGROUND BEYOND THE RIDGE. - Knight Foundry, 13 Eureka Street, Sutter Creek, Amador County, CA

  19. Validity Shrinkage in Ridge Regression: A Simulation Study.

    ERIC Educational Resources Information Center

    Faden, Vivian; Bobko, Philip

    1982-01-01

    Ridge regression offers advantages over ordinary least squares estimation when a validity shrinkage criterion is considered. Comparisons of cross-validated multiple correlations indicate that ridge estimation is superior when the predictors are multicollinear, the number of predictors is large relative to sample size, and the population multiple…

  20. 247. Axial Parkway alignment along ridge top. Note the open ...

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

    247. Axial Parkway alignment along ridge top. Note the open vistas to either side of the roadway. These are maintained through vegetation management. The wood guide rail is a primary safety feature. View is to the northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  1. Oak Ridge Reservation Annual Site environmental report summary for 1994

    SciTech Connect

    1995-09-01

    This document presents a summary of the information collected for the Oak Ridge Reservation 1994 site environmental report. Topics discussed include: Oak Ridge Reservation mission; ecology; environmental laws; community participation; environmental restoration; waste management; radiation effects; chemical effects; risk to public; environmental monitoring; and radionuclide migration.

  2. Mantle anisotropy beneath the Earth's mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Nowacki, Andy; Kendall, J.-Michael; Wookey, James

    2012-02-01

    Observations of seismic anisotropy at oceanic spreading centres offer insights into mid-ocean ridge processes and the formation of new plates. Here, remote observations of seismic anisotropy beneath mid-ocean ridges are made using measurements of source-side shear wave splitting. Over 100 high-quality measurements are made using earthquakes that occur near mid-ocean ridges and transform faults, but are observed at teleseismic distances. In general, for off-axis ridge events, the polarisation of fast shear waves, ϕ″, is approximately parallel to the spreading direction. Nearer the ridge (<~50 km), ϕ″ becomes more scattered and is often ridge-parallel. Delay times, δt, tend to increase from < 1 s near the ridge axis to ˜ 3 s further away. Slow-spreading regions (Gakkel and Southwest Indian Ridges) show smaller amounts of splitting than faster spreading centres. At transform zones, the pattern is more complex. Coverage beneath the East Pacific Rise is especially good, and we observe a systematic increase in delay times in S wave splitting measurements compared to previous SKS splitting observations made at ocean-bottom seismometers. One compatible explanation is the presence of horizontally-aligned, connected layers of melt at depth; this is also compatible with other observations of the 'LAB' discontinuity and surface-wave derived measurements of radial anisotropy.

  3. Ridge Regression: A Regression Procedure for Analyzing Correlated Independent Variables.

    ERIC Educational Resources Information Center

    Rakow, Ernest A.

    Ridge regression is presented as an analytic technique to be used when predictor variables in a multiple linear regression situation are highly correlated, a situation which may result in unstable regression coefficients and difficulties in interpretation. Ridge regression avoids the problem of selection of variables that may occur in stepwise…

  4. 13. Whetstone Ridge. View of the restaurant and gift shop. ...

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

    13. Whetstone Ridge. View of the restaurant and gift shop. It's board-and-batten construction with a long integral shed porch across the front, a jerkinhead roof and stone chimney are a reflection of the Appalachian Culture the parkway endeavors to interpret. The view is toward the southwest. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  5. Site characterization of the West Chestnut Ridge site

    SciTech Connect

    Ketelle, R H; Huff, D D

    1984-09-01

    This report summarizes the results of investigations performed to date on the West Chestnut Ridge Site, on the Department of Energy (DOE) Oak Ridge Reservation. The investigations performed include geomorphic observations, areal geologic mapping, surficial soil mapping, subsurface investigations, soil geochemical and mineralogical analyses, geohydrologic testing, groundwater fluctuation monitoring, and surface water discharge and precipitation monitoring. 33 references, 32 figures, 24 tables.

  6. Dielectrophoresis device and method having insulating ridges for manipulating particles

    DOEpatents

    Cummings, Eric B.; Fiechtner, Gregory J.

    2008-03-25

    Embodiments of the present invention provide methods and devices for manipulating particles using dielectrophoresis. Insulating ridges and valleys are used to generate a spatially non-uniform electrical field. Particles may be concentrated, separated, or captured during bulk fluid flow in a channel having insulating ridges and valleys.

  7. 1. AERIAL VIEW, LOOKING SOUTHWEST, ALONG THE RIDGE WITH RESIDENTIAL ...

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

    1. AERIAL VIEW, LOOKING SOUTHWEST, ALONG THE RIDGE WITH RESIDENTIAL DISTRICTS EXTENDING EAST TO THE RADIO TOWERS AT U.S. 31 (TOP RIGHT), SHADES VALLEY (TO LEFT OF RIDGE), AND JONES VALLEY AND CITY OF BIRMINGHAM (TO RIGHT BUT NOT PICTURED) - Red Mountain Suburbs, Crest of Red Mountain, Birmingham, Jefferson County, AL

  8. Oblique view of Bonita Ridge Access Road Retaining Wall, showing ...

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

    Oblique view of Bonita Ridge Access Road Retaining Wall, showing southernmost portion of intact wall and portion of concrete drainage ditch from Signal Corps Radar 296 Station 5 Transmitter Building foundation above, camera facing west-north - Fort Barry, Bonita Ridge Access Road, Retaining Wall, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  9. Vesicularity of basalt erupted at Reykjanes Ridge crest

    USGS Publications Warehouse

    Duffield, W.A.

    1978-01-01

    Average vesicularity of basalt drilled at three sites on the west flank of the Reykjanes Ridge increases with decreasing age. This change apparently records concomitant decrease in water depth at the ridge crest where the basalt was erupted and suggests substantial upward growth of the crest during the past 35 Myr. ?? 1978 Nature Publishing Group.

  10. Physiographic constraints on the origin of lunar wrinkle ridges

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Franklin, B. J.

    1987-01-01

    Wrinkle ridges are linear asymmetric topographic highs with considerable morphologic complexity that are commonly found on the lunar maria and the smooth plains of Mars and Mercury. The origin of planetary wrinkle ridges has been a much argued and debated topic. Early ideas suggested that wrinkle ridges resulted from volcanic intrusion and extrusion of high viscosity lavas; these early ideas were countered with suggestions that wrinkle ridges formed from tectonic processes involving folding and faulting. Combined volcanic and tectonic mechanisms have also been suggested. The identification and analysis of a number of morphologically similar structures on the earth has helped in the recent interpretation of wrinkle ridges as thrust faults that deform surface rocks. Nevertheless, there remains the uncertainty of the dominant role of thrusting versus folding in the formation of planetary wrinkle ridges. Presented is a detailed physiographic analysis of lunar wrinkle ridges in an effort to help distinguish the dominant deformation mechanism. Results agree with the findings of the earth analog study and support the hypothesis that wrinkle ridges form from thrust faults that deform surface rocks.

  11. 36 CFR 7.34 - Blue Ridge Parkway.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Blue Ridge Parkway. 7.34 Section 7.34 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.34 Blue Ridge Parkway. (a) Snowmobiles. After consideration of any special situations,...

  12. 36 CFR 7.34 - Blue Ridge Parkway.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Blue Ridge Parkway. 7.34 Section 7.34 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.34 Blue Ridge Parkway. (a) Snowmobiles. After...

  13. FY 1995 remedial investigation work plan for Waste Area Grouping 2 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Watkins, D.R.; Herbes, S.E.

    1994-09-01

    Field activities to support the remedial investigation (RI) of Waste Area Grouping (WAG) 2 at Oak Ridge National Laboratory (ORNL) include characterization of the nature and extent of contamination in WAG 2, specifically to support risk-based remediation decisions. WAG 2 is the major drainage system downgradient of other WAGs containing significant sources of contamination at ORNL. The RI of WAG 2 is developed in three phases: Phase 1, initial scoping characterization to determine the need for early action; Phase 2, interim activities during remediation of upgradient WAGs to evaluate potential changes in the contamination status of WAG 2 that would necessitate reevaluation of the need for early action; and Phase 3, completion of the RI process following remediation of upslope WAGs. Specifically, Phase 2 activities are required to track key areas to determine if changes have occurred in WAG 2 that would require (1) interim remedial action to protect human health and the environment or (2) changes in remedial action plans and schedules for WAG2 because of changing contaminant release patterns in upslope WAGs or because of the effects of interim remedial or removal actions in other WAGs. This report defines activities to be conducted in FY 1995 for completion of the Phase 1 RI and initiation of limited Phase 2 field work.

  14. RCRA Facility investigation report for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1991-09-01

    This report provides a detailed summary of the activities carried out to sample groundwater at Waste Area Grouping (WAG) 6. The analytical results for samples collected during Phase 1, Activity 2 of the WAG 6 Resource Conservation and Recovery Act Facility Investigation (RFI) are also presented. In addition, analytical results for Phase 1, activity sampling events for which data were not previously reported are included in this TM. A summary of the groundwater sampling activities of WAG 6, to date, are given in the Introduction. The Methodology section describes the sampling procedures and analytical parameters. Six attachments are included. Attachments 1 and 2 provide analytical results for selected RFI groundwater samples and ORNL sampling event. Attachment 3 provides a summary of the contaminants detected in each well sampled for all sampling events conducted at WAG 6. Bechtel National Inc. (BNI)/IT Corporation Contract Laboratory (IT) RFI analytical methods and detection limits are given in Attachment 4. Attachment 5 provides the Oak Ridge National Laboratory (ORNL)/Analytical Chemistry Division (ACD) analytical methods and detection limits and Resource Conservation and Recovery Act (RCRA) quarterly compliance monitoring (1988--1989). Attachment 6 provides ORNL/ACD groundwater analytical methods and detection limits (for the 1990 RCRA semi-annual compliance monitoring).

  15. Evidence for melt channelization in Galapagos plume-ridge interaction

    NASA Astrophysics Data System (ADS)

    Mittal, T.; Richards, M. A.

    2015-12-01

    Many present-day hot spots are located within ~ 1000 km of a mid-ocean ridge, either currently or in the geologic past, leading to frequent interaction between these two magmatic regimes. The consequent plume-ridge interactions provide a unique opportunity to test models for asthenosphere-lithosphere dynamics, with the plume acting as a tracer fluid in the problem, and excess magmatism reflecting otherwise unsampled sub-surface phenomena. Galapagos is an off-ridge hotspot with the mantle plume located ~150-250 km south of the plate boundary. Plume-ridge interaction in Galapagos is expressed by the formation of volcanic lineaments of islands and seamounts - e.g., the Wolf-Darwin lineament (WDL) - providing a direct probe of the plume-ridge interaction process, especially in regards to geochemical data. Although several models have been proposed to explain plume-ridge interaction in Galapagos, none adequately explain the observed characteristics, especially the WDL. In particular, predicted lithospheric fault orientations and melt density considerations appear at odds with observations, suggesting that lithospheric extension is not the primary process for formation of these islands. Other off-ridge hotspots interacting with nearby spreading ridges, such as Reunion and Louisville, also exhibit volcanic lineaments linking the plume and the ridge. Thus these lineament-type features are a common outcome of plume-ridge interaction that are indicative of the underlying physics. We propose that the lineaments are surface expressions of narrow sub-lithospheric melt channels focused towards the spreading ridge. These channels should form naturally due to the reactive infiltration instability in a two-phase flow of magma and solid mantle as demonstrated in two-phase flow simulations (e.g., Katz & Weatherley 2012). For Galapagos, we show that melt channels can persist thermodynamically over sufficient length-scales to link the plume and nearby ridge segments. We also show that

  16. Sonographic measurement versus mapping for determination of residual ridge width.

    PubMed

    Traxler, M; Ulm, C; Solar, P; Lill, W

    1992-03-01

    To achieve long-term success of dental implants, evaluation of the dimensions of the resorbing alveolar process must be accurate because an implant should be surrounded by at least 1 mm of bone. Estimating the thickness of bone is more difficult because the mucosal contour can mask the actual dimension of the residual ridge. With ultrasound, it is possible to analyze and visualize the diameter of maxillary or mandibular residual ridges. Data obtained from ultrasound measurement of residual ridges were compared with the data from ridge mapping with the Wilson bone caliper and the Spoerlein caliper. The ultrasound measurement produced nearly the same data at all measurement points as ridge mapping. Ultrasound also provides exact information about the location of the mental foramen and the maxillary sinus. By using all three methods the initial stage of implant treatment can be planned. PMID:1507101

  17. Mare ridges and lava lakes. [Apollo 17 investigation

    NASA Technical Reports Server (NTRS)

    Hodges, C. A.

    1973-01-01

    The autointrusive hypothesis of the origin of several vagaries of prominent mare ridges is explained. Data are based on a comparison between the structure of a Hawaiian lava lake and the mare ridges. Resulting data suggest that these ridges may have formed as squeeze-ups and autointrusives in tension fractures over buried topography in the crust of luna lava lakes. Data also suggest that mare ridges may result from: (1) pressure ridges in flows, (2) compressional features resulting from subsidence of mare lava, (3) volcanic ring structures and extrusives, or loccoliths fed by lunar grid controlled dikes, (4) draped topography and fissure eruptives, (5) drag folds or tension-gash dikes caused by wrench faulting at depth, and (6) postmare thrust faults.

  18. Gunite and associated tanks dry well conductivity monitoring report, Oak Ridge National Laboratory, Oak Ridge, Tennessee, February 1998--December 1998

    SciTech Connect

    1999-04-01

    A waste removal program is being implemented for the Gunite and Associated Tanks Operable Unit at Oak Ridge National Laboratory, Oak Ridge, Tennessee. The waste is being removed by means of remotely operated, in-tank, confined sluicing equipment. During sluicing operations the dry wells adjacent to each of the tanks are instrumented so that potential releases can be detected by means external to the tank. The method of detection is by monitoring the electrical conductivity of the water in the dry well associated with each tank. This report documents the dry well conductivity monitoring data for the period from February 1998 through December 1998. The dry wells monitored during this period include DW-5, DW-6, DW-7, DW-8, DW-9 and DW-10. The conductivity of the water passing through Pump Station 1 (PS1) was also monitored. During this period the sluicing activities at Tank W-6 were initiated and successfully completed. In addition, flight mixers were used to remove wastes from Tank W-5, and sluicing operations were initiated on Tank W-7. Presented in this report are the dry well conductivity, rainfall, tank level, and other appropriate information relevant to the analysis and interpretation of the monitoring data for the reporting period. A thorough analysis of the monitoring results from the six dry wells in the STF and PS1 for the period between February 1998 and December 1998 indicates that no releases have occurred from the gunite tanks being monitored. Overall, the dry well conductivity monitoring continues to provide a robust and sensitive method for detecting potential releases from the gunite tanks and for monitoring seasonal and construction-related changes in the dry well and drain system.

  19. Postconstruction report for the mercury tanks interim action at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Voskuil, T.L.

    1993-09-01

    Three underground concrete settling tanks (tanks 2101-U, 2104-U, and 2100-U) at the Y-12 Plant on the Oak Ridge Reservation in Oak Ridge, Tennessee, contained contaminated sludges contributing mercury to the Upper East Fork Poplar Creek (UEFPC). These tanks were cleaned out as an interim action under the Comprehensive Environmental Response, Compensation, and Liability Act as part of the Reduction of Mercury in Plant Effluent subproject. Cleaning out these tanks prevented the sludge that had settled in the bottom from resuspending and carrying mercury into UEFPC. Tanks 2104-U and 2100-U were returned to service and will continue to receive effluent from buildings 9201-4 and 9201-5. Tank 2101-U had been abandoned and its effluent redirected to Tank 2100-U during previous activities. This interim action permanently sealed Tank 2101-U from the storm sewer system. Upon removal of materials and completion of cleanup, inspections determined that the project`s cleanup criteria had been met. The structural integrity of the tanks was also inspected, and minor cracks identified in tanks 2101-U and 2104-U were repaired. This project is considered to have been completed successfully because it met its performance objectives as addressed in the Interim Record of Decision and the work plan: to remove the waste from the three storage tanks; to ensure that the tanks were cleaned to the levels specified; to return tanks 2100-U and 2104-U to service; to isolate Tank 2101-U permanently; and to manage the wastes in an appropriate fashion.

  20. Oak Ridge Reservation environmental report for 1989

    SciTech Connect

    Jacobs, V.A.; Wilson, A.R.

    1990-10-01

    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1989. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1989 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Vol. 2. The tables in Vol. 2 are addressed in Vol. 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Vol. 1. 16 figs., 194 tabs.

  1. Pulsed reactor experiments at Oak Ridge

    SciTech Connect

    Mihalczo, J.T.

    1994-12-31

    This paper describes dynamic experiments for 3 pulsed reactors. 1st reactor was pulsed from some average power by rotating a partial Be reflector past an unreflected core face; the other 2 reactors were pulsed by rapid insertion of a fuel rod into the unmoderated and unreflected reactor at essentially zero neutron level with no significant neutron source present. The first reactor was a mockup of an EURATOM design (never constructed) of the proposed SORA Reactor, and the other two were the Health Physics Research Reactor and the Army Pulse Radiation Facility Reactor (APRFR). This paper describes the experiments performed in initial testing of these systems, including destructive tests of APRFR, to set operating limits for this type of reactor in pulsed operation. All the experiments described were performed at the Oak Ridge Critical Experiments Facility.

  2. Oak Ridge Reservation Environmental report for 1990

    SciTech Connect

    Wilson, A.R.

    1991-09-01

    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1990. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1990 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Vol. 2. The tables in Vol. 2 are addressed in Vol. 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Vol. 1.

  3. Melton Valley Storage Tanks Capacity Increase Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-04-01

    The US Department of Energy (DOE) proposes to construct and maintain additional storage capacity at Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee, for liquid low-level radioactive waste (LLLW). New capacity would be provided by a facility partitioned into six individual tank vaults containing one 100,000 gallon LLLW storage tank each. The storage tanks would be located within the existing Melton Valley Storage Tank (MVST) facility. This action would require the extension of a potable water line approximately one mile from the High Flux Isotope Reactor (HFIR) area to the proposed site to provide the necessary potable water for the facility including fire protection. Alternatives considered include no-action, cease generation, storage at other ORR storage facilities, source treatment, pretreatment, and storage at other DOE facilities.

  4. Soil and surficial geology guidebook to the Oak Ridge Reservation, Oak Ridge, Tennessee

    SciTech Connect

    Lee, S.Y.; Lietzke, D.A.; Ketelle, R.H.; Ammons, J.T.

    1988-06-01

    This soil and surficial geology guidebook was prepared primarily for the field trip of the Southern Regional Soil Survey Work Planning Conference to be held in Knoxville, but will be available for future field trips of other regional, national, and international conferences related to soil and geomorphic research. This guidebook is organized into: (1) introduction to be Oak Ridge area; (2) geologic and hydrologic setting: (3) soil, surficial geology, and geomorphic relations; and (4) sitelogs, including soil description and characterization data. Physical, chemical, mineralogical, and engineering characterization of soils described in this guidebook is in progress. This guidebook will be revised when the characterization project is completed. Soil survey and characterization studies were begun about 5 years ago to support the Nuclear and Chemical Waste programs at ORNL and at the Oak Ridge Y-12 Plant. 15 refs; 8 figs; 6 tabs.

  5. Oak Ridge Health Studies phase 1 report, Volume 1: Oak Ridge Phase 1 overview

    SciTech Connect

    Yarbrough, M.I.; Van Cleave, M.L.; Turri, P.; Daniel, J.

    1993-09-01

    In July 1991, the State of Tennessee initiated the Health Studies Agreement with the United States Department of Energy to carry out independent studies of possible adverse health effects in people living in the vicinity of the Oak Ridge Reservation. The health studies focus on those effects that could have resulted or could result from exposures to chemicals and radioactivity released at the Reservation since 1942. The major focus of the first phase was to complete a Dose Reconstruction Feasibility Study. This study was designed to find out if enough data exist about chemical and radionuclide releases from the Oak Ridge Reservation to conduct a second phase. The second phase will lead to estimates of the actual amounts or the ``doses`` of various contaminants received by people as a result of off-site releases. Once the doses of various contaminants have been estimated, scientists and physicians will be better able to evaluate whether adverse health effects could have resulted from the releases.

  6. Ridges swimming in a sea of dust

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The muted terrain of northern Acidalia Planitia testifies to the fact that the region is heavily mantled with dust. The most interesting features in this image are the small terraces located along the flanks of the ridges and the patterned ground seen at the base of the largest ridge (upper right). These features appear to be classic examples of periglacial landforms and may indicate the presence of shallow subsurface ice.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 54.9, Longitude 351 East (9 West). 19 meter/pixel resolution.

  7. New high-resolution topographic data and updated tectonic geomorphology at Wheeler Ridge, California

    NASA Astrophysics Data System (ADS)

    Kleber, E.; Arrowsmith, R.

    2014-12-01

    Wheeler Ridge is an eastward propagating and north-vergent fault-bend fold (10km axis, 330m relief) at the front of the Transverse Range thrust system, southern San Joaquin Valley, CA. The occurrence of wind and water gaps along tear faults as well as elevated, distinct geomorphic surfaces along the fold axis show that Wheeler Ridge is actively growing over the kyr-timescale. The soils, tectonic geomorphology, structural modeling, and slip rate estimations were research foci in the 1990's. Previous studies used total station surveys, contour maps, trenches (5m deep), RASCAL (RAster SCanning Airborne Lidar) scanning (~1pnt/1.54m, ~0.8 km2) on the forelimb, and aerial photographs to map distinct geomorphic surfaces & features, and generate topographic profiles perpendicular and parallel to the fault axis. In September 2014, a ~40 km2 area of high resolution (>4pnts/m2) light detection and ranging (lidar) data will be collected at Wheeler Ridge by the National Center for Airborne Laser Mapping (NCALM) via a graduate student Seed grant. The new topographic data will enable us to build on previous studies of meter scale topography on the 10km fold and refine the geometric characterization of identified landforms that have been used to infer uplift, east fault tip propagation, and fold geometry in the last 250 kyr. These features include 5 geomorphic surfaces, stream channel geometry, alluvial terraces on the forelimb as well as wind and water gaps. This initial work will refine the representation of these features with high resolution topography as well as apply additional morphometric techniques to the hillslopes and channels, examine the spatial variation of landforms with independently determined uplift rates, create an updated, detailed geomorphic map of the 10km fold axis of Wheeler Ridge, and use previous subsurface modeling and these new constraints to inform an updated structural model for the growth history of Wheeler Ridge.

  8. Evidence for the Evolution of Grain Properties in the NGC 2024 Star Forming Ridge

    NASA Technical Reports Server (NTRS)

    Chandler, C. J.; Carlstrom, J. E.; Richer, J. S.; Visser, A.; Padman, R.

    1996-01-01

    High-resolution images of the NGC 2024 molecular ridge in CS(2-1) and 3 mm continuum emission have been obtained using the Owens Valley millimeter array. The data are used to determine the temperature and dynamics of the ridge, and to ascertain the evolutionary state of the embedded protostars FIR2-7. Dust continuum emission is detected from all six FIR sources. The CS(2-1) follows the ridge closely, but does not always coincide with the FIR sources. Direct comparison of column density estimates derived from the CS and the dust emission in the ridge shows that for all FIR sources except FIR5 both methods are in agreement to within a factor of two, assuming a dust opacity k(sub 3 mm) = 0.01 cm(exp 2)/g. However, away from the FIR sources strong CS(1-0) emission is observed in several compact clumps which, with the above dust opacity, should have been detected in 3 mm dust continuum. The brightness temperature of the CS, approx. 40 K, rules out the possibility that the high line-to-continuum ratio is due to low gas temperatures; the discrepancy can be resolved if k(sub 3 mm) is a factor of 10 lower away from the FIR sources. A new high-resolution image of the 450-micron dust continuum emission obtained using the James Clerk Maxwell Telescope supports this hypothesis. These results suggest an evolution in the physical properties of the dust grains, possibly grain size, between quiescent regions in the ridge and the sites of active star formation.

  9. Seismicity of mid-oceanic ridges and its geodynamic implications: a review [review article

    NASA Astrophysics Data System (ADS)

    Rundquist, D. V.; Sobolev, P. O.

    2002-07-01

    The global system of mid-oceanic ridges (MOR) is one of the longest active seismic belts where most of the earthquake epicenters are located continuously within a narrow axial zone. We summarized the principal results of the studies in MOR seismicity and their implications for geodynamics. The studies of epicenter distribution along the ridges and of focal mechanisms make an important contribution to the development of plate tectonics. During recent decades, a great amount of information on MOR structure and sea-floor spreading has become available. Geological and geophysical observations revealed a partitioning of the ridge by numerous discontinuities of several orders, which is reflected in the seismicity. There is a clear difference in seismic regime between two kinds of first-order segments—transform faults and spreading centers. The first have seismic moment release one-two orders higher; their contribution into the total seismic budget of MOR increases with higher spreading rate. The relationships between the seismic moment release, fault length and spreading rate are quite different for transform and rift parts of MOR; this confirms the difference in the geometry of their respective earthquake source volumes. In both these cases, the principal factor controlling the ridge seismicity is the thermal structure of the lithosphere. Microseismic experiments using ocean bottom seismometers, hydrophones and sonobuoys have perceptibly reduced the cutoff magnitude of complete reporting and the location uncertainty. Large numbers of microearthquakes are usually recorded almost everywhere near the ridge axis, even during relatively short recording times. More detailed location of epicenters and focal depths acquired great significance in the studies of magmatism, hydrothermal circulation and fracturing on MOR. Some spatial relationships seem to emerge between epicenter distribution and the location of hydrothermal sulfide deposits along the MOR. Several hierarchical

  10. Ridge-parallel-shearing and localized vertical melt migration during spreading: A phenomenon underestimated so far?

    NASA Astrophysics Data System (ADS)

    Herwegh, Marco; Mercolli, Ivan; Linckens, Jolien; Muntener, Othmar

    2016-04-01

    At spreading ridges, melt generation in the asthenospheric mantle followed by melt extraction, ascend, reaction and crystallization is an important mechanism for the generation of new oceanic crust. In contrast to original concepts, assuming a continuous and steady melt supply, recent studies indicate that melt ascend preferentially occurs in spatially restricted areas that both vary in space and time heavily segmenting the ridges. Based on field investigations in the Semail ophiolite (Oman) we found a close interplay between ductile strike-slip shearing along a vertical ridge-parallel shear zone in mantle harzburgite and melt ascend in the center of the shear zone. Here, melt rise was episodic and started at stages of initial high temperature deformation (>1100°C) but persisted during spreading induced retrograde cooling to deformation temperatures of about 800°C. The locations of ductile deformation and melt ascend (dikes) are very localized and coincide. Moreover, old dikes are spread over wider domains in the shear zones, while young dikes are concentrated in the immediate shear zone center, i.e. in the parts of youngest ductile deformation. These observations suggest that stress concentration along already crystallized dikes, continuous ductile strain localization and lubrication by younger melts all contributed to shear zone focusing with progressive cooling. Hence initial mechanical anisotropies are repeatedly overprinted resulting in a complex 3D shear zone pattern with temporal and spatial hydraulic variations in melt activity. Extrapolated to the scale of the entire Oman ophiolite we suggest that the ductile shear zones separate major mantle diapirs. They therefore seem to represent important zones of heterogeneous thermo-mechanical strain accommodation between the cooling diapirs and might be more common along spreading ridges than recognized so far contributing to ridge-segmentation.

  11. Radar and photoclinometric studies of wrinkle ridges on Mars

    USGS Publications Warehouse

    Watters, T.R.; Robinson, M.S.

    1997-01-01

    Earth-based radar altimetry and image derived photoclinometric profiles were analyzed to examine both the long- and short-wavelength topography associated with wrinkle ridges on Mars. Photoclinometrically derived elevation data across wrinkle ridges were evaluated to determine the sensitivity of profiles to two empirical photoclinometric parameters, the horizontal digital number (HDN) and the scattered light value (SLV). The photoclinometric profiles are extremely sensitive to small variations in HDN. The sense of slope of a profile can be completely reversed over a range in HDN of as little as ?? 1. Comparably small variations in the SLV have relatively minor effects on the photoclinometrically derived elevations. The existence of elevation offsets from one side of the ridge to the other, reported in previous photoclinometric studies of martian wrinkles, were not confirmed through photoclinometry. In addition, no evidence of elevation offsets were found in Earth-based radar altimetry profiles across wrinkle ridges. In order to more accurately model wrinkle ridge topography, we controlled photoclinometrically derived elevations with long-wavelength topography obtained from the radar altimetry. The results of this study do not support kinematic models for the origin of planetary wrinkle ridges that involve deeply rooted thrust faults which separate crustal blocks at different elevations. A kinematic model involving buckling of shallow crustal layers into concentric folds that close, leading to the development of thrust faults, is consistent with wrinkle ridge morphology and terrestrial analogs. Recent geophysical studies of terrestrial analogs and the influence of shallow subsurface structures, particularly buried craters, on the localization of many wrinkle ridges on Mars suggest that thrust faults associated with the ridges are confined to the ridged plains material and do not extend into the lithosphere. Copyright 1997 by the American Geophysical Union.

  12. Geological mapping of the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Lemiszki, P.J.

    1994-01-01

    The Oak Ridge K-25 Site (formerly known as the Oak Ridge Gaseous Diffusion Plant) is located in the southern Appalachian Valley and Ridge province of east Tennessee and overlies an area of folded and faulted Cambrian through Ordovician sedimentary rocks in the footwall of the Whiteoak Mountain fault. Environmental restoration plans for the area require that the geology of the site be well understood because various aspects of the groundwater system are directly influenced by stratigraphic and structural characteristics of the bedrock. This study involved mapping the bedrock geology of an 18-square mile area in and around the plant site. Field mapping focused on: (1) checking the accuracy of previously mapped stratigraphic and fault contacts, (2) dividing the bedrock into distinct stratigraphic units based on field criteria, (3) determining the geometry of map-scale folds and faults, and (4) documenting various aspects of the local fracture system. Besides accomplishing all of the above tasks, results from this study have led to a number of new hypotheses regarding various aspects of the site geology. First, faulting and folding within carbonates of the Chickamauga Supergroup in the plant area has repeated certain rock units, which requires that there be a thrust fault in the subsurface below them. This thrust fault may project to the surface with the Carters Limestone. Second, thrust slices of the Rome Formation that overlie the Chickamauga carbonates may be extremely thin and have a limited aerial extent. Third, part of the Knox Group on McKinney Ridge is folded into an anticline. Evaluating the above hypotheses will require information about the subsurface that can only be acquired through drilling and surface geophysical surveys. The geologic map produced from this study can be used to evaluate the location of coreholes that will more effectively intersect a combination of stratigraphic, structural, and hydrologic targets.

  13. Tiger team assessment of the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    none,

    1990-02-01

    This document contains findings identified during the Tiger Team Compliance Assessment of the Department of Energy's (DOE's) Y-12 Plant in Oak Ridge, Tennessee. The Y-12 Plant Tiger Team Compliance Assessment is comprehensive in scope. It covers the Environmental, Safety, and Health (including Occupational Safety and Health Administration (OSHA) compliance), and Management areas and determines the plant's compliance with applicable federal (including DOE), state, and local regulations and requirements. 4 figs., 12 tabs.

  14. Site descriptions of environmental restoration units at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Kuhaida, A.J. Jr.; Parker, A.F.

    1997-02-01

    This report provides summary information on Oak Ridge National Laboratory (ORNL) Environmental Restoration (ER) sites as listed in the Oak Ridge Reservation Federal Facility Agreement (FFA), dated January 1, 1992, Appendix C. The Oak Ridge National Laboratory was built in 1943 as part of the World War II Manhattan Project. The original mission of ORNL was to produce and chemically separate the first gram-quantities of plutonium as part of the national effort to produce the atomic bomb. The current mission of ORNL is to provide applied research and development in support of the U.S. Department of Energy (DOE) programs in nuclear fusion and fission, energy conservation, fossil fuels, and other energy technologies and to perform basic scientific research in selected areas of the physical, life, and environmental sciences. ER is also tasked with clean up or mitigation of environmental impacts resulting from past waste management practices on portions of the approximately 37,000 acres within the Oak Ridge Reservation (ORR). Other installations located within the ORR are the Gaseous Diffusion Plant (K-25) and the Y-12 plant. The remedial action strategy currently integrates state and federal regulations for efficient compliance and approaches for both investigations and remediation efforts on a Waste Area Grouping (WAG) basis. As defined in the ORR FFA Quarterly Report July - September 1995, a WAG is a grouping of potentially contaminated sites based on drainage area and similar waste characteristics. These contaminated sites are further divided into four categories based on existing information concerning whether the data are generated for scoping or remedial investigation (RI) purposes. These areas are as follows: (1) Operable Units (OU); (2) Characterization Areas (CA); (3) Remedial Site Evaluation (RSE) Areas; and (4) Removal Site Evaluation (RmSE) Areas.

  15. First hydrothermal discoveries on the Australian-Antarctic Ridge: Discharge sites, plume chemistry, and vent organisms

    NASA Astrophysics Data System (ADS)

    Hahm, Doshik; Baker, Edward T.; Siek Rhee, Tae; Won, Yong-Jin; Resing, Joseph A.; Lupton, John E.; Lee, Won-Kyung; Kim, Minjeong; Park, Sung-Hyun

    2015-09-01

    The Australian-Antarctic Ridge (AAR) is one of the largest unexplored regions of the global mid-ocean ridge system. Here, we report a multiyear effort to locate and characterize hydrothermal activity on two first-order segments of the AAR: KR1 and KR2. To locate vent sites on each segment, we used profiles collected by Miniature Autonomous Plume Recorders on rock corers during R/V Araon cruises in March and December of 2011. Optical and oxidation-reduction-potential anomalies indicate multiple active sites on both segments. Seven profiles on KR2 found 3 sites, each separated by ˜25 km. Forty profiles on KR1 identified 17 sites, some within a few kilometer of each other. The spatial density of hydrothermal activity along KR1 and KR2 (plume incidence of 0.34) is consistent with the global trend for a spreading rate of ˜70 mm/yr. The densest area of hydrothermal activity, named "Mujin," occurred along the 20 km-long inflated section near the segment center of KR1. Continuous plume surveys conducted in January-February of 2013 on R/V Araon found CH4/3He (1 - 15 × 106) and CH4/Mn (0.01-0.5) ratios in the plume samples, consistent with a basaltic-hosted system and typical of ridges with intermediate spreading rates. Additionally, some of the plume samples exhibited slightly higher ratios of H2/3He and Fe/Mn than others, suggesting that those plumes are supported by a younger hydrothermal system that may have experienced a recent eruption. The Mujin-field was populated by Kiwa crabs and seven-armed Paulasterias starfish previously recorded on the East Scotia Ridge, raising the possibility of circum-Antarctic biogeographic connections of vent fauna.

  16. Microgravity survey of the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Kaufmann, R.D.

    1996-05-01

    Karst features are known to exist within the carbonate bedrock of the Oak Ridge K-25 Site and may play an important role in groundwater flow and contaminant migration. This report discusses the results of a microgravity survey of the Oak Ridge K-25 Site. The main objective of the survey is to identify areas containing bedrock cavities. Secondary objectives included correlating the observed gravity to the geology and to variations in overburden thickness. The analysis includes 11 profile lines that are oriented perpendicular to the geologic strike and major structures throughout the K-25 Site. The profile lines are modeled in an effort to relate gravity anomalies to karst features such as concentrations of mud-filled cavities. Regolith thickness and density data provided by boreholes constrain the models. Areally distributed points are added to the profile lines to produce a gravity contour map of the site. In addition, data from the K-901 area are combined with data from previous surveys to produce a high resolution map of that site. The K-25 Site is located in an area of folded and faulted sedimentary rocks within the Appalachian Valley and Ridge physiographic province. Paleozoic age rocks of the Rome Formation, Knox Group, and Chickamauga Supergroup underlie the K-25 Site and contain structures that include the Whiteoak Mountain Fault, the K-25 Fault, a syncline, and an anticline. The mapped locations of the rock units and complex structures are currently derived from outcrop and well log analysis.

  17. The RAMESSES experiment-II. Evidence for accumulated melt beneath a slow spreading ridge from wide-angle refraction and multichannel reflection seismic profiles

    NASA Astrophysics Data System (ADS)

    Navin, D. A.; Peirce, C.; Sinha, M. C.

    1998-12-01

    The RAMESSES study (Reykjanes Axial Melt Experiment: Structural Synthesis from Electromagnetics and Seismics) targeted an apparently magmatically active axial volcanic ridge (AVR), centred on 57°45'N at the Reykjanes Ridge, with the aim of investigating the processes of crustal accretion at a slow spreading mid-ocean ridge. As part of this multicomponent experiment, airgun and explosive wide-angle seismic data were recorded by 10 digital ocean-bottom seismometers (OBSs) along profiles oriented both across- and along-axis. Coincident normal-incidence seismic, bathymetry and underway gravity and magnetic data were also collected. Forward modelling of the seismic and gravity data has revealed layer thicknesses, velocities and densities similar to those observed elsewhere within the oceanic crust near mid-ocean ridges. At 57°45'N, the Reykjanes Ridge has a crustal thickness of approximately 7.5 km on-axis. However, the crust is modelled to decrease in thickness slightly off-axis (i.e. with age), which implies that full crustal thickness is achieved on-axis and that it is subsequently thinned, most likely, by off-axis extension. Modelling also indicates that the AVR is underlain by a thin (~100 m), narrow (~4 km) melt lens some 2.5 km beneath the seafloor, which overlies a broader zone of partial melt approximately 8 km in width. Thus the results of this study provide the first clear evidence for a crustal magma chamber beneath any slow spreading ridge. The size and depth of this magma chamber (the melt lens and underlying zone of partial melt) are similar to those observed beneath fast and intermediate spreading ridges, which implies that the processes of crustal accretion are similar at all spreading rates. Hence the lack of previous observations of magma chambers beneath slow spreading ridges is probably temporally related to the periods of magmatic activity being considerably shorter and more widely spaced in time than at fast and intermediate spreading ridges.

  18. Advanced Seismic Studies of the Endeavour Ridge: Understanding the Interplay among Magmatic, Hydrothermal, and Tectonic Processes at Mid-Ocean Ridges

    NASA Astrophysics Data System (ADS)

    Arnoux, G. M.; VanderBeek, B. P.; Morgan, J. V.; Hooft, E. E. E.; Toomey, D. R.; Wilcock, W. S. D.; Warner, M.

    2014-12-01

    At mid-ocean ridges magmatic, hydrothermal, and tectonic processes are linked. Understanding their interactions requires mapping magmatic systems and tectonic structures, as well as their relationship to hydrothermal circulation. Three-dimensional seismic images of the crust can be used to infer the size, shape, and location of magma reservoirs, in addition to the structure of the thermal boundary layer that connects magmatic and hydrothermal processes. Travel time tomography has often been used to study these processes, however, the spatial resolution of travel time tomography is limited. Three-dimensional full waveform inversion (FWI) is a state-of-the art seismic method developed for use in the oil industry to obtain high-resolution models of the velocity structure. The primary advantage of FWI is that it has the potential to resolve subsurface structures on the order of half the seismic wavelength—a significant improvement on conventional travel time tomography. Here, we apply anisotropic FWI to data collected on the Endeavour segment of the Juan de Fuca Ridge. Starting models for anisotropic P-wave velocity were obtained by travel time tomography [Weekly et al., 2014]. During FWI, the isotropic velocity model is updated and anisotropy is held constant. We have recovered low-velocity zones approximately 2-3 km beneath the ridge axis that likely correspond to a segmented magma-rich body and are in concert with those previously resolved using multi-channel seismic reflection methods. The segmented crustal magma body underlies all five known high-temperature hydrothermal vent fields along the Endeavour segment. A high-velocity zone, shallower than the observed low-velocity zones, underlies the southernmost hydrothermal vent field. This may be indicative of waning hydrothermal activity in which minerals are crystallizing beneath the vent field. Our FWI study of the Endeavour Ridge will provide the most detailed three-dimensional images of the crustal structure to

  19. Water mass exchanges between the Norwegian and Iceland seas over the Jan Mayen Ridge using in-situ current measurements

    NASA Astrophysics Data System (ADS)

    Mork, Kjell Arne; Drinkwater, Kenneth F.; Jónsson, Steingrímur; Valdimarsson, Héðinn; Ostrowski, Marek

    2014-11-01

    The Jan Mayen Ridge, with bottom depths of 1000 m and less, runs southwards from Jan Mayen and separates the warmer and saltier Atlantic Water in the Norwegian Sea from the colder and fresher Arctic water in the Iceland Sea. During the International Polar Year (IPY, 2007-2008), three current meter moorings were deployed with the purpose to investigate water mass exchanges between the Norwegian and Iceland seas over the Ridge and their forcing mechanisms. These are the first in-situ current measurements for this region. The results showed relatively weak currents on the Ridge that frequently shifted direction except near-bottom and at the western slope of the Ridge. All current measurements showed low eddy activity and tidal velocities (less than 0.05 ms- 1). Wind-forced near-inertial motion generated from transient atmospheric low pressure systems were observed in the mixed layer being strongest during autumn and winter when ocean velocities reached 0.7 ms- 1. Near surface currents on the Ridge are influenced by local winds on a time scale of 6 days and longer, but during the two-year deployment no pronounced seasonal variation was observed, mainly due to a lack of seasonality in the local winds. In a 2000 m deep channel that cuts the Ridge, there was pronounced seasonal