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Sample records for southern mid-atlantic ridge

  1. Nematocarcinus Milne Edwards, 1881 (Crustacea, Decapoda) from Southwestern Atlantic, including the Southern Mid-Atlantic Ridge area.

    Cardoso, Irene A; Burukovsky, Rudolf N

    2014-11-26

    The deep sea shrimp genus Nematocarcinus Milne Edwards, 1881 includes 47 species, ten of them have been recorded from the Atlantic Ocean. Herein, material sampled during three scientific projects (REVIZEE Central Fishery project; Campos Basin Deep Sea Environmental Project; Evaluation of Environmental Heterogeneity in the Campos Basin) made in the Southwestern Atlantic, off Brazil, is examined. In addition, material sampled from the South Mid Atlantic Ridge (MAR-ECO Project) was also examined. Four species are recorded for the first time to the southwestern Atlantic Ocean including Mid Atlantic Ridge area: Nematocarcinus faxoni Burukovsky, 2001; N. gracilipes Filhol, 1884; N. rotundus Crosnier & Forest, 1973 and N. tenuipes Spence-Bate, 1888.

  2. Tectonic environments and local geologic controls of potential hydrothermal fields along the Southern Mid-Atlantic Ridge (12-14°S)

    Li, Bing; Shi, Xuefa; Wang, Jixin; Yan, Quanshu; Liu, Chenguang; DY125-21 (Leg 3) Science Party; DY125-22 (Legs 2-5) Science Party; DY125-26 (Leg 3) Science Party

    2018-05-01

    Systematic hydrothermal exploration and multi-beam bathymetry mapping have been conducted along a 220-km-long section of the Southern Mid-Atlantic Ridge (SMAR) from 12°S (Bode Verde Fracture Zone) to 14°S (Cardno Fracture Zone), and previously reported deposits (Tao et al., 2011) are now being thoroughly investigated. Here, we present the characterization of three possible hydrothermal fields, a complete bathymetry data set of the ridge segment, gravity data, and the petrologic characteristics of collected rock samples. The magmatism characteristics, evolution of the ridge segment, and the local geological controls of the possible hydrothermal fields are then discussed. The studied segment can be divided into two segments by a Non-Transform Discontinuity (NTD). Our morphotectonic analysis shows significant along-axis heterogeneity in the surveyed segments: three distinctive cross-axis grabens were identified in the northern segment, and two were identified in the southern segment. Moreover, based on the gravity data (a relatively low spherical Bouguer anomaly) and petrologic data (low Mg# values and relatively low FeO and relatively high Al2O3 and CaO contents compared to nearby seafloor samples), a volcanic feature, the ZouYu seamount, on this segment is considered to be associated with strong magmatic activity, and the magmatic activity of the inside corner at the southern end of the segment has increased and decreased. The three possible hydrothermal fields occur in different local geological settings: a shallow magmatic seamount (ZouYu), an NTD (TaiJi), and an inside-corner high (CaiFan). These potential hydrothermal fields are significantly different from other fields in similar tectonic settings in terms of local geologic controls and products. The ZouYu field is primarily related to a newly formed cone, resulting in the production of sulfides, and differs from other fields on shallow magmatic seamounts. The TaiJi field is largely controlled by the tectonic

  3. Geochemical features of sulfides from the Deyin-1 hydrothermal field at the southern Mid-Atlantic Ridge near 15°S

    Wang, Shujie; Li, Huaiming; Zhai, Shikui; Yu, Zenghui; Cai, Zongwei

    2017-12-01

    In this study, geochemical compositions of elements in sulfide samples collected from the Deyin-1 hydrothermal field near the 15°S southern Mid-Atlantic Ridge (SMAR) were analyzed by the X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) to examine the enrichment regulations of ore-forming elements and hydrothermal mineralization. These sulfide precipitates can be classified macroscopically into three types: Fe-rich sulfide, Fe-Cu-rich sulfide and Fe-Zn-rich sulfide, and are characterized by the enrichment of base metal elements along with a sequence of Fe>Zn>Cu. Compared with sulfides from other hydrothermal fields on MAR, Zn concentrations of sulfides in the research area are significantly high, while Cu concentrations are relatively low. For all major, trace or rare-earth elements (REE), their concentrations and related characteristic parameters exhibit significant variations (up to one or two orders of magnitude), which indicates the sulfides from different hydrothermal vents or even a same station were formed at different stages of hydrothermal mineralization, and suggests the variations of chemical compositions of the hydrothermal fluid with respect to time. The hydrothermal temperatures of sulfides precipitation decreased gradually from station TVG10 (st.TVG10) to st.TVG12, and to st.TVG11, indicating that the precipitation of hydrothermal sulfides is subjected to conditions changed from high temperature to low temperature, and that the hydrothermal activity of study area was at the late stage of a general trend of evolution from strong to weak. The abnormally low concentrations of REE in sulfides and their similar chondrite-normalized REE patterns show that REEs in all sulfides were derived from a same source, but underwent different processes of migration or enrichment, or sulfides were formed at different stages of hydrothermal mineralization. The sulfides collected from the active hydrothermal vent were

  4. Equatorial segment of the mid-atlantic ridge

    NONE

    1997-12-31

    The Equatorial Segment of the Mid-Atlantic Ridge is a part of this mid-oceanic ridge limited by a cluster of fracture zones - Cape Verde, Marathon, Mercury, Vema, Doldrums, Vernadsky and Sierra Leone - in the North, and a similar cluster of fracture zones - St Paul, Romanche and Chain - in the South. During recent decades, following the publication of the 5. edition of the General Bathymetric Chart of the Oceans (GEBCO), there has been a great deal of geological-geophysical research and mapping of the World Ocean. The results have led to the development of a number of theories concerning the essential heterogeneity of the structure of the ocean floor and, in particular, the heterogeneity of the structure and segmentation of mid-oceanic ridges. Research on the nature of such segmentation is of great importance for an understanding of the processes of development of such ridges and oceanic basins as a whole. Chapter 20 is dedicated to the study of the atlantic ocean mantle by using (Th.U)Th, (Th/U)pb and K/Ti systematics 380 refs.

  5. Equatorial segment of the mid-atlantic ridge

    1996-01-01

    The Equatorial Segment of the Mid-Atlantic Ridge is a part of this mid-oceanic ridge limited by a cluster of fracture zones - Cape Verde, Marathon, Mercury, Vema, Doldrums, Vernadsky and Sierra Leone - in the North, and a similar cluster of fracture zones - St Paul, Romanche and Chain - in the South. During recent decades, following the publication of the 5. edition of the General Bathymetric Chart of the Oceans (GEBCO), there has been a great deal of geological-geophysical research and mapping of the World Ocean. The results have led to the development of a number of theories concerning the essential heterogeneity of the structure of the ocean floor and, in particular, the heterogeneity of the structure and segmentation of mid-oceanic ridges. Research on the nature of such segmentation is of great importance for an understanding of the processes of development of such ridges and oceanic basins as a whole. Chapter 20 is dedicated to the study of the atlantic ocean mantle by using (Th.U)Th, (Th/U)pb and K/Ti systematics

  6. Equatorial segment of the mid-atlantic ridge

    NONE

    1996-12-31

    The Equatorial Segment of the Mid-Atlantic Ridge is a part of this mid-oceanic ridge limited by a cluster of fracture zones - Cape Verde, Marathon, Mercury, Vema, Doldrums, Vernadsky and Sierra Leone - in the North, and a similar cluster of fracture zones - St Paul, Romanche and Chain - in the South. During recent decades, following the publication of the 5. edition of the General Bathymetric Chart of the Oceans (GEBCO), there has been a great deal of geological-geophysical research and mapping of the World Ocean. The results have led to the development of a number of theories concerning the essential heterogeneity of the structure of the ocean floor and, in particular, the heterogeneity of the structure and segmentation of mid-oceanic ridges. Research on the nature of such segmentation is of great importance for an understanding of the processes of development of such ridges and oceanic basins as a whole. Chapter 20 is dedicated to the study of the atlantic ocean mantle by using (Th.U)Th, (Th/U)pb and K/Ti systematics 380 refs.

  7. Mid-Atlantic Ridge Deepwater Biodiversity Exploration (HB0902, EK60)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives: With the overall goal of surveying and describing the biodiversity of the bathypelagic fauna near the Mid-Atlantic Ridge, a team of biological...

  8. Stratified flows and internal waves in the Vema Fracture Zone of the Mid Atlantic Ridge

    Makarenko, Nikolay; Morozov, Eugene; Tarakanov, Roman; Demidova, Tatiana; Frey, Dmitri; Grigorenko, Klim

    2017-04-01

    In this paper, we study stratified flows and internal waves in the Vema fracture zone of the Mid Atlantic Ridge. This fracture provides intense transportation of cold abyssal waters from the West Atlantic to the equatorial region of the East Atlantic [1]. The results of measurements [2,3] carried out in the cruises of RV Akademik Sergey Vavilov in 2014-2016 are presented. The structure of the near-bottom flow is studied experimentally on the basis of CTD- and LADCP profiling. Theoretical analysis involves mathematical formulation of stratified fluid flow which uses CTD-data obtained from field observation. Spectral properties and kinematic characteristics of internal waves are calculated and discussed. This work was supported by RFBR (grants No 15-01-03942, 16-35-50158). References [1] Morozov E., Demidov A., Tarakanov R. and Zenk W. Abyssal Channels in the Atlantic Ocean: Water Structure and Flows, Springer, Dordrecht, 2010. [2] Morozov E.G., Tarakanov R.Yu., and Makarenko N.I. Flows of Antarctic Bottom Water through fractures in the southern part of the North Mid Atlantic Ridge, Oceanology, 2015, 55, 796-800. [3] Grigorenko K.S., Makarenko N.I., Morozov E.G., Tarakanov R.Yu., and Frey D.I. Stratified flows and internal waves in the Central West Atlantic, J. Physics: Conf. Series, 2016, 722, 012011.

  9. Trophic Structure Over the Northern Mid-Atlantic Ridge: The Bathypelagic Zone Really Matters

    We present preliminary results and ongoing efforts to characterize the trophic structure and energy flow of the pelagic ecosystems of the northern Mid-Atlantic Ridge (MAR), from Iceland to the Azores. This study is one component of the international CoML field project MAR-ECO (ww...

  10. Genetic connectivity between north and south Mid-Atlantic Ridge chemosynthetic bivalves and their symbionts.

    Karina van der Heijden

    Full Text Available Transform faults are geological structures that interrupt the continuity of mid-ocean ridges and can act as dispersal barriers for hydrothermal vent organisms. In the equatorial Atlantic Ocean, it has been hypothesized that long transform faults impede gene flow between the northern and the southern Mid-Atlantic Ridge (MAR and disconnect a northern from a southern biogeographic province. To test if there is a barrier effect in the equatorial Atlantic, we examined phylogenetic relationships of chemosynthetic bivalves and their bacterial symbionts from the recently discovered southern MAR hydrothermal vents at 5°S and 9°S. We examined Bathymodiolus spp. mussels and Abyssogena southwardae clams using the mitochondrial cytochrome c oxidase subunit I (COI gene as a phylogenetic marker for the hosts and the bacterial 16S rRNA gene as a marker for the symbionts. Bathymodiolus spp. from the two southern sites were genetically divergent from the northern MAR species B. azoricus and B. puteoserpentis but all four host lineages form a monophyletic group indicating that they radiated after divergence from their northern Atlantic sister group, the B. boomerang species complex. This suggests dispersal of Bathymodiolus species from north to south across the equatorial belt. 16S rRNA genealogies of chemoautotrophic and methanotrophic symbionts of Bathymodiolus spp. were inconsistent and did not match the host COI genealogy indicating disconnected biogeography patterns. The vesicomyid clam Abyssogena southwardae from 5°S shared an identical COI haplotype with A. southwardae from the Logatchev vent field on the northern MAR and their symbionts shared identical 16S phylotypes, suggesting gene flow across the Equator. Our results indicate genetic connectivity between the northern and southern MAR and suggest that a strict dispersal barrier does not exist.

  11. Elastic and electrical properties and permeability of serpentinites from Atlantis Massif, Mid-Atlantic Ridge

    Falcon-Suarez, Ismael; Bayrakci, Gaye; Minshull, Tim A.; North, Laurence J.; Best, Angus I.; Rouméjon, Stéphane

    2017-11-01

    Serpentinized peridotites co-exist with mafic rocks in a variety of marine environments including subduction zones, continental rifts and mid-ocean ridges. Remote geophysical methods are crucial to distinguish between them and improve the understanding of the tectonic, magmatic and metamorphic history of the oceanic crust. But, serpentinite peridotites exhibit a wide range of physical properties that complicate such a distinction. We analysed the ultrasonic P- and S-wave velocities (Vp, Vs) and their respective attenuation (Qp-1, Qs-1), electrical resistivity and permeability of four serpentinized peridotite samples from the southern wall of the Atlantis Massif, Mid-Atlantic Ridge, collected during International Ocean Discovery Program Expedition 357. The measurements were taken over a range of loading-unloading stress paths (5-45 MPa), using ∼1.7 cm length, 5 cm diameter samples horizontally extracted from the original cores drilled on the seafloor. The measured parameters showed variable degrees of stress dependence, but followed similar trends. Vp, Vs, resistivity and permeability show good inter-correlations, while relationships that included Qp-1 and Qs-1 are less clear. Resistivity showed high contrast between highly serpentinized ultramafic matrix (>50 Ω m) and mechanically/geochemically altered (magmatic/hydrothermal-driven alteration) domains (serpentinization and the alteration state of the rock, contrasted by petrographic analysis. This study shows the potential of combining seismic techniques and controlled source electromagnetic surveys for understanding tectonomagmatic processes and fluid pathways in hydrothermal systems.

  12. Phytoplankton Assemblage Patterns in the Southern Mid-Atlantic Bight

    Makinen, Carla; Moisan, Tiffany A. (Editor)

    2012-01-01

    As part of the Wallops Coastal Oceans Observing Laboratory (Wa-COOL) Project, we sampled a time-series transect in the southern Mid-Atlantic Bight (MAB) biweekly. Our 2-year time-series data included physical parameters, nutrient concentrations, and chlorophyll a concentrations. A detailed phytoplankton assemblage structure was examined in the second year. During the 2-year study, chlorophyll a concentration (and ocean color satellite imagery) indicated that phytoplankton blooms occurred in January/February during mixing conditions and in early autumn under stratified conditions. The chlorophyll a concentrations ranged from 0.25 microgram 1(exp -1) to 15.49 microgram 1(exp -1) during the 2-year period. We were able to discriminate approximately 116 different species under phase contrast microscopy. Dominant phytoplankton included Skeletonema costatum, Rhizosolenia spp., and Pseudo-nitzschia pungens. In an attempt to determine phytoplankton species competition/succession within the assemblage, we calculated a Shannon Weaver diversity index for our diatom microscopy data. Diatom diversity was greatest during the winter and minimal during the spring. Diatom diversity was also greater at nearshore stations than at offshore stations. Individual genera appeared patchy, with surface and subsurface patches appearing abruptly and persisting for only 1-2 months at a time. The distribution of individual species differed significantly from bulk variables of the assemblage (chlorophyll a ) and total phytoplankton assemblage (cells), which indicates that phytoplankton species may be limited in growth in ways that differ from those of the total assemblage. Our study demonstrated a highly diverse phytoplankton assemblage throughout the year, with opportunistic species dominating during spring and fall in response to seasonal changes in temperature and nutrients in the southern MAB.

  13. Focused volcanism and growth of a slow spreading segment (Mid-Atlantic Ridge, 35°N)

    Rabain, Aline; Cannat, Mathilde; Escartín, Javier; Pouliquen, Gaud; Deplus, Christine; Rommevaux-Jestin, Céline

    2001-02-01

    Using off axis bathymetry, gravity and magnetic data, we studied the formation of a prominent seamount chain across segment OH1 (Mid-Atlantic Ridge, 35°N), and its relation to the past segmentation of the area. We also studied the size and shape of the seamounts to understand the processes leading to their formation. The chain is elongated in the spreading direction, and extends from the present day segment center to ˜6 Ma on both flanks. It coincides with a pronounced low in the residual mantle Bouguer gravity anomaly, suggesting thicker crust and thus more abundant magmatism than in surrounding areas. Magnetic anomalies are well defined over the seamount chain, consistent with formation on or near the axis. The seamounts within the chain are larger on average than those from other areas of the Mid-Atlantic Ridge, reflecting higher magma volumes and fluxes during eruptions. The distribution of seamounts suggests a focused magmatic source, located beneath the eastern side of the ridge axis, at a constant distance (˜45 km) from the Oceanographer transform fault. A V-shaped trend defines the southern end of OH1 and indicates that the segment propagated rapidly southwards, increasing in length from 50 to 90 km. The onset of propagation at ˜6 Ma coincided with the initiation of the volcanic chain, suggesting that magma supply at that time was focused at the end of the segment rather than at its center, as is typical for Mid-Atlantic Ridge segments. We propose that this unusual configuration is a consequence of the cold edge effect of the Oceanographer fracture zone. We also propose that enhanced and focused magmatism beneath the seamount chain may have caused the rapid southward propagation of OH1 over the past ˜6 Ma.

  14. Magnetic Anomalies over the Mid-Atlantic Ridge near 27{degrees}N.

    Phillips, J D

    1967-08-25

    Ten magnetic profiles across the mid-Atlantic ridge near 27 degrees N show trends that are parallel to the ridge axis and symmetrical about the ridge axis. The configuration of magnetic bodies that could account for the pattern supports the Vine and Matthews hypothesis for the origin of magnetic anomalies over oceanic ridges. A polarity-reversal time scale inferred from models for sea-floor spreading in the Pacific-Antarctic ridge and radiometrically dated reversals of the geomagnetic field indicates a spreading rate of 1.25 centimeters per year during the last 6 million years and a rate of 1.65 centimeters per year between 6 and 10 million years ago. A similar analysis of more limited data over the mid-Atlantic ridge near 22 degrees N also indicates a change in the spreading rate. Here a rate of 1.4 centimeters per year appears to have been in effect during the last 5 million years; between 5 and 9 million years ago, an increased rate of 1.7 centimeters per year is indicated. The time of occurrence and relative magnitude of these changes in the spreading rate, about 5 to 6 million years ago and 18 to 27 percent, respectively, accords with the spreading rate change implied for the Juan de Fuca ridge in the northeast Pacific.

  15. Mapping the mantle transition zone beneath the central Mid-Atlantic Ridge using Ps receiver functions.

    Agius, M. R.; Rychert, C.; Harmon, N.; Kendall, J. M.

    2017-12-01

    Determining the mechanisms taking place beneath ridges is important in order to understand how tectonic plates form and interact. Of particular interest is establishing the depth at which these processes originate. Anomalies such as higher temperature within the mantle transition zone may be inferred seismically if present. However, most ridges are found in remote locations beneath the oceans restricting seismologists to use far away land-based seismometers, which in turn limits the imaging resolution. In 2016, 39 broadband ocean-bottom seismometers were deployed across the Mid-Atlantic Ridge, along the Romanche and Chain fracture zones as part of the PI-LAB research project (Passive Imaging of the Lithosphere and Asthenosphere Boundary). The one-year long seismic data is now retrieved and analysed to image the mantle transition zone beneath the ridge. We determine P-to-s (Ps) receiver functions to illuminate the 410- and 660-km depth mantle discontinuities using the extended multitaper deconvolution. The data from ocean-bottom seismometers have tilt and compliance noise corrections and is filtered between 0.05-0.2 Hz to enhance the signal. 51 teleseismic earthquakes generated hundreds of good quality waveforms, which are then migrated to depth in 3-D. The topography at the d410 deepens towards the west of the Romanche and Chain fracture zone by 15 km, whereas the topography of d660 shallows beneath the ridge between the two zones. Transition zone thickness thins from 5 to 20 km. Thermal anomalies determined from temperature relationships with transition zone thickness and depth variations of the d410 and d660 suggests hotter temperatures of about 200 K. Overall, the result suggests mid-ocean ridges may have associated thermal signatures as deep as the transition zone.

  16. Biodiversity patterns, environmental drivers and indicator species on a high-temperature hydrothermal edifice, Mid-Atlantic Ridge

    Sarrazin, Jozée; Legendre, Pierre; de Busserolles, Fanny; Fabri, Marie-Claire; Guilini, Katja; Ivanenko, Viatcheslav N.; Morineaux, Marie; Vanreusel, Ann; Sarradin, Pierre-Marie

    2015-01-01

    Knowledge on quantitative faunal distribution patterns of hydrothermal communities in slow-spreading vent fields is particularly scarce, despite the importance of these ridges in the global mid-ocean system. This study assessed the composition, abundance and diversity of 12 benthic faunal assemblages from various locations on the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) and investigated the role of key environmental conditions (temperature, total dissolved iron (TdFe...

  17. Nuclear microprobe analysis of serpentine from the mid-Atlantic ridge

    Orberger, Beate; Metrich, Nicole; Mosbah, Michelle; Mevel, Catherine; Fouquet, Yves

    1999-01-01

    At mid-ocean ridges, ultramafic rocks are serpentinized by interaction with seawater-derived fluids. Elements, dissolved in large quantities in seawater, e.g., Na, K, Cl, Br, Ca and Sr, can be, in small amounts, incorporated as traces into the crystal structure of the various serpentine minerals (Mg 3 Si 2 O 5 (OH) 4 ). These trace elements can be used to track the composition of the reacting fluids and to constrain physico-chemical conditions. This paper represents the first application of particle-induced X- and γ-ray emission (PIXE/PIGE) analysis to serpentine using the nuclear microprobe at the Laboratoire Pierre Suee (CEA-CNRS). Three types of serpentine, belonging to two different serpentinization generations, have been analysed in samples collected from the Mid-Atlantic Ridge (14 deg. 45'N/45 deg. W) that exposes serpentinized peridotites on which the Logachev black smoker is placed. The trace elements Cl, F, S, Cu, Zn, Ca, K, Ni, Cr and Mn were detected from several tens to several thousands of ppm. Bromine, As and Sr are close to the detection limit of about 5 ppm. The trace element concentrations and interelement relationships in serpentines vary (a) with the serpentine type and (b) with the geographic location to the black smoker. Chlorine and in part S originated from seawater, whereas Cu, Zn, Ca, K, Ni, Cr and Fe and the major amount of S were mobilized from the unaltered host rock and partitioned between the serpentine and the aqueous solution

  18. Controls of Plume Dispersal at the Slow Spreading Mid-Atlantic Ridge

    Walter, M.; Mertens, C.; Koehler, J.; Sueltenfuss, J.; Rhein, M.; Keir, R. S.; Schmale, O.; Schneider v. Deimling, J.; German, C. R.; Yoerger, D. R.; Baker, E. T.

    2011-12-01

    The slow-spreading Mid-Atlantic Ridges hosts a multitude of different types of hydrothermal systems. Here, we compare the fluxes and the plume dispersal at three high temperature sites located in very diverse settings at comparable depths (~3000m): The recently discovered sites Turtle Pits, and Nibelungen on the southern MAR, and the Logatchev field in the North Atlantic. Plume mapping for these sites on cruises between 2004 and 2009 consisted of CTD Towyo-, Yoyo,- and station work, including velocity profiling, as well as water sampling for analysis of trace gases (CH4, H2, 3He/4He) and metals; temperature measurements and fluid sampling at the vent sites were carried out with an ROV. The aim of this work is to gain a better understanding of how the setting of a vent site affects the dispersal of the particle plume, and what means can be used to infer possible locations of vent sites based on the hydrographic properties and plume observations, using high resolution bathymetric mapping and hydrographic information. The ultramafic-hosted Nibelungen site (8°18'S) consists of a single active smoking crater, along with several extinct smokers, which is located off-axis south of a non-transform offset. The setting is characterized by rugged topography, favorable for the generation of internal tides, internal wave breaking, and vertical mixing. Elevated mixing with turbulent diffusivities Kρ up to 0.1 m2 s-1, 3 to 4 orders of magnitude higher than open ocean values, was observed close to the vent site. The mixing as well as the flow field exhibited a strong tidal cycle; the plume dispersal is thus dominated by the fast and intermittent vertical exchange and characterized by small scale spatial and temporal variability. The Turtle Pits vent fields (4°48'S) are located on a sill in a north-south orientated rift valley. The site consists of three (known) high temperature fields: Turtle Pits, Comfortless Cove, and Red Lion. The particle plume is confined to the rift

  19. Comparison between the shrimp species richness (Caridea and Dendrobranchiata, Decapoda, Crustacea of the south and north mid Atlantic ridge

    Irene Azevedo Cardoso

    2014-03-01

    Full Text Available The Mid Atlantic Ridge (MAR is a seamount chain extending for 60.000 km, divided into south and north regions by the Equatorial Fracture which cuts across it. This latter has a maximum depth of 7,760 m and an average width of 19 km. In this study we include data from the two cruises of the international project MAR-ECO, undertaken, respectively, one on the north and the other on the south MAR. Our main objective is to compare the species richness and species composition of pelagic and benthic decapod shrimps of these two areas to observe the patterns of their latitudinal distribution along the MAR. Using rarefaction methods, we obtained interesting results: the pelagic samples curve of the northern MAR is almost an asymptote, so we concluded that we are close to the true number of pelagic shrimp species for this region. The pelagic samples curve of the southern MAR had the greatest slope, so our conclusion is that we are still far from the true number of species for this region. A comparison of species richness at 12 samples (the smallest number of samples shared by both the surveys revealed that the pelagic species richness was greater than the demersal, and that the northern MAR contained a larger number of species than the southern.

  20. Anisotropy of the upper mantle beneath the equatorial part of the Mid-Atlantic Ridge

    Kendall, J. M.; Rychert, C.; Harmon, N.; Tharimena, S.; Agius, M. R.

    2017-12-01

    It has been long-known that the mantle beneath ocean spreading centres is anisotropic, holding the signature of the formation of new oceanic lithosphere and its coupling with the underlying convecting asthenosphere. Numerical studies have suggested that there should be significant differences between the anisotropy at slow versus fast spreading centres, but there is little observational evidence to calibrate these simulations, especially at slow spreading centres. Near the ridge axis, the anisotropic effects of melt versus the lattice preferred orientation of minerals is not well understood. Finally, the mantle flow near ridge-transform interactions is also poorly understood. Here we present observations of SKS splitting in a region of the Mid-Atlantic Ridge near the equator and offset by the Romanche and Chain Fracture Zones. An array of 37 ocean-bottom seismometers were deployed for a year in depths of up to nearly 6000m, with the aim of studying the nature of the lithosphere-asthenosphere boundary as it forms (the PiLAB - Passive Imaging of the lithosphere-asthenosphere boundary - experiment). Stations were deployed on crust that varies from newly formed to 80 My old. We analyse 40 teleseismic events of magnitude greater than 5.8 and with epicentral distances between 88 and 130 degrees. The ocean-bottom is a noisy environment and a range of filters are used to isolate the SKS, SKKS, and related signals. Furthermore, stacking splitting error envelopes is used to improve confidence in the splitting parameters. Many of the splitting measurements show an orientation parallel to the direction of plate spreading, as expected, but variability in the orientation of the anisotropy increases towards the ridge axis. The magnitude of the anisotropy is also quite variable and suggests larger delay times near the ridge axis. Off-axis anisotropy is interpreted in terms of deformation of peridotite due to mantle flow. Near the ridge axis, the effect of ridge-parallel melt

  1. Heat Flow and Hydrothermal Circulation of the Lucky Strike Segment, Mid Atlantic Ridge

    Bonneville, A.; Escartin, J.; Lucazeau, F.; Cannat, M.; Gouze, P.; von Herzen, R. P.; Adam, C.; Le Bars, M.; Monoury, E.; Vidal, V.

    2003-12-01

    In June 2003, expedition Luckyflux aboard the R/V Poseidon conducted a heat flow survey of a zone centred on the Lucky Strike segment of the Mid Atlantic ridge south of the Azores between ˜35° N and 39° N. Using a 5 m-long lance with 7 outrigger thermal probes, about 150 successful thermal gradient measurements were obtained, 140 of these with in-situ thermal conductivity. Measurements were made at ˜1 mile intervals along several profiles, where adequately sedimented sites were identified using 6-channel and 3.5 kHz seismic data from the previous Sudazores'98 cruise. We conducted heat flow measurements in two areas: a near axis region within the V-shaped ridge of overthickened crust that emanated from the Azores hotspot between ˜14 and 4 Ma, and an off-axis region East of the V-shaped ridge. The off-axis region is characterized by an homogeneous sediment cover, 300-400 m thick, and crustal ages varying between ˜6 and >10 Ma. Long wavelength (tens of km) low heat flow anomalies can be identified but the mean of 160 mWm-2 is comparable to the conductive heat flow expected for a crust of that age. Along two 80-km profiles perpendicular to the ridge, we observed coherent but different patterns. On the first profile, low heat flow values of 20-50 mWm-2 are observed at the base of the V-shaped ridge. These values are 100 mWm-2 below the profile average, showing that hydrothermal circulations can also affect oceanic crust beneath a thick and relatively impermeable sediment cover. On the other profile, heat flow generally decreases from west to east. On both profiles, higher than average values of heat flow are also present, associated on one of them with a nearly outcropping basement elevation. These contrasting overall heat flow patterns in similar geological context indicate that the likely pattern of hydrothermal circulations is mainly 3D, and not driven only by the presence of basement outcrops. In the near-axis region, where the tectonic structure is more

  2. Local Seismicity of the Rainbow Massif on the Mid-Atlantic Ridge

    Horning, G.; Sohn, R. A.; Canales, J. P.; Dunn, R. A.

    2018-02-01

    The Rainbow massif, an oceanic core complex located in a nontransform discontinuity on the Mid-Atlantic Ridge (36°N), is notable for hosting high-temperature hydrothermal discharge through ultramafic rocks. Here we report results from a 9 month microearthquake survey conducted with a network of 13 ocean bottom seismometers deployed on and around the Rainbow massif as part of the MARINER experiment in 2013-2014. High rates ( 300 per day) of low-magnitude (average ML 0.5) microearthquakes were detected beneath the massif. The hypocenters do not cluster along deeply penetrating fault surfaces and do not exhibit mainshock/aftershock sequences, supporting the hypothesis that the faulting associated with the exhumation of the massif is currently inactive. Instead, the hypocenters demarcate a diffuse zone of continuous, low-magnitude deformation at relatively shallow (serpentinized ultramafic host rock, and although the seismic network we deployed was not capable of constraining the focal mechanism of most events, our analysis suggests that serpentinization may play an important role in microearthquake generation at the Rainbow massif.

  3. Delta-proteobacterial SAR324 group in hydrothermal plumes on the South Mid-Atlantic Ridge

    Cao, Huiluo

    2016-03-08

    In the dark ocean, the SAR324 group of Delta-proteobacteria has been associated with a chemolithotrophic lifestyle. However, their electron transport chain for energy generation and information system has not yet been well characterized. In the present study, four SAR324 draft genomes were extracted from metagenomes sampled from hydrothermal plumes in the South Mid-Atlantic Ridge. We describe novel electron transport chain components in the SAR324 group, particularly the alternative complex III, which is involved in energy generation. Moreover, we propose that the C-type cytochrome, for example the C553, may play a novel role in electron transfer, adding to our knowledge regarding the energy generation process in the SAR324 cluster. The central carbon metabolism in the described SAR324 genomes exhibits several new features other than methanotrophy e.g. aromatic compound degradation. This suggests that methane oxidation may not be the main central carbon metabolism component in SAR324 cluster bacteria. The reductive acetyl-CoA pathway may potentially be essential in carbon fixation due to the absence of components from the Calvin-Benson cycle. Our study provides insight into the role of recombination events in shaping the genome of the SAR324 group based on a larger number of repeat regions observed, which has been overlooked thus far.

  4. Local Prediction Models on Mid-Atlantic Ridge MORB by Principal Component Regression

    Ling, X.; Snow, J. E.; Chin, W.

    2017-12-01

    The isotopic compositions of the daughter isotopes of long-lived radioactive systems (Sr, Nd, Hf and Pb ) can be used to map the scale and history of mantle heterogeneities beneath mid-ocean ridges. Our goal is to relate the multidimensional structure in the existing isotopic dataset with an underlying physical reality of mantle sources. The numerical technique of Principal Component Analysis is useful to reduce the linear dependence of the data to a minimum set of orthogonal eigenvectors encapsulating the information contained (cf Agranier et al 2005). The dataset used for this study covers almost all the MORBs along mid-Atlantic Ridge (MAR), from 54oS to 77oN and 8.8oW to -46.7oW, including replicating the dataset of Agranier et al., 2005 published plus 53 basalt samples dredged and analyzed since then (data from PetDB). The principal components PC1 and PC2 account for 61.56% and 29.21%, respectively, of the total isotope ratios variability. The samples with similar compositions to HIMU and EM and DM are identified to better understand the PCs. PC1 and PC2 are accountable for HIMU and EM whereas PC2 has limited control over the DM source. PC3 is more strongly controlled by the depleted mantle source than PC2. What this means is that all three principal components have a high degree of significance relevant to the established mantle sources. We also tested the relationship between mantle heterogeneity and sample locality. K-means clustering algorithm is a type of unsupervised learning to find groups in the data based on feature similarity. The PC factor scores of each sample are clustered into three groups. Cluster one and three are alternating on the north and south MAR. Cluster two exhibits on 45.18oN to 0.79oN and -27.9oW to -30.40oW alternating with cluster one. The ridge has been preliminarily divided into 16 sections considering both the clusters and ridge segments. The principal component regression models the section based on 6 isotope ratios and PCs. The

  5. Nuclear microprobe analysis of serpentine from the mid-Atlantic ridge

    Orberger, Beate E-mail: orberger@geol.u-psud.fr; Metrich, Nicole; Mosbah, Michelle E-mail: mosbah@drecam.cea.fr; Mevel, Catherine; Fouquet, Yves

    1999-09-02

    At mid-ocean ridges, ultramafic rocks are serpentinized by interaction with seawater-derived fluids. Elements, dissolved in large quantities in seawater, e.g., Na, K, Cl, Br, Ca and Sr, can be, in small amounts, incorporated as traces into the crystal structure of the various serpentine minerals (Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}). These trace elements can be used to track the composition of the reacting fluids and to constrain physico-chemical conditions. This paper represents the first application of particle-induced X- and {gamma}-ray emission (PIXE/PIGE) analysis to serpentine using the nuclear microprobe at the Laboratoire Pierre Suee (CEA-CNRS). Three types of serpentine, belonging to two different serpentinization generations, have been analysed in samples collected from the Mid-Atlantic Ridge (14 deg. 45'N/45 deg. W) that exposes serpentinized peridotites on which the Logachev black smoker is placed. The trace elements Cl, F, S, Cu, Zn, Ca, K, Ni, Cr and Mn were detected from several tens to several thousands of ppm. Bromine, As and Sr are close to the detection limit of about 5 ppm. The trace element concentrations and interelement relationships in serpentines vary (a) with the serpentine type and (b) with the geographic location to the black smoker. Chlorine and in part S originated from seawater, whereas Cu, Zn, Ca, K, Ni, Cr and Fe and the major amount of S were mobilized from the unaltered host rock and partitioned between the serpentine and the aqueous solution.

  6. Popping Rocks Revealed: Investigations from 14°N on the Mid-Atlantic Ridge

    Wanless, V. D.; Jones, M.; Kurz, M. D.; Soule, S. A.; Fornari, D. J.; Bendana, S.; Mittelstaedt, E. L.

    2017-12-01

    The popping rock, recovered in dredge 2πD43 in 1985, is commonly considered to be one of the most representative samples of undegassed upper mantle, based on high volatile and noble gas abundances. While this basalt is used to reconstruct mantle volatile contents and CO2 fluxes from mid-ocean ridges (MOR), the origin of the popping rock has remained ambiguous due to a lack of geologic context. Here, we present results from the first combined geochemical, geophysical, and geologic investigation of popping rocks from 14N on the Mid-Atlantic Ridge. By combining lava compositions with high-resolution bathymetric maps, we show that the popping rocks are confined to a single geographic area, at the transition between magmatic and tectonic segments. Fifteen popping rocks were collected in situ using the Alvin submersible in 2016. X-ray microtomography indicates that these lavas have variable vesicle abundances; including the highest vesicularities (>19%) recorded for any MOR basalt. Dissolved CO2 contents (163-175 ppm) are similar to proximal non-popping rocks and are in equilibrium at their eruption depths (>3600 m); however, total CO2 contents (based on vesicularity, dissolved CO2, and vesicle gas contents) are higher than non-popping rocks, ranging from 2800-14150 ppm. The popping rocks have average 3He/4He ratios of 8.17 ± 0.1 Ra and 4He concentrations of 1.84e-5 to 7.67e-5 cc/g STP. Compared to non-popping lavas, the popping rocks have a narrow range of major and trace element concentrations, suggesting little to no crystallization occurred during ascent or eruption. REE patterns and trace element ratios are indistinguishable in the popping rocks (La/Sm = 2.89 ± 0.05), indicating similar mantle sources and extents of melting. Based on lava compositions and spatial distribution, we suggest that the popping rocks at 14N were produced under similar magmatic conditions and erupted over short timescales, perhaps during a series of closely timed eruptions.

  7. Origin of major element chemical trends in DSDP Leg 37 basalts, Mid-Atlantic Ridge

    Byerly, G.R.; Wright, T.L.

    1978-01-01

    In this paper we summarize the major element chemical variation for basalts from the Deep Sea Drilling Project Leg 37 and relate it to stratigraphic position in each of five drilling sites. Least-squares techniques are successfully used to quantify the nature and extent of alteration in these basalts, and to correct the major element analysis back to a magmatic, or alteration-free, composition on the assumption that alteration takes place in two ways: (1) secondary minerals are introduced into veins and vesicles, and (2) CO2 and H2O react with components in the rock to form a simple alteration assemblage. A chemical stratigraphy is defined for these basalts by grouping lavas whose chemistries are related by low-pressure phenocryst-liquid differentiation as identified by least-squares calculation. Major chemical-stratigraphic units are as much as 200 m thick; correlations of these units can be made between the holes at site 332 (about 100 m apart), but not between the other sites. Compositions of parental magmas are calculated by extrapolating low-pressure variations to a constant value of 9% MgO. The differences in these extrapolated compositions reflect high-pressure processes, and suggest that clinopyroxene may be an important phase in either intermediate-level fractionation of basaltic liquids, or as a residual phase during the partial melting which produces these basaltic liquids. Several of the basaltic liquids calculated as parental to the Leg 37 basalts have CaO contents greater than 14% and indicate that the oceanic mantle is richer in CaO and Al2O3 than values used in pyrolite models for the upper mantle. A model for magma generation and eruption beneath the Mid-Atlantic Ridge embodies the following characteristics: 1. (1) Separate magma batches are generated in the mantle. 2. (2) Each of these may be erupted directly or stored at shallow depth where significant fractionation takes place. Common fractionation processes are inferred to be gravitative

  8. Abundance, distribution and diversity of gelatinous predators along the northern Mid-Atlantic Ridge: A comparison of different sampling methodologies.

    Aino Hosia

    Full Text Available The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four species of scyphozoans were identified to species level from macrozooplankton trawl samples. Additional taxa were identified to higher taxonomic levels and a single ctenophore genus was observed. Samples were collected at 17 stations along the MAR between the Azores and Iceland. A divergence in the species assemblages was observed at the southern limit of the Subpolar Frontal Zone. The catch composition of gelatinous zooplankton is compared between different sampling methodologies including: a macrozooplankton trawl; a Multinet; a ringnet attached to bottom trawl; and optical platforms (Underwater Video Profiler (UVP & Remotely Operated Vehicle (ROV. Different sampling methodologies are shown to exhibit selectivity towards different groups of gelatinous zooplankton. Only ~21% of taxa caught during the survey were caught by both the macrozooplankton trawl and the Multinet when deployed at the same station. The estimates of gelatinous zooplankton abundance calculated using these two gear types also varied widely (1.4 ± 0.9 individuals 1000 m-3 estimated by the macrozooplankton trawl vs. 468.3 ± 315.4 individuals 1000 m-3 estimated by the Multinet (mean ± s.d. when used at the same stations (n = 6. While it appears that traditional net sampling can generate useful data on pelagic cnidarians, comparisons with results from the optical platforms suggest that ctenophore diversity and abundance are consistently underestimated, particularly when net sampling is conducted in combination with formalin fixation. The results emphasise the importance of considering

  9. Abundance, distribution and diversity of gelatinous predators along the northern Mid-Atlantic Ridge: A comparison of different sampling methodologies

    Falkenhaug, Tone; Baxter, Emily J.

    2017-01-01

    The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR) from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four species of scyphozoans were identified to species level from macrozooplankton trawl samples. Additional taxa were identified to higher taxonomic levels and a single ctenophore genus was observed. Samples were collected at 17 stations along the MAR between the Azores and Iceland. A divergence in the species assemblages was observed at the southern limit of the Subpolar Frontal Zone. The catch composition of gelatinous zooplankton is compared between different sampling methodologies including: a macrozooplankton trawl; a Multinet; a ringnet attached to bottom trawl; and optical platforms (Underwater Video Profiler (UVP) & Remotely Operated Vehicle (ROV)). Different sampling methodologies are shown to exhibit selectivity towards different groups of gelatinous zooplankton. Only ~21% of taxa caught during the survey were caught by both the macrozooplankton trawl and the Multinet when deployed at the same station. The estimates of gelatinous zooplankton abundance calculated using these two gear types also varied widely (1.4 ± 0.9 individuals 1000 m-3 estimated by the macrozooplankton trawl vs. 468.3 ± 315.4 individuals 1000 m-3 estimated by the Multinet (mean ± s.d.) when used at the same stations (n = 6). While it appears that traditional net sampling can generate useful data on pelagic cnidarians, comparisons with results from the optical platforms suggest that ctenophore diversity and abundance are consistently underestimated, particularly when net sampling is conducted in combination with formalin fixation. The results emphasise the importance of considering sampling methodology

  10. Abundance, distribution and diversity of gelatinous predators along the northern Mid-Atlantic Ridge: A comparison of different sampling methodologies.

    Hosia, Aino; Falkenhaug, Tone; Baxter, Emily J; Pagès, Francesc

    2017-01-01

    The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR) from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four species of scyphozoans were identified to species level from macrozooplankton trawl samples. Additional taxa were identified to higher taxonomic levels and a single ctenophore genus was observed. Samples were collected at 17 stations along the MAR between the Azores and Iceland. A divergence in the species assemblages was observed at the southern limit of the Subpolar Frontal Zone. The catch composition of gelatinous zooplankton is compared between different sampling methodologies including: a macrozooplankton trawl; a Multinet; a ringnet attached to bottom trawl; and optical platforms (Underwater Video Profiler (UVP) & Remotely Operated Vehicle (ROV)). Different sampling methodologies are shown to exhibit selectivity towards different groups of gelatinous zooplankton. Only ~21% of taxa caught during the survey were caught by both the macrozooplankton trawl and the Multinet when deployed at the same station. The estimates of gelatinous zooplankton abundance calculated using these two gear types also varied widely (1.4 ± 0.9 individuals 1000 m-3 estimated by the macrozooplankton trawl vs. 468.3 ± 315.4 individuals 1000 m-3 estimated by the Multinet (mean ± s.d.) when used at the same stations (n = 6). While it appears that traditional net sampling can generate useful data on pelagic cnidarians, comparisons with results from the optical platforms suggest that ctenophore diversity and abundance are consistently underestimated, particularly when net sampling is conducted in combination with formalin fixation. The results emphasise the importance of considering sampling methodology

  11. Research Drilling on the Mid-Atlantic Ridge: IDDP Wells of Opportunity at Reykjanes, Iceland

    Fridleifsson, G. O.; Franzson, H.; Thorhallsson, S.; Elders, W. A.

    2005-12-01

    There are some 10 new geothermal wells at Reykjanes, in SW-Iceland, being considered by the Iceland Deep Drilling Project (IDDP) as potential candidate wells of opportunity to explore for deep (4-5 km) supercritical fluids. The drill field is located where the Mid-Atlantic Ridge emerges from the Atlantic ocean at the tip of the Reykjanes Peninsula. The site is an ideal locality for a combined study on the evolution of a rifted oceanic crust and an active black smoker-type geothermal system. However, the oceanic pillow basaltic crust at Reykjanes is some 2-3 times thicker than normal ocean floor crust, which undoubtedly relates to it being part of the Icelandic Large Igneous Province. The deepest of the geothermal wells at Reykjanes is Drillhole RN-17, that was completed to 3082 m depth in February 2005. It is currently the prime candidate for deepening by the IDDP. The plan is to deepen it to 4 km in 2006, and to 5 km depth in 2007, with funding coming from Icelandic energy companies (Hitaveita Sudurnesja, Landsvirkjun and Orkuveita Reykjavikur), the Government of Iceland, the International Scientific Continental Drilling Program (ICDP) and the US National Science Foundation (NSF). The well RN-17 was drilled as a conventional production well with a 12 ¼ inch drillbit to 3082 m depth, and left barefoot, with a 13 3/8 inch production casing cemented down to 900 m. It will be flow tested this autumn. If the RN-17 well is selected by the IDDP for deepening, a 9 5/8 inch in casing will be cemented to 3081 m and drilling will be continued with an 8 ½ inch tricone bit to 4 km in the autumn of 2006. The ICDP and NSF will fund spot coring for scientific studies in this depth interval and a second flow test would be performed in winter 2007. The following autumn, a 7 inch casing would be cemented to 4 km depth and then a 5 inch retrievable liner would be inserted to support a hybrid coring system to continuously core down to 5 km depth, retrieving HQ sized core. A third

  12. Panmixia in a fragmented and unstable environment: the hydrothermal shrimp Rimicaris exoculata disperses extensively along the Mid-Atlantic Ridge.

    Sara Teixeira

    Full Text Available Dispersal plays a fundamental role in the evolution and persistence of species, and especially for species inhabiting extreme, ephemeral and highly fragmented habitats as hydrothermal vents. The Mid-Atlantic Ridge endemic shrimp species Rimicaris exoculata was studied using microsatellite markers to infer connectivity along the 7100-Km range encompassing the sampled sites. Astonishingly, no genetic differentiation was found between individuals from the different geographic origins, supporting a scenario of widespread large-scale dispersal despite the habitat distance and fragmentation. We hypothesize that delayed metamorphosis associated to temperature differences or even active directed migration dependent on physical and/or chemical stimuli could explain these results and warrant further studies on adaptation and dispersal mechanisms.

  13. Lead-strontium isotopic variations along the East Pacific Rise and the Mid-Atlantic Ridge: A comparative study

    Hamelin, B.; Dupre, B.; Allegre, C.J.

    1984-01-01

    We have determined the Pb and Sr isotopic compositions in a number of fresh young oceanic basalts from the East Pacific Rise (between 20 0 N and 21 0 S latitudes), and from the Mid-Atlantic Ridge (between 65 0 N and 10 0 N). A comparison between the Atlantic and Pacific results reveals that there is a wider range of values for the Atlantic than for the Pacific. After filtering the short wavelengths, a good correlation is obtained between long-wavelength bathymetric and isotopic variations for the Atlantic. The preferred model proposed to explain these differences involves the constant presence of hot spots under ridges. On slow-spreading ridges like the Atlantic, the host spots signature is clearly visible in both bathymetry and isotopic ratios. On fast-spreading centres, the hot spot signature in both the bathymetry and isotopic signature may be diluted by the rapid supply of material coming from the asthenosphere. However, an alternative explanation for which no hot spot influence is found on the East Pacific Rise cannot be definitely ruled out. In two occurrences, south of the Hayes fracture zone (Atlantic), large isotopic heterogeneities are observed within a single dredge. This does not contradict the concept of regional isotopic regularities, but suggests that blob injection and source mixing may be observed at very different scales under the ridges. (orig./WB)

  14. Seismicity And Accretion Process Along The North Mid-Atlantic Ridge From The SIRENA Autonomous Hydrophone Data

    Perrot, J.; Goslin, J.; Dziak, R. P.; Haxel, J. H.; Maia, M. A.; Tisseau, C.; Royer, J.

    2009-12-01

    The seismicity of the North Atlantic Ocean was recorded by the SIRENA array of 6 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed north of the Azores Plateau between 40° and 50°N from June 2002 to September 2003. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation result in a detection threshold reduction to a magnitude completeness level (Mc) of ~2.8, to be compared to a Mc~4.7 for MAR events recorded by land-based seismic networks. A spatio-temporal analysis was performed over the 1696 events localized inside the SIRENA array. For hydrophone-derived catalogs, the acoustic magnitude, or Source Level (SL), is used as a measure of earthquake size. The ''source level completeness'', above which the data set is complete, is SLc=208 dB. The SIRENA catalog was searched for swarms using the cluster software of the SEISAN distribution. A minimum SL of 210 dB was chosen to detect a possible mainshock, and all subsequent events within 40 days following the possible mainshock, located within a radius of 15 km from the mainshock were considered as events of the swarm. 15 km correspond to the maximum fault length in a slow-ridge context. 11 swarms with more than 15 events were detected along the MAR between 40°et 50°N during the SIRENA deployment. The maximum number of earthquakes in a swarm is 40 events. The SL vs. time distribution within each swarm allowed a first discrimination between the swarms occurring in a tectonic context and those which can be attributed to volcanic processes, the latter showing a more constant SL vs. time distribution. Moreover, the swarms occurring in a tectonic context show a "mainshock-afterschock" distribution of the cumulative number of events vs. time, fitting a Modified Omori Law. The location of tectonic and volcanic swarms correlates well with regions where a positive and negative Mantle Bouguer

  15. Noble gases in basalt glasses from a Mid-Atlantic Ridge topographic high at 14deg N - geodynamic consequences

    Staudacher, T.; Sarda, P.; Richardson, S.H.; Allegre, C.J.; Sagna, I.; Dmitriev, L.V.

    1989-01-01

    We present a complete noble gas study of mid-oceanic ridge basalt glasses (MORB) from a small ridge segment, centered on an along-strike topographic elevation of the Mid-Atlantic Ridge at about 14deg N. We have found the highest 40 Ar/ 36 Ar ratio ever observed for a MORB glass, i.e. 28,150±330 for sample 2ΠD40, correlated with high 129 Xe/ 130 Xe ratios and the highest noble gas concentrations in a so-called popping-rock, labeled 2ΠD43. The latter sample displays a 4 He/ 40 Ar * ratio of 2.0-2.7, which is close to the production ratio in the mantle due to the radioactive decay of U, Th and K. Hence, this sample probably best represents the elemental noble gas ratios in the mantle, from which we have computed the 4 He concentration in the mantle source of MORB to be 1.5x10 -5 cm 3 STP g -1 . High 4 He/ 3 He ratios in two of the samples from the summit of the topographic high indicate the presence of a U, Th-rich component in the mantle source, possibly old subducted oceanic crust and/or sediments, which could originate in the so-called mesosphere boundary layer. (orig.)

  16. Methane- and Hydrogen-Influenced Microbial Communities in Hydrothermal Plumes above the Atlantis Massif, Mid Atlantic Ridge

    Stewart, C. L.; Schrenk, M.

    2017-12-01

    Ultramafic-hosted hydrothermal systems associated with slow-spreading mid ocean ridges emit copious amounts of hydrogen and methane into the deep-sea, generated through a process known as serpentinization. Hydrothermal plumes carrying the reduced products of water-rock interaction dissipate and mix with deep seawater, and potentially harbor microbial communities adapted to these conditions. Methane and hydrogen enriched hydrothermal plumes were sampled from 3 sites near the Atlantis Massif (30°N, Mid Atlantic Ridge) during IODP Expedition 357 and used to initiate cultivation experiments targeting methanotrophic and hydrogenotrophic microorganisms. One set of experiments incubated the cultures at in situ hydrostatic pressures and gas concentrations resulting in the enrichment of gammaproteobacterial assemblages, including Marinobacter spp. That may be involved in hydrocarbon degradation. A second set of experiments pursued the anaerobic enrichment of microbial communities on solid media, resulting in the enrichment of alphaproteobacteria related to Ruegeria. The most prodigious growth in both case occurred in methane-enriched media, which may play a role as both an energy and carbon source. Ongoing work is evaluating the physiological characteristics of these isolates, including their metabolic outputs under different physical-chemical conditions. In addition to providing novel isolates from hydrothermal habitats near the Lost City Hydrothermal Field, these experiments will provide insight into the ecology of microbial communities from serpentinization influenced hydrothermal systems that may aid in future exploration of these sites.

  17. Long-term evolution of a propagating non-transform offset on the Mid-Atlantic Ridge over the last 26 m.y.

    Zheng, T.; Tucholke, B. E.; Lin, J.

    2017-12-01

    By making plate reconstructions from Chron 8n ( 26.54 Ma) to present and analyzing multibeam bathymetry, long-range HMR1 sidescan sonar images, residual mantle Bouguer gravity anomaly (RMBA) and gravity-derived crust thickness, we investigated the structure and evolution of a propagating non-transform discontinuity (NTD) and adjacent ridge segments that now intersect the Mid-Atlantic Ridge (MAR) axis at 25°37'N. The NTD has propagated consistently northward since Chron 8n at a rate of 4.76 km/m.y. Offset across the NTD since Chron 6an (22 Ma) has been right lateral and has ranged from 8-52 km. Key features are: 1) Inside-corner (IC) crust consistently has higher values of RMBA than the adjacent ridge segments, implying thinner crust. 2) IC crust typically exhibits elevated, irregular edifices. Slopes of the NTD walls are steeper at ICs than at outside corners (OCs). Steep (up to 40°), abrupt slopes are particularly pronounced at the IC on the north side of the NTD. 3) OC crust is deeper and normally exhibits long linear ridges that curve toward the MAR axis at the southern edge of the NTD but show little curvature at the northern edge. 4) Width of the NTD between its northern and southern walls (at mid-depth) has ranged from 2 to 22 km, averaging 15 km. 5) The NTD valley was intermittently crossed by individual ridges or blocks every 5-60 km (average 20 km) along the run of the NTD. The ridges curve along the transtensional plate boundary within the NTD but are often discontinuous. HMR1 data show lumpy small-scale topography and occasional volcanic cones on the ridges and blocks. Their intermittency indicates that melt intruded sporadically into the NTD. Propagation of the NTD occurred as the transtensional plate boundary within the NTD jumped northward from a volcanic ridge axis or block, apparently as magmatism waned. The jumps captured crust and transferred it to the east flank only within the NTD, not from the northern IC edifices. We propose two possible

  18. Serpentinization of abyssal peridotites from the MARK area, Mid-Atlantic Ridge: Sulfur geochemistry and reaction modeling

    Alt, J.C.; Shanks, Wayne C.

    2003-01-01

    The opaque mineralogy and the contents and isotope compositions of sulfur in serpentinized peridotites from the MARK (Mid-Atlantic Ridge, Kane Fracture Zone) area were examined to understand the conditions of serpentinization and evaluate this process as a sink for seawater sulfur. The serpentinites contain a sulfur-rich secondary mineral assemblage and have high sulfur contents (up to 1 wt.%) and elevated ??34Ssulfide (3.7 to 12.7???). Geochemical reaction modeling indicates that seawater-peridotite interaction at 300 to 400??C alone cannot account for both the high sulfur contents and high ??34Ssulfide. These require a multistage reaction with leaching of sulfide from subjacent gabbro during higher temperature (???400??C) reactions with seawater and subsequent deposition of sulfide during serpentinization of peridotite at ???300??C. Serpentinization produces highly reducing conditions and significant amounts of H2 and results in the partial reduction of seawater carbonate to methane. The latter is documented by formation of carbonate veins enriched in 13C (up to 4.5???) at temperatures above 250??C. Although different processes produce variable sulfur isotope effects in other oceanic serpentinites, sulfur is consistently added to abyssal peridotites during serpentinization. Data for serpentinites drilled and dredged from oceanic crust and from ophiolites indicate that oceanic peridotites are a sink for up to 0.4 to 6.0 ?? 1012 g seawater S yr-1. This is comparable to sulfur exchange that occurs in hydrothermal systems in mafic oceanic crust at midocean ridges and on ridge flanks and amounts to 2 to 30% of the riverine sulfate source and sedimentary sulfide sink in the oceans. The high concentrations and modified isotope compositions of sulfur in serpentinites could be important for mantle metasomatism during subduction of crust generated at slow spreading rates. ?? 2003 Elsevier Science Ltd.

  19. Biogeographical distribution of Rimicaris exoculata resident gut epibiont communities along the Mid-Atlantic Ridge hydrothermal vent sites.

    Durand, Lucile; Roumagnac, Marie; Cueff-Gauchard, Valérie; Jan, Cyrielle; Guri, Mathieu; Tessier, Claire; Haond, Marine; Crassous, Philippe; Zbinden, Magali; Arnaud-Haond, Sophie; Cambon-Bonavita, Marie-Anne

    2015-10-01

    Rimicaris exoculata is a deep-sea hydrothermal vent shrimp whose enlarged gill chamber houses a complex trophic epibiotic community. Its gut harbours an autochthonous and distinct microbial community. This species dominates hydrothermal ecosystem megafauna along the Mid-Atlantic Ridge, regardless of contrasting geochemical conditions prevailing in them. Here, the resident gut epibiont community at four contrasted hydrothermal vent sites (Rainbow, TAG, Logatchev and Ashadze) was analysed and compiled with previous data to evaluate the possible influence of site location, using 16S rRNA surveys and microscopic observations (transmission electron microscopy, scanning electron microscopy and fluorescence in situ hybridization analyses). Filamentous epibionts inserted between the epithelial cell microvilli were observed on all examined samples. Results confirmed resident gut community affiliation to Deferribacteres, Mollicutes, Epsilonproteobacteria and to a lesser extent Gammaproteobacteria lineages. Still a single Deferribacteres phylotype was retrieved at all sites. Four Mollicutes-related operational taxonomic units were distinguished, one being only identified on Rainbow specimens. The topology of ribotype median-joining networks illustrated a community diversification possibly following demographic expansions, suggesting a more ancient evolutionary history and/or a larger effective population size at Rainbow. Finally, the gill chamber community distribution was also analysed through ribotype networks based on sequences from R. exoculata collected at the Rainbow, Snake Pit, TAG, Logatchev and Ashadze sites. Results allow the refining of hypotheses on the epibiont role and transmission pathways. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Changes in Bottom Water Physical Properties Above the Mid-Atlantic Ridge Flank in the Brazil Basin

    Zhao, Jian; Thurnherr, Andreas M.

    2018-01-01

    Warming of abyssal waters in recent decades has been widely documented around the global ocean. Here repeat hydrographic data collected in 1997 and 2014 near a deep fracture zone canyon in the eastern Brazil Basin are used to quantify the long-term change. Significant changes are found in the Antarctic Bottom Water (AABW) within the canyon. The AABW in 2014 was warmer (0.08 ± 0.06°C), saltier (0.01 ± 0.005), and less dense (0.005 ± 0.004 kg m-3) than in 1997. In contrast, the change in the North Atlantic Deep Water has complicated spatial structure and is almost indistinguishable from zero at 95% confidence. The resulting divergence in vertical displacement of the isopycnals modifies the local density stratification. At its peak, the local squared buoyancy frequency (N2) near the canyon is reduced by about 20% from 1997 to 2014. Similar reduction is found in the basinwide averaged profiles over the Mid-Atlantic Ridge flank along 25°W in years 1989, 2005, and 2014. The observed changes in density stratification have important implications for internal tide generation and dissipation.

  1. Heavy metal bioaccumulation in the organisms at hydrothermal fields of the Mid-Atlantic Ridge and East-Pacific Rise

    Demina, L.L.; Galkin, S.V.

    2008-01-01

    The influence of geochemical environment as well as biological parameters on the heavy metal bioaccumulation in the hydrothermal fauna at certain fields of the Mid-Atlantic ridge (MAR) and East Pacific Rise (EPR) are studied. The highest concentration of Fe, Zn, Cu, Mn, Ni, Cr, Co, Pb, Cd, Ag, Se, Sb, As, and Hg were detected in the tubes of the most thermophilic organism Alvinella caudata inhabited sulfide chimneys at 9 0 50 ' N EPR, i.e. at place where the influence of hydrothermal fluids was the maximal. Elevated heavy metals levels were typical for organs associated with the endo symbiotic bacteria activity, such as gills of specialized mussels Bathymodiolus, clams Archivestica gigas (Calyptogena magnifica), trophosome of vestimentifera Riftia, maxillipeds of shrimps Rimicaris exoculata. Inter-site (Broken Spur vs. Rainbow) comparison of the partitioning of metals within soft tissues has revealed that metal concentrations in the fauna habitats is an important albeit not the single factor that controls the metal content in the interior organs of the taxa. The external parts of mussels, such as shells, demonstrate patterns of bioaccumulation reflecting the metal concentrations in the micro-habitats. In spite of the minimal metal content was found in the mussel shells, they serve as a great reservoirs for heavy metal deposition and storage at the hydrothermal regions. For some elements a trend of heavy metal transferring through the food chains was revealed. There were no clear dependence between age of mussels and metal content (except Hg) in the soft tissues

  2. Initial chronology of a recently discovered hydrothermal field at 14°45‧N, Mid-Atlantic Ridge

    Lalou, Claude; Reyss, Jean Louis; Brichet, Evelyne; Krasnov, Sergey; Stepanova, Tamara; Cherkashev, Georgiy; Markov, Vladimir

    1996-11-01

    Two expeditions of the 'Sevmorgeologija' association (1991-1994) led to the discovery of two new hydrothermal sites on the Mid Atlantic Ridge (MAR), south of the 15°20‧ North Fracture Zone, one around 14°45‧N and the other around 14°42‧N. The northern one, between 14°45‧ and 14°45.3‧N has been studied in detail. About 12 mounds have been mapped and 3 of them have been sampled using a large hydraulic grab sampler. The largest one is about 200 m long and 200 m wide. When progressively moving up on the slope of an uplifted block of the rift valley floor, the sulphide samples have revealed ages ranging from about 10 ka to 60 ka. The ages were obtained using the 230Th/234U dating method used for chronological studies of diverse hydrothermal fields. The general picture of this lateral location of the samples of different ages provides evidence of a shift in the focus of hydrothermal activity with time. Moreover, there were rejuvenation stages of hydrothermal activity, including black and white smokers.

  3. Free-living nematode species (Nematoda) dwelling in hydrothermal sites of the North Mid-Atlantic Ridge

    Tchesunov, Alexei V.

    2015-12-01

    Morphological descriptions of seven free-living nematode species from hydrothermal sites of the Mid-Atlantic Ridge are presented. Four of them are new for science: Paracanthonchus olgae sp. n. (Chromadorida, Cyatholaimidae), Prochromadora helenae sp. n. (Chromadorida, Chromadoridae), Prochaetosoma ventriverruca sp. n. (Desmodorida, Draconematidae) and Leptolaimus hydrothermalis sp. n. (Plectida, Leptolaimidae). Two species have been previously recorded in hydrothermal habitats, and one species is recorded for the first time in such an environment. Oncholaimus scanicus (Enoplida, Oncholaimidae) was formerly known from only the type locality in non-hydrothermal shallow milieu of the Norway Sea. O. scanicus is a very abundant species in Menez Gwen, Lucky Strike and Lost City hydrothermal sites, and population of the last locality differs from other two in some morphometric characteristics. Desmodora marci (Desmodorida, Desmodoridae) was previously known from other remote deep-sea hydrothermal localities in south-western and north-eastern Pacific. Halomonhystera vandoverae (Monhysterida, Monhysteridae) was described and repeatedly found in mass in Snake Pit hydrothermal site. The whole hydrothermal nematode assemblages are featured by low diversity in comparison with either shelf or deep-sea non-hydrothermal communities. The nematode species list of the Atlantic hydrothermal vents consists of representatives of common shallow-water genera; the new species are also related to some shelf species. On the average, the hydrothermal species differ from those of slope and abyssal plains of comparable depths by larger sizes, diversity of buccal structures, presence of food content in the gut and ripe eggs in uteri.

  4. Turbulence and finestructure in a deep ocean channel with sill overflow on the mid-Atlantic ridge

    Tippenhauer, Sandra; Dengler, Marcus; Fischer, Tim; Kanzow, Torsten

    2015-05-01

    Diapycnal mixing in the deep ocean is known to be much stronger in the vicinity of rough topography of mid-ocean ridges than above abyssal plains. In this study a horizontally profiling microstructure probe attached to an autonomous underwater vehicle (AUV) is used to infer the spatial distribution of the dissipation rate of turbulent kinetic energy (ε) in the central valley of the Mid-Atlantic Ridge. To the authors' knowledge, this is the first successful realization of a horizontal, deep-ocean microstructure survey. More than 22 h of horizontal, near-bottom microstructure data from the Lucky Strike segment (37°N) are presented. The study focuses on a channel with unidirectional sill overflow. Density was found to decrease along the channel following the mean northward flow of 3 to 8 cm/s. The magnitude of the rate of turbulent kinetic energy dissipation was distributed asymmetrically relative to the position of the sill. Elevated dissipation rates were present in a segment 1-4 km downstream (north) of the sill with peak values of 1 ×10-7 W/kg. Large flow speeds and elevated density finestructure were observed within this segment. Lowered hydrographic measurements indicated unstable stratification in the same region. The data indicate that hydraulic control was established at least temporarily. Inside the channel at wavelengths between 1 m and 250 m the slopes of AUV-inferred horizontal temperature gradient spectra were found to be consistent with turbulence in the inertial-convective subrange. Integrated temperature gradient variance in this wavelength interval was consistent with an ε2/3 dependence. The results illustrate that deep-reaching AUVs are a useful tool to study deep ocean turbulence over complex terrain where free-falling and lowered turbulence measurements are inefficient and time-consuming.

  5. Metabasalts from the Mid-Atlantic Ridge: new insights into hydrothermal systems in slow-spreading crust

    Gillis, Kathryn M.; Thompson, Geoffrey

    1993-12-01

    An extensive suite of hydrothermally altered rocks were recovered by Alvin and dredging along the MARK [Mid-Atlantic Ridge, south of the Kane Fracture Zone (23 24°N)] where detachment faulting has provided a window into the crustal component of hydrothermal systems. Rocks of basaltic composition are altered to two assemblages with these characteristics: (i) type I: albitic plagioclase (An02 10)+mixed-layer smectite/chlorite or chlorite±actinolite±quartz±sphene, 20% of the clinopyroxene is altered, and Cu and Zn are leached. The geochemical signature of these alteration types reflects the relative proportion and composition of secondary minerals, and the degree of alteration of primary phases, and does not show simple predictive relationships. Element mobilities indicate that both alteration types formed at low water/rock ratios. The MARK assemblages are typical of the greenschist and transition to the amphibolite facies, and represent two distinct, albeit overlapping, temperature regimes: type I-180 to 300°C and type II-250 to 450°C. By analogy with DSDP/ODP Hole 504B and many ophiolites, the MARK metabasalts were altered within the downwelling limb of a hydrothermal cell and type I and II samples formed in the upper and lower portions of the sheeted like complex, respectively. Episodic magmatic and hydrothermal events at slow-spreading ridges suggest that these observed mineral assemblages represent the cumulative effects of more than one hydrothermal event. Groundmass and vein assemblages in the MARK metabasalts indicate either that alteration conditions did not change during successive hydrothermal events or that these assemblages record only the highest temperature event. Lack of retrograde reactions or overprinting of lower temperature assemblages (e.g., zeolites) suggests that there is a continuum in alteration conditions while crustal segments remain in the ridge axis environment. The type II samples may be representative of the reaction zone where

  6. Heat flow, morphology, pore fluids and hydrothermal circulation in a typical Mid-Atlantic Ridge flank near Oceanographer Fracture Zone

    Le Gal, V.; Lucazeau, F.; Cannat, M.; Poort, J.; Monnin, C.; Battani, A.; Fontaine, F.; Goutorbe, B.; Rolandone, F.; Poitou, C.; Blanc-Valleron, M.-M.; Piedade, A.; Hipólito, A.

    2018-01-01

    Hydrothermal circulation affects heat and mass transfers in the oceanic lithosphere, not only at the ridge axis but also on their flanks, where the magnitude of this process has been related to sediment blanket and seamounts density. This was documented in several areas of the Pacific Ocean by heat flow measurements and pore water analysis. However, as the morphology of Atlantic and Indian ridge flanks is generally rougher than in the Pacific, these regions of slow and ultra-slow accretion may be affected by hydrothermal processes of different regimes. We carried out a survey of two regions on the eastern and western flanks of the Mid-Atlantic Ridge between Oceanographer and Hayes fracture zones. Two hundred and eight new heat flow measurements were obtained along six seismic profiles, on 5 to 14 Ma old seafloor. Thirty sediment cores (from which porewaters have been extracted) have been collected with a Kullenberg corer equipped with thermistors thus allowing simultaneous heat flow measurement. Most heat flow values are lower than those predicted by purely conductive cooling models, with some local variations and exceptions: heat flow values on the eastern flank of the study area are more variable than on the western flank, where they tend to increase westward as the sedimentary cover in the basins becomes thicker and more continuous. Heat flow is also higher, on average, on the northern sides of both the western and eastern field regions and includes values close to conductive predictions near the Oceanographer Fracture Zone. All the sediment porewaters have a chemical composition similar to that of bottom seawater (no anomaly linked to fluid circulation has been detected). Heat flow values and pore fluid compositions are consistent with fluid circulation in volcanic rocks below the sediment. The short distances between seamounts and short fluid pathways explain that fluids flowing in the basaltic aquifer below the sediment have remained cool and unaltered

  7. The Production of Methane, Hydrogen, and Organic Compounds in Ultramafic-Hosted Hydrothermal Vents of the Mid-Atlantic Ridge

    Charlou, J.L.; Holm, N.G.; Mousis, O.

    2015-01-01

    Abstract Both hydrogen and methane are consistently discharged in large quantities in hydrothermal fluids issued from ultramafic-hosted hydrothermal fields discovered along the Mid-Atlantic Ridge. Considering the vast number of these fields discovered or inferred, hydrothermal fluxes represent a significant input of H2 and CH4 to the ocean. Although there are lines of evidence of their abiogenic formation from stable C and H isotope results, laboratory experiments, and thermodynamic data, neither their origin nor the reaction pathways generating these gases have been fully constrained yet. Organic compounds detected in the fluids may also be derived from abiotic reactions. Although thermodynamics are favorable and extensive experimental work has been done on Fischer-Tropsch-type reactions, for instance, nothing is clear yet about their origin and formation mechanism from actual data. Since chemolithotrophic microbial communities commonly colonize hydrothermal vents, biogenic and thermogenic processes are likely to contribute to the production of H2, CH4, and other organic compounds. There seems to be a consensus toward a mixed origin (both sources and processes) that is consistent with the ambiguous nature of the isotopic data. But the question that remains is, to what proportions? More systematic experiments as well as integrated geochemical approaches are needed to disentangle hydrothermal geochemistry. This understanding is of prime importance considering the implications of hydrothermal H2, CH4, and organic compounds for the ocean global budget, global cycles, and the origin of life. Key Words: Hydrogen—Methane—Organics—MAR—Abiotic synthesis—Serpentinization—Ultramafic-hosted hydrothermal vents. Astrobiology 15, 381–399. PMID:25984920

  8. New Noble Gas Studies on Popping Rocks from the Mid-Atlantic Ridge near 14°N

    Kurz, M. D.; Curtice, J.; Jones, M.; Péron, S.; Wanless, V. D.; Mittelstaedt, E. L.; Soule, S. A.; Klein, F.; Fornari, D. J.

    2017-12-01

    New Popping Rocks were recovered in situ on the Mid-Atlantic Ridge (MAR) near 13.77° N, using HOV Alvin on cruise AT33-03 in 2016 on RV Atlantis. We report new helium, neon, argon, and CO2 step-crushing measurements on a subset of the glass samples, with a focus on a new procedure to collect seafloor samples with minimal exposure to air. Glassy seafloor basalts were collected in sealed containers using the Alvin mechanical arm and transported to the surface without atmospheric exposure. On the ship, the seawater was drained, the volcanic glass was transferred to stainless steel ultra-high-vacuum containers (in an oxygen-free glove box), which were then evacuated using a turbo-molecular pump and sealed for transport under vacuum. All processing was carried out under a nitrogen atmosphere. A control sample was collected from each pillow outcrop and processed normally in air. The preliminary step-crushing measurements show that the anaerobically collected samples have systematically higher 20Ne/22Ne, 21Ne/22Ne and 40Ar/36Ar than the control samples. Helium abundances and isotopes are consistent between anaerobically collected samples and control samples. These results suggest that minimizing atmospheric exposure during sample processing can significantly reduce air contamination for heavy noble gases, providing a new option for seafloor sampling. Higher vesicle abundances appear to yield a greater difference in neon and argon isotopes between the anaerobic and control samples, suggesting that atmospheric contamination is related to vesicle abundance, possibly through micro-fractures. The new data show variability in the maximum mantle neon and argon isotopic compositions, and abundance ratios, suggesting that the samples experienced variable outgassing prior to eruption, and may represent different phases of a single eruption, or multiple eruptions.

  9. Metal interactions between the polychaete Branchipolynoe seepensis and the mussel Bathymodiolus azoricus from Mid-Atlantic-Ridge hydrothermal vent fields.

    Bebianno, Maria João; Cardoso, Cátia; Gomes, Tânia; Blasco, Julian; Santos, Ricardo Serrão; Colaço, Ana

    2018-04-01

    The vent blood-red commensal polynoid polychaete Branchipolynoe seepensis is commonly found in the pallial cavity of the vent mussel Bathymodiolus azoricus, the dominant bivalve species along the Mid-Atlantic-Ridge (MAR) and is known to be kleptoparasitic. Mussels were collected from three hydrothermal vent fields in the MAR: Menez Gwen (850 m depth, MG2, MG3 and MG4), Lucky Strike (1700 m depth, Montségur-MS and Eiffel Tower-ET) and Rainbow (2300 m depth). Polychaetes were absent in all Menez Gwen vent mussels, while the highest percentage was detected in mussels from Lucky Strike, where more than 70% of the mussels had at least one polychaete in their mantle cavity, followed by Rainbow with 33% of mussels with polychaetes. Total metal concentrations (Ag, Cd, Co, Cu, Fe, Mn, Ni and Zn) were determined in polychaetes whole body and in the mussel tissues (gills, digestive gland and mantle). To understand the possible metal interactions between symbiont and host, the activity of antioxidant defence (catalase (CAT), metallothioneins (MTs)), biotransformation enzymes (glutathione-s-transferases (GST)) activities and lipid peroxidation (LPO) were determined in polychaete whole soft tissues and in mussel tissues (gills, digestive gland and mantle). Metal concentrations in polychaetes and mussels tissues indicated that the accumulation patterns were species specific and also influenced by, and possibly dependent upon, the inter- and intra-variation of vent physico-chemistry between hydrothermal fields. Despite not detecting any strong correlations between metal and enzymes activities in polychaetes and mussels, when in presence of polychaetes, mussels presented less metal concentrations in the gills and digestive gland and lower activity of enzymatic biomarkers. This leads to infer that the polychaete plays a role on the detoxification process, and the interaction between the polychaete mussel association is probably an adaptation to metals concentrations at the

  10. Distribution and feeding ecology of dolphins along the Mid-Atlantic Ridge between Iceland and the Azores

    Doksæter, L.; Olsen, E.; Nøttestad, L.; Fernö, A.

    2008-01-01

    During Leg 1 of the MAR-ECO expedition on the R.V. G.O. Sars in June 2004 four main species of dolphins were observed along the Mid-Atlantic Ridge from Iceland to the Azores: pilot whale ( Globicephala melas) ( n=326), short-beaked common dolphin ( Delphinus delphis) ( n=273), white-sided dolphin ( Lagenorhynchus acutus) ( n=103), and striped dolphin ( Stenella coeruleoalba) ( n=86). Pilot whales and white-sided dolphins were found in cold (5-16 °C) and less-saline (34.6-35.8‰) water masses in the northern part of the study area, whereas common and striped dolphins inhabited warmer (12-22 °C) and more-saline (34.8-36.7‰) waters in the south. Dolphins tended to aggregate in areas of steep slopes, but actual bottom depth appeared to be less important. Based on spatial correlations between dolphin occurrence and candidate prey organisms recorded acoustically and by midwater trawling, mesopelagic fishes and squids were assumed to be important prey items, with Benthosema glaciale probably being the most important prey for pilot whales and white-sided dolphins, while Lampanyctus macdonaldi, Stomias boa ferox and Chauliodus sloani were probably of particular importance for common dolphins. Cephalopods, especially Gonatus sp. and Teuthowenia megalops were the most likely prey species of pilot whales and striped dolphins, respectively. The difference in physical habitat north and south of the Sub-polar Frontal Zone seemed to have important effects on prey distribution, in turn influencing dolphin distribution.

  11. Biodiversity patterns, environmental drivers and indicator species on a High-temperature Hydrothermal edifice, mid-Atlantic ridge

    Sarrazin, Jozée

    2015-04-25

    Knowledge on quantitative faunal distribution patterns of hydrothermal communities in slow-spreading vent fields is particularly scarce, despite the importance of these ridges in the global mid-ocean system. This study assessed the composition, abundance and diversity of 12 benthic faunal assemblages from various locations on the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) and investigated the role of key environmental conditions (temperature, total dissolved iron (TdFe), sulfide (TdS), copper (TdCu) and pH) on the distribution of macro- and meiofaunal species at small spatial scales (< 1 m). There were differences in macro- and meiofaunal community structure between the different sampling locations, separating the hydrothermal community of the Eiffel Tower edifice into three types of microhabitats: (1) cold microhabitats characterized by low temperatures (<6 °C), high TdCu (up to 2.4±1.37 µmol l−1), high pH (up to 7.34±0.13) but low TdS concentrations (<6.98±5.01 µmol l−1); (2) warm microhabitats characterized by warmer temperatures (>6 °C), low pH (<6.5) and high TdS/TdFe concentrations (>12.8 µmol l−1/>1.1 µmol l−1 respectively); and (3) a third microhabitat characterized by intermediate abiotic conditions. Environmental conditions showed more variation in the warm microhabitats than in the cold microhabitats. In terms of fauna, the warm microhabitats had lower macro- and meiofaunal densities, and lower richness and Shannon diversity than the cold microhabitats. Six macrofaunal species (Branchipolynoe seepensis, Amathys lutzi, Bathymodiolus azoricus, Lepetodrilus fucensis, Protolira valvatoides and Chorocaris chacei) and three meiofaunal taxa (Paracanthonchus, Cephalochaetosoma and Microlaimus) were identified as being significant indicator species/taxa of particular microhabitats. Our results also highlight very specific niche separation for copepod juveniles among the different hydrothermal microhabitats. Some sampling

  12. Massive Sulphide Exploration at the Mid-Atlantic Ridge 26oN: an interdisciplinary geophysical study

    Gehrmann, R. A. S.; Hölz, S.; Jegen, M. D.; Graber, S.; Szitkar, F.; Petersen, S.; Yeo, I. A.; North, L. J.; Gil, A.; Vardy, M. E.; Haroon, A.; Schroeder, H.; Bialas, J.; Tan, Y. Y.; Attias, E.; Sommer, M.; Minshull, T. A.; Murton, B. J.

    2017-12-01

    During the summer 2016 two cruises (M127 and JC138) conducted an interdisciplinary survey as part of the EU FP7 project `Blue Mining' in the Trans-Atlantic Geotraverse (TAG) hydrothermal field, at the Mid-Atlantic Ridge (26° N), to study the geophysical and geochemical signature of extinct seafloor massive sulphide (eSMS) deposits. The survey comprised AUV-based high-resolution bathymetric mapping, magnetic and self-potential data acquisition, reflection and refraction seismic imaging and three types of controlled source electromagnetic (CSEM) experiments (Geomar, UoS). Additionally seafloor coring, drilling and video imaging (NOC, University of Lisbon, BGS) were realized. Laboratory measurements of physical and chemical properties were taken on and post-cruise from rock samples and sediment cores. Here, we present results from the geophysical data analysis with emphasis on the electromagnetic studies in respect to eSMS detection. Six multi-kilometre-long profiles were acquired with the towed CSEM experiment (UoS) and preliminary results indicate the sensitivity to the conductive eSMS deposits and the resistive background to a depth of about 200 m. The system is also sensitive to the rough topography and interpretation of eSMS deposits requires validation from other methods such as measurements with the MARTEMIS system, a seafloor source-receiver coil (Geomar), which were conducted in two collocated work areas for high-resolution imaging with a depth penetration of up to 50 m. Each geophysical method is sensitive to different SMS characteristics, for example, bathymetric and seismic data are sensitive to the shape and structure of the whole deposit, magnetic data are susceptive to the hydrothermal alteration of magnetic minerals, and self-potential and electromagnetic data respond to the electrically conductive sulphide bodies. Each method has different resolution, penetration depths and challenges with the rough-topographic terrain and navigation. Only

  13. Three-Dimensional Seismic Structure of the Mid-Atlantic Ridge: An Investigation of Tectonic, Magmatic, and Hydrothermal Processes in the Rainbow Area

    Dunn, Robert A.; Arai, Ryuta; Eason, Deborah E.; Canales, J. Pablo; Sohn, Robert A.

    2017-12-01

    To test models of tectonic, magmatic, and hydrothermal processes along slow-spreading mid-ocean ridges, we analyzed seismic refraction data from the Mid-Atlantic Ridge INtegrated Experiments at Rainbow (MARINER) seismic and geophysical mapping experiment. Centered at the Rainbow area of the Mid-Atlantic Ridge (36°14'N), this study examines a section of ridge with volcanically active segments and a relatively amagmatic ridge offset that hosts the ultramafic Rainbow massif and its high-temperature hydrothermal vent field. Tomographic images of the crust and upper mantle show segment-scale variations in crustal structure, thickness, and the crust-mantle transition, which forms a vertical gradient rather than a sharp boundary. There is little definitive evidence for large regions of sustained high temperatures and melt in the lower crust or upper mantle along the ridge axes, suggesting that melts rising from the mantle intrude as small intermittent magma bodies at crustal and subcrustal levels. The images reveal large rotated crustal blocks, which extend to mantle depths in some places, corresponding to off-axis normal fault locations. Low velocities cap the Rainbow massif, suggesting an extensive near-surface alteration zone due to low-temperature fluid-rock reactions. Within the interior of the massif, seismic images suggest a mixture of peridotite and gabbroic intrusions, with little serpentinization. Here diffuse microearthquake activity indicates a brittle deformation regime supporting a broad network of cracks. Beneath the Rainbow hydrothermal vent field, fluid circulation is largely driven by the heat of small cooling melt bodies intruded into the base of the massif and channeled by the crack network and shallow faults.

  14. Distribution, population biology, and trophic ecology of the deepwater demersal fish Halosauropsis macrochir (Pisces: Halosauridae on the mid-Atlantic Ridge.

    Odd Aksel Bergstad

    Full Text Available Halosauropsis macrochir ranked amongst the most abundant and widespread demersal fishes on the mid-Atlantic Ridge of the North Atlantic (Iceland-Azores with greatest abundance at 1700-3500 m. All sizes, ranging from 10-76 cm total length, occurred in the area without any apparent spatial pattern or depth trend. Using otolith sections displaying growth increments assumed to represent annuli, the age range recorded was 2-36 years, but most individuals were <20 years. Length and weight at age data were used to fit growth models. No differences between sexes in length and weight at age were observed. The majority of samples had a surplus of males. Diet analysis showed that H. macrochir feeds on Crustacea, Teleostei, Polychaeta, and Cephalopoda, but few prey could be identified to lower taxonomical levels. The mid-Atlantic Ridge constitutes a major portion of the North Atlantic living space of the abyssal halosaur where it completes its full life cycle, primarily as an actively foraging euryophagous micronekton/epibenthos and infauna feeder, becoming a partial piscivore with increasing size.

  15. Analysis of the Spatial and Temporal Distribution of the Seismicity of the Mid-Atlantic Ridge Using the SIRENA and the South Azores Autonomous Hydrophone Arrays

    Simão, N.; Goslin, J.; Perrot, J.; Haxel, J.; Dziak, R.

    2006-12-01

    Acoustic data recorded by two Autonomous Hydrophone Arrays (AHA) were jointly processed in Brest (IUEM) and Newport (PMEL-VENTS) to monitor the seismicity of the Mid-Atlantic Ridge (MAR) over a ten month period, at a wide range of spatial scales. Over the deployment period, nearly 6000 T-phase generating earthquakes were localized using a semi-automatic algorithm. Our analysis of the temporal and spatial distribution of these events combined with their acoustic energy source levels provides important insights for the generation mechanisms and characteristic behavior of MAR seismicity. It shows for the AHA catalog a variation of the cumulative number of events with time almost linear. Taking in account the area inside the arrays, the section of the ridge north of the Azores is more seismically active than the southern part of it and the seismic activity occurs in large localized clusters. Our (AHA) catalog of acoustic events was used to compare locations, focal mechanisms and magnitude observations with correlated data from land-based stations of the NEIC global seismic network to establish completeness levels from both within and outside of the hydrophone array. The (AHA) catalog has a Source Level of Completeness (SLc) of 204dB, and a b-value of 0.0605. The NEIC catalog for this region during this period has a Magnitude of Completeness (Mc) of 4.6 and a b-value of 1.01. Regressing the AHA values onto the NEIC derived Mc/b-value relationship suggests a Mc of 3.2 for the AHA catalog. By restricting the events to the region inside the AHA, the NEIC catalog has an Mc of 4.7 with a b-value of 1.09, while the AHA catalog has a SLc of 205dB with a b-value of 0.0753. Comparing the b-values of the NEIC catalog with the AHA catalog, we obtain an improved Mc of 3.0 for the AHA inside the array. A time- and space-dependent Single-Link-Cluster algorithm was applied to the events localized inside the AHA. This allowed us to gather cluster sequences of earthquakes for higher

  16. Palaeomagnetic constraints on the evolution of the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N)

    Morris, A.; Pressling, N.; Gee, J. S.

    2012-04-01

    Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. They represent a fundamental component of the seafloor spreading system at slow and ultraslow axes. One of the most extensively studied oceanic core complexes is Atlantis Massif, located at 30°N at the intersection of the Atlantis Transform Fault and the Mid Atlantic Ridge (MAR). The central dome of the massif exposes the corrugated detachment fault surface and was drilled during IODP Expedition 304/305 (Hole U1309D). This sampled a 1.4 km faulted and complexly layered footwall section dominated by gabbroic lithologies with minor ultramafic rocks. Palaeomagnetic analyses demonstrate that the gabbroic sequences at Atlantis Massif carry highly stable remanent magnetizations that provide valuable information on the evolution of the section. Thermal demagnetization experiments recover high unblocking temperature components of reversed polarity (R1) throughout the gabbroic sequences. Correlation of structures observed on oriented borehole (FMS) images and those recorded on unoriented core pieces allows reorientation of R1 remanences. The mean remanence direction in true geographic coordinates constrains the tectonic rotation experienced by the Atlantis Massif footwall, indicating a 46°±6° counterclockwise around a MAR-parallel horizontal axis trending 011°±6°. The detachment fault therefore initiated at a steep dip of >50° and then rotated flexurally to its present day low angle geometry (consistent with a 'rolling-hinge' model for detachment evolution). In a number of intervals, the gabbros exhibit a complex remanence structure with the presence of additional intermediate temperature normal (N1) and lower temperature reversed (R2) polarity components, suggesting an extended period of remanence acquisition during different polarity intervals. Sharp break-points between different polarity components suggest

  17. Investigation of extractable organic compounds in deep-sea hydrothermal vent fluids along the Mid-Atlantic Ridge

    McCollom, Thomas M.; Seewald, Jeffrey S.; German, Christopher R.

    2015-05-01

    The possibility that deep-sea hydrothermal vents may contain organic compounds produced by abiotic synthesis or by microbial communities living deep beneath the surface has led to numerous studies of the organic composition of vent fluids. Most of these studies have focused on methane and other light hydrocarbons, while the possible occurrence of more complex organic compounds in the fluids has remained largely unstudied. To address this issue, the presence of higher molecular weight organic compounds in deep-sea hydrothermal fluids was assessed at three sites along the Mid-Atlantic Ridge that span a range of temperatures (51 to >360 °C), fluid compositions, and host-rock lithologies (mafic to ultramafic). Samples were obtained at several sites within the Lucky Strike, Rainbow, and Lost City hydrothermal fields. Three methods were employed to extract organic compounds for analysis, including liquid:liquid extraction, cold trapping on the walls of a coil of titanium tubing, and pumping fluids through cartridges filled with solid phase extraction (SPE) sorbents. The only samples to consistently yield high amounts of extractable organic compounds were the warm (51-91 °C), highly alkaline fluids from Lost City, which contained elevated concentrations of C8, C10, and C12n-alkanoic acids and, in some cases, trithiolane, hexadecanol, squalene, and cholesterol. Collectively, the C8-C12 acids can account for about 15% of the total dissolved organic carbon in the Lost City fluids. The even-carbon-number predominance of the alkanoic acids indicates a biological origin, but it is unclear whether these compounds are derived from microbial activity occurring within the hydrothermal chimney proximal to the site of fluid discharge or are transported from deeper within the system. Hydrothermal fluids from the Lucky Strike and Rainbow fields were characterized by an overall scarcity of extractable dissolved organic compounds. Trace amounts of aromatic hydrocarbons including

  18. Microbial iron mats at the Mid-Atlantic Ridge and evidence that Zetaproteobacteria may be restricted to iron-oxidizing marine systems.

    Jarrod J Scott

    Full Text Available Chemolithoautotrophic iron-oxidizing bacteria play an essential role in the global iron cycle. Thus far, the majority of marine iron-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine iron-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of iron-oxidizing communities at hydrothermal systems along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent systems on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit using the ROV Jason II. The goal of these efforts was to determine if iron-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high iron(II concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial iron mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of iron-oxyhydroxide structures, indicating that active iron-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these iron mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other iron-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an iron source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests

  19. Hydrothermal circulation, serpentinization, and degassing at a rift valley-fracture zone intersection: Mid-Atlantic Ridge near 15[degree]N, 45[degree]W

    Rona, P.A.; Nelson, T.A. (National Oceanic and Atmospheric Administration, Miami, FL (United States)); Bougault, H.; Charlou, J.L.; Needham, H.D. (Inst. Francais de Recherche pour I' Exploitation de la Mer, Centre de Brest (France)); Appriou, P. (Univ. of Western Brittany, Brest (France)); Trefry, J.H. (Florida Inst. of Technology, Melbourne (United States)); Eberhart, G.L.; Barone, A. (Lamont-Doherty Geological Observatory, Palisades, NY (United States))

    1992-09-01

    A hydrothermal system characterized by high ratios of methane to both manganese and suspended particulate matter was detected in seawater sampled at the eastern intersection of the rift valley of the Mid-Atlantic Ridge with the Fifteen-Twenty Fracture Zone. This finding contrasts with low ratios in black smoker-type hydrothermal systems that occur within spreading segments. Near-bottom water sampling coordinated with SeaBeam bathymetry and camera-temperature tows detected the highest concentrations of methane at fault zones in rocks with the appearance of altered ultramafic units in a large dome that forms part of the inside corner high at the intersection. The distinct chemical signatures of the two types of hydrothermal systems are inferred to be controlled by different circulation pathways related to reaction of seawater primarily with ultramafic rocks at intersections of spreading segments with fracture zones but with mafic rocks within spreading segments.

  20. Seismicity And Accretion Processes Along The Mid-Atlantic Ridge south of the Azores using data from the MARCHE Autonomous Hydrophone Array

    Perrot, Julie; Cevatoglu, Melis; Cannat, Mathilde; Escartin, Javier; Maia, Marcia; Tisseau, Chantal; Dziak, Robert; Goslin, Jean

    2013-04-01

    The seismicity of the South Atlantic Ocean has been recorded by the MARCHE network of 4 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed south of the Azores Plateau between 32° and 39°N from July 2005 to August 2008. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation result in a detection threshold reduction from a magnitude completeness level (Mc) of ~4.3 for MAR events recorded by the land-based seismic networks to Mc=2.1 using this hydrophone array. A spatio-temporal analysis has been performed among the 5600 events recorded inside the MARCHE array. Most events are distributed along the ridge between lat. 39°N on the Azores Platform and the Rainbow (36°N) segment. In the hydrophone catalogue, acoustic magnitude (Source Level, SL) is used as a measure of earthquake size. The source level above which the data set is complete is SLc=205 dB. We look for seismic swarms using the cluster software of the SEISAN package. The criterion used are a minimum SL of 210 to detect a possible mainshock, and a radius of 30 km and a time window of 40 days after this mainshock (Cevatoglu, 2010, Goslin et al., 2012). 7 swarms with more than 15 events are identified using this approach between 32°et 39°N of latitude. The maximum number of earthquake in a swarm is 57 events. This result differs from the study of Simao et al. (2010) as we processed a further year of data and selected sequences with fewer events. Looking at the distribution of the SL as a function of time after the mainshock, we discuss the possible mechanism of these earthquakes : tectonic events with a "mainshock-aftershock" distribution fitting a modified Omori law or volcanic events showing more constant SL values. We also present the geophysical setting of these 7 swarms, using gravity, bathymetry, and available local geological data. This study illustrates the potential of

  1. Depth-varying seismogenesis on an oceanic detachment fault at 13°20‧N on the Mid-Atlantic Ridge

    Craig, Timothy J.; Parnell-Turner, Ross

    2017-12-01

    Extension at slow- and intermediate-spreading mid-ocean ridges is commonly accommodated through slip on long-lived faults called oceanic detachments. These curved, convex-upward faults consist of a steeply-dipping section thought to be rooted in the lower crust or upper mantle which rotates to progressively shallower dip-angles at shallower depths. The commonly-observed result is a domed, sub-horizontal oceanic core complex at the seabed. Although it is accepted that detachment faults can accumulate kilometre-scale offsets over millions of years, the mechanism of slip, and their capacity to sustain the shear stresses necessary to produce large earthquakes, remains subject to debate. Here we present a comprehensive seismological study of an active oceanic detachment fault system on the Mid-Atlantic Ridge near 13°20‧N, combining the results from a local ocean-bottom seismograph deployment with waveform inversion of a series of larger teleseismically-observed earthquakes. The unique coincidence of these two datasets provides a comprehensive definition of rupture on the fault, from the uppermost mantle to the seabed. Our results demonstrate that although slip on the deep, steeply-dipping portion of detachment faults is accommodated by failure in numerous microearthquakes, the shallow, gently-dipping section of the fault within the upper few kilometres is relatively strong, and is capable of producing large-magnitude earthquakes. This result brings into question the current paradigm that the shallow sections of oceanic detachment faults are dominated by low-friction mineralogies and therefore slip aseismically, but is consistent with observations from continental detachment faults. Slip on the shallow portion of active detachment faults at relatively low angles may therefore account for many more large-magnitude earthquakes at mid-ocean ridges than previously thought, and suggests that the lithospheric strength at slow-spreading mid-ocean ridges may be concentrated

  2. Hydrothermal sediments as a potential record of seawater Nd isotope compositions: The Rainbow vent site (36°14'N, Mid-Atlantic Ridge)

    Chavagnac, ValéRie; Palmer, Martin R.; Milton, J. Andrew; Green, Darryl R. H.; German, Christopher R.

    2006-09-01

    Geochemical compositions and Sr and Nd isotopes were measured in two cores collected ˜2 and 5 km from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge. Overall, the cores record enrichments in Fe and other metals from hydrothermal fallout, but sequential dissolution of the sediments allows discrimination between a leach phase (easily leachable) and a residue phase (refractory). The oxy-anion and transition metal distribution combined with rare earth element (REE) patterns suggest that (1) the leach fraction is a mixture of biogenic carbonate and hydrothermal Fe-Mn oxy-hydroxide with no significant contribution from detrital material and (2) >99.5% of the REE content of the leach fraction is of seawater origin. In addition, the leach fraction has an average 87Sr/86Sr ratio indistinguishable from modern seawater at 0.70916. Although we lack the ɛNd value of present-day deep water at the Rainbow vent site, we believe that the REE budget of the leach fraction is predominantly of seawater origin. We suggest therefore that the leach fraction provides a record of local seawater ɛNd values. Nd isotope data from these cores span the period of 4-14 ka (14C ages) and yield ɛNd values for North East Atlantic Deep Water (NEADW) that are higher (-9.3 to -11.1) than those observed in the nearby Madeira Abyssal Plain from the same depth (-12.4 ± 0.9). This observation suggests that either the Iceland-Scotland Overflow Water (ISOW) and Lower Deep Water contributions to the formation of NEADW are higher along the Mid-Atlantic Ridge than in the surrounding basins or that the relative proportion of ISOW was higher during this period than is observed today. This study indicates that hydrothermal sediments have the potential to provide a higher-resolution record of deep water ɛNd values, and hence deepwater circulation patterns in the oceans, than is possible from other types of sediments.

  3. Seismic Velocity Variation and Evolution of the Upper Oceanic Crust across the Mid-Atlantic Ridge at 1.3°S

    Jian, H.; Singh, S. C.

    2017-12-01

    The oceanic crust that covers >70% of the solid earth is formed at mid-ocean ridges, but get modified as it ages. Understanding the evolution of oceanic crust requires investigations of crustal structures that extend from zero-age on the ridge axis to old crust. In this study, we analyze a part of a 2000-km-long seismic transect that crosses the Mid-Atlantic Ridge segment at 1.3°S, south of the Chain transform fault. The seismic data were acquired using a 12-km-long multi-sensor streamer and dense air-gun shots. Using a combination of downward continuation and seismic tomography methods, we have derived a high-resolution upper crustal velocity structure down to 2-2.5 km depth below the seafloor, from the ridge axis to 3.5 Ma on both sides of the ridge axis. The results demonstrate that velocities increase at all depths in the upper crust as the crust ages, suggesting that hydrothermal precipitations seal the upper crustal pore spaces. This effect is most significant in layer 2A, causing a velocity increase of 0.5-1 km/s after 1-1.5 Ma, beyond which the velocity increase is very small. Furthermore, the results exhibit a significant decrease in both the frequency and amplitude of the low-velocity anomalies associated with faults beyond 1-1.5 Ma, when faults become inactive, suggesting a linkage between the sealing of fault space and the extinction of hydrothermal activity. Besides, the off-axis velocities are systematically higher on the eastern side of the ridge axis compared to on the western side, suggesting that a higher hydrothermal activity should exist on the outside-corner ridge flank than on the inside-corner flank. While the tomography results shown here cover 0-3.5 Ma crust, the ongoing research will further extend the study area to older crust and also incorporating pre-stack migration and full waveform inversion methods to improve the seismic structure.

  4. Modelling of hydrothermal fluid circulation in a heterogeneous medium: Application to the Rainbow Vent site (Mid-Atlantic-Ridge, 36°14N)

    Perez, F.; Mügler, C.; Jean-Baptiste, P.; Charlou, J. L.

    2012-04-01

    Hydrothermal activity at the axis of mid-ocean ridges is a key driver for energy and matter transfer from the interior of the Earth to the ocean floor. At mid-ocean ridges, seawater penetrates through the permeable young crust, warms at depth and exchanges chemicals with the surrounding rocks. This hot fluid focuses and flows upwards, then is expelled from the crust at hydrothermal vent sites in the form of black or white smokers completed by diffusive emissions. We developed a new numerical tool in the Cast3M software framework to model such hydrothermal circulations. Thermodynamic properties of one-phase pure water were calculated from the IAPWS formulation. This new numerical tool was validated on several test cases of convection in closed-top and open-top boxes. Simulations of hydrothermal circulation in a homogeneous-permeability porous medium also gave results in good agreement with already published simulations. We used this new numerical tool to construct a geometric and physical model configuration of the Rainbow Vent site at 36°14'N on the Mid-Atlantic Ridge. In this presentation, several configurations will be discussed, showing that high temperatures and high mass fluxes measured at the Rainbow site cannot be modelled with hydrothermal circulation in a homogeneous-permeability porous medium. We will show that these high values require the presence of a fault or a preferential pathway right below the venting site. We will propose and discuss a 2-D one-path model that allows us to simulate both high temperatures and high mass fluxes. This modelling of the hydrothermal circulation at the Rainbow site constitutes a first but necessary step to understand the origin of high concentrations of hydrogen issued from this ultramafic-hosted vent field.

  5. 230Th-238U radioactive disequilibria in tholeiites from the FAMOUS zone (Mid-Atlantic Ridge, 36050'N): Th and Sr isotopic geochemistry

    Condomines, M.; Morand, P.; Allegre, C.J.

    1981-01-01

    We analyzed, U, Th and 230 Th/ 232 Th activity ratios for a few tholeiites from the Mid-Atlantic Ridge FAMOUS zone at 36 0 50'N. The results show a fairly wider scatter for both Th/U and ( 230 Th/ 232 Th) ratios. Seawater contamination appears to be responsible for this scatter and, for the uranium, produces an increase in content yielding a ( 234 U/ 238 U) ratio greater than 1 and, for the Th, an increase of the ( 230 Th/ 232 Th) ratio which is a very sensitive indicator for contamination. Also, the latter often is selective: U, Th and Sr are not affected in the same manner. When discarding all data for contaminated samples, the FAMOUS zone appears to be very homogeneous with a Th/U ratio value of 3.05 and a ( 230 Th/ 232 Th) ratio value of 1.24. Comparison with other active volcanic areas reveals a negative correlation between ( 230 Th/ 232 Th) and 87 Sr/ 86 Sr ratios for present lavas which is indicative of a consistency in Th-U and Rb-Sr fractionation in the source regions of these magmas. The Th isotopic geochemistry can thus provide useful information for the study of present volcanism, information as valuable as that from Sr, Pb or Nd isotopes. (orig.)

  6. Microbe-mediated transformations of marine dissolved organic matter during 2,100 years of natural incubation in the cold, oxic crust of the Mid-Atlantic Ridge.

    Shah Walter, S. R.; Jaekel, U.; Huber, J. A.; Dittmar, T.; Girguis, P. R.

    2015-12-01

    On the western flank of the Mid-Atlantic Ridge, oxic seawater from the deep ocean is downwelled into the basaltic crust, supplying the crustal aquifer with an initial inoculum of organic matter and electron acceptors. Studies have shown that fluids circulating within the crust are minimally altered from original seawater, making this subsurface environment a unique natural experiment in which the fate of marine organic matter and the limitations of microbial adaptability in the context of reduced carbon supply can be examined. To make the subsurface crustal aquifer accessible, two CORK (Circulation Obviation Retrofit Kit) observatories have been installed at North Pond, a sediment-filled depression beneath the oligotrophic Sargasso Sea. Radiocarbon analysis of dissolved inorganic (DIC) and organic carbon (DOC) in samples recovered from these observatories show uncoupled aging between DOC and DIC with Δ14C values of DOC as low as -933‰ despite isolation from the open ocean for, at most, 2,100 years. This extreme value is part of a general trend of decreasing DOC δ13C and Δ14C values with increasing incubation time within the aquifer. Combined with reduced concentrations of DOC, our results argue for selective microbial oxidation of the youngest, most 13C-enriched components of downwelled DOC, possibly identifying these as characteristics of the more bioavailable fractions of deep-ocean dissolved organic matter. They also suggest that microbial oxidation during low-temperature hydrothermal circulation could be an important sink for aged marine dissolved organic matter.

  7. Chemical characteristics of hydrothermal fluids from the TAG Mound of the Mid-Atlantic Ridge in August 1994: Implications for spatial and temporal variability of hydrothermal activity

    Gamo, Toshitaka; Chiba, Hitoshi; Masuda, Harue; Edmonds, Henrietta N.; Fujioka, Kantaro; Kodama, Yukio; Nanba, Hiromi; Sano, Yuji

    The TAG hydrothermal mound on the Mid-Atlantic Ridge (26°08‧N, 44°50‧W) was revisited in August 1994 with the submersible Shinkai 6500 in order to characterize time-series fluid chemistry prior to the ODP drilling. Fluid samples were taken from both black smokers and white smokers. Si, pH, alkalinity, H2S, major cations (Na+, K+, Ca2+, Mg2+), major anions (Cl-, SO42-), and minor elements (Li, Sr, B, Fe, Mn, Cu, Zn, Br) as well as Sr isotope ratios were measured. We report the first Br/Cl ratios for the TAG hydrothermal fluids, showing no fractionation between Br and Cl during the fluid-rock interaction. This study shows small changes in composition of the black smoker fluids from the 1990 data (Edmond et al., 1995). Changes of pH, alkalinity, Fe, K, and 87Sr/86Sr values are suggestive of subsurface FeS precipitation and a decrease of water/rock ratio at a deeper reaction zone. Differences in chemical characteristics between the black and white smoker fluids were similarly observed as in 1990.

  8. Joint inversion of shear wave travel time residuals and geoid and depth anomalies for long-wavelength variations in upper mantle temperature and composition along the Mid-Atlantic Ridge

    Sheehan, Anne F.; Solomon, Sean C.

    1991-01-01

    Measurements were carried out for SS-S differential travel time residuals for nearly 500 paths crossing the northern Mid-Atlantic Ridge, assuming that the residuals are dominated by contributions from the upper mantle near the surface bounce point of the reflected phase SS. Results indicate that the SS-S travel time residuals decrease linearly with square root of age, to an age of 80-100 Ma, in general agreement with the plate cooling model. A joint inversion was formulated of travel time residuals and geoid and bathymetric anomalies for lateral variation in the upper mantle temperature and composition. The preferred inversion solutions were found to have variations in upper mantle temperature along the Mid-Atlantic Ridge of about 100 K. It was calculated that, for a constant bulk composition, such a temperature variation would produce about a 7-km variation in crustal thickness, larger than is generally observed.

  9. Mechanical Mixing and Metamorphism of Mafic and Ultramafic Lithologies during Mylonisis at the ST. Paul Transform System, Mid-Atlantic Ridge

    Adrião, Á.; Maia, M.; Hemond, C.; Kaczmarek, M. A.; Briais, A.; Vincent, C.; Brunelli, D.

    2017-12-01

    The St. Paul Transform System offsets by 630 km the Equatorial Mid Atlantic Ridge at 1° N. It consists of four major faults separating three intra transform ridge axes. This region shows a transition from a transpressive, hot spot affected, regional-scale shear zone to the North to a region dominated by a particular oceanic core complex spreading to the South (Vincent et al., this congress). Samples collected in the region during the COLMEIA cruise (Maia et al., 2016) were studied for textures and whole-rock major and trace element contents. All samples experienced pervasive deformation at ductile to brittle conditions overprinted by late low-T alteration. Mylonitic and ultramylonitic rocks can be grouped in three main types: peridotitic, gabbroic and talc-chlorite schist. Peridotitic ultramylonites preserve few opx, cpx and sp porphyroclasts; they have homogeneous nano-micro grain size groundmass, banded foliation and late amphibole and sulfide crystallization. Locally S-C fabric overprints the mylonitic texture. Micro cracks, filled with serpentine, chlorite and oxides are common, as well fluid inclusions trails in olivine and plagioclase crystals of peridotite and gabbros respectively. Major and trace element content of the peridotitic mylonites plot in the depleted field of the abyssal peridotites; however, they present marked LREE enrichment and Eu positive anomaly. Gabbroic and talc-chlorite mylonites display REE-enriched patterns (up to 100x CI) and variable Eu anomalies. Major elements show a remarkable linear trend in the talc-chlorite group suggesting mixing of pure talc and chlorite end-members. These compositional characteristics suggest variable assimilation of MORB and E-MORB during mylonisis or early melt-rock interaction and hydrothermal evolution at variable metamorphic conditions. Vincent et al., 2017. Particular Oceanic Core Complex evolution …; this congress Maia et al., 2016. Extreme mantle uplift and exhumation ... Nat. Geo. doi:10

  10. The ecosystem of the Mid-Atlantic Ridge at the sub-polar front and Charlie-Gibbs Fracture Zone; ECO-MAR project strategy and description of the sampling programme 2007-2010

    Priede, Imants G.; Billett, David S. M.; Brierley, Andrew S.; Hoelzel, A. Rus; Inall, Mark; Miller, Peter I.; Cousins, Nicola J.; Shields, Mark A.; Fujii, Toyonobu

    2013-12-01

    The ECOMAR project investigated photosynthetically-supported life on the North Mid-Atlantic Ridge (MAR) between the Azores and Iceland focussing on the Charlie-Gibbs Fracture Zone area in the vicinity of the sub-polar front where the North Atlantic Current crosses the MAR. Repeat visits were made to four stations at 2500 m depth on the flanks of the MAR in the years 2007-2010; a pair of northern stations at 54°N in cold water north of the sub-polar front and southern stations at 49°N in warmer water influenced by eddies from the North Atlantic Current. At each station an instrumented mooring was deployed with current meters and sediment traps (100 and 1000 m above the sea floor) to sample downward flux of particulate matter. The patterns of water flow, fronts, primary production and export flux in the region were studied by a combination of remote sensing and in situ measurements. Sonar, tow nets and profilers sampled pelagic fauna over the MAR. Swath bathymetry surveys across the ridge revealed sediment-covered flat terraces parallel to the axis of the MAR with intervening steep rocky slopes. Otter trawls, megacores, baited traps and a suite of tools carried by the R.O.V. Isis including push cores, grabs and a suction device collected benthic fauna. Video and photo surveys were also conducted using the SHRIMP towed vehicle and the R.O.V. Isis. Additional surveying and sampling by landers and R.O.V. focussed on the summit of a seamount (48°44‧N, 28°10‧W) on the western crest of the MAR between the two southern stations.

  11. Variations in deep-sea hydrothermal vent communities on the Mid-Atlantic Ridge near the Azores plateau

    Desbruyères, D.; Biscoito, M.; Caprais, J.-C.; Colaço, A.; Comtet, T.; Crassous, P.; Fouquet, Y.; Khripounoff, A.; Le Bris, N.; Olu, K.; Riso, R.; Sarradin, P.-M.; Segonzac, M.; Vangriesheim, A.

    2001-05-01

    Near the Azores Triple Junction as the Azores Plateau is approached, the ridge axis becomes shallower; its depth decreases from ca. 2400 m in the R AINBOW vent field (36°13'N) to ca. 850 m in the M ENEZ G WEN vent field (37°35'N). In this area, extensive mussel beds of the mytilid Bathymodiolus azoricus dominate the hydrothermal vent fauna, along with populations of three shrimps ( Rimicaris exoculata, Mirocaris fortunata and Chorocaris chacei). The main physical and chemical characteristics of the vent habitat were studied by discrete sampling, in situ analysis and sediment trap moorings. The vent fauna is distributed along a variable band where the vent fluids and seawater mix, with R. exoculata living in the most concentrated areas and Bathymodiolus azoricus in the most diluted zones. Various non-endemic species live at the border of the vent field. The variations observed in structure and composition of the communities along the depth gradient are most likely due to changes in vent fluid toxicity (metallic and sulphide content) and suspended mineral particles, which render the fluids harsher for species living there. The main faunal differences observed between L UCKY S TRIKE and M ENEZ G WEN hydrothermal fields are due to an impoverishment in the hydrothermal endemic species and to the penetration of bathyal species. The comparison of the three studied vent fields suggests the existence of a succession of several biogeographic islands rather than a single province.

  12. Structural Iron (II) of Basaltic Glass as an Energy Source for Zetaproteobacteria in an Abyssal Plain Environment, Off the Mid Atlantic Ridge.

    Henri, Pauline A; Rommevaux-Jestin, Céline; Lesongeur, Françoise; Mumford, Adam; Emerson, David; Godfroy, Anne; Ménez, Bénédicte

    2015-01-01

    To explore the capability of basaltic glass to support the growth of chemosynthetic microorganisms, complementary in situ and in vitro colonization experiments were performed. Microbial colonizers containing synthetic tholeitic basaltic glasses, either enriched in reduced or oxidized iron, were deployed off-axis from the Mid Atlantic Ridge on surface sediments of the abyssal plain (35°N; 29°W). In situ microbial colonization was assessed by sequencing of the 16S rRNA gene and basaltic glass alteration was characterized using Scanning Electron Microscopy, micro-X-ray Absorption Near Edge Structure at the Fe-K-edge and Raman microspectroscopy. The colonized surface of the reduced basaltic glass was covered by a rind of alteration made of iron-oxides trapped in a palagonite-like structure with thicknesses up to 150 μm. The relative abundance of the associated microbial community was dominated (39% of all reads) by a single operational taxonomic unit (OTU) that shared 92% identity with the iron-oxidizer Mariprofundus ferrooxydans PV-1. Conversely, the oxidized basaltic glass showed the absence of iron-oxides enriched surface deposits and correspondingly there was a lack of known iron-oxidizing bacteria in the inventoried diversity. In vitro, a similar reduced basaltic glass was incubated in artificial seawater with a pure culture of the iron-oxidizing M. ferrooxydans DIS-1 for 2 weeks, without any additional nutrients or minerals. Confocal Laser Scanning Microscopy revealed that the glass surface was covered by twisted stalks characteristic of this iron-oxidizing Zetaproteobacteria. This result supported findings of the in situ experiments indicating that the Fe(II) present in the basalt was the energy source for the growth of representatives of Zetaproteobacteria in both the abyssal plain and the in vitro experiment. In accordance, the surface alteration rind observed on the reduced basaltic glass incubated in situ could at least partly result from their activity.

  13. Mapping Shear-wave Velocity Structures of the "African Anomaly" Along a Northwest to Southeast Arc From New Zealand to the Mid-Atlantic Ridge

    Frodsham, A. E.; Wen, L.

    2006-12-01

    A previous study [Wang and Wen, 2006] investigated the geometry and shear velocity structure of the "African Anomaly" along a great circle arc from the East Pacific Rise to the Japan Sea, and concluded the anomaly extends 1300 km above the core-mantle boundary, that the sides of the anomaly slope towards the apex and has velocity deviations of -5% in the base and -2% to -3% in the mid-lower mantle. Wang and Wen [2004] also reported on the very low velocity province that forms the base of the "African Anomaly" and its lateral extent, but the northern edge of the anomaly was poorly constrained because of the nature of the seismic data. In this presentation we focus on the nature of the anomaly in a cross-section of the mantle along a great arc, from New Zealand, to the Mid-Atlantic Ridge off the coast of Newfoundland, centered over the anomaly. In particular, we focus on the northern edge of the "African Anomaly" where a paucity of large, deep focus earthquakes makes seismic arrivals from the northwest difficult to analyze. We map the lateral extent, thickness, and shear velocity structures of the "African Anomaly" on the basis of forward travel time and waveform modeling of direct S, ScS, and SKS waves. Seismic data used in this study were collected from PASSCAL arrays: KAAPVAAL seismic array (operating years 1997-1999), Tanzania seismic array (1994- 1995), Ethiopia/Kenya seismic array (2000-2002), and the Global Seismographic Network (1994-2002). We minimize uncertainty from earthquake mislocation by relocation of the earthquakes using a global tomographic shear wave velocity model and also correct for heterogeneities outside the anomaly. We explore various methods of data processing, such as frequency filtration, low fold stacking, and cross correlation, to best interpret the arrival times of the various seismic phases and constrain the nature of the "African Anomaly" along a northwest to southeast cross-section.

  14. Meso- and bathy-pelagic fish parasites at the Mid-Atlantic Ridge (MAR): Low host specificity and restricted parasite diversity

    Klimpel, Sven; Busch, Markus Wilhelm; Sutton, Tracey; Palm, Harry Wilhelm

    2010-04-01

    Seven meso- and bathy-pelagic fish species from the Mid-Atlantic Ridge (MAR) were firstly studied for fish parasites and feeding ecology. With a total of seven parasite species, the 247 meso- and bathy-pelagic deep-sea fish specimens belonging to the families Melamphaidae (3 spp.), Myctophidae (3 spp.) and Stomiidae (1 sp.) revealed low parasite diversity. The genetically identified nematodes Anisakis simplex (s.s.) and Anisakis pegreffii from the body cavity, liver and muscles of Myctophum punctatum were the most abundant parasites, reaching a prevalence of 91.4% and mean intensity of 3.1 (1-14). Anisakis sp. (unidentified) infected Chauliodus sloani and Poromitra crassiceps. Bothriocephalidean and tetraphyllidean cestode larvae infected Benthosema glaciale, the latter also occurring in C. sloani and Scopelogadus beanii, at low prevalences. Adult parasites at low infection rates included the digenean Lethadena sp. (2.9%), and the two copepod species Sarcotretes scopeli (5.7%) and Tautochondria dolichoura (5.3-11.4%). The myctophid Lampanyctus macdonaldi and the melamphaid Scopelogadus mizolepis mizolepis were free of parasites. Analyses of the stomach contents revealed crustaceans, especially copepods and euphausiids for the myctophids and also amphipods for the melamphaids as predominant prey items. While all stomachs showing distinct content comprising often unidentified 'tissue' (possibly gelatinous zooplankton), only C. sloani preyed upon fish. Though this feeding habit would enable transfer of a variety of crustacean-transmitted parasites into the fish, the parasite fauna in the meso- and bathy-pelagic fish was species poor. All observed parasites showed low host specificity, demonstrating no distinct pattern of host-parasite co-evolution. The MAR is no barrier for the parasite distribution in the North Atlantic meso- and bathy-pelagial.

  15. First data on benthic and fish communities from the Mid-Atlantic Ridge, 16°40‧- 17°14‧N

    Molodtsova, Tina N.; Galkin, Sergey V.; Kobyliansky, Stanislav G.; Simakova, Ulyana V.; Vedenin, Andrey A.; Dobretsova, Irina G.; Gebruk, Andrey V.

    2017-03-01

    The first ecological survey in the tropical part of the northern Mid-Atlantic Ridge (MAR) was conducted between 17°14‧N and 16°40‧N in February-March 2015 during the 37th cruise of the RV Professor Logachev. Significant effort of the survey was aimed at studies of benthic non-vent soft sediment fauna at depths from 2270 m to 3900 m. Samples of this fauna at seven stations revealed 780 specimens and at least 136 species. The most common species was the hermit crab Parapagurus cf. nudus. Also common were the ophiuroids Ophiotypa simplex and Ophiomusium cf. lymani. Most benthic organisms were the depth range from 0 to 3850 m included 1128 specimens represented by 48 species from 16 families. The highest number of species was in the families Myctophidae (18), Gonostomatidae (9) and Sternoptychidae (5). In the course of the cruise, two new fields of massive sulphide deposits were discovered on the south-western slope of the seamount on the eastern flank of the rift valley, one at 17°08.7‧N and second at 17°07.45‧N. During video profiling in this area indications of modern hydrothermal activity were recorded. Extensive fields of shells of Bathymodiolus puteoserpentis and Thyasira sp. were discovered and samples of bivalves were taken using the TV-grab and geological square corer. Surprisingly high concentration of drowned pelagic algae Sargassum sp. (Phaeophyceae, Fucales) in different state of degradation was observed at TV transects at the seafloor both on soft and hard substrates. Thalli of Sargassum fluitans appeared in trawl catches. Massive aggregations of Sargassum also were abundant at the sea surface in the area from December 2014 to April 2015.

  16. Long-Term Seismicity of Northern (15° N-60° N) Mid-Atlantic Ridge (MAR) Recorded by two Regional Hydrophone Arrays: a Widespread Along-Ridge Influence of the Azores and Iceland Hotspots

    Goslin, J.; Bazin, S.; Dziak, R. P.; Fox, C.; Fowler, M.; Haxel, J.; Lourenco, N.; Luis, J.; Martin, C.; Matsumoto, H.; Perrot, J.; Royer, J.

    2004-12-01

    The seismicity of the North Atlantic was recorded by two networks of hydrophones moored in the SOFAR channel, north and south of the Azores Plateau. The interpretation of the hydro-acoustic signals recorded during the first six-month common period of operation of the two networks (June 2002 to Nov. 2002) provides a unique data set on the spatial and time distributions of the numerous low-magnitude earthquakes which occurred along the Mid-Atlantic Ridge. Close to 2000 events were localized during this six-month period between latitudes 15° N and 63° N, 501 of which are localized within the SIRENA network (40° N-51° N) and 692 within the wider South Azores network (17° N-33° N). Using hydrophones to locate seafloor earthquakes by interpreting T-wave signals lowers the detection threshold of Mid-Atlantic Ridge events to 3.0 mb from the 4.7 mb of global seismic networks. This represents an average thirty-fold increase in the number of events: 62 events were detected by global seismological networks within the same area during the same period. An along-ridge spatial distribution of the seismicity is obtained by computing the cumulated numbers of events in 1° -wide latitudinal bins. When plotted vs. latitude, this first-order distribution shows remarkable long-wavelength patterns: the seismicity rate is low when approaching the Azores and Iceland (reaching values as low as 10 events/d° ), while it peaks to 70 events/d° in the vicinity of the Gibbs FZ. Moreover, the latitudinal distribution of the seismicity hints at an asymmetric influence of the Azores hotpot on the MAR. Finally, the spatial distribution of the seismicity anti-correlates well at long wavelengths with the zero-age depths along the MAR and correlates with the zero-age Mantle Bouguer (MBA) anomaly values and the Vs velocity anomalies at 100 km in the upper mantle. It is thus proposed that the seismicity level would be partly tied to the rheology and thickness of the brittle layer and be thus

  17. Copepod colonization of organic and inorganic substrata at a deep-sea hydrothermal vent site on the Mid-Atlantic Ridge

    Plum, Christoph; Pradillon, Florence; Fujiwara, Yoshihiro; Sarrazin, Jozée

    2017-03-01

    The few existing studies on deep-sea hydrothermal vent copepods indicate low connectivity with surrounding environments and reveal high endemism among vents. However, the finding of non-endemic copepod species in association with engineer species at different reduced ecosystems poses questions about the dispersal of copepods and the colonization of hydrothermal vents as well as their ecological connectivity. The objective of this study is to understand copepod colonization patterns at a hydrothermal vent site in response to environmental factors such as temperature and fluid flow as well as the presence of different types of substrata. To address this objective, an in situ experiment was deployed using both organic (woods, pig bones) and inorganic (slates) substrata along a gradient of hydrothermal activity at the Lucky Strike vent field (Eiffel Tower, Mid-Atlantic Ridge). The substrata were deployed in 2011 during the MoMARSAT cruise and were recovered after two years in 2013. Overall, copepod density showed significant differences between substrata types, but was similar among different hydrothermal activity regimes. Highest densities were observed on woods at sites with moderate or low fluid input, whereas bones were the most densely colonized substrata at the 2 sites with higher hydrothermal influence. Although differences in copepod diversity were not significant, the observed trends revealed overall increasing diversity with decreasing temperature and fluid input. Slates showed highest diversity compared to the organic substrata. Temperature and fluid input had a significant influence on copepod community composition, resulting in higher similarity among stations with relatively high and low fluid inputs, respectively. While vent-specialists such as dirivultids and the tegastid Smacigastes micheli dominated substrata at high vent activity, the experiment demonstrated increasing abundance and dominance of non-vent taxa with decreasing temperature and fluid

  18. Recent massive sulfide deposits of the Semenov ore district, Mid-Atlantic Ridge, 13°31' N: Associated rocks of the oceanic core complex and their hydrothermal alteration

    Pertsev, A. N.; Bortnikov, N. S.; Vlasov, E. A.; Beltenev, V. E.; Dobretsova, I. G.; Ageeva, O. A.

    2012-09-01

    The oceanic core complexes and large-offset detachment faults characteristic of the slow-spreading Mid-Atlantic Ridge are crucial for the structural control of large hydrothermal systems, including those forming sub-seafloor polymetallic sulfide mineralization. The structural-geological, petrographic, and mineralogical data are considered for the oceanic core complex enclosing the Semenov-1, -2, -3, -4, and -5 inactive hydrothermal sulfide fields recently discovered on the Mid-Oceanic Ridge at 13°31' N. The oceanic core complex is composed of serpentinized and talc-replaced peridotites and sporadic gabbroic rocks, however, all hydrothermal fields reveal compositional indications of basaltic substrate. The volcanic structures superposed on the oceanic core complex are marked by outcrops of pillow lavas with fresh quenched glass. Dolerites regarded as volcanic conduits seem to represent separate dike swarms. The superposed volcanic structures develop largely along the near-latitudinal high-angle tectonic zone controlling the Semenov-1, -2, -5, and -3 hydrothermal sulfide fields. The manifestations of hydrothermal metasomatic alteration are diverse. The widespread talcose rocks with pyrrhotite-pyrite mineralization after serpentinite, as well as finding of talc-chlorite metabasalt are interpreted as products of hydrothermal activity in the permeable zone of detachment fault. Chloritization and brecciation of basalts with superposed quartz or opal, barite, and pyrite or chalcopyrite mineralization directly related to the sub-seafloor sulfide deposition. The native copper mineralization in almost unaltered basalts at the Semenov-4 field is suggested to precipitate from ore-forming fluids before they reach the level of sub-seafloor sulfide deposition. Amphibolites with plagiogranite veinlets are interpreted as tectonic fragments of the highest-temperature portions of hydrothermal systems, where partial melting of basic rocks in the presence of aqueous fluid with

  19. Behavioural study of two hydrothermal crustacean decapods: Mirocaris fortunata and Segonzacia mesatlantica, from the Lucky Strike vent field (Mid-Atlantic Ridge)

    Matabos, M.; Cuvelier, D.; Brouard, J.; Shillito, B.; Ravaux, J.; Zbinden, M.; Barthelemy, D.; Sarradin, P. M.; Sarrazin, J.

    2015-11-01

    Identifying the factors driving community dynamics in hydrothermal vent communities, and in particular biological interactions, is challenged by our ability to make direct observations and the difficulty to conduct experiments in those remote ecosystems. As a result, we have very limited knowledge on species' behaviour and interactions in these communities and how they in turn influence community dynamics. Interactions such as competition or predation significantly affect community structure in vent communities, and video time-series have successfully been used to gain insights in biological interactions and species behaviour, including responses to short-term changes in temperature or feeding strategies. In this study, we combined in situ and ex situ approaches to characterise the behaviour and interactions among two key species encountered along the Mid-Atlantic Ridge (MAR): the shrimp Mirocaris fortunata and the crab Segonzacia mesatlantica. In situ, species small-scale distribution, interactions and behaviour were studied using the TEMPO observatory module deployed on the seafloor at the base of the active Eiffel Tower edifice in the Lucky Strike vent field as part of the EMSO-Açores MoMAR observatory. TEMPO sampled 2 min of video four times a day from July 2011 to April 2012. One week of observations per month was used for 'long-term' variations, and a full video data set was analysed for January 2012. In addition, observations of crab and shrimp individuals maintained for the first time under controlled conditions in atmospheric pressure (classic tank) and pressurised (AbyssBox) aquaria allowed better characterisation and description of the different types of behaviour and interactions observed in nature. While the identified in situ spatial distribution pattern was stable over the nine months, both species displayed a significant preference for mussel bed and anhydrite substrata, and preferentially occupied the area located directly in the fluid flow axis

  20. Spatiotemporal distribution of the seismicity along the Mid-Atlantic Ridge north of the Azores from hydroacoustic data: Insights into seismogenic processes in a ridge-hot spot context

    Goslin, J.; Perrot, J.; Royer, J.-Y.; Martin, C.; LourençO, N.; Luis, J.; Dziak, R. P.; Matsumoto, H.; Haxel, J.; Fowler, M. J.; Fox, C. G.; Lau, A. T.-K.; Bazin, S.

    2012-02-01

    The seismicity of the North Atlantic was monitored from May 2002 to September 2003 by the `SIRENA array' of autonomous hydrophones. The hydroacoustic signals provide a unique data set documenting numerous low-magnitude earthquakes along the section of the Mid-Atlantic Ridge (MAR) located in a ridge-hot spot interaction context. During the experiment, 1696 events were detected along the MAR axis between 40°N and 51°N, with a magnitude of completeness level ofmb≈ 2.4. Inside the array, location errors are in the order of 2 km, and errors in the origin time are less than 1 s. From this catalog, 15 clusters were detected. The distribution of source level (SL) versus time within each cluster is used to discriminate clusters occurring in a tectonic context from those attributed to non-tectonic (i.e. volcanic or hydrothermal) processes. The location of tectonic and non-tectonic sequences correlates well with regions with positive and negative Mantle Bouguer Anomalies (MBAs), indicating the presence of thinner/colder and thicker/warmer crust respectively. At the scale of the entire array, both the complete and declustered catalogs derived from the hydroacoustic signals show an increase of the seismicity rate from the Azores up to 43°30'N suggesting a diminishing influence of the Azores hot spot on the ridge-axis temperature, and well correlated with a similar increase in the along-axis MBAs. The comparison of the MAR seismicity with the Residual MBA (RMBA) at different scales leads us to think that the low-magnitude seismicity rates are directly related to along-axis variations in lithosphere rheology and temperatures.

  1. Intense CH{sub 4} plumes generated by serpentinization of ultramafic rocks at the intersection of the 15{degree}20[minutes]N fracture zone and the Mid-Atlantic Ridge

    Charlou, J.L.; Fouquet, Y.; Bougault, H.; Donval, J.P.; Etoubleau, J. [IFREMER Centre de Brest, Plouzane (France). Dept. Geosciences Marines; Jean-Baptiste, P.; Dapoigny, A. [CEA Saclay, Gif-sur-Yvette (France); Appriou, P. [Univ. de Bretagne Occidentale, Brest (France); Rona, P.A. [Rutgers-the State Univ. of New Jersey, New Brunswick, NJ (United States)

    1998-07-01

    As part of the FARA French-US Program designed to study the Mid-Atlantic Ridge (MAR) between 15{degree}N and the Azores, twenty-three dives with the submersible Nautile were conducted during the French-US Faranaut 15N cruise on the eastern and western parts of the Fracture Zone/Ridge axis intersection. South of the eastern ridge-transform fault intersection, nine Nautile dives were made within the rift valley and along the western rift valley wall. CH{sub 4} concentrations in the bottom waters reach 53.2 nmol/kg along faulted zones on top and on the east flank of the ultramafic inner corner high where serpentinized rocks outcrop. No {sup 3}He anomaly is associated with methane, ruling out any primary mantle component. High CH{sub 4} anomalies (up to 22 nmol/kg) are also present in the bottom waters of the rift valley northern segment on both the western and eastern valley walls and on the inner high adjacent to the eastern wall where ultramafic rocks outcrop. Seven vertical hydrocasts carried out in the axial valley (4500 M deep) show an intense CH{sub 4} anomaly, with a maximum (35.8 nmol/kg) at 3200 m depth. CH{sub 4} concentrations of 9.9--14.9 nmol/kg are also present on the western wall along the 3200 m isobath. CH{sub 4} output from ultramafic outcrops on the western and eastern intersections of the Fracture Zone with the MAR is believed to reflect ongoing serpentinization.

  2. Different TDM/CH4 hydrothermal plume signatures: TAG site at 26N and serpentinized ultrabasic diapir at 15 degrees 05'N on the Mid-Atlantic ridge

    Charlou, J.L.; Bougault, H. (IFREMER Centre de Brest, Plouzane (France)); Appriou, P. (Univ. de Bretagne Occidentale, Brest (France)); Nelsen, T.; Rona, P. (NOAA-AOML-OCD, Miami, FL (United States))

    1991-11-01

    As a part of the 1988 NOAA VENTS Program, CH{sub 4} and Mn tracers were used to identify and compare hydrothermal plumes found above the TAG Field (26{degrees}N) and in the rift valley at 15{degrees}N close to the eastern intersection of the ridge axis with the 15{degrees}20'N Fracture Zone at the Mid-Atlantic Ridge (MAR). Active hydrothermal venting was confirmed at TAG, based on elevated concentrations of total dissolved Mn (TDM up to 30 nmol/kg), high CH{sub 4} concentrations (up to 200 nL/L), and elevated nephelometry signals. Plumes of a different composition were identified at 15{degree}N with high CH{sub 4} concentrations (up to 400 nL/L), low total dissolved Mn concentrations (TDM < 1 nmol/kg) and no significant nephelometry signal. The different properties of these tracers and the different tracer ratios can be used to deduce vent fluid characteristics and compare one hydrothermal area to another. TDM/CH{sub 4} and Nephel/CH{sub 4} ratios at TEG are of the same order of magnitude as those observed at other spreading axis hydrothermal fields. At 15{degrees}N, the low TDM/CH{sub 4} ratio provides evidence of fluid circulation into ultrabasic rocks and offers a potentially useful and single method of exploring for hydrothermal activity associated with serpentinization. Mantle degassing through hydrothermal activity associated with serpentinization is an important process with respect to chemical and thermal exchanges between the upper mantle and the ocean. Different ratios of hydrothermal tracers (i.e., TDM/CH{sub 4}) provide a useful framework for identifying subseafloor processes along mid-oceanic ridges.

  3. Deformation associated with the denudation of mantle-derived rocks at the Mid-Atlantic Ridge 13°-15°N: The role of magmatic injections and hydrothermal alteration

    Picazo, Suzanne; Cannat, Mathilde; Delacour, AdéLie; EscartíN, Javier; RouméJon, StéPhane; Silantyev, Sergei

    2012-09-01

    Outcrops of deeply derived ultramafic rocks and gabbros are widespread along slow spreading ridges where they are exposed in the footwall of detachment faults. We report on the microstructural and petrological characteristics of a large number of samples from ultramafic exposures in the walls of the Mid-Atlantic Ridge (MAR) axial valley at three distinct locations at lat. 13°N and 14°45'N. One of these locations corresponds to the footwall beneath a corrugated paleo-fault surface. Bearing in mind that dredging and ROV sampling may not preserve the most fragile lithologies (fault gouges), this study allows us to document a sequence of deformation, and the magmatic and hydrothermal history recorded in the footwall within a few hundred meters of the axial detachment fault. At the three sampled locations, we find that tremolitic amphiboles have localized deformation in the ultramafic rocks prior to the onset of serpentinization. We interpret these tremolites as hydrothermal alteration products after evolved gabbroic rocks intruded into the peridotites. We also document two types of brittle deformation in the ultramafic rocks, which we infer could produce the sustained low magnitude seismicity recorded at ridge axis detachment faults. The first type of brittle deformation affects fresh peridotite and is associated with the injection of the evolved gabbroic melts, and the second type affects serpentinized peridotites and is associated with the injection of Si-rich hydrothermal fluids that promote talc crystallization, leading to strain localization in thin talc shear zones. We also observed chlorite + serpentine shear zones but did not identify samples with serpentine-only shear zones. Although the proportion of magmatic injections in the ultramafic rocks is variable, these characteristics are found at each investigated location and are therefore proposed as fundamental components of the deformation in the footwall of the detachment faults associated with denudation of

  4. Uranium accumulation in modern and ancient Fe-oxide sediments: Examples from the Ashadze-2 hydrothermal sulfide field (Mid-Atlantic Ridge) and Yubileynoe massive sulfide deposit (South Urals, Russia)

    Ayupova, N. R.; Melekestseva, I. Yu.; Maslennikov, V. V.; Tseluyko, A. S.; Blinov, I. A.; Beltenev, V. E.

    2018-05-01

    Fe-oxyhydroxide sediments (gossans) from the Ashadze-2 hydrothermal sulfide field (Mid-Atlantic Ridge) and hematite-carbonate-quartz rocks (gossanites) from the Yubileynoe Cu-Zn VHMS deposit (South Urals) are characterized by anomalously high U contents (up to 352 ppm and 73 ppm, respectively). In gossans from the Ashadze-2 hydrothermal sulfide field, rare isometric anhedral uraninite grains (up to 2 μm) with outer P- and Ca-rich rims, and numerous smaller (<1 μm) grains, occur in Fe-oxyhydroxides and sepiolite, associated with pyrite, isocubanite, chalcopyrite, galena, atacamite and halite. In gossanites from the Yubileynoe deposit, numerous uraninite particles (<3 μm) are associated with apatite, V-rich Mg-chlorite, micro-nodules of pyrite, Se-bearing galena, hessite and acanthite in a hematite-carbonate-quartz matrix. Small (1-3 μm) round grains of uraninite, which locally coalesce to large grains up to 10 μm in size, are associated with authigenic chalcopyrite. The similar diagenetic processes of U accumulation in modern and ancient Fe-oxyhydroxide sediments were the result of U fixation from seawater during the oxidation of sulfide minerals. Uraninite in gossanites was mainly deposited from diagenetic pore fluids, which circulated in the sulfide-hyaloclast-carbonate sediments.

  5. Characterisation of dissolved organic compounds in hydrothermal fluids by stir bar sorptive extraction - gas chomatography - mass spectrometry. Case study: the Rainbow field (36°N, Mid-Atlantic Ridge

    Konn Cecile

    2012-11-01

    Full Text Available Abstract The analysis of the dissolved organic fraction of hydrothermal fluids has been considered a real challenge due to sampling difficulties, complexity of the matrix, numerous interferences and the assumed ppb concentration levels. The present study shows, in a qualitative approach, that Stir Bar Sorptive Extraction (SBSE followed by Thermal Desorption – Gas Chromatography – Mass Spectrometry (TD-GC-MS is suitable for extraction of small sample volumes and detection of a wide range of volatile and semivolatile organic compounds dissolved in hydrothermal fluids. In a case study, the technique was successfully applied to fluids from the Rainbow ultramafic-hosted hydrothermal field located at 36°14’N on the Mid-Atlantic Ridge (MAR. We show that n-alkanes, mono- and poly- aromatic hydrocarbons as well as fatty acids can be easily identified and their retention times determined. Our results demonstrate the excellent repeatability of the method as well as the possibility of storing stir bars for at least three years without significant changes in the composition of the recovered organic matter. A preliminary comparative investigation of the organic composition of the Rainbow fluids showed the great potential of the method to be used for assessing intrafield variations and carrying out time series studies. All together our results demonstrate that SBSE-TD-GC-MS analyses of hydrothermal fluids will make important contributions to the understanding of geochemical processes, geomicrobiological interactions and formation of mineral deposits.

  6. Tissue and size-related changes in the fatty acid and stable isotope signatures of the deep sea grenadier fish Coryphaenoides armatus from the Charlie-Gibbs Fracture Zone region of the Mid-Atlantic Ridge

    Mayor, Daniel J.; Sharples, Caroline J.; Webster, Lynda; Walsham, Pamela; Lacaze, Jean-Pierre; Cousins, Nicola J.

    2013-12-01

    Coryphaenoides armatus is a cosmopolitan deep-sea fish that plays a major role in the ecology of abyssal ecosystems. We investigated the trophic ecology and physiology of this species by determining the δ13C, δ15N and fatty acid signatures of muscle, liver and ovary tissues of individuals collected from ∼2700 m to the north and south of the Charlie-Gibbs Fracture Zone (CGFZ) of the Mid-Atlantic Ridge, NE Atlantic. Fatty acid and δ13C data both suggested that C. armatus shows an ontogenetic dietary shift, with the relative contributions of benthic and pelagic prey decreasing and increasing respectively as the animals grow. They also indicated that dietary overlap between animals living to the north and south of the CGFZ increases as they grow, suggesting that larger animals forage over greater distances and are not hindered by the presence of the CGFZ. Comparison of tissue-specific fatty acid signatures with previously published data suggests compositional homeostasis of the fatty acids 20:5(n-3) and 22:6(n-3) in the muscle, and 18:1(n-9) in the liver tissues. We ascribe this primarily to strict physiological requirements for these compounds, rather than simply to their abundance in the diet. We pose several speculative mechanisms to explain the observed trends in tissue-specific δ13C and δ15N values, illustrating some of the numerous processes that can influence the isotopic signatures of bulk tissues.

  7. Bimodal volcanism in northeast Puerto Rico and the Virgin Islands (Greater Antilles Island Arc): Genetic links with Cretaceous subduction of the mid-Atlantic ridge Caribbean spur

    Jolly, Wayne T.; Lidiak, Edward G.; Dickin, Alan P.

    2008-07-01

    Bimodal extrusive volcanic rocks in the northeast Greater Antilles Arc consist of two interlayered suites, including (1) a predominantly basaltic suite, dominated by island arc basalts with small proportions of andesite, and (2) a silicic suite, similar in composition to small volume intrusive veins of oceanic plagiogranite commonly recognized in oceanic crustal sequences. The basaltic suite is geochemically characterized by variable enrichment in the more incompatible elements and negative chondrite-normalized HFSE anomalies. Trace element melting and mixing models indicate the magnitude of the subducted sediment component in Antilles arc basalts is highly variable and decreases dramatically from east to west along the arc. In the Virgin Islands, the sediment component ranges between 4% during the Cenomanian-Campanian interval. The silicic suite, consisting predominantly of rhyolites, is characterized by depleted Al 2O 3 (average Virgin Islands on the east, rhyolites comprise up to 80% of Lower Albian strata (112 to 105 Ma), and about 20% in post-Albian strata (105 to 100 Ma). Farther west, in Puerto Rico, more limited proportions (Atlantic Ridge, which was located approximately midway between North and South America until Campanian times. Within this hypothetical setting the centrally positioned Virgin Islands terrain remained approximately fixed above the subducting ridge as the Antilles arc platform swept northeastward into the slot between the Americas. Accordingly, heat flow in the Virgin Islands was elevated throughout the Cretaceous, giving rise to widespread crustal melting, whereas the subducted sediment flux was limited. Conversely, toward the west in central Puerto Rico, which was consistently more remote from the subducting ridge, heat flow was relatively low and produced limited crustal melting, while the sediment flux was comparatively elevated.

  8. Investigation of a marine magnetic polarity reversal boundary in cross section at the northern boundary of the Kane Megamullion, Mid-Atlantic Ridge, 23°40'N

    Xu, Min; Tivey, M. A.

    2016-05-01

    Near-bottom magnetic field measurements made by the submersible Nautile during the 1992 Kanaut Expedition define the cross-sectional geometry of magnetic polarity reversal boundaries and the vertical variation of crustal magnetization in lower oceanic crust exposed along the Kane Transform Fault (TF) at the northern boundary of the Kane Megamullion (KMM). The KMM exposes lower crust and upper mantle rocks on a low-angle normal fault that was active between 3.3 Ma and 2.1 Ma. The geometry of the polarity boundaries is estimated from an inversion of the submarine magnetic data for crustal magnetization. In general, the polarity boundaries dip away from the ridge axis along the Kane TF scarp, with a west dipping angle of ~45° in the shallow (Williams (2007) that the lower crust cools through the Curie temperature of magnetite to become magnetic, with the polarity boundaries representing both frozen isotherms and isochrons. We also test the effects of the rotation of this isotherm structure and/or footwall rotation and find that the magnetic polarity boundary geometry is not sensitive to these directional changes.

  9. Platinum-group elements, S, Se and Cu in highly depleted abyssal peridotites from the Mid-Atlantic Ocean Ridge (ODP Hole 1274A): Influence of hydrothermal and magmatic processes

    Marchesi, Claudio; Garrido, Carlos J.; Harvey, Jason; González-Jiménez, José María; Hidas, Károly; Lorand, Jean-Pierre; Gervilla, Fernando

    2013-11-01

    Highly depleted harzburgites and dunites were recovered from ODP Hole 1274A, near the intersection between the Mid-Atlantic Ocean Ridge and the 15°20'N Fracture Zone. In addition to high degrees of partial melting, these peridotites underwent multiple episodes of melt-rock reaction and intense serpentinization and seawater alteration close to the seafloor. Low concentrations of Se, Cu and platinum-group elements (PGE) in harzburgites drilled at around 35-85 m below seafloor are consistent with the consumption of mantle sulfides after high degrees (>15-20 %) of partial melting and redistribution of chalcophile and siderophile elements into PGE-rich residual microphases. Higher concentrations of Cu, Se, Ru, Rh and Pd in harzburgites from the uppermost and lowest cores testify to late reaction with a sulfide melt. Dunites were formed by percolation of silica- and sulfur-undersaturated melts into low-Se harzburgites. Platinum-group and chalcophile elements were not mobilized during dunite formation and mostly preserve the signature of precursor harzburgites, except for higher Ru and lower Pt contents caused by precipitation and removal of platinum-group minerals. During serpentinization at low temperature (desulfurization to S-poor sulfides (mainly heazlewoodite) and awaruite. Contrary to Se and Cu, sulfur does not record the magmatic evolution of peridotites but was mostly added in hydrothermal sulfides and sulfate from seawater. Platinum-group elements were unaffected by post-magmatic low-temperature processes, except Pt and Pd that may have been slightly remobilized during oxidative seawater alteration.

  10. Initiation of long-term coupled microbiological, geochemical, and hydrological experimentation within the seafloor at North Pond, western flank of the Mid-Atlantic Ridge

    Edwards, K.J.; Backert, N.; Bach, W.; Becker, K.; Klaus, A.; Griffin, Dale W.; Anderson, L.; Haddad, A.G.; Harigane, Y.; Campion, P.L.; Hirayama, H.; Mills, H.J.; Hulme, S.M.; Nakamura, K.; Jorgensen, S.L.; Orcutt, B.; Insua, T.L.; Park, Y.-S.; Rennie, V.; Salas, E.C.; Rouxel, O.; Wang, F.; Russel, J.A.; Wheat, C.G.; Sakata, K.; Brown, M.; Magnusson, J.L.; Ettlinger, Z.

    2012-01-01

    Integrated Ocean Drilling Program (IODP) Expedition 336 successfully initiated subseafloor observatory science at a young mid-ocean-ridge flank setting. All of the drilled sites are located in the North Pond region of the Atlantic Ocean (22??45'N, 46??05'W) in 4414-4483 m water depth. This area is known from previous ocean drilling and site survey investigations as a site of particularly vigorous circulation of seawater in permeable 8 Ma basaltic basement underlying a logged in Holes U1382A and U1383C. Upper oceanic crust in Hole U1382A, which is only 50 m west of Deep Sea Drilling Project (DSDP) Hole 395A, recovered 32 m of core between 110 and 210 meters below seafloor (mbsf). Core recovery in basement was 32%, yielding a number of volcanic flow units with distinct geochemical and petrographic characteristics. A unit of sedimentary breccia containing clasts of basalt, gabbroic rocks, and mantle peridotite was found intercalated between two volcanic flow units and was interpreted as a rock slide deposit. From Hole U1383C we recovered 50.3 m of core between 69.5 and 331.5 mbsf (19%). The basalts are aphyric to highly plagioclase-olivine-phyric tholeiites that fall on a liquid line of descent controlled by olivine fractionation. They are fresh to moderately altered, with clay minerals (saponite, nontronite, and celadonite), Fe oxyhydroxide, carbonate, and zeolite as secondary phases replacing glass and olivine to variable extents. In addition to traditional downhole logs, we also used a new logging tool for detecting in situ microbial life in ocean floor boreholes-the Deep Exploration Biosphere Investigative tool (DEBI-t). Sediment thickness was ???90 m at Sites U1382 and U1384 and varied between 38 and 53 m at Site U1383. The sediments are predominantly nannofossil ooze with layers of coarse foraminiferal sand and occasional pebble-size clasts of basalt, serpentinite, gabbroic rocks, and bivalve debris. The bottommost meters of sections cored with the advanced

  11. Mid-Atlantic elasmobranchs: Suitable metal scouts?

    Torres, Paulo; Tristão da Cunha, Regina; Rodrigues, Armindo dos Santos

    2017-01-01

    Heavy metals are a hazard to marine fauna and human health. In this study we assess stable isotopes and metal content in Prionace glauca and Isurus oxyrinchus and analyse these results within and among other species and across regions and geographical areas. Also, we evaluate their suitability, together with Raja clavata and Galeorhinus galeus, as Mid-Atlantic bioindicators. Prionace glauca and I. oxyrinchus shared the same trophic level in a pelagic food web and did not present significant differences between genders or metals, except for As. Arsenic and Hg accumulated while Cd and Pb were not detected. One I. oxyrinchus presented Hg values above regulatory limits. A high Hg exposure was associated with I. oxyrinchus since its maximum weekly intake was exceeded. Elasmobranchs can be used as metal sentinels, each presenting different key features which defines a good marine bioindicator, allowing long-term monitoring at different temporal and spatial scales. - Highlights: • We analysed P. glauca and I. oxyrinchus muscle from Mid-Atlantic. • We determined stable isotopes, trophic ecology and heavy metal content. • Results reflect bioaccumulation for As and Hg. • Oxyrinchus already presented Hg values above regulatory limits. • Mid-Atlantic elasmobranchs appear to be effective metal bioindicators.

  12. WATER TEMPERATURE and SALINITY - SURFACE WATER, and other parameters collected from R.V. Celtic Explorer in Mid Atlantic Ridge from 2016-05-12 to 2016-05-21 (NCEI Accession 0157069)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains in situ sea surface measurements from R.V. Celtic Explorer in Mid Altlantic Ridge. The survey was conducted between May 12th and May 21, 2016...

  13. Mid-Atlantic Wind - Overcoming the Challenges

    Daniel F. Ancona III; Kathryn E. George; Richard P. Bowers; Dr. Lynn Sparling; Bruce Buckheit; Daniel LoBue

    2012-05-31

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  14. Mid-Atlantic Wind - Overcoming the Challenges

    Daniel F. Ancona III; Kathryn E. George; Lynn Sparling; Bruce C. Buckheit; Daniel LoBue; and Richard P. Bowers

    2012-06-29

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  15. High-resolution bathymetry as a primary exploration tool for seafloor massive sulfide deposits - lessons learned from exploration on the Mid-Atlantic and Juan de Fuca Ridges, and northern Lau Basin

    Jamieson, J. W.; Clague, D. A.; Petersen, S.; Yeo, I. A.; Escartin, J.; Kwasnitschka, T.

    2016-12-01

    High-resolution, autonomous underwater vehicle (AUV)-derived multibeam bathymetry is increasingly being used as an exploration tool for delineating the size and extent of hydrothermal vent fields and associated seafloor massive sulfide deposits. However, because of the limited amount of seafloor that can be surveyed during a single dive, and the challenges associated with distinguishing hydrothermal chimneys and mounds from other volcanic and tectonic features using solely bathymetric data, AUV mapping surveys have largely been employed as a secondary exploration tool once hydrothermal sites have been discovered using other exploration methods such as plume, self-potential and TV surveys, or ROV and submersible dives. Visual ground-truthing is often required to attain an acceptable level of confidence in the hydrothermal origin of features identified in AUV-derived bathymetry. Here, we present examples of high-resolution bathymetric surveys of vent fields from a variety of tectonic environments, including slow- and intermediate-rate mid-ocean ridges, oceanic core complexes and back arc basins. Results illustrate the diversity of sulfide deposit morphologies, and the challenges associated with identifying hydrothermal features in different tectonic environments. We present a developing set of criteria that can be used to distinguish hydrothermal deposits in bathymetric data, and how AUV surveys can be used either on their own or in conjunction with other exploration techniques as a primary exploration tool.

  16. The Mid-Atlantic Twin Registry, revisited.

    Lilley, Emily C H; Silberg, Judy L

    2013-02-01

    The Mid-Atlantic Twin Registry (MATR) is a population-based registry of more than 56,000 twins primarily born or living in Virginia, North Carolina, and South Carolina. The MATR employs several methods of ascertaining twins, and devotes considerable resources to tracking and maintaining communication with MATR participants. Researchers may utilize the MATR for administration of research services including study recruitment, collection of DNA, archival data set creation, as well as data collection through mailed, phone, or online surveys. In addition, the MATR houses the MATR Repository, with over 1,200 blood samples available for researchers interested in DNA genotyping. For over 35 years MATR twins have participated in research studies with investigators from diverse scientific disciplines and various institutions. These studies, which have resulted in numerous publications, have covered a range of topics, including the human microbiome, developmental psychopathology, depression, anxiety, substance use, epigenetics of aging, children of twins, pre-term birth, social attitudes, seizures, eating disorders, as well as sleep homeostasis. Researchers interested in utilizing twins are encouraged to contact the MATR to discuss potential research opportunities.

  17. The seasonal evolution of shelf water masses around Bouvetøya, a sub-Antarctic island in the mid-Atlantic sector of the Southern Ocean, determined from an instrumented southern elephant seal

    Andrew D. Lowther

    2016-10-01

    Full Text Available Our study makes use of a fortuitous oceanographic data set collected around the remote sub-Antarctic island of Bouvetøya by a conductivity–temperature–depth recorder (CTD integrated with a satellite-relayed data logger deployed on an adult female southern elephant seal (Mirounga leonina to describe the seasonal evolution of the western shelf waters. The instrumented seal remained in waters over the shelf for 259 days, collecting an average of 2.6 (±0.06 CTD profiles per day, providing hydrographic data encompassing the late austral summer and the entire winter. These data document the thermal stratification of the upper water layer due to summer surface heating of the previous year's Antarctic Surface Water, giving way to a cold subsurface layer at about 100 m as the austral winter progressed, with a concomitant increase in salinity of the upper layer. Upper Circumpolar Deep Water was detected at a depth of approximately 200 m along the western shelf of Bouvetøya throughout the year. These oceanographic data represent the only seasonal time series for this region and the second such animal–instrument oceanographic time series in the sub-Antarctic domain of the Southern Ocean.

  18. 76 FR 56742 - Mid-Atlantic Fishery Management Council; Workshop

    2011-09-14

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XA700 Mid-Atlantic... and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of a workshop. SUMMARY: The Eight..., economic and social perspectives. DATES: The workshop will be held Tuesday, October 4 through Thursday...

  19. State of mid-atlantic region forests in 2000

    Kenneth W. Stolte; Barbara L. Conkling; Stephanie Fulton; M. Patricia Bradley

    2012-01-01

    Wet and warm climate, mountainous topography, and deep rich soils produced one of the most magnificent and diverse temperate forests in the world. In 1650 the Mid-Atlantic forests covered 95 percent of the region, but were greatly reduced in 1900 by extensive tree harvesting, and conversion to farms and pastures. Settlement of forests also led to severe wildfires, soil...

  20. Forests and People in the Mid-Atlantic Region

    Stephanie Fulton; Evan Mercer; M. Patricia Bradley

    2012-01-01

    Human populations in the Mid-Atlantic region over the last 250 years have increased nearly 100-fold, from an estimated few hundred thousand people to over 30 million people (Mercer and Murthy 2000). Increased population growth usually results in the conversion of forestland to nonforest uses, particularly agriculture, pastureland, and urban development. Not only is the...

  1. 2014 Mid-Atlantic Telehealth Resource Center Annual Summit

    Katharine Hsu Wibberly

    2013-12-01

    Full Text Available The Mid-Atlantic Resource Center (MATRC; http://www.matrc.org/ advances the adoption and utilization of telehealth within the MATRC region and works collaboratively with the other federally funded Telehealth Resource Centers to accomplish the same nationally. MATRC offers technical assistance and other resources within the following mid-Atlantic states: Delaware, District of Columbia, Kentucky, Maryland, North Carolina, Pennsylvania, Virginia and West Virginia.   The 2014 MATRC Summit “Adding Value through Sustainable Telehealth” will be held March 30-April 1, 2014, at the Fredericksburg Expo & Conference Center, Fredericksburg, VA. The Summit will explore how telehealth adds value to patients, practitioners, hospitals, health systems, and other facilities. Participants will experience a highly interactive program built around the case history of “Mr. Doe” as he progresses through the primary care, inpatient hospitalization, and post-discharge environments. The Summit will conclude with a session on financial and business models for providing sustainable telehealth services.   For further information and registration, visit: http://matrc.org/component/content/article/2-uncategorised/80-mid-atlantic-telehealth-resource-summit-2014    

  2. The influence of climate modes on streamflow in the Mid-Atlantic region of the United States

    Justin A. Schulte

    2016-03-01

    Full Text Available Study region: The Mid-Atlantic region of the United States. Study focus: An understanding of past streamflow variability is necessary for developing future management practices that will help mitigate the impacts of extreme events such as drought or floods on agriculture and other human activities. To better understand mechanisms driving streamflow variability at all timescales, annual to multi-decadal streamflow variability of three major rivers in the Mid-Atlantic region of the United States (the Susquehanna, Delaware, and Hudson Rivers was studied in the context of climate modes using correlation and wavelet analyses. New hydrological insights for the region: Results from the correlation analysis detected statistically significant relationships between climate indices and streamflow that were similar for the three rivers. The results from the wavelet analysis showed that 18- and 26-year periodicities were embedded in the streamflow time series. Decadal variability of streamflow was coherent with the El-Niño Southern Oscillation (SO and the Pacific Decadal Oscillation (PDO. The time series for the PDO and SO indices and precipitation were found to be synchronized to the decadal variability of a global circulation pattern consisting of a Rossby wave train emanating from the North Pacific. The SO explained 37–54% of the 1960s drought, 33–49% of the 1970s pluvial, and 19–50% of the 2000s pluvial in the three river basins. Keywords: Streamflow, Climate, Climate variability, Wavelet analysis, El-Niño-Southern Oscillation, Mid-Atlantic region

  3. Arsenic speciation in shrimp and mussel from the Mid-Atlantic hydrothermal vents

    Larsen, Erik Huusfeldt; Quetel, C. R.; Munoz, R.

    1997-01-01

    Specimens of shrimp (Rimicaris exoculata) and mussel (Bathymodiolus puteoserpentis) were collected 3500 m below the ocean surface at the hydrothermal vents of the mid-Atlantic Ridge (TAG and Snake Pit sites, respectively). Arsenic, a potentially toxic element, is among the substances emitted...... by the hydrothermal vents. The hydrothermal vent shrimp, which are known to be a primary consumer of the primary producing chemolithoautotrophic bacteria, contained arsenic at 13 mu g g(-1) almost exclusively as arsenobetaine (AsB). Arsenic was present in the soft:issues of the mussel at 40 mu g g(-1) and the major...... of arsenic species found in the shrimp and mussel species in the deep-sea is similar to that found in their counterparts from the ocean surface. It is concluded that the autotrophic bacteria of the hydrothermal vent ecosystem and the symbiotic bacteria harboured in the mussel species are responsible...

  4. Geoelectric Hazard Maps for the Mid-Atlantic United States: 100 Year Extreme Values and the 1989 Magnetic Storm

    Love, Jeffrey J.; Lucas, Greg M.; Kelbert, Anna; Bedrosian, Paul A.

    2018-01-01

    Maps of extreme value geoelectric field amplitude are constructed for the Mid-Atlantic United States, a region with high population density and critically important power grid infrastructure. Geoelectric field time series for the years 1983-2014 are estimated by convolving Earth surface impedances obtained from 61 magnetotelluric survey sites across the Mid-Atlantic with historical 1 min (2 min Nyquist) measurements of geomagnetic variation obtained from a nearby observatory. Statistical models are fitted to the maximum geoelectric amplitudes occurring during magnetic storms, and extrapolations made to estimate threshold amplitudes only exceeded, on average, once per century. For the Mid-Atlantic region, 100 year geoelectric exceedance amplitudes have a range of almost 3 orders of magnitude (from 0.04 V/km at a site in southern Pennsylvania to 24.29 V/km at a site in central Virginia), and they have significant geographic granularity, all of which is due to site-to-site differences in magnetotelluric impedance. Maps of these 100 year exceedance amplitudes resemble those of the estimated geoelectric amplitudes attained during the March 1989 magnetic storm, and, in that sense, the March 1989 storm resembles what might be loosely called a "100 year" event. The geoelectric hazard maps reported here stand in stark contrast with the 100 year geoelectric benchmarks developed for the North American Electric Reliability Corporation.

  5. Energy situation in the Mid-Atlantic region

    Munson, J S; Brainard, J P

    1977-08-01

    This report presents a review of the energy situation in the Mid-Atlantic Region. It describes the patterns of energy production, supply and demand by state and compares these to national and regional averages. It presents a picture of existing energy and environmental interactions and a view of potential energy and environmental conflicts. A review of the major issues by energy sector is included as is a description of the existing energy actors and major energy programs for Ohio, West Virginia, Virginia, Pennsylvania, New Jersey, New York, Delaware, Maryland, Puerto Rico, Virgin Islands, and Washington, DC.

  6. Millennial-scale variations in dustiness recorded in Mid-Atlantic sediments from 0 to 70 ka

    Middleton, Jennifer L.; Mukhopadhyay, Sujoy; Langmuir, Charles H.; McManus, Jerry F.; Huybers, Peter J.

    2018-01-01

    Sedimentary records of dust deposition in the subtropical Atlantic provide important constraints on millennial- and orbital-scale variability in atmospheric circulation and North African aridity. Constant flux proxies, such as extraterrestrial helium-3, yield dust flux records that are independent of the biases caused by lateral sediment transport and limited resolution that may be associated with age-model-derived mass accumulation rates. However, Atlantic dust records constrained using constant flux proxies are sparsely distributed and generally limited to the past 20 ka. Here we extend the Atlantic record of North African dust deposition to 70 ka using extraterrestrial helium-3 and measurements of titanium, thorium, and terrigenous helium-4 in two sediment cores collected at 26°N and 29°N on the Mid-Atlantic Ridge and compare results to model estimates for dust deposition in the subtropical North Atlantic. Dust proxy fluxes between 26°N and 29°N are well correlated, despite variability in lateral sediment transport, and underscore the utility of extraterrestrial helium-3 for constraining millennial-scale variability in dust deposition. Similarities between Mid-Atlantic dust flux trends and those observed along the Northwest African margin corroborate previous interpretations of dust flux variability over the past 20 ka and suggest that long distance transport and depositional processes do not overly obscure the signal of North African dust emissions. The 70 ka Mid-Atlantic record reveals a slight increase in North African dustiness from Marine Isotope Stage 4 through the Last Glacial Maximum and a dramatic decrease in dustiness associated with the African Humid Period. On the millennial-scale, the new records exhibit brief dust maxima coincident with North Atlantic cold periods such as the Younger Dryas, and multiple Heinrich Stadials. The correlation between Mid-Atlantic dust fluxes and previous constraints on North African aridity is high. However

  7. Comparative visual ecophysiology of mid-Atlantic temperate reef fishes

    Andrij Z. Horodysky

    2013-11-01

    The absolute light sensitivities, temporal properties, and spectral sensitivities of the visual systems of three mid-Atlantic temperate reef fishes (Atlantic spadefish [Ephippidae: Chaetodipterus faber], tautog [Labridae: Tautoga onitis], and black sea bass [Serranidae: Centropristis striata] were studied via electroretinography (ERG. Pelagic Atlantic spadefish exhibited higher temporal resolution but a narrower dynamic range than the two more demersal foragers. The higher luminous sensitivities of tautog and black sea bass were similar to other benthic and demersal coastal mid-Atlantic fishes. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of the three species spanned 400–610 nm, with high likelihood of cone dichromacy providing the basis for color and contrast discrimination. Significant day-night differences in spectral responses were evident in spadefish and black sea bass but not tautog, a labrid with characteristic structure-associated nocturnal torpor. Atlantic spadefish responded to a wider range of wavelengths than did deeper-dwelling tautog or black sea bass. Collectively, these results suggest that temperate reef-associated fishes are well-adapted to their gradient of brighter to dimmer photoclimates, representative of their unique ecologies and life histories. Continuing anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may however impede visual foraging and reproductive signaling in temperate reef fishes.

  8. 78 FR 23223 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2013-04-18

    .... SUMMARY: The Scientific and Statistical Committee (SSC) of the Mid- Atlantic Fishery Management Council... Fishery Management Council (MAFMC); Public Meeting AGENCY: National Marine Fisheries Service (NMFS...: (410) 522-7377. Council address: Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite...

  9. 75 FR 2488 - Mid-Atlantic Fishery Management Council; Public Meeting

    2010-01-15

    ... Mid-Atlantic Fishery Management Council's (MAFMC) Scientific and Statistical Committee (SSC) will hold... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National... 21240; telephone: (410) 859-3300. Council address: Mid-Atlantic Fishery Management Council, 300 S. New...

  10. 76 FR 3878 - Mid-Atlantic Fishery Management Council; Public Meeting

    2011-01-21

    ... Mid-Atlantic Fishery Management Council's (MAFMC) Scientific and Statistical Committee (SSC) will hold... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National.... ADDRESSES: The webinar will be held at Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite...

  11. 78 FR 13867 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2013-03-01

    ...: The Mid-Atlantic Fishery Management Council's Scientific and Statistical Committee (SSC) will hold a... Fishery Management Council (MAFMC); Public Meeting AGENCY: National Marine Fisheries Service (NMFS... address: Mid-Atlantic Fishery Management Council, 800 North State Street, Suite 201, Dover, DE 19901...

  12. 78 FR 21915 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2013-04-12

    .... SUMMARY: The Scientific and Statistical Committee (SSC) of the Mid- Atlantic Fishery Management Council... Fishery Management Council (MAFMC); Public Meeting AGENCY: National Marine Fisheries Service (NMFS...://www.mafmc.org . Council address: Mid-Atlantic Fishery Management Council, 800 North State Street...

  13. 75 FR 56994 - Mid-Atlantic Fishery Management Council; Public Meeting

    2010-09-17

    ... Mid-Atlantic Fishery Management Council's (MAFMC) Scientific and Statistical Committee (SSC) will hold... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National.... ADDRESSES: The webinar will be held at Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite...

  14. 77 FR 55192 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2012-09-07

    .... SUMMARY: The Scientific and Statistical Committee (SSC) of the Mid- Atlantic Fishery Management Council... Fishery Management Council (MAFMC); Public Meeting AGENCY: National Marine Fisheries Service (NMFS.... Council address: Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite 201, Dover, DE 19901...

  15. 77 FR 51968 - Mid-Atlantic Fishery Management Council; Public Meeting

    2012-08-28

    ... Mid-Atlantic Fishery Management Council's (Council) Scientific and Statistical Committee (SSC) will... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National....mafmc.org . Council address: Mid-Atlantic Fishery Management Council, 800 North State Street, Suite 201...

  16. 77 FR 23662 - Mid-Atlantic Fishery Management Council; Public Meeting

    2012-04-20

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XB170 Mid-Atlantic... Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The Social and Economic Sub-Committee of the Mid-Atlantic Fishery Management Council's (Council) Scientific...

  17. 76 FR 9553 - Mid-Atlantic Fishery Management Council; Public Meeting

    2011-02-18

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XA226 Mid-Atlantic... Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meeting. SUMMARY: The Social and Economic Sub-Committee of the Mid-Atlantic Fishery Management Council's (Council) Scientific...

  18. 76 FR 16620 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting

    2011-03-24

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XA316 Mid-Atlantic... Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meeting. SUMMARY: The Social and Economic Sub-Committee of the Mid-Atlantic Fishery Management Council's (Council) Scientific...

  19. 76 FR 68719 - Mid-Atlantic Fishery Management Council; Public Meeting

    2011-11-07

    ... Mid-Atlantic Fishery Management Council's (Council) Scientific and Statistical Committee (SSC) will... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National....org . Council address: Mid-Atlantic Fishery Management Council, 800 North State Street, Suite 201...

  20. 75 FR 55743 - Mid-Atlantic Fishery Management Council; Public Meeting

    2010-09-14

    ... Mid-Atlantic Fishery Management Council's (MAFMC) Scientific and Statistical Committee (SSC) will hold... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National... address: Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite 201, Dover, DE 19901...

  1. 78 FR 53731 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2013-08-30

    ...: The Scientific and Statistical Committee (SSC) of the Mid- Atlantic Fishery Management Council... Fishery Management Council (MAFMC); Public Meeting AGENCY: National Marine Fisheries Service (NMFS..., MD 21231, telephone: (410) 522-7380. Council address: Mid-Atlantic Fishery Management Council, 800 N...

  2. Mid-Atlantic Consumer Purchasing Behavior and Knowledge of Locally Grown and Seasonal Produce

    Chamberlain, Amy J.; Kelley, Kathleen M.; Hyde, Jeffrey

    2013-01-01

    Mid-Atlantic urban consumers were surveyed on their fruit and vegetable purchasing behaviors and their knowledge of produce grown in the region. Consumers were generally unaware of what produce is grown in the mid-Atlantic and during what months they are harvested. Additionally, differences pertaining to number of produce items purchased were…

  3. 78 FR 48419 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2013-08-08

    ...: The Mid-Atlantic Fishery Management Council's (Council) Bluefish Advisory Panel (AP) will meet to develop a Fishery Performance Report for the Bluefish fishery in preparation for the Council and the... Council address below. Webinar link: http://mafmc.adobeconnect.com/bluefish/ Council address: Mid-Atlantic...

  4. Microbial ecology of deep-water mid-Atlantic canyons

    Kellogg, Christina A.

    2011-01-01

    The research described in this fact sheet will be conducted from 2012 to 2014 as part of the U.S. Geological Survey's DISCOVRE (DIversity, Systematics, and COnnectivity of Vulnerable Reef Ecosystems) Program. This integrated, multidisciplinary effort will be investigating a variety of topics related to unique and fragile deep-sea ecosystems from the microscopic level to the ecosystem level. One goal is to improve understanding, at the microbiological scale, of the benthic communities (including corals) that reside in and around mid-Atlantic canyon habitats and their associated environments. Specific objectives include identifying and characterizing the microbial associates of deep-sea corals, characterizing the microbial biofilms on hard substrates to better determine their role in engineering the ecosystem, and adding a microbial dimension to benthic community structure and function assessments by characterizing micro-eukaryotes, bacteria, and archaea in deep-sea sediments.

  5. Karst of the Mid-Atlantic region in Maryland, West Virginia, and Virginia

    Doctor, Daniel H.; Weary, David J.; Brezinski, David K.; Orndorff, Randall C.; Spangler, Lawrence E.; Brezinski, David K.; Halka, Jeffrey; Ortt, Richard A.

    2015-01-01

    The Mid-Atlantic region hosts some of the most mature karst landscapes in North America, developed in highly deformed rocks within the Piedmont and Valley and Ridge physiographic provinces. This guide describes a three-day excursion to examine karst development in various carbonate rocks by following Interstate 70 west from Baltimore across the eastern Piedmont, across the Frederick Valley, and into the Great Valley proper. The localities were chosen in order to examine the structural and lithological controls on karst feature development in marble, limestone, and dolostone rocks with an eye toward the implications for ancient landscape evolution, as well as for modern subsidence hazards. A number of caves will be visited, including two commercial caverns that reveal strikingly different histories of speleogenesis. Links between karst landscape development, hydrologic dynamics, and water resource sustainability will also be emphasized through visits to locally important springs. Recent work on quantitative dye tracing, spring water geochemistry, and groundwater modeling reveal the interaction between shallow and deep circulation of groundwater that has given rise to the modern karst landscape. Geologic and karst feature mapping conducted with the benefit of lidar data help reveal the strong bedrock structural controls on karst feature development, and illustrate the utility of geologic maps for assessment of sinkhole susceptibility.

  6. Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

    Taylor, Vivien F.; Jackson, Brian P.; Siegfried, Matthew R.; Navratilova, Jana; Francesconi, Kevin A.; Kirshtein, Julie; Voytek, Mary

    2012-01-01

    Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.

  7. Arsenic speciation in food chains from mid-Atlantic hydrothermal vents.

    Taylor, Vivien F; Jackson, Brian P; Siegfried, Matthew; Navratilova, Jana; Francesconi, Kevin A; Kirshtein, Julie; Voytek, Mary

    2012-05-04

    Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata , the vent chimney-dwelling mussel, Bathymodiolus azoricus , Branchipolynoe seepensis , a commensal worm of B. azoricus , and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ 13 C and δ 15 N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata , whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys, covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a food web without algae or other photosynthetic life.

  8. Estuarine Living Marine Resources: Mid-Atlantic Regional Distribution and Abundance (NCEI Accession 0162403)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is the Mid-Atlantic regional component of NOAA’s Estuarine Living Marine Resources (ELMR) Project, a national database of ecologically and economically...

  9. 75 FR 8673 - Mid-Atlantic Fishery Management Council; Public Meeting

    2010-02-25

    ... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National... Mid-Atlantic Fishery Management Council (Council) will conduct an educational workshop on catch shares in cooperation with the Fisheries Leadership and Sustainability Forum (FLSF), the Atlantic States...

  10. Wind effects on coastal zone color scanner chlorophyll patterns in the U.S. Mid-Atlantic Bight during spring 1979

    Eslinger, David L.; Iverson, Richard L.

    1986-01-01

    Coastal zone color scanner (CZCS) chlorophyll concentration increases in the Mid-Atlantic Bight were associated with high wind speeds in continental shelf waters during March and May 1979. Maximum spring CZCS chlorophyll concentrations occurred during April when the water column was not thermally stratified and were spatially and temporally associated with reductions in wind speed both in onshelf and in offshelf regions. Increased chlorophyll concentrations in offshelf waters were associated with high wind speeds during May when a deep chlorophyll maximum was present. Chlorophyll patchiness was observed on length scales typical of those controlled by biological processes during the April low-wind period but not during March or May when wind speeds were greater. The spring CZCS chlorophyll maximum in the southern portion of the Mid-Atlantic Bight occurred in response to a reduction in mixed layer depth caused by decreased wind speeds and not by increased water column stratification.

  11. Mid-Atlantic Technology Applications Center. Quarters 1-4

    1997-01-01

    Mid-atlantic Technology Application Center (MTAC) pursued a number of initiatives designed to enhance the strategic position of the Langley Research Center (LaRC) and NASA in industry. Among these was a closer association with the ISA, International Society for Measurement and Control. During 1997, MTAC placed articles regarding NASA-developed technologies in each In Tech magazine. The monthly magazine is sent to 46,000 sensors and instrumentation professionals. In addition, MTAC coordinated NASXs participation in the ISA Tech 97 Conference, securing $112,000 of free exhibit space, 1500 NASA sensors posters at no cost to NASA, and thousands of dollars of free publicity. MTAC was awarded a contract by ISA to operate its Technical Resource Center (TRC). The goal of this project is to determine what user needs are in order to identify opportunities for collaboration between NASA centers and companies. In addition, the TRC work will lay the groundwork for the Technology Development Consortium (TDC) proposed by MTAC. The purpose of the TDC is to: match current industry needs with NASA technologies available now, and to identify future needs of NASA and industry which may lead to dual use projects. The goal of these activities is twofold: to infuse NASA technologies into the sensors and instrumentation industry and to secure industry funds to support NASA technology development projects. The instrumentation and sensors industry is valued at $30 billion worldwide, with $12 billion in sales in the United States. The growth rate averages 13.5%, so that by the year 2000, the industry will produce products worth $49 billion. More than 80% of instruments, sensors and control systems are currently manufactured in the United States. NASA and the industry do not have a history of collaborative projects; MTAC's initiatives in this area are designed to foster working relationships between the two parties that will help maintain U.S. leadership in this field. Mid-atlantic Technology

  12. Traumatic uveitis in the mid-Atlantic United States

    Engelhard SB

    2015-10-01

    Full Text Available Stephanie B Engelhard,1 James Patrie,2 John Prenshaw,1 Asima Bajwa,1 Rose Monahan,1 Ashvini K Reddy1 1Department of Ophthalmology, 2Department of Public Health Sciences, University of Virginia, Charlottesville, VA, USA Purpose: The purpose of this study was to conduct an in-depth analysis of traumatic uveitis in patients managed in a mid-Atlantic tertiary care center with the goal of better characterizing the clinical features and outcomes of this large and important subset of uveitis patients.Methods: This was a retrospective, observational study comparing traumatic uveitis patients with nontraumatic uveitis patients seen at the University of Virginia, Charlottesville, VA, USA, from 1984 to 2014.Results: Fifty-four traumatic uveitis patients (55 eyes were identified. The patient population was 70.4% male, 57.4% Caucasian, and 37.0% African American. Mean age at diagnosis was 31.2 years; mean duration of follow-up was 5.4 years; and mean number of visits to the clinic was 4. The most common treatment modality was local steroids (77.8%. Glaucoma was medically managed in eight patients (14.8%. Cataract surgery was performed in five patients (9.3%. Mean best-corrected visual acuity at baseline for traumatic uveitis patients was 0.33 logMAR (SD 0.42 at the initial visit and 0.16 logMAR (SD 0.33 at the final visit. Mean baseline intraocular pressure (IOP in the traumatic uveitis group was 15.5 mmHg (SD 7.4 at the initial visit and 14.6 mmHg (SD 4.0 at the final visit. Patients in the traumatic uveitis cohort tended to have better visual outcomes than those in the nontraumatic uveitis cohort.Conclusion: In our series, traumatic uveitis patients tended to be young and male and present with unilateral disease, all findings consistent with other reports. Despite relatively good visual outcomes, the traumatic uveitis patients still experienced a high burden of disease, measured both in the number of clinic visits and duration of follow-up. Due to the

  13. Morphotectonic and petrological variations along the southern Central Indian Ridge

    Mukhopadhyay, R.; Iyer, S.D.; Ray, Dwijesh; Karisiddaiah, S.M.; Drolia, R.K.

    above the DM and Enriched Mantle (EM2) end member and resemble a linear mixing with Indian Ocean pelagic sediments (Fig. 4a, b). By contrast, the isotope data of IOTJ-MORB occupy a distinct field in the radiogenic Pb-Pb and Sr-Pb binary plots... EM, Karsten JL, 1995 Ocean-ridge basalts with convergent-margin geochemical affinities from the Chile Ridge. Nature 374:52-57 Klein EM, Langmuir CH, 1987 Global correlations of ocean ridge basalt chemistry with axial depth and crustal chemistry...

  14. Magnetic anomalies across the southern Central Indian Ridge: evidence for a new transform fault

    Chaubey, A.K.; Krishna, K.S.; SubbaRaju, L.V.; Rao, D.G.

    , Vol. 37. No. 4. pp. MT-~a56, 1990. 0198-.0149/90 $3.(gl + 0.00 Pnnled in Great Britain. (~ 1990 Pergartma Ptes6 pie Magnetic anomalies across the southern Central Indian Ridge: evidence for a new transform fault A. K. CHAUBEY,* K. S. KRISHNA,* L. V... to the ridge are identified as sea-floor spreading lineations 2.2A,3.3A and 4. A half spreading rate of 2.2 cm y- t is estimated for the last I0 Ma. The ridge jump between the anomalies 2-2A (approx. 2.5 Ma) and a new left lateral transform fault offsetting...

  15. 78 FR 54644 - 2013 Fall Joint Meeting of the Ozone Transport Commission and the Mid-Atlantic Northeast...

    2013-09-05

    ... Transport Commission and the Mid-Atlantic Northeast Visibility Union AGENCY: Environmental Protection Agency...-Atlantic Northeast Visibility Union (MANE-VU). The meeting agenda will include topics regarding reducing...-level ozone formation, transport, and control within the OTR. The Mid-Atlantic/Northeast Visibility...

  16. 77 FR 65380 - 2012 Fall Joint Meeting of the Ozone Transport Commission and the Mid-Atlantic Northeast...

    2012-10-26

    ... ENVIRONMENTAL PROTECTION AGENCY [FRL-9745-9] 2012 Fall Joint Meeting of the Ozone Transport Commission and the Mid-Atlantic Northeast Visibility Union AGENCY: Environmental Protection Agency (EPA... Fall Meeting of the Ozone Transport Commission (OTC) and the Mid-Atlantic Northeast Visibility Union...

  17. The Role of Mid-Atlantic Ocean Data Portal in Supporting Ocean Planning

    Richard G. Lathrop

    2017-08-01

    Full Text Available The Mid-Atlantic Regional Council on the Ocean (MARCO was established in 2009 to enhance the vitality of the region's ocean ecosystem and economy. One of MARCO's first action items was the development of the Mid-Atlantic Ocean Data Portal to serve as an on-line platform to engage stakeholders across the region with the objective of improving their understanding of how ocean resources and places are being used, managed, and conserved. A key component is the Marine Planner, an interactive map-based visualization and decision support tool. These types of on-line tools are becoming increasingly popular means of putting essential data and state-of-the-art visualization technology into the hands of the agencies, industry, community leaders, and stakeholders engaged in ocean planning. However, to be effective, the underlying geospatial data has to be seen as objective, comprehensive, up-to-date and regionally consistent. To meet this challenge, the portal utilizes a distributed network of web map services from credible and authoritative sources. Website analytics and feedback received during the review and comment period of the 2016 release of the Mid-Atlantic Ocean Action Plan confirm that the Data Portal is viewed as integral to this ocean planning process by the MidAtlantic Regional Planning Body and key stakeholders. While not all stakeholders may agree with specific planning decisions, there is broad based agreement on the need for better data and making access to that data widely available.

  18. 77 FR 16811 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2012-03-22

    ... meet. 5 p.m. until 6 p.m.--There will be a public listening session. Wednesday, April 11, 2012 9 a.m... Coral and discussion of Mid-Atlantic Council action will follow. The public listening session will focus..., finalize goals and objectives, purpose and need, discuss transition strategies to move EBFM, and...

  19. DECISION TOOL FOR RIPARIAN ECOSYSTEM MANAGMENT IN THE MID-ATLANTIC HIGHLANDS

    In the Canaan Valley Highlands of the Mid-Atlantic, riparian zone restoration has been identified as a critical watershed management practice not only for the ecosystem services provided but also for the potential socioeconomic growth from environmental investment and job creatio...

  20. 75 FR 20567 - Mid-Atlantic Fishery Management Council; Public Meeting

    2010-04-20

    ... Mid-Atlantic Fishery Management Council's (MAFMC) Scientific and Statistical Committee (SSC) will hold... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National... Fishery Management Council, 800 N. State Street, Suite 201, Dover, DE 19901; telephone: (302) 674-2331...

  1. 76 FR 42684 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2011-07-19

    .... SUMMARY: The Mid-Atlantic Fishery Management Council Staff will hold a meeting of the Visioning Project Advisory Panel to discuss communications strategies and data gathering tools for the Visioning Project... project's results to develop future management actions. Although non-emergency issues not contained in...

  2. Persistence of Allegheny woodrats Neotoma magister across the mid-Atlantic Appalachian Highlands landscape, USA

    W. Mark Ford; Steven B. Castleberry; Michael T. Mengak; Jane L. Rodrigue; Daniel J. Feller; Kevin R. Russell

    2006-01-01

    We examined a suite of macro-habitat and landscape variables around active and inactive Allegheny woodrat Neotoma magister colony sites in the Appalachian Mountains of the mid-Atlantic Highlands of Maryland, Virginia, and West Virginia using an information-theoretic modeling approach. Logistic regression analyses suggested that Allegheny woodrat presence was related...

  3. 77 FR 44216 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2012-07-27

    ... MAFMC Strategic Planning--Objective, Process, and Possible Outcomes and an introduction to the new.... SUMMARY: The Mid-Atlantic Fishery Management Council (Council) and its Strategic Planning Working Group... INFORMATION: Monday, August 13, 2012 9 a.m. until 5 p.m.--The Visioning and Strategic Planning Working Group...

  4. 77 FR 2961 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2012-01-20

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XA943 Mid-Atlantic...), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of a public meeting... with the Council's Social and Economic Sub-committee of the Scientific and Statistical Committee (SSC...

  5. 77 FR 77036 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2012-12-31

    ...: The Scientific and Statistical Committee (SSC) of the Mid- Atlantic Fishery Management Council... Fishery Management Council (MAFMC); Public Meeting AGENCY: National Marine Fisheries Service (NMFS... Management Council, 800 N. State Street, Suite 201, Dover, DE 19901; telephone: (302) 674-2331. FOR FURTHER...

  6. Climate change and fire management in the mid-Atlantic region

    Kenneth L. Clark; Nicholas Skowronski; Heidi Renninger; Robert. Scheller

    2014-01-01

    In this review, we summarize the potential impacts of climate change on wildfire activity in the mid-Atlantic region, and then consider how the beneficial uses of prescribed fire could conflict with mitigation needs for climate change, focusing on patters of carbon (C) sequestration by forests in the region. We use a synthesis of field studies, eddy flux tower...

  7. Potential effects of climate change on freshwater ecosystems of the New England/Mid-Atlantic Region

    Marianne V. Moore; Michael L. Pace; John R. Mather; [and others; [Editor’s note: Patricia A. Flebbe is the SRS co-author for this publication.

    1997-01-01

    Numerous freshwater ecosystems, dense concentrations of humans along the eastern seaboard, extensive forests, and a history of intensive land use distinguish the New England/Mid-Atlantic Region. Human population densities are forecast to increase in portions of the region at the same time that climate is expected to be changing. Consequently, the effects of humans and...

  8. 78 FR 52505 - Mid-Atlantic Fishery Management Council; Public Meeting

    2013-08-23

    ... Mid-Atlantic Fishery Management Council's (MAFMC) Bluefish Monitoring Committee and Summer Flounder...: The Bluefish Monitoring Committee and Summer Flounder, Scup, and Black Sea Bass Monitoring Committee... associated management measures for the bluefish, summer flounder, scup, and black sea bass fisheries. Multi...

  9. 78 FR 44539 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2013-07-24

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XC777 Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings AGENCY: National Marine Fisheries Service (NMFS... Amendment, Amendment 5 to Dolphin/Wahoo, Amendment 19 and 20 to the Joint Coastal Migratory Pelagics (CMP...

  10. Modeling complex effects of multiple environmental stresses on carbon dynamics of Mid-Atlantic temperate forests

    Yude Pan; Richard Birdsey; John Hom; Kevin McCullough

    2007-01-01

    We used our GIS variant of the PnET-CN model to investigate changes of forest carbon stocks and fluxes in Mid-Atlantic temperate forests over the last century (1900-2000). Forests in this region are affected by multiple environmental changes including climate, atmospheric CO2 concentration, N deposition and tropospheric ozone, and extensive land disturbances. Our...

  11. Importance of Foliar Nitrogen Concentration to Predict Forest Productivity in the Mid-Atlantic Region

    Yude Pan; John Hom; Jennifer Jenkins; Richard Birdsey

    2004-01-01

    To assess what difference it might make to include spatially defined estimates of foliar nitrogen in the regional application of a forest ecosystem model (PnET-II), we composed model predictions of wood production from extensive ground-based forest inventory analysis data across the Mid-Atlantic region. Spatial variation in foliar N concentration was assigned based on...

  12. Timber harvesting patterns for major states in the central, northern, and mid-Atlantic hardwood regions

    William G. Luppold; Matthew S. Bumgardner

    2018-01-01

    Timber harvesting is a major disturbance agent influencing the composition and structure of eastern hardwood forests. To better understand timber harvesting practices, we examined roundwood harvesting patterns in 13 eastern states in the Central, Mid-Atlantic, and Northern regions that contained high proportional volumes of hardwood in their forest inventories. Nearly...

  13. State of mid-atlantic region forests in 2000-Summary Report

    Kenneth W. Stolte

    2012-01-01

    Wet and warm climate, mountainous topography, and deep rich soils produced one of the most magnificent and diverse temperate forests in the world. In 1650 the Mid-Atlantic forests covered 95 percent of the region, but were greatly reduced in 1900 by extensive tree harvesting, and conversion to farms and pastures. Settlement of forests also led to severe wildfires, soil...

  14. Geomorphology, active tectonics, and landscape evolution in the Mid-Atlantic region: Chapter

    Pazzaglia, Frank J.; Carter, Mark W.; Berti, Claudio; Counts, Ronald C.; Hancock, Gregory S.; Harbor, David; Harrison, Richard W.; Heller, Matthew J.; Mahan, Shannon; Malenda, Helen; McKeon, Ryan; Nelson, Michelle S.; Prince, Phillip; Rittenour, Tammy M.; Spotilla, James; Whittecar, G. Richard

    2015-01-01

    In 2014, the geomorphology community marked the 125th birthday of one of its most influential papers, “The Rivers and Valleys of Pennsylvania” by William Morris Davis. Inspired by Davis’s work, the Appalachian landscape rapidly became fertile ground for the development and testing of several grand landscape evolution paradigms, culminating with John Hack’s dynamic equilibrium in 1960. As part of the 2015 GSA Annual Meeting, the Geomorphology, Active Tectonics, and Landscape Evolution field trip offers an excellent venue for exploring Appalachian geomorphology through the lens of the Appalachian landscape, leveraging exciting research by a new generation of process-oriented geomorphologists and geologic field mapping. Important geomorphologic scholarship has recently used the Appalachian landscape as the testing ground for ideas on long- and short-term erosion, dynamic topography, glacial-isostatic adjustments, active tectonics in an intraplate setting, river incision, periglacial processes, and soil-saprolite formation. This field trip explores a geologic and geomorphic transect of the mid-Atlantic margin, starting in the Blue Ridge of Virginia and proceeding to the east across the Piedmont to the Coastal Plain. The emphasis here will not only be on the geomorphology, but also the underlying geology that establishes the template and foundation upon which surface processes have etched out the familiar Appalachian landscape. The first day focuses on new and published work that highlights Cenozoic sedimentary deposits, soils, paleosols, and geomorphic markers (terraces and knickpoints) that are being used to reconstruct a late Cenozoic history of erosion, deposition, climate change, and active tectonics. The second day is similarly devoted to new and published work documenting the fluvial geomorphic response to active tectonics in the Central Virginia seismic zone (CVSZ), site of the 2011 M 5.8 Mineral earthquake and the integrated record of Appalachian

  15. Copepod distribution and production in a Mid-Atlantic Ridge archipelago

    PEDRO A.M.C. MELO

    2014-12-01

    Full Text Available The Saint Peter and Saint Paul Archipelago (SPSPA are located close to the Equator in the Atlantic Ocean. The aim of this study was to assess the spatial variations in the copepod community abundance, and the biomass and production patterns of the three most abundant calanoid species in the SPSPA. Plankton samples were collected with a 300 µm mesh size net along four transects (north, east, south and west of the SPSPA, with four stations plotted in each transect. All transects exhibited a tendency toward a decrease in copepod density with increasing distance from the SPSPA, statistically proved in the North. Density varied from 3.33 to 182.18 ind.m−3, and differences were also found between the first perimeter (first circular distance band and the others. The total biomass varied from 15.25 to 524.50 10−3 mg C m−3 and production from 1.19 to 22.04 10−3 mg C m−3d−1. The biomass and production of Undinula vulgaris (Dana, 1849, Acrocalanus longicornis Giesbrecht, 1888 and Calocalanus pavo (Dana, 1849 showed differences between some transects. A trend of declining biodiversity and production with increasing distance from archipelago was observed, suggesting that even small features like the SPSPA can affect the copepod community in tropical oligotrophic oceanic areas.

  16. Potential effects of climate change on freshwater ecosystems of the New England/Mid-Atlantic Region

    Moore, M.V.; Pace, M.L.; Mather, J.R.; Murdoch, Peter S.; Howarth, R.W.; Folt, C.L.; Chen, C.-Y.; Hemond, Harold F.; Flebbe, P.A.; Driscoll, C.T.

    1997-01-01

    Numerous freshwater ecosystems, dense concentrations of humans along the eastern seaboard, extensive forests and a history of intensive land use distinguish the New England/Mid-Atlantic Region. Human population densities are forecast to increase in portions of the region at the same time that climate is expected to be changing. Consequently, the effects of humans and climatic change are likely to affect freshwater ecosystems within the region interactively. The general climate, at present, is humid continental, and the region receives abundant precipitation. Climatic projections for a 2 ??CO2 atmosphere, however, suggest warmer and drier conditions for much of this region. Annual temperature increases ranging from 3-5??C are projected, with the greatest increases occurring in autumn or winter. According to a water balance model, the projected increase in temperature will result in greater rates of evaporation and evapotranspiration. This could cause a 21 and 31% reduction in annual stream flow in the southern and northern sections of the region, respectively, with greatest reductions occurring in autumn and winter. The amount and duration of snow cover is also projected to decrease across the region, and summer convective thunderstorms are likely to decrease in frequency but increase in intensity. The dual effects of climate change and direct anthropogenic stress will most likely alter hydrological and biogeochemical processes, and, hence, the floral and faunal communities of the region's freshwater ecosystems. For example, the projected increase in evapotranspiration and evaporation could eliminate most bog ecosystems, and increases in water temperature may increase bioaccumulation, and possibly biomagnification, of organic and inorganic contaminants. Not all change may be adverse. For example, a decrease in runoff may reduce the intensity of ongoing estuarine eutrophication, and acidification of aquatic habitats during the spring snowmelt period may be

  17. Pathways of fish invasions in the Mid-Atlantic region of the United States

    Lapointe, Nicolas W. R.; Fuller, Pam; Neilson, Matthew; Murphy, Brian R.; Angermeier, Paul

    2016-01-01

    Non-native fish introductions are a major threat to biodiversity and fisheries, and occur through numerous pathways that vary regionally in importance. A key strategy for managing invasions is to focus prevention efforts on pathways posing the greatest risk of future introductions. We identified high-risk pathways for fish establishment in the Mid-Atlantic region of the United States based on estimates of probability of establishment and records of previous introductions, which were considered in the context of emerging socioeconomic trends. We used estimates of propagule pressure, species’ environmental tolerance, and size of species pool to assess the risk of establishment by pathway. Pathways varied considerably in historic importance and species composition, with the majority of species introduced intentionally via stocking (primarily for sport, forage, or biocontrol) or bait release. Bait release, private stocking, illegal introductions intended to establish reproducing populations (e.g., of sport fish), aquaculture, and the sale of live organisms all create risks for future invasions in the Mid-Atlantic region. Of these pathways, bait release probably poses the greatest risk of introductions for the Mid-Atlantic region because propagule pressure is moderate, most released species are tolerant of local environmental conditions, and the pool of species available for transplantation is large. Our findings differ considerably from studies in other regions (e.g., bait release is a dominant pathway in the Mid-Atlantic region, whereas illegal introduction of sport fish is dominant in the western US and aquarium releases are dominant in Florida), demonstrating the need for regional-scale assessments of, and management strategies for, introduction pathways.

  18. Assessing Phytoplankton Nutritional Status and Potential Impact of Wet Deposition in Seasonally Oligotrophic Waters of the Mid-Atlantic Bight

    Sedwick, P. N.; Bernhardt, P. W.; Mulholland, M. R.; Najjar, R. G.; Blumen, L. M.; Sohst, B. M.; Sookhdeo, C.; Widner, B.

    2018-04-01

    To assess phytoplankton nutritional status in seasonally oligotrophic waters of the southern Mid-Atlantic Bight, and the potential for rain to stimulate primary production in this region during summer, shipboard bioassay experiments were performed using natural seawater and phytoplankton collected north and south of the Gulf Stream. Bioassay treatments comprised iron, nitrate, iron + nitrate, iron + nitrate + phosphate, and rainwater. Phytoplankton growth was inferred from changes in chlorophyll a, inorganic nitrogen, and carbon-13 uptake, relative to unamended control treatments. Results indicated the greatest growth stimulation by iron + nitrate + phosphate, intermediate growth stimulation by rainwater, modest growth stimulation by nitrate and iron + nitrate, and no growth stimulation by iron. Based on these data and analysis of seawater and atmospheric samples, nitrogen was the proximate limiting nutrient, with a secondary limitation imposed by phosphorus. Our results imply that summer rain events increase new production in these waters by contributing nitrogen and phosphorus, with the availability of the latter setting the upper limit on rain-stimulated new production.

  19. Cold-climate slope deposits and landscape modifications of the Mid-Atlantic Coastal Plain, Eastern USA

    Newell, Wayne L.; Dejong, B.D.

    2011-01-01

    The effects of Pleistocene cold-climate geomorphology are distributed across the weathered and eroded Mid-Atlantic Coastal Plain uplands from the Wisconsinan terminal moraine south to Tidewater Virginia. Cold-climate deposits and landscape modifications are superimposed on antecedent landscapes of old, weathered Neogene upland gravels and Pleistocene marine terraces that had been built during warm periods and sea-level highstands. In New Jersey, sequences of surficial deposits define a long history of repeating climate change events. To the south across the Delmarva Peninsula and southern Maryland, most antecedent topography has been obscured by Late Pleistocene surficial deposits. These are spatially variable and are collectively described as a cold-climate alloformation. The cold-climate alloformation includes time-transgressive details of climate deterioration from at least marine isotope stage (MIS) 4 through the end of MIS 2. Some deposits and landforms within the alloformation may be as young as the Younger Dryas. Southwards along the trend of the Potomac River, these deposits and their climatic affinities become diffused. In Virginia, a continuum of erosion and surficial deposits appears to be the product of ‘normal’ temperate, climate-forced processes. The cold-climate alloformation and more temperate deposits in Virginia are being partly covered by Holocene alluvium and bay mud.

  20. Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    Saracino-Brown, Jocelyn [Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Smith, Courtney [Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Gilman, Patrick [Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States)

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. The workshop was planned by Federal agency, academic, and private partners to promote collaboration between ongoing offshore ecological survey efforts, and to promote the collaborative development of complementary predictive models and compatible databases. The meeting primarily focused on efforts to establish and predict marine mammal, seabird, and sea turtle abundance, density, and distributions extending from the shoreline to the edge of the Exclusive Economic Zone between Nantucket Sound, Massachusetts and Cape Hatteras, North Carolina.

  1. A new species of Nidalia Gray, 1835 from Mid-Atlantic seamounts (Octocorallia, Alcyonacea, Nidaliidae)

    López-González, Pablo J.; Gili, Josep-Maria

    2008-12-01

    A new soft coral species of the genus Nidalia, from seamounts to the south of the Azores Archipelago is described. The main features of Nidalia aurantia n. sp. are as following: colony torch-like, a capitulum light orange in colour, not laterally flattened, dome-shaped and not distinctly projecting beyond the stalk, an introvert with sparse sclerites transversally placed, and an anthocodial crown with 13 17 sclerite rows. The new species is compared with its closest congeners. This is the first time that a species of Nidalia has been located in the Mid-Atlantic Ocean.

  2. The Usumacinta-Grijalva beach-ridge plain in southern Mexico : A high-resolution archive of river discharge and precipitation

    Nooren, C.A.M.; Hoek, W.Z.; Winkels, T.G.; Huizinga, A.; van der Plicht, J.; Van Dam, R.; Van Heteren, S.; van Bergen, M.J.; Prins, M.A.; Reimann, T.; Wallinga, J.; Cohen, K.M.; Minderhoud, P.S.J.; Middelkoop, H.

    2017-01-01

    The beach-ridge sequence of the Usumacinta-Grijalva delta borders a 300 km long section of the southern Gulf of Mexico coast. With around 500 beach ridges formed in the last 6500 years, the sequence is unsurpassed in the world in terms of numbers of individual ridges preserved, continuity of the

  3. Potassium-argon radiometric dates of the mid-atlantic ocean floor

    Agyei, E.K.

    1989-01-01

    The basalt and six trachyte rock samples from the King's Trough in the mid-Atlantic ocean floor have been dated by the conventional potassium-argon method. The basalts give two different ages, 155+/-6 Ma (late Jurassic) and 53+/-6 Ma (lower Eocene), while the trachytes give a range of ages from 31.6+/-0.6 Ma to 35.2=0.2 Ma and an average of 33.0+/=0.4 Ma (lower oligocene). The Lower Eocene age of the in-situ basalt matches the age of the original volcanic activity of the region while the lower Oligocene age is associated with the subsequent faulting event. The late Jurassic age of the erratic basalt is interesting because of the scarcity of extrusive igneous rocks of that age along the margins of the North Atlantic and, therefore,needs to be investigated further. (author). 4 refs. 2 tabs

  4. Distributions and habitat associations of deep-water corals in Norfolk and Baltimore Canyons, Mid-Atlantic Bight, USA

    Brooke, S.D.; Watts, M.W.; Heil, A.D.; Rhode, M.; Mienis, F.; Duineveld, G.C.A.; Davies, A.J.; Ross, S.W.

    2017-01-01

    A multi-disciplinary study of two major submarine canyons, Baltimore Canyon and Norfolk Canyon, off the US mid-Atlantic coast focused on the ecology and biology of canyon habitats, particularly those supporting deep-sea corals. Historical data on deep-sea corals from these canyons were sparse with

  5. 75 FR 48666 - Calpine Mid-Atlantic Marketing, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    2010-08-11

    ...-Atlantic Marketing, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... proceeding, of Calpine Mid-Atlantic Marketing, LLC's application for market-based rate authority, with an... of protests and interventions in lieu of paper, using the FERC Online links at http://www.ferc.gov...

  6. Assessing the Impacts of Forests on Human Welfare: Prelimnary Results from the Mid-Atlantic Integrated Assessement

    D. Evan Mercer; P.B. Aruna

    2000-01-01

    Abstract. This paper presents results from the first phase of the socio-economic assessment of forest ecosystems in the Mid-Atlantic Integrated Assessment (MAIA). First, we present results of the analysis of changes in the distribution of human population and forest land use in the region. Then, trends in wood products employment and income between...

  7. Appendix E of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    None

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the fifth appendix to the report, the bibliography of references.

  8. Appendix C of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    None

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the third appendix to the report, the compendium of pre-workshop answers.

  9. 75 FR 20591 - AES Sparrows Point LNG, LLC and Mid-Atlantic Express, LLC; Notice of Final General Conformity...

    2010-04-20

    ...] AES Sparrows Point LNG, LLC and Mid-Atlantic Express, LLC; Notice of Final General Conformity... revised draft Final General Conformity Determination (GCD) for Pennsylvania to assess the potential air... the above-referenced dockets. In accordance with the General Conformity Regulations under the Code of...

  10. Using Resource Economics to Anticipate Forest Land Use Change in the U.S. Mid-Atlantic Region

    Peter J. Parks; Ian W. Hardie; Cheryl A. Tedder; David N. Wear

    2000-01-01

    Demands for forest, farm, and developed land are evolving in the U.S. mid-Atlantic region. The demand for land in developed uses, as well as demands for various forest and farm products are changing in response to population growth, demographic shifts, and market forces. As demand factors change so do relative land values. Land area in future forest, farm, and...

  11. Physical trajectory profile data from glider ru23 deployed by Rutgers, the State University of New Jersey in the Mid-Atlantic Bight from 2014-08-14 to 2014-09-06 (NCEI Accession 0137967)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. IOOS Mid-Atlantic Regional Consortium of Ocean Observing Systems (MARACOOS) glider deployment to survey the physical and biological properties of Mid-Atlantic...

  12. Physical trajectory profile data from glider ru23 deployed by Rutgers, the State University of New Jersey in the Mid-Atlantic Bight from 2013-03-05 to 2013-03-23 (NCEI Accession 0137964)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. IOOS Mid-Atlantic Regional Consortium of Ocean Observing Systems (MARACOOS) glider deployment to survey the physical and biological properties of Mid-Atlantic...

  13. Physical trajectory profile data from glider ru23 deployed by Rutgers, the State University of New Jersey in the Mid-Atlantic Bight from 2014-09-16 to 2014-09-29 (NCEI Accession 0137968)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. IOOS Mid-Atlantic Regional Consortium of Ocean Observing Systems (MARACOOS) glider deployment to survey the physical and biological properties of Mid-Atlantic...

  14. Physical trajectory profile data from glider ru23 deployed by Rutgers, the State University of New Jersey in the Mid-Atlantic Bight from 2015-10-08 to 2015-10-27 (NCEI Accession 0153545)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. IOOS Mid-Atlantic Regional Consortium of Ocean Observing Systems (MARACOOS) glider deployment to survey the physical and biological properties of Mid-Atlantic...

  15. Physical trajectory profile data from glider ru23 deployed by Rutgers, the State University of New Jersey in the Mid-Atlantic Bight from 2013-10-17 to 2013-11-06 (NCEI Accession 0137966)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. IOOS Mid-Atlantic Regional Consortium of Ocean Observing Systems (MARACOOS) glider deployment to survey the physical and biological properties of Mid-Atlantic...

  16. Extreme Morphologic and Venting Changes in Methane Seeps at Southern Hydrate Ridge, Cascadia Margin

    Bigham, K.; Kelley, D. S.; Solomon, E. A.; Delaney, J. R.

    2017-12-01

    Two highly active methane hydrate seeps have been visited over a 7-year period as part of the construction and operation of NSF's Ocean Observatory Initiative's Regional Cable Array at Southern Hydrate Ridge. The site is located 90 km west of Newport, Oregon, at a water depth of 800 m. The seeps, Einstein's Grotto (OOI instrument deployment site) and Smokey Tavern (alternate site to the north), have been visited yearly from 2010 to 2017 with ROVs. Additionally, a digital still camera deployed from 2014 to 2017 at Einstein's Grotto, has been documenting the profound morphologic and biological changes at this site. A cabled pressure sensor, Acoustic Doppler Current Profiler, hydrophone, seismometer array, and uncabled fluid samplers have also been operational at the site for the duration of the camera's deployment. During this time, Einstein's Grotto has evolved from a gentle mound with little venting, to a vigorously bubbling pit bounded by a near vertical wall. Early on bubble emissions blew significant amounts of sediment into the water column and thick Beggiatoa mats coverd the mound. Most recently the face of the pit has collapsed, although bubble plumes are still emitted from the site. The Smokey Tavern site has undergone more extreme changes. Similar to Einstein's Grotto it was first characterized by gentle hummocks with dispersed bacterial mats. In subsequent years, it developed an extremely rugged, elongated collapsed area with vertical walls and jets of methane bubbles rising from small pits near the base of the collapse zone. Meter-across nearly sediment-free blocks of methane hydrate were exposed on the surface and in the walls of the collapse zone. In 2016, this area was unrecognizable with a much more subdued topography, and weak venting of bubbles. Exposed methane hydrate was not visible. From these observations new evolutionary models for methane seeps are being developed for Southern Hydrate Ridge.

  17. Expanded U.S. mid-Atlantic Margin Deep-Water Allostratigraphy; Bottom-Current Controls on Margin Evolution

    Gibson, J. C.; Miller, N. C.; Hutchinson, D. R.; Ten Brink, U. S.; Mountain, G. S.; Chaytor, J. D.; Shillington, D. J.

    2017-12-01

    There is a long history of seismic stratigraphic interpretation/analysis of the sedimentary sequence along the U.S. mid-Atlantic Margin (MAM). Here we expand the allostratigraphic (unconformity-bound) framework from the outer continental shelf to the Hatteras Abyssal Plain by correlating recently acquired 2D multi-channel seismic reflection data with existing drill sites and legacy 2D seismic data collected over the past 42 yrs. The new 2D post-stack Kirchhoff time migrated seismic data were acquired using R/V Marcus G. Langseth in 2014-2015 during USGS ECS surveys MGL1407 & MGL1506 and NSF-funded ENAM-CSE survey MGL1408. We map six seismic horizons along 1.5x104 km of 2D data and tie each to stratigraphic unconformities sampled at DSDP site 603 (lower rise). From shallow to deep they are: (1) M2, latest Miocene; (2) X, middle Miocene; (3) Au, late Oligocene; (4) A*, Late Cretaceous; (5) Km, early Late Cretaceous; and (6) Beta, middle Early Cretaceous. The horizons were converted to depth (mbsl) using high-resolution interval velocity models generated for each 2D survey line and isopachs were produced using the depth-converted stratigraphic framework for each allostratigraphic unit. The time-to-depth function was confirmed to be within 5% of drilling results at DSDP Sites 603 and nearby 105. Additionally, we tie horizon Au to upper-slope ODP Sites 902 & 1073, and trace it to the outer shelf. Interpretation of the framework and resulting isopachs show total sediment thickness uniformly decreasing seaward from the shelf edge, and overall thickening to the south. Regional depositional trends display a combination of both down slope and along slope processes (e.g. mass wasting, submarine fan formation, contourite and sediment drift deposits). The unit bound by horizons Au & Beta confirms pervasive excavation from the mid-slope to the continental rise and across the central and southern MAM (from New Jersey to North Carolina). How the excavated sediments were

  18. Conceptual ecological model for management of breeding shrubland birds in the Mid-Atlantic Region

    Peterjohn, Bruce G.

    2006-01-01

    While grassland birds have become the focus of increased conservation activities, the status of birds occupying shrubland habitats has received relatively little attention (Hunter et al. 2001). Yet, in eastern North America, shrubland birds exhibited consistent population declines during the past 40 years, based on data from the North American Breeding Bird Survey (Pardieck and Sauer 2001). These population declines primarily reflect large-scale changes in land use patterns during the previous century (Lorimer 2001). Large areas of marginal farmland were abandoned and underwent secondary succession during the first half of the twentieth century, producing abundant successional habitats favored by shrubland birds. As these habitats matured, combined with strict fire-suppression policies (Hunter et al. 2001), shrublands succeeded into mature forests, and shrubland bird communities were replaced by woodland birds (Irland 1982; Askins 1993). For example, while nearly 29% of New England forests were classified as sapling stage in 1950, only 8% remained at that stage in the 1980s (Askins 1993). The trend towards forest maturation and loss of shrubland habitats continues, yet concerted conservation activities have not been directed to benefit declining shrubland bird populations. The National Park Service (NPS) could contribute to shrubland bird conservation in the Mid- Atlantic Region. The NPS maintains a number of historic sites and former battlefields managed for their cultural significance but also support wildlife populations. Many of these “cultural parks” maintain open landscapes, recreating land use patterns existing at the times of the historical events. While these open landscapes are frequently managed grasslands, some parks also support successional habitats that could be managed to benefit shrubland birds. In 2005, the NPS initiated a project exploring the potential of “cultural parks” to support significant breeding grassland and shrubland bird

  19. Geology and Geochemistry of Magmatic Rocks from the Southern Part of the Kyushu-Palau Ridge in the Philippine Sea

    Lelikov, E. P.; Sedin, V. T.; Pugachev, A. A.

    2018-03-01

    The paper reports the results of a geochemical study of volcanogenic rocks from the southern part of the Kyushu-Palau Ridge. Volcanic structures, such as plateaulike rises, mountain massifs, and single volcanoes, are the major relief-forming elements of the southern part of the Kyushu-Palau Ridge. They are divided into three types according to the features of the relief and geological structure: shield, cone-shaped, and dome-shaped volcanoes. The ridge was formed on oceanic crust in the Late Mesozoic and underwent several stages of evolution with different significance and application of forces (tension and compression). Change in the geodynamic conditions during the geological evolution of the ridge mostly determined the composition of volcanic rocks of deep-mantle nature. Most of the ridge was formed by the Early Paleogene under geodynamic conditions close to the formation of oceanic islands (shield volcanoes) under tension. The island arc formed on the oceanic basement in the compression mode in the Late Eocene-Early Oligocene. Dome-shaped volcanic edifices composed of alkaline volcanic rocks were formed in the Late Oligocene-Early Miocene under tension. Based on the new geochemical data, detailed characteristics of volcanic rocks making up the shield, cone-shape, and dome-shape stratovolcanoes resulting in the features of these volcanic edifices are given for the first time. Continuous volcanism (with an age from the Cretaceous to the Late Miocene and composition from oceanic tholeiite to calc-alkaline volcanites of the island arc type) resulting in growth of the Earth's crust beneath the Kyushu-Palau Ridge was the major factor in the formation this ridge.

  20. Monitoring stink bugs (Hemiptera: Pentatomidae) in mid-Atlantic apple and peach orchards.

    Leskey, T C; Hogmire, H W

    2005-02-01

    Pyramid traps coated with "industrial safety yellow" exterior latex gloss enamel paint and baited with Euschistus spp. aggregation pheromone, methyl (2E,4Z)-decadienoate captured more stink bugs than all other baited and unbaited trap types in both apple and peach orchards in 2002 and 2003. Commercial sources of dispensers of methyl (2E,4Z)-decadienoate deployed in association with pyramid traps had a significant impact on trap captures. Captures in pyramid traps were four-fold greater when baited with lures from IPM Technologies, Inc. (Portland, OR) than with lures from Suterra (Bend, OR). Variation in yellow pyramid trap color ("industrial safety yellow" and "standard coroplast yellow") and material (plywood, plastic, and masonite) did not affect trap captures. Brown stink bug was the predominant species captured (58%), followed by dusky stink bug, Euschistus tristigmus (Say) (20%); green stink bug, Acrosternum hilare (Say) (14%); and other stink bugs (Brochymena spp. and unidentified nymphs) (8%). Captures in baited pyramid traps were significantly correlated with tree beating samples in both managed and unmanaged apple orchards and with sweep netting samples in the unmanaged apple orchard. However, problems associated with trapping mechanisms of pyramid trap jar tops and jar traps likely resulted in reduced captures in baited traps. Improved trapping mechanisms must be established to develop an effective monitoring tool for stink bugs in mid-Atlantic orchards.

  1. Genotypic Diversity of Phytophthora cinnamomi and P. plurivora in Maryland's Nurseries and Mid-Atlantic Forests.

    Beaulieu, Justine; Ford, Blaine; Balci, Yilmaz

    2017-06-01

    Genetic diversity of two Phytophthora spp.-P. cinnamomi (102 isolates), commonly encountered in Maryland nurseries and forests in the Mid-Atlantic United States, and P. plurivora (186 isolates), a species common in nurseries-was characterized using amplified fragment length polymorphism. Expected heterozygosity and other indices suggested a lower level of diversity among P. cinnamomi than P. plurivora isolates. Hierarchical clustering showed P. cinnamomi isolates separated into four clusters, and two of the largest clusters were closely related, containing 80% of the isolates. In contrast, P. plurivora isolates separated into six clusters, one of which included approximately 40% of the isolates. P. plurivora isolates recovered from the environment (e.g., soil and water) were genotypically more diverse than those found causing lesions. For both species, isolate origin (forest versus nursery or among nurseries) was a significant factor of heterozygosity. Clonal groups existed within P. cinnamomi and P. plurivora and included isolates from both forest and nurseries, suggesting that a pathway from nurseries to forests or vice versa exists.

  2. US Geological Survey BLM/OCS Baltimore Canyon (Mid-Atlantic) Sediment Analyses (Samples collected 1 July 1975 to 30 June 1976)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains analytical data from samples acquired from the Baltimore Canyon (Mid-Atlantic) area of the Outer Continental Shelf, U.S. East Coast, by the...

  3. Long-term Bat Monitoring on Islands, Offshore Structures, and Coastal Sites in the Gulf of Maine, mid-Atlantic, and Great Lakes—Final Report

    Peterson, Trevor [Stantec Consulting Services Inc., Topsham, ME (United States); Pelletier, Steve [Stantec Consulting Services Inc., Topsham, ME (United States); Giovanni, Matt [Stantec Consulting Services Inc., Topsham, ME (United States)

    2016-01-15

    This report summarizes results of a long-term regional acoustic survey of bat activity at remote islands, offshore structures, and coastal sites in the Gulf of Maine, Great Lakes, and mid-Atlantic coast.

  4. Brassica cover crops for nitrogen retention in the Mid-Atlantic coastal plain.

    Dean, Jill E; Weil, Ray R

    2009-01-01

    Brassica cover crops are new to the mid-Atlantic region, and limited information is available on their N uptake capabilities for effective N conservation. Forage radish (Raphanus sativus L. cv. Daikon), oilseed radish (Raphanus sativus L. cv. Adagio), and rape (Brassica napus L. cv. Dwarf Essex) were compared with rye (Secale cereale L. cv. Wheeler), a popular cover crop in the region, with regard to N uptake ability and potential to decrease N leaching at two sites in Maryland. Plants were harvested in fall and spring for dry matter and N analysis. Soil samples from 0 cm to 105 to 180 cm depth were obtained in fall and spring for NH(4)-N and NO(3)-N analyses. Ceramic cup tension lysimeters were installed at depths of 75 to 120 cm to monitor NO(3)-N in soil pore water. Averaged across 3 site-years, forage radish and rape shoots had greater dry matter production and captured more N in fall than rye shoots. Compared with a weedy fallow control, rape and rye caused similar decreases in soil NO(3)-N in fall and spring throughout the sampled profile. Cover crops had no effect on soil NH(4)-N. During the spring on coarse textured soil, pore water NO(3)-N concentrations in freeze-killed Brassica (radish) plots were greater than in control and overwintering Brassica (rape) and rye plots. On fine textured soil, all cover crops provided a similar decrease in pore water NO(3)-N concentration compared with control. On coarse textured soils, freeze-killed Brassica cover crops should be followed by an early-planted spring main crop.

  5. Biodiversity patterns, environmental drivers and indicator species on a High-temperature Hydrothermal edifice, mid-Atlantic ridge

    Sarrazin, Jozé e; Legendre, Pierre; Busserolles, Fanny de; Fabri, Marie-Claire; Guilini, Katja; Ivanenko, Viatcheslav N.; Morineaux, Marie; Vanreusel, Ann; Sarradin, Pierre-Marie

    2015-01-01

    . Environmental conditions showed more variation in the warm microhabitats than in the cold microhabitats. In terms of fauna, the warm microhabitats had lower macro- and meiofaunal densities, and lower richness and Shannon diversity than the cold microhabitats

  6. Structural control on basaltic dike and sill emplacement, Paiute Ridge mafic intrusion complex, southern Nevada

    Carter Krogh, K.E.; Valentine, G.A.

    1996-08-01

    Late Miocene basaltic sills and dikes in the Paiute Ridge area of southern nevada show evidence that their emplacement was structurally controlled. Basaltic dikes in this area formed by dilating pre-existing vertical to steeply E-dipping normal faults. Magma propagation along these faults must have required less energy than the creation of a self-propagated fracture at dike tips and the magma pressure must have been greater than the compressive stress perpendicular to the fault surface. N- to NE-trending en echelon dikes formed locally and are not obviously attached to the three main dikes in the area. The en echelon segments are probably pieces of deeper dikes, which are segmented perhaps as a result of a documented rotation of the regional stresses. Alternatively, changes in orientation of principal stresses in the vicinity of each en echelon dike could have resulted from local loads associated with paleotopographic highs or nearby structures. Sills locally branched off some dikes within 300 m of the paleosurface. These subhorizontal bodies occur consistently in the hanging wall block of the dike-injected faults, and intrude Tertiary tuffs near the Paleozoic-Tertiary contact. The authors suggest that the change in stresses near the earth's surface, the material strength of the tuff and paleozoic rocks, and the Paleozoic bedding dip direction probably controlled the location of sill formation and direction of sill propagation. The two largest sills deflected the overlying tuffs to form lopoliths, indicating that the magma pressure exceeded vertical stresses at that location and that the shallow level and large size of the sills allowed interaction with the free (earth's) surface. 32 refs., 4 figs., 1 tab

  7. National Assessment of Shoreline Change; historical shoreline change along the New England and Mid-Atlantic coasts

    Hapke, Cheryl J.; Himmelstoss, Emily A.; Kratzmann, Meredith G.; List, Jeffrey H.; Thieler, E. Robert

    2011-01-01

    Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, internally consistent updates regarding coastal erosion and land loss can be made nationally. In the case of this study, the shoreline is the interpreted boundary between the ocean water surface and the sandy beach. This report on the New England and Mid-Atlantic coasts is the fifth in a series of reports on historical shoreline change. Previous investigations include analyses and descriptive reports of the Gulf of Mexico, the Southeast Atlantic, and, for California, the sandy shoreline and the coastal cliffs. The rates of change presented in this report represent conditions up to the date of the most recent shoreline data and therefore are not intended for predicting future shoreline positions or rates of change. Because of the geomorphology of the New England and Mid-Atlantic (rocky coastlines, large embayments and beaches) as well as data gaps in some areas, this report presents beach erosion rates for 78 percent of the 1,360 kilometers of the New England and Mid-Atlantic coasts. The New England and Mid-Atlantic shores were subdivided into a total of 10 analysis regions for the purpose of reporting regional trends in shoreline change rates. The average rate of long

  8. Southern high latitude squat lobsters II: description of Uroptychus macquariae sp. nov. from Macquarie Ridge.

    Schnabel, Kareen E; Burghardt, Ingo; Ahyong, Shane T

    2017-11-23

    Squat lobsters have only recently been recorded from the Macquarie Ridge, which extends south between New Zealand and Antarctica. Among these, Uroptychus insignis (Henderson, 1885) was recorded for the first time outside the western Indian Ocean, exhibiting only subtle morphological differences. Reexamination of the Macquarie Ridge and Indian Ocean specimens attributed to U. insignis using morphological and molecular data revealed the Macquarie Ridge form to represent a separate species. Subtle but consistent morphological differences are evident and partial CO1 sequence data indicates that the specimens collected on Macquarie Ridge differ from those collected in the Indian Ocean by more than 7%. The Macquarie Ridge species is described herein as Uroptychus macquariae n.sp. Subtle morphological differences between the new species and U. insignis are discussed.

  9. Simulation of the 1979 spring bloom in the Mid-Atlantic Bight - A coupled physical/biological/optical model

    Gregg, Watson W.; Walsh, John J.

    1992-01-01

    A coupled physical/biological/optical model is developed for studies of phytoplankton variability in the spring 1979 Mid-Atlantic Bight, as observed by CZCS imagery. The model incorporates advection, mixing, sinking, growth as a function of light, temperature, nutrient availability, and death as a function of ingestion. It produced chlorophyll concentrations within the first attenuated depth within 1 standard deviation of CZCS imagery on large scale. The primary production estimates obtained using this model were within reasonable agreement with those measured in situ.

  10. Sociocultural dimensions of supply and demand for natural aggregate; examples from the Mid-Atlantic region, United States

    Robinson, Gilpin R.; Brown, William M.

    2002-01-01

    The United States uses large quantities of natural aggregate to build and maintain a continuously expanding infrastructure. In recent years, per capita demand for aggregate in the United States has grown to about 9.7 metric tons (10.7 tons) per person per year. Over the next 25 years, the aggregate industry expects to mine quantities equivalent to all aggregate mined in the United States over the past 100 years. The issues surrounding supply and demand for aggregate in the mid-Atlantic states of Maryland, Pennsylvania, Virginia, and West Virginia illustrate competing requirements for industrial minerals and many simultaneous social and environmental objectives.

  11. Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge.

    Philpotts, J.A.; Aruscavage, P. J.; Von Damm, Karen L.

    1987-01-01

    Abundances of Li, Na, K, Rb, Ca, Sr, Ba, Mn, Fe, Zn, and Si have been determined in fluid samples from 7 vents located in three areas on the southern Juan de Fuca Ridge. The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among other elements, in acid-stabilized solutions appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low.-from Authors

  12. A watershed-based method for environmental vulnerability assessment with a case study of the Mid-Atlantic region

    Tran, Liem T., E-mail: ltran1@utk.edu [Department of Geography, University of Tennessee, Knoxville, TN (United States); O& #x27; Neill, Robert V. [OTIE and Associates, Oak Ridge, TN (United States); Smith, Elizabeth R. [U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park, NC (United States)

    2012-04-15

    The paper presents a method for environmental vulnerability assessment with a case study of the Mid-Atlantic region. The method is based on the concept of 'self-/peer-appraisal' of a watershed in term of vulnerability. The self-/peer-appraisal process is facilitated by two separate linear optimization programs. The analysis provided insights on the environmental conditions, in general, and the relative vulnerability pattern, in particular, of the Mid-Atlantic region. The suggested method offers a simple but effective and objective way to perform a regional environmental vulnerability assessment. Consequently the method can be used in various steps in environmental assessment and planning. - Highlights: Black-Right-Pointing-Pointer We present a method for regional environmental vulnerability assessment. Black-Right-Pointing-Pointer It is based on the self-/peer-appraisal concept in term of vulnerability. Black-Right-Pointing-Pointer The analysis is facilitated by two separate linear optimization programs. Black-Right-Pointing-Pointer The method provides insights on the regional relative vulnerability pattern.

  13. Further Interpretation of the Relationship between Faunal Community and Seafloor Geology at Southern Hydrate Ridge, Cascadia Margin: Exploring Machine Learning

    Bigham, K.; Kelley, D. S.; Marburg, A.; Delaney, J. R.

    2017-12-01

    In 2011, high-resolution, georeferenced photomoasiacs were taken of Einstein's Grotto, an active methane hydrate seep within the field at Southern Hydrate Ridge located 90 km west of Newport, Oregon at a water depth of 800 m. Methods used to analyze the relationships between the seep site, seafloor geology, and the spatial distribution and abundances of microbial and macrofaunal communities at Einstein's Grotto were expanded to three other sites over the 200 by 300 m active seep field. These seeps were documented in the same survey in 2011 conducted by the remotely operated vehicle ROPOS on board the R/V Thompson. Over 10,000 high definition images allowed for the further quantification and characterization of the diversity and structure of the faunal community at this seep field. The new results support the study's initial findings of high variability in the distribution and abundance of seep organisms across the field, with correlation to seafloor geology. The manual classification of organisms was also used to train a series of convolutional neural networks in Nvidia DIGITS and Google Tensorflow environments for automated identification. The developed networks proved highly accurate at background/non-background segmentation ( 96%) and slightly less reliable for fauna identification ( 89%). This study provides a baseline for the faunal community at the Southern Hydrate Ridge methane seeps and a more efficient computer assisted method for processing follow on studies.

  14. Effects of Watershed Land Use and Geomorphology on Stream Baseflows in the Southern Blue Ridge Mountains

    The current understanding of watershed hydrology does not provide insight into prediction of low-flow response to land-use change in developing regions like the Blue Ridge of north Georgia and western North Carolina. To address this problem, three separate but complementary stud...

  15. Potential for shoreline changes due to sea-level rise along the U.S. mid-Atlantic region

    Gutierrez, Benjamin T.; Williams, S. Jeffress; Thieler, E. Robert

    2007-01-01

    Sea-level rise over the next century is expected to contribute significantly to physical changes along open-ocean shorelines. Predicting the form and magnitude of coastal changes is important for understanding the impacts to humans and the environment. Presently, the ability to predict coastal changes is limited by the scientific understanding of the many variables and processes involved in coastal change, and the lack of consensus regarding the validity of existing conceptual, analytical, or numerical models. In order to assess potential future coastal changes in the mid-Atlantic U.S. for the U.S. Climate Change Science Program (CCSP), a workshop was convened by the U.S. Geological Survey. Assessments of future coastal change were made by a committee of coastal scientists with extensive professional experience in the mid-Atlantic region. Thirteen scientists convened for a two-day meeting to exchange information and develop a consensus opinion on potential future coastal changes for the mid-Atlantic coast in response to sea-level rise. Using criteria defined in past work, the mid-Atlantic coast was divided into four geomorphic compartments: spits, headlands, wave-dominated barriers, and mixed-energy barriers. A range of potential coastal responses was identified for each compartment based on four sea-level rise scenarios. The four scenarios were based on the assumptions that: a) the long-term sea-level rise rate observed over the 20th century would persist over the 21st century, b) the 20th century rate would increase by 2 mm/yr, c) the 20th century rate would increase by 7 mm/yr, or d) sea-level would rise by 2 m over the next few hundred years. Potential responses to these sea-level rise scenarios depend on the landforms that occur within a region and include increased likelihood for erosion and shoreline retreat for all coastal types, increased likelihood for erosion, overwash and inlet breaching for barrier islands, as well as the possibility of a threshold

  16. Anthropocene streams and base-level controls from historic dams in the unglaciated mid-Atlantic region, USA

    Merritts, Dorothy; Walter, Robert; Rahnis, Michael; Hartranft, Jeff; Cox, Scott; Gellis, Allen; Potter, Noel; Hilgartner, William; Langland, Michael; Manion, Lauren; Lippincott, Caitlin; Siddiqui, Sauleh; Rehman, Zain; Scheid, Chris; Kratz, Laura; Shilling, Andrea; Jenschke, Matthew; Datin, Katherine; Cranmer, Elizabeth; Reed, Austin; Matuszewski, Derek; Voli, Mark; Ohlson, Erik; Neugebauer, Ali; Ahamed, Aakash; Neal, Conor; Winter, Allison; Becker, Steven

    2011-01-01

    Recently, widespread valley-bottom damming for water power was identified as a primary control on valley sedimentation in the mid-Atlantic US during the late seventeenth to early twentieth century. The timing of damming coincided with that of accelerated upland erosion during post-European settlement land-use change. In this paper, we examine the impact of local drops in base level on incision into historic reservoir sediment as thousands of ageing dams breach. Analysis of lidar and field data indicates that historic milldam building led to local base-level rises of 2-5 m (typical milldam height) and reduced valley slopes by half. Subsequent base-level fall with dam breaching led to an approximate doubling in slope, a significant base-level forcing. Case studies in forested, rural as well as agricultural and urban areas demonstrate that a breached dam can lead to stream incision, bank erosion and increased loads of suspended sediment, even with no change in land use. After dam breaching, key predictors of stream bank erosion include number of years since dam breach, proximity to a dam and dam height. One implication of this work is that conceptual models linking channel condition and sediment yield exclusively with modern upland land use are incomplete for valleys impacted by milldams. With no equivalent in the Holocene or late Pleistocene sedimentary record, modern incised stream-channel forms in the mid-Atlantic region represent a transient response to both base-level forcing and major changes in land use beginning centuries ago. Similar channel forms might also exist in other locales where historic milling was prevalent.

  17. Watershed Scale Impacts of Stormwater Green Infrastructure on Hydrology and Nutrient Fluxes in the Mid-Atlantic Region.

    Jaffe, P. R.; Pennino, M. J.; McDonald, R.

    2015-12-01

    Stormwater green infrastructure (SGI), including rain gardens, detention ponds, bioswales, and green roofs, is being implemented in cities across the globe to help reduce flooding, decrease combined sewer overflows, and lessen pollutant transport to streams and rivers. Despite the increasing use of urban SGI, there is much uncertainty regarding the cumulative effects of multiple SGI projects on hydrology and water quality at the watershed scale. To assess the cumulative effects of SGI, major cities across the mid-Atlantic were selected based on availability of SGI, water quality, and stream flow data. The impact of SGI was evaluated by comparing similar watersheds, with and without SGI or by assessing how long-term changes in SGI impact hydrologic and water quality metrics over time. Most mid-Atlantic cities have a goal of achieving 10-75% SGI by 2030. Of these cites, Washington D.C. currently has the highest density of SGI (15.5%), while Philadelphia, PA and New York, NY have the lowest (0.14% and 0.28%, respectively). When comparing watersheds of similar size and percent impervious surface cover, watersheds with lower amounts of SGI, on average, show up to 40% greater annual total nitrogen and 75% greater total phosphorus loads and show flashier hydrology (as indicated by 35% greater average peak discharge, 26% more peak discharge events per year, and 21% higher peak-to-volume ratio) compared to watersheds with higher amounts of SGI. However, for cities with combined sewer systems (e.g. Washington, D.C. and Philadelphia, PA), there was no relationship between the level of combined sewer overflows (CSOs) and the amount of SGI, indicating the level of SGI may not yet be sufficient to reduce CSOs as intended. When comparing individual watersheds over time, increases in SGI show no significant effect on the long-term trends in nutrient loads or hydrologic variables, potentially being obscured by the larger effect of interannual variability.

  18. Impact of the invasive brown marmorated stink bug, Halyomorpha halys (Stal) in Mid-Atlantic tree fruit orchards in the United States: case studies of commercial management

    Four commercial orchards in the mid-Atlantic region of the United States were surveyed weekly in 2010 and 2011 for the presence of brown marmorated stink bug and the injury caused to both apple and peaches. Among tested sampling techniques, baited pyramid traps yielded the most brown marmorated sti...

  19. An Investigation of the Relationship between the Components of School Climate and Leadership Behaviors on Student Achievement: Urban School Districts in the Mid-Atlantic Region

    Collins, Karmen J.

    2015-01-01

    The purpose of this research study was to investigate the relationship between the components of school climate and leadership behaviors on student achievement in an urban school district in the mid-atlantic region. School climate and leadership behaviors for the participating school districts was determined by the School Climate Survey (Corner…

  20. What English Language Arts, Math, and Science Instructional Materials Have Districts in the Mid-Atlantic Region States Adopted? Summary. Issues & Answers. REL 2010-No. 096

    Burzichelli, Claudia; Morrill, William; Bausmith, Jennifer; Mackey, Philip E.; Magarelli, Christopher

    2010-01-01

    Despite increasing accountability requirements and a national call for transparency in public policy, Mid-Atlantic Region state education agencies indicate that they have little information about what instructional materials districts adopt. This report describes first-year results of an ongoing project to generate and share information on core…

  1. What English Language Arts, Math, and Science Instructional Materials Have Districts in the Mid-Atlantic Region States Adopted? Issues & Answers. REL 2010-No. 096

    Burzichelli, Claudia; Morrill, William; Bausmith, Jennifer; Mackey, Philip E.; Magarelli, Christopher

    2010-01-01

    Despite increasing accountability requirements and a national call for transparency in public policy, Mid-Atlantic Region state education agencies indicate that they have little information about what instructional materials districts adopt. This report describes first-year results of an ongoing project to generate and share information on core…

  2. Dropout Prevention Programs in Nine Mid-Atlantic Region School Districts: Additions to a Dropout Prevention Database. Issues & Answers. REL 2011-No. 103

    Burzichelli, Claudia; Mackey, Philip E.; Bausmith, Jennifer

    2011-01-01

    The current study replicates work of Regional Educational Laboratory (REL) Northeast and Islands. It describes dropout prevention programs in nine Mid-Atlantic Region (Delaware, the District of Columbia, Maryland, New Jersey, and Pennsylvania) school districts serving communities with populations of 24,742-107,250 (as of July 2008). All nine…

  3. Dropout Prevention Programs in Nine Mid-Atlantic Region School Districts: Additions to a Dropout Prevention Database. Summary. Issues & Answers. REL 2011-No. 103

    Burzichelli, Claudia; Mackey, Philip E.; Bausmith, Jennifer

    2011-01-01

    The current study replicates work of Regional Educational Laboratory (REL) Northeast and Islands. It describes dropout prevention programs in nine Mid-Atlantic Region (Delaware, the District of Columbia, Maryland, New Jersey, and Pennsylvania) school districts serving communities with populations of 24,742-107,250 (as of July 2008). All nine…

  4. Common Core State Standards and Teacher Effectiveness. Q&A with Ross Wiener, Ph.D. REL Mid-Atlantic Teacher Effectiveness Webinar Series

    Regional Educational Laboratory Mid-Atlantic, 2013

    2013-01-01

    In this REL Mid-Atlantic webinar, Dr. Ross Wiener, Vice President and Executive Director of the Education and Society Program, Aspen Institute, discussed strategies for integrating the Common Core State Standards (CCSS) into teacher effectiveness systems, including ways in which the CCSS can support professional growth and inform teacher…

  5. Appendix D of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data. Workshop to Establish Coordination and Communication

    None

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the fourth appendix to the report, the presentations from the workshop.

  6. Emergency Contraceptive Pills: A 10-Year Follow-up Survey of Use and Experiences at College Health Centers in the Mid-Atlantic United States

    Miller, Laura McKeller; Sawyer, Robin G.

    2006-01-01

    The authors conducted a 10-year follow-up study using a telephone survey to investigate the availability of emergency contraceptive pills (ECPs) at college health centers in the mid-Atlantic region of the United States. They also examined related issues, such as distribution procedure, existence of a written protocol, personnel involved,…

  7. Multi-millennial record of erosion and fires in the southern Blue Ridge Mountains, USA In: Greenberg, CH and BS Collins (eds.)

    David S. Leigh

    2016-01-01

    Bottomland sediments from the southern Blue Ridge Mountains provide a coarse-resolution, multi-millennial stratigraphic record of past regional forest disturbance (soil erosion). This record is represented by 12 separate vertical accretion stratigraphic profi les that have been dated by radiocarbon, luminescence, cesium-137, and correlation methods...

  8. Effects of Watershed Land Use and Geomorphology on Stream Low Flows During Severe Drought Conditions in the Southern Blue Ridge Mountains, Georgia and North Carolina, United States

    Land use and physiographic variability influence stream low flows, yet their interactions and relative influence remain unresolved. Our objective was to assess the influence of land use and watershed geomorphic characteristics on low-flow variability in the southern Blue Ridge Mo...

  9. Effects of watershed land use and geomorphology on stream low flows during severe drought conditions in the southern Blue Ridge Mountains, Georgia and North Carolina, United States

    Katie Price; C. Jackson; Albert Parker; Trond Reitan; John Dowd; Mike Cyterski

    2011-01-01

    Land use and physiographic variability influence stream low flows, yet their interactions and relative influence remain unresolved. Our objective was to assess the influence of land use and watershed geomorphic characteristics on low-flow variability in the southern Blue Ridge Mountains of North Carolina and Georgia. Ten minute interval discharge data for 35 streams (...

  10. Surface elevation dynamics in vegetated Spartina marshes versus unvegetated tidal ponds along the mid-Atlantic coast, USA, with implications to waterbirds

    Erwin, R. Michael; Cahoon, Donald R.; Prosser, Diann J.; Sanders, Geoffrey; Hensel, Philippe

    2006-01-01

    Mid Atlantic coastal salt marshes contain a matrix of vegetation diversified by tidal pools, pannes, and creeks, providing habitats of varying importance to many species of breeding, migrating, and wintering waterbirds. We hypothesized that changes in marsh elevation were not sufficient to keep pace with those of sea level in both vegetated and unvegetated Spartina alterniflora sites at a number of mid lagoon marsh areas along the Atlantic coast. We also predicted that northern areas would suffer less of a deficit than would southern sites. Beginning in August 1998, we installed surface elevation tables at study sites on Cape Cod, Massachusetts, southern New Jersey, and two locations along Virginia's eastern shore. We compared these elevation changes over the 4-4.5 yr record with the long-term (> 50 yr) tidal records for each locale. We also collected data on waterbird use of these sites during all seasons of the year, based on ground surveys and replicated surveys from observation platforms. Three patterns of marsh elevation change were found. At Nauset Marsh, Cape Cod, the Spartina marsh surface tracked the pond surface, both keeping pace with regional sea-level rise rates. In New Jersey, the ponds are becoming deeper while marsh surface elevation remains unchanged from the initial reading. This may result in a submergence of the marsh in the future, assuming sea-level rise continues at current rates. Ponds at both Virginia sites are filling in, while marsh surface elevation rates do not seem to be keeping pace with local sea-level rise. An additional finding at all sites was that subsidence in the vegetated marsh surfaces was less than in unvegetated areas, reflecting the importance of the root mat in stabilizing sediments. The implications to migratory waterbirds are significant. Submergence of much of the lagoonal marsh area in Virginia and New Jersey over the next century could have major negative (i.e., flooding) effects on nesting populations of marsh

  11. Short term effects of particle exposure on hospital admissions in the Mid-Atlantic states: a population estimate.

    Itai Kloog

    Full Text Available Many studies report significant associations between PM(2.5 (particulate matter <2.5 micrometers and hospital admissions. These studies mostly rely on a limited number of monitors which introduces exposure error, and excludes rural and suburban populations from locations where monitors are not available, reducing generalizability and potentially creating selection bias.Using prediction models developed by our group, daily PM(2.5 exposure was estimated across the Mid-Atlantic (Washington D.C., and the states of Delaware, Maryland, New Jersey, Pennsylvania, Virginia, New York and West Virginia. We then investigated the short-term effects of PM(2.5exposures on emergency hospital admissions of the elderly in the Mid-Atlantic region.We performed case-crossover analysis for each admission type, matching on day of the week, month and year and defined the hazard period as lag01 (a moving average of day of admission exposure and previous day exposure.We observed associations between short-term exposure to PM(2.5 and hospitalization for all outcomes examined. For example, for every 10-µg/m(3 increase in short-term PM(2.5 there was a 2.2% increase in respiratory diseases admissions (95% CI = 1.9 to 2.6, and a 0.78% increase in cardiovascular disease (CVD admission rate (95% CI = 0.5 to 1.0. We found differences in risk for CVD admissions between people living in rural and urban areas. For every10-µg/m(3 increase in PM(2.5 exposure in the 'rural' group there was a 1.0% increase (95% CI = 0.6 to 1.5, while for the 'urban' group the increase was 0.7% (95% CI = 0.4 to 1.0.Our findings showed that PM(2.5 exposure was associated with hospital admissions for all respiratory, cardio vascular disease, stroke, ischemic heart disease and chronic obstructive pulmonary disease admissions. In addition, we demonstrate that our AOD (Aerosol Optical Depth based exposure models can be successfully applied to epidemiological studies investigating the health

  12. Effects of highway construction on stream water quality and macroinvertebrate condition in a mid-atlantic highlands watershed, USA.

    Chen, Yushun; Viadero, Roger C; Wei, Xinchao; Fortney, Ronald; Hedrick, Lara B; Welsh, Stuart A; Anderson, James T; Lin, Lian-Shin

    2009-01-01

    Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997-2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region.

  13. Cumulative impoundment evaporation in water resource management within the mid-Atlantic: A case study in Virginia

    Scott, D.; Burgholzer, R.; Kleiner, J.; Brogan, C. O.; Julson, C.; Withers, E.

    2017-12-01

    Across the eastern United States, successful management of water resources to satisfy the competing demands for human consumption, industry, agriculture, and ecosystems requires both water quality and water quantity considerations. Over the last 2 decades, low streamflows during dry summers have increased scrutiny on water supply withdrawals. Within Virginia, a statewide hydrologic model provides quantitative assessments on impacts from proposed water withdrawals to downstream river flow. Currently, evaporative losses are only accounted for from the large reservoirs. In this study, we sought to provide a baseline estimate for the cumulative evaporation from impoundments across all of the major river basins in Virginia. Virginia provides an ideal case study for the competing water demands in the mid-Atlantic region given the unique tracking of water withdrawals throughout the river corridor. In the over 73,000 Virginia impoundments, the cumulative annual impoundment evaporation was 706 MGD, or 49% of the permitted water withdrawal. The largest reservoirs (>100 acres) represented over 400 MGD, and 136 MGD for the smaller impoundments (water loss (evaporation + demand), with some areas where impoundment evaporation was greater than human water demand. Seasonally, our results suggest that cumulative impoundment evaporation in some watersheds greatly impacts streamflow during low flow periods. Our results demonstrate that future water supply planning will require not only understanding evaporation within large reservoirs, but also the thousands of small impoundments across the landscape.

  14. Carbon storage in old-growth forests of the Mid-Atlantic: toward better understanding the eastern forest carbon sink.

    McGarvey, Jennifer C; Thompson, Jonathan R; Epstein, Howard E; Shugart, Herman H

    2015-02-01

    Few old-growth stands remain in the matrix of secondary forests that dominates the eastern North American landscape. These remnant stands offer insight on the potential carbon (C) storage capacity of now-recovering secondary forests. We surveyed the remaining old-growth forests on sites characteristic of the general Mid-Atlantic United States and estimated the size of multiple components of forest C storage. Within and between old-growth stands, variability in C density is high and related to overstory tree species composition. The sites contain 219 ± 46 Mg C/ha (mean ± SD), including live and dead aboveground biomass, leaf litter, and the soil O horizon, with over 20% stored in downed wood and snags. Stands dominated by tulip poplar (Liriodendron tulipifera) store the most live biomass, while the mixed oak (Quercus spp.) stands overall store more dead wood. Total C density is 30% higher (154 Mg C/ha), and dead wood C density is 1800% higher (46 Mg C/ha) in the old-growth forests than in the surrounding younger forests (120 and 5 Mg C/ha, respectively). The high density of dead wood in old growth relative to secondary forests reflects a stark difference in historical land use and, possibly, the legacy of the local disturbance (e.g., disease) history. Our results demonstrate the potential for dead wood to maintain the sink capacity of secondary forests for many decades to come.

  15. Scientists and Stakeholders in the Chesapeake Bay: How the Mid-Atlantic RISA Strengthens Climate Resilience Through Participatory Decision-Making Processes

    Knopman, D.; Berg, N.

    2017-12-01

    The NOAA Mid-Atlantic Regional Integrated Sciences and Assessments (MARISA) program was formed in September 2016 to increase climate resilience in the Mid-Atlantic, with an initial focus on the Chesapeake Bay Watershed. In this talk, we will discuss how the program's unique structure and approach are designed to advance resilience to a changing climate through improved data, place-based decision support, and public engagement. Emphasis will be placed on MARISA's approach to integrating stakeholder perspectives from the onset of decision scoping, through the creation of actionable data sets, and concluding with the co-development of adaptation strategies between the scientific community, decision-makers, and stakeholders. Specific examples of this process involving climate-sensitive decisions and investments regarding water resources, land management, and urban corridors will be discussed.

  16. Temperature and other data collected using visual observations and other instruments in the Mid-Atlantic Bight and other Seas from GYRE from 01 August 1985 to 26 May 1990 (NODC Accession 9300074)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature and other data were collected using visual observations, bottle casts, and other instruments from GYRE and other platforms in the Mid-Atlantic Bight and...

  17. Physical trajectory profile data from glider blue deployed by University of Massachusetts; University of Massachusetts - Dartmouth in the Mid-Atlantic Bight from 2016-08-18 to 2016-08-22 (NCEI Accession 0156657)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. IOOS Mid-Atlantic Regional Association Coastal Ocean Observing System (MARACOOS) glider deployment. This is the second of a series of yearly seasonal...

  18. Physical trajectory profile data from glider ru23 deployed by Rutgers, the State University of New Jersey in the Mid-Atlantic Bight from 2012-10-25 to 2012-11-05 (NCEI Accession 0145723)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slocum glider ru23 was deployed prior to the movement of Hurrican Sandy into the Mid-Atlantic Bight and was deployed to sample the sub-surface waters during the...

  19. Physical trajectory profile data from glider blue deployed by University of Massachusetts; University of Massachusetts - Dartmouth in the Mid-Atlantic Bight from 2016-05-18 to 2016-06-06 (NCEI Accession 0153544)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. IOOS Mid-Atlantic Regional Association Coastal Ocean Observing System (MARACOOS) glider deployment. This is the first of a series of yearly seasonal deployments...

  20. Observation of carbonaceous aerosols and carbon monoxide in Mid-Atlantic region: Seasonal and inter-annual variations

    Chen, L. A.; Doddridge, B. G.; Doddridge, B. G.; Dickerson, R. R.; Dickerson, R. R.

    2001-05-01

    As part of Maryland Aerosol Research and Characterization (MARCH-Atlantic) study, a long-term monitoring of ambient elemental and organic carbon (EC and OC) aerosols has been made at Fort Meade, MD (39.16° N 76.51° W; elevation 46 m MSL), a suburban site within the Baltimore-Washington (B-W) corridor, since July 1999. 24-hr average EC and OC are measured every day during the season-representative months (July 1999, October 1999, January 2000, April 2000 and July 2000). Carbon monoxide (CO) was also measured nearly continuously over the period. Strong correlation between EC and CO (r = 0.7 ~ 0.9) in every month suggests common or proximate sources, likely traffic emissions. The EC versus CO slope, however, varies in different seasons and is found to increase nonlinearly with the ambient temperature. EC source strength may peak in summer. OC shows strong correlation with EC (r ~ 0.95) only in winter, suggesting that OC is also of the same primary sources during wintertime. The Interagency Monitoring of Protected Visual Environments (IMPROVE) network has been measuring EC and OC around the United States since 1988. The FME data during July 1999 are also compared with simultaneous measurements at nearby IMPROVE sites, showing B-W corridor could be a major contributor to the carbonaceous aerosols in the Mid-Atlantic region. A decreasing trend of EC level is found in three IMPROVE sites in this region. This actually agrees with the decreasing trend of CO observed previously at Big Meadow, Shenandoah National Park if CO and EC are both influenced by traffic emissions.

  1. Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

    Obelcz, Jeffrey; Brothers, Daniel S.; Chaytor, Jason D.; ten Brink, Uri S.; Ross, Steve W.; Brooke, Sandra

    2013-01-01

    Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only

  2. Landscape controls on the timing of spring, autumn, and growing season length in mid-Atlantic forests

    Elmore, A.J.; Guinn, S.M.; Minsley, B.J.; Richardson, A.D.

    2012-01-01

    The timing of spring leaf development, trajectories of summer leaf area, and the timing of autumn senescence have profound impacts to the water, carbon, and energy balance of ecosystems, and are likely influenced by global climate change. Limited field-based and remote-sensing observations have suggested complex spatial patterns related to geographic features that influence climate. However, much of this variability occurs at spatial scales that inhibit a detailed understanding of even the dominant drivers. Recognizing these limitations, we used nonlinear inverse modeling of medium-resolution remote sensing data, organized by day of year, to explore the influence of climate-related landscape factors on the timing of spring and autumn leaf-area trajectories in mid-Atlantic, USA forests. We also examined the extent to which declining summer greenness (greendown) degrades the precision and accuracy of observations of autumn offset of greenness. Of the dominant drivers of landscape phenology, elevation was the strongest, explaining up to 70% of the spatial variation in the onset of greenness. Urban land cover was second in importance, influencing spring onset and autumn offset to a distance of 32 km from large cities. Distance to tidal water also influenced phenological timing, but only within ~5 km of shorelines. Additionally, we observed that (i) growing season length unexpectedly increases with increasing elevation at elevations below 275 m; (ii) along gradients in urban land cover, timing of autumn offset has a stronger effect on growing season length than does timing of spring onset; and (iii) summer greendown introduces bias and uncertainty into observations of the autumn offset of greenness. These results demonstrate the power of medium grain analyses of landscape-scale phenology for understanding environmental controls on growing season length, and predicting how these might be affected by climate change.

  3. Time-series measurements of bubble plume variability and water column methane distribution above Southern Hydrate Ridge, Oregon

    Philip, Brendan T.; Denny, Alden R.; Solomon, Evan A.; Kelley, Deborah S.

    2016-03-01

    An estimated 500-2500 gigatons of methane carbon is sequestered in gas hydrate at continental margins and some of these deposits are associated with overlying methane seeps. To constrain the impact that seeps have on methane concentrations in overlying ocean waters and to characterize the bubble plumes that transport methane vertically into the ocean, water samples and time-series acoustic images were collected above Southern Hydrate Ridge (SHR), a well-studied hydrate-bearing seep site ˜90 km west of Newport, Oregon. These data were coregistered with robotic vehicle observations to determine the origin of the seeps, the plume rise heights above the seafloor, and the temporal variability in bubble emissions. Results show that the locations of seep activity and bubble release remained unchanged over the 3 year time-series investigation, however, the magnitude of gas release was highly variable on hourly time scales. Bubble plumes were detected to depths of 320-620 m below sea level (mbsl), in several cases exceeding the upper limit of hydrate stability by ˜190 m. For the first time, sustained gas release was imaged at the Pinnacle site and in-between the Pinnacle and the Summit area of venting, indicating that the subseafloor transport of fluid and gas is not restricted to the Summit at SHR, requiring a revision of fluid-flow models. Dissolved methane concentrations above background levels from 100 to 300 mbsl are consistent with long-term seep gas transport into the upper water column, which may lead to the build-up of seep-derived carbon in regional subsurface waters and to increases in associated biological activity.

  4. St Paul fracture zone intratransform ridge basalts (Equatorial Atlantic): Insight within the mantle source diversity

    Hemond, C.; Brunelli, D.; Maia, M.; Prigent, S.; Sichel, S. E.

    2017-12-01

    The St Paul Transform System offsets by 630 km the Equatorial Mid Atlantic Ridge at 1° N. It consists of four Major faults separating three intra transform ridge axes. Volcanic glassy samples were collected inside two intratransform ridge (ITR) segments during the COLMEIA cruise (Maia et al ; 2016) and samples from the third ITR available from a previous cruise ST PAUL (Hékinian et al. 2000). Major, trace elements and Hf, Pb, Sr and Nd isotopes were determined on selected hand picked glass chips. Few glassy samples recovered and analysed from abyssal hill samples open a time window of about 4.5 million years in the chemistry of the northern ITR. Results show that all samples are basaltic in composition but trace elements display contrasting images for the three ITR. The northern ITR samples are all light REE and highly incompatible enriched and are E-MORB; the central ITR samples display rather flat REE pattern with a level on enrichment of the HREE higher than the other two ITR and are T-MORB. Southern ITR samples are more heterogeneous N-MORB to T-MORB with a lower level of HREE. Isotopes reveal that the ITRs sample distinct mantle sources. In various isotope plans, the northern ITR samples plot together with published results from the MAR directly north of the St Paul F.Z. Therefore they exhibit some flavor of the Sierra Leone hotspot interacting with the MAR at 1.7°N. Central and southern ITR samples have very distinct composition from the northern ITR but resemble each other. However, for identical 206Pb/204Pb ratios, central ITR has slightly but significantly higher 207Pb/204Pb and 208Pb/204Pb, also higher 143Nd/144Nd for a given 87Sr/86Sr. Southern ITR is in chemical continuity of the MAR southward. So that central ITR samples display a rather specific composition. Off axis samples corresponding to the activity of the northern ITR up to 4.6 m.y. show that the hotspot contribution was even bigger on the spreading axis than today and might be fading with

  5. Long-term seismicity of the Reykjanes Ridge (North Atlantic) recorded by a regional hydrophone array

    Goslin, Jean; Lourenço, Nuno; Dziak, Robert P.; Bohnenstiehl, DelWayne R.; Haxel, Joe; Luis, Joaquim

    2005-08-01

    The seismicity of the northern Mid-Atlantic Ridge was recorded by two hydrophone networks moored in the sound fixing and ranging (SOFAR) channel, on the flanks of the Mid-Atlantic Ridge, north and south of the Azores. During its period of operation (05/2002-09/2003), the northern `SIRENA' network, deployed between latitudes 40° 20'N and 50° 30'N, recorded acoustic signals generated by 809 earthquakes on the hotspot-influenced Reykjanes Ridge. This activity was distributed between five spatio-temporal event clusters, each initiated by a moderate-to-large magnitude (4.0-5.6 M) earthquake. The rate of earthquake occurrence within the initial portion of the largest sequence (which began on 2002 October 6) is described adequately by a modified Omori law aftershock model. Although this is consistent with triggering by tectonic processes, none of the Reykjanes Ridge sequences are dominated by a single large-magnitude earthquake, and they appear to be of relatively short duration (0.35-4.5 d) when compared to previously described mid-ocean ridge aftershock sequences. The occurrence of several near-equal magnitude events distributed throughout each sequence is inconsistent with the simple relaxation of mainshock-induced stresses and may reflect the involvement of magmatic or fluid processes along this deep (>2000 m) section of the Reykjanes Ridge.

  6. Legacy effects of colonial millponds on floodplain sedimentation, bank erosion, and channel morphology, MID-Atlantic, USA

    Schenk, E.R.; Hupp, C.R.

    2009-01-01

    Many rivers and streams of the Mid-Atlantic Region, United States (U.S.) have been altered by postcolonial floodplain sedimentation (legacy sediment) associated with numerous milldams. Little Conestoga Creek, Pennsylvania, a tributary to the Susquehanna River and the Chesapeake Bay, is one of these streams. Floodplain sedimentation rates, bank erosion rates, and channel morphology were measured annually during 2004-2007 at five sites along a 28-km length of Little Conestoga Creek with nine colonial era milldams (one dam was still in place in 2007). This study was part of a larger cooperative effort to quantify floodplain sedimentation, bank erosion, and channel morphology in a high sediment yielding region of the Chesapeake Bay watershed. Data from the five sites were used to estimate the annual volume and mass of sediment stored on the floodplain and eroded from the banks for 14 segments along the 28-km length of creek. A bank and floodplain reach based sediment budget (sediment budget) was constructed for the 28 km by summing the net volume of sediment deposited and eroded from each segment. Mean floodplain sedimentation rates for Little Conestoga Creek were variable, with erosion at one upstream site (-5 mm/year) to deposition at the other four sites (highest = 11 mm/year) despite over a meter of floodplain aggradation from postcolonial sedimentation. Mean bank erosion rates range between 29 and 163 mm/year among the five sites. Bank height increased 1 m for every 10.6 m of channel width, from upstream to downstream (R2 = 0.79, p scouring downstream. The floodplain and bank along the 28-km reach produced a net mean sediment loss of 5,634 Mg/year for 2004-2007, indicating that bank erosion was exceeding floodplain sedimentation. In particular, the three segments between the existing dam and the confluence with the Conestoga River (32% of the studied reach) account for 97% of the measured net sediment budget. Future research directed at understanding channel

  7. Habitat risk assessment for regional ocean planning in the U.S. Northeast and Mid-Atlantic.

    Wyatt, Katherine H; Griffin, Robert; Guerry, Anne D; Ruckelshaus, Mary; Fogarty, Michael; Arkema, Katie K

    2017-01-01

    Coastal habitats provide important benefits to people, including habitat for species targeted by fisheries and opportunities for tourism and recreation. Yet, such human activities also can imperil these habitats and undermine the ecosystem services they provide to people. Cumulative risk assessment provides an analytical framework for synthesizing the influence of multiple stressors across habitats and decision-support for balancing human uses and ecosystem health. To explore cumulative risk to habitats in the U.S. Northeast and Mid-Atlantic Ocean Planning regions, we apply the open-source InVEST Habitat Risk Assessment model to 13 habitats and 31 stressors in an exposure-consequence framework. In doing so, we advance the science priorities of EBM and both regional planning bodies by synthesizing the wealth of available data to improve our understanding of human uses and how they affect marine resources. We find that risk to ecosystems is greatest first, along the coast, where a large number of stressors occur in close proximity and secondly, along the continental shelf, where fewer, higher consequence activities occur. Habitats at greatest risk include soft and hard-bottom nearshore areas, tidal flats, soft-bottom shelf habitat, and rocky intertidal zones-with the degree of risk varying spatially. Across all habitats, our results indicate that rising sea surface temperatures, commercial fishing, and shipping consistently and disproportionally contribute to risk. Further, our findings suggest that management in the nearshore will require simultaneously addressing the temporal and spatial overlap as well as intensity of multiple human activities and that management in the offshore requires more targeted efforts to reduce exposure from specific threats. We offer a transparent, generalizable approach to evaluating cumulative risk to multiple habitats and illustrate the spatially heterogeneous nature of impacts along the eastern Atlantic coast and the importance of

  8. Effects of non-native earthworms on on below- and aboveground processes in the Mid-Atlantic region

    Szlavecz, K. A.; McCormick, M. K.; Xia, L.; Pitz, S.; O'Neill, J.; Bernard, M.; Chang, C.; Whigham, D. F.

    2011-12-01

    Many biotic and abiotic disturbances have shaped the structure of the deciduous forests in the Mid-Atlantic region. One major anthropogenic factor is land use history. Agricultural practices in the past undoubtedly facilitated non-native earthworm colonization and establishment. Today most secondary forests are dominated by European lumbricid earthworms, although native species also occur in some habitats. To investigate how earthworm community composition and abundance affect belowground processes and tree seedling growth we set up a field manipulation experiment at the Smithsonian Environmental Research Center in Edgewater, MD. A total of 66 experimental plots were set up in successional (70 yrs) and mature (150 yrs) Tulip-poplar-Oak associations. We manipulated earthworm abundance and leaf litter input, and planted seedlings of Tulip poplar, Red maple, Red oak, and American beech. The experiment lasted for two years during which we regularly monitored density, biomass and species composition of earthworm assemblages and measured soil respiration. Soil moisture, temperature and air temperature were also continuously monitored using a wireless sensor network. At harvest, soil bulk density, pH, N pools, C:N ratio, potential N-mineralization rates, and enzyme activity were determined. We used quantitative PCR to assess the community composition of soil fungi. We also determined the extent of mycorrhizal colonization and biomass of roots, shoots and leaves. We conducted likelihood ratio tests for random and fixed effects based on mixed model analyses of variance. Differences between soil depths and among sites and plots accounted for a large portion of the variation in many soil properties. Litter quality affected soil pH and N mineralization. Earthworm densities affected bulk density, inorganic N content, and N mineralization. Both mycorrhizal groups were more abundant in mature than in successional forests. Both ectomycorrhizal (ECM) and arbuscular (AM) fungi were

  9. Legacy effects of colonial millponds on floodplain sedimentation, bank erosion, and channel morphology, MID-Atlantic, USA

    Schenk, E.R.; Hupp, C.R.

    2009-01-01

    Many rivers and streams of the Mid-Atlantic Region, United States (U.S.) have been altered by postcolonial floodplain sedimentation (legacy sediment) associated with numerous milldams. Little Conestoga Creek, Pennsylvania, a tributary to the Susquehanna River and the Chesapeake Bay, is one of these streams. Floodplain sedimentation rates, bank erosion rates, and channel morphology were measured annually during 2004-2007 at five sites along a 28-km length of Little Conestoga Creek with nine colonial era milldams (one dam was still in place in 2007). This study was part of a larger cooperative effort to quantify floodplain sedimentation, bank erosion, and channel morphology in a high sediment yielding region of the Chesapeake Bay watershed. Data from the five sites were used to estimate the annual volume and mass of sediment stored on the floodplain and eroded from the banks for 14 segments along the 28-km length of creek. A bank and floodplain reach based sediment budget (sediment budget) was constructed for the 28 km by summing the net volume of sediment deposited and eroded from each segment. Mean floodplain sedimentation rates for Little Conestoga Creek were variable, with erosion at one upstream site (-5 mm/year) to deposition at the other four sites (highest = 11 mm/year) despite over a meter of floodplain aggradation from postcolonial sedimentation. Mean bank erosion rates range between 29 and 163 mm/year among the five sites. Bank height increased 1 m for every 10.6 m of channel width, from upstream to downstream (R2 = 0.79, p channel and the floodplain. Floodplain sedimentation and bank erosion rates also appear to be affected by the proximity of the segments to one existing milldam, which promotes deposition upstream and scouring downstream. The floodplain and bank along the 28-km reach produced a net mean sediment loss of 5,634 Mg/year for 2004-2007, indicating that bank erosion was exceeding floodplain sedimentation. In particular, the three segments

  10. Decadal Declines of Mercury in Adult Bluefish (1972-2011) from the Mid-Atlantic Coast of the U.S.A.

    Cross, Ford A; Evans, David W; Barber, Richard T

    2015-08-04

    Concentrations of total mercury were measured in muscle of adult bluefish (Pomatomus saltatrix) collected in 2011 off North Carolina and compared with similar measurements made in 1972. Concentrations of mercury decreased by 43% in the fish between the two time periods, with an average rate of decline of about 10% per decade. This reduction is similar to estimated reductions of mercury observed in atmospheric deposition, riverine input, seawater, freshwater lakes, and freshwater fish across northern North America. Eight other studies between 1973 and 2007 confirm the decrease in mercury levels in bluefish captured in the Mid-Atlantic Bight. These findings imply that (1) reductions in the release of mercury across northern North America were reflected rather quickly (decades) in the decline of mercury in adult bluefish; (2) marine predatory fish may have been contaminated by anthropogenic sources of mercury for over 100 years; and (3) if bluefish are surrogates for other predators in the Mid-Atlantic Bight, then a reduction in the intake of mercury by the fish-consuming public has occurred. Finally, with global emissions of mercury continuing to increase, especially from Asia, it is important that long-term monitoring programs be conducted for mercury in marine fish of economic importance.

  11. Organic storage of CO/sub 2/ on the continental slope off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast

    Walsh, J.J.; Premuzic, E.T.; Gaffney, J.S.; Rowe, G.T.; Harbottle, G.; Stoenner, R.W.; Balsam, W.L.; Betzer, P.R.; Macko, S.A.

    1985-01-01

    A comparison is made of organic content, sedimentation rates derived from /sup 14/C and /sup 210/Pb analyses, /sup 13/C and /sup 15/N isotope ratios, amorphous silica, particle size, and calcium carbonate within sediments from slopes off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast. These sediments are mainly marine, diatom-rich, and about one-third of the organic carbon is recent, reflecting a possible transient of shelf export in response to man's increased activities since the industrial revolution. Using a combination of sedimentation and mixing rates of carbon, the C:N ratio of sediments within the upper 50 cm, and the amount of nitrogen thought to be released from the coastal zone, independent estimates suggest a carbon loading to world slopes of approx. 0.3 to 0.5 x 10/sup 9/ tons C y/sup -1/. The Bering slope exhibits no anthropogenic transients, however, while increased carbon loading may have occurred off Peru in response to overfishing and off the mid-Atlantic bight in response to eutrophication. The generality of their results depends on which of the three systems is most representative of world slopes.

  12. Dynamic Management of NOx and SO2 Emissions in the Texas and Mid-Atlantic Electric Power Systems and Implications for Air Quality.

    McDonald-Buller, Elena; Kimura, Yosuke; Craig, Michael; McGaughey, Gary; Allen, David; Webster, Mort

    2016-02-02

    Cap and trade programs have historically been designed to achieve annual or seasonal reductions in emissions of nitrogen oxides and sulfur dioxide from power plants. Emissions reductions may not be temporally coincident with meteorological conditions conducive to the formation of peak ozone and fine particulate matter concentrations. Integrated power system and air quality modeling methods were developed to evaluate time-differentiated emissions price signals on high ozone days in the Mid-Atlantic portion of the Pennsylvania-New Jersey-Maryland (PJM) Interconnection and Electric Reliability Council of Texas (ERCOT) grids. Sufficient flexibility exists in the two grids with marked differences in demand and fuel generation mix to accommodate time-differentiated emissions pricing alone or in combination with a season-wide program. System-wide emissions reductions and production costs from time-differentiated pricing are shown to be competitive with those of a season-wide program on high ozone days and would be more cost-effective if the primary policy goal was to target emissions reductions on these days. Time-differentiated pricing layered as a complement to the Cross-State Air Pollution Rule had particularly pronounced benefits for the Mid-Atlantic PJM system that relies heavily on coal-fired generation. Time-differentiated pricing aimed at reducing ozone concentrations had particulate matter reduction co-benefits, but if particulate matter reductions are the primary objective, other approaches to time-differentiated pricing may lead to greater benefits.

  13. Cover Crop-Based, Organic Rotational No-Till Corn and Soybean Production Systems in the Mid-Atlantic United States

    John M. Wallace

    2017-04-01

    Full Text Available Cover crop-based, organic rotational no-till (CCORNT corn and soybean production is becoming a viable strategy for reducing tillage in organic annual grain systems in the mid-Atlantic, United States. This strategy relies on mechanical termination of cover crops with a roller-crimper and no-till planting corn and soybean into cover crop mulches. Here, we report on recent research that focuses on integrated approaches for crop, nutrient and pest management in CCORNT systems that consider system and regional constraints for adoption in the mid-Atlantic. Our research suggests that no-till planting soybean into roller-crimped cereal rye can produce consistent yields. However, constraints to fertility management have produced less consistent no-till corn yields. Our research shows that grass-legume mixtures can improve N-release synchrony with corn demand and also improve weed suppression. Integration of high-residue inter-row cultivation improves weed control consistency and may reduce reliance on optimizing cover crop biomass accumulation for weed suppression. System-specific strategies are needed to address volunteer cover crops in later rotational phases, which result from incomplete cover crop termination with the roller crimper. The paucity of adequate machinery for optimizing establishment of cash crops into thick residue mulch remains a major constraint on CCORNT adoption. Similarly, breeding efforts are needed to improve cover crop germplasm and develop regionally-adapted varieties.

  14. A serpentinite-hosted ecosystem in the Southern Mariana Forearc.

    Ohara, Yasuhiko; Reagan, Mark K; Fujikura, Katsunori; Watanabe, Hiromi; Michibayashi, Katsuyoshi; Ishii, Teruaki; Stern, Robert J; Pujana, Ignacio; Martinez, Fernando; Girard, Guillaume; Ribeiro, Julia; Brounce, Maryjo; Komori, Naoaki; Kino, Masashi

    2012-02-21

    Several varieties of seafloor hydrothermal vents with widely varying fluid compositions and temperatures and vent communities occur in different tectonic settings. The discovery of the Lost City hydrothermal field in the Mid-Atlantic Ridge has stimulated interest in the role of serpentinization of peridotite in generating H(2)- and CH(4)-rich fluids and associated carbonate chimneys, as well as in the biological communities supported in highly reduced, alkaline environments. Abundant vesicomyid clam communities associated with a serpentinite-hosted hydrothermal vent system in the southern Mariana forearc were discovered during a DSV Shinkai 6500 dive in September 2010. We named this system the "Shinkai Seep Field (SSF)." The SSF appears to be a serpentinite-hosted ecosystem within a forearc (convergent margin) setting that is supported by fault-controlled fluid pathways connected to the decollement of the subducting slab. The discovery of the SSF supports the prediction that serpentinite-hosted vents may be widespread on the ocean floor. The discovery further indicates that these serpentinite-hosted low-temperature fluid vents can sustain high-biomass communities and has implications for the chemical budget of the oceans and the distribution of abyssal chemosynthetic life.

  15. Patterns and contributions of floodplain and legacy sediments remobilized from Piedmont streams of the mid-Atlantic U.S.

    Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen

    2015-04-01

    The perceived role of streambank erosion as a contributor to watershed sediment yield is an important driver of policy decisions for managing downstream impacts in the United States. In the Piedmont physiographic province of the eastern U.S. and in other regions of the south and midwest, the issue of 'legacy' sediment stored in stream valleys has long been recognized as a consequence of rapid deforestation and erosive agricultural practices following European settlement. Remobilization of stored floodplain sediment by bank erosion is frequently cited as a dominant component of watershed sediment budgets, with legacy sediment comprising the largest portion of this source. However there are few published studies documenting spatially extensive measurements of channel change throughout the drainage network on time scales of more than a few years. In this study we document 1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, 2) proportions of streambank sediment derived from legacy deposits, and 3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont. We measured gross erosion and channel deposition rates over 45 years within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 by comparing stream channel and floodplain morphology from LiDAR-based digital elevation data collected in 2005 with channel positions recorded on 1:2400-scale topographic maps from 1959-1961. Results were extrapolated to estimate contributions to watershed sediment yield from 1005 km2 of northern Baltimore County. Results indicate that legacy sediment is a dominant component (62%) of the sediment derived from bank erosion and that its relative importance is greater in larger valleys with broader valley floors and lower gradients. Although mass of sediment remobilized per unit channel length is greater in

  16. Zoogeography of fish parasites of the pearlside (Maurolicus muelleri), with genetic evidence of Anisakis simplex (s.s.) from the Mid-Atlantic Ridge

    Klimpel, S.; Kellermanns, E.; Palm, H. W.; Moravec, František

    2007-01-01

    Roč. 152, č. 3 (2007), s. 725-732 ISSN 0025-3162 Grant - others:German Research Council(DE) DFG KL 2087/1, PA 664/4-1; German Academic Exchange Service(DE) DAAD Klimpel D/05/51605 Institutional research plan: CEZ:AV0Z60220518 Keywords : Anisakis * Maurolicus * Atlantic Ocean Subject RIV: EG - Zoology Impact factor: 2.215, year: 2007

  17. Turbulence-driven shifts in holobionts and planktonic microbial assemblages in St Peter & St Paul Archipelago, Mid-Atlantic Ridge, Brazil

    Ana Paula B. Moreira

    2015-10-01

    Full Text Available The aim of this study was to investigate the planktonic and the holobiont Madracis decactis (Scleractinia microbial diversity along a turbulence-driven upwelling event, in the world´s most isolated tropical island, St Peter and St Paul Archipelago (SPSPA, Brazil. Twenty one metagenomes were obtained for seawater (N=12, healthy and bleached holobionts (N=9 before, during and after the episode of high seawater turbulence and upwelling. Microbial assemblages differed between low turbulence-low nutrient (LLR and high-turbulence-high nutrient (HHR regimes in seawater. During LLR there was a balance between autotrophy and heterotrophy in the bacterioplankton and the ratio cyanobacteria:heterotrophs ~1 (C:H. Prochlorales, unclassified Alphaproteobacteria and Euryarchaeota were the dominant bacteria and archaea, respectively. Basic metabolisms and cyanobacterial phages characterized the LLR. During HHR C:H << 0.05 and Gammaproteobacteria approximated 50% of the most abundant organisms in seawater. Alteromonadales, Oceanospirillales and Thaumarchaeota were the dominant bacteria and archaea. Prevailing metabolisms were related to membrane transport, virulence, disease and defense. Phages targeting heterotrophs and virulence factor genes characterized HHR. Shifts were also observed in coral microbiomes, according to both annotation–indepent and -dependent methods. HHR bleached corals metagenomes were the most dissimilar and could be distinguished by their di- and tetranucleotides frequencies, Iron Acquision metabolism and virulence genes, such as V. cholerae-related virulence factors. The healthy coral holobiont was shown to be less sensitive to transient seawater-related perturbations than the diseased animals. A conceptual model for the turbulence-induced shifts is put forward.

  18. Two new species of cystidicolid nematodes from the digestive tract of the deep-sea fish Coryphaenoides mediterraneus (Giglioli) (Macrouridae) from the Mid-Atlantic Ridge

    Moravec, František; Klimpel, S.

    2009-01-01

    Roč. 73, č. 1 (2009), s. 37-47 ISSN 0165-5752 R&D Projects: GA MŠk LC522; GA ČR(CZ) GA524/06/0170 Institutional research plan: CEZ:AV0Z60220518 Keywords : Ascarophis * Neoascarophis * Coryphaenoides Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 0.911, year: 2009

  19. Faunal and stable isotopic analyses of benthic foraminifera from the Southeast Seep on Kimki Ridge offshore southern California, USA

    McGann, Mary; Conrad, James E.

    2018-01-01

    We investigated the benthic foraminiferal faunal and stable carbon and oxygen isotopic composition of a 15-cm push core (NA075-092b) obtained on a Telepresence-Enabled cruise to the Southeast Seep on Kimki Ridge offshore southern California. The seep core was taken at a depth of 973 m in the vicinity of a Beggiatoa bacterial mat and vesicomyid clams (Calyptogena) and compared to previously published data of living assemblages from ~ 714 m, four reference cores obtained at ~ 1030 m, and another one at 739 m. All of the reference sites are also from the Inner Continental Borderland but with no evidence of methane seepage.No endemic species were found at the seep site and most of the taxa recovered there have been reported previously from other seep or low oxygen environments. Q- and R-mode cluster analyses clearly illustrated differences in the faunal assemblages of the seep and non-seep sites. The living assemblage at Southeast Seep was characterized by abundant Takayanagia delicata, Cassidulina translucens, and Spiroplectammina biformis, whereas the non-seep San Pedro Basin reference assemblage was comprised primarily of Chilostomella oolina and Globobulimina pacifica. Density and species richness were lower at the seep site compared to the non-seep site, reflecting the harsher living conditions there. The dead assemblage at the seep site was dominated by Gyroidina turgida compared to Cassidulina translucens at the ~ 1030 m non-seep site and Cassidulina translucens, Pseudoparrella pacifica, and Takayanagia delicata at the 739 m non-seep site. Density was three times lower at Southeast Seep than at the non-seep sites of comparable water depth but species richness was ~ 30% higher. Stable carbon isotopic values were considerably depleted in the seep samples compared to the non-seep samples, with a progression from lightest to heaviest average δ13C values evident at the seep site reflecting microhabitat preference and vital effect: the

  20. Trace element and isotopic effects arising from magma migration beneath mid-ocean ridges

    Kenyon, P.M.

    1990-01-01

    The trace element concentrations and isotopic ratios in the magma erupted on mid-ocean ridges may differ from those in the source material due to physical effects such as porous flow dispersion, exchange of trace elements between the fluid and solid phases during magma migration, and convective mixing in magma chambers. These differences are in addition to those produced by better known processes such as fractional crystallization and partial melting. The effects of the three former processes are described. It is predicted that magma typically reaches the sub-ridge magma chambers with a spatial heterogeneity only slightly reduced from that of the source material, but with a subdued variation in time. Convective mixing then further reduces the spatial heterogeneity. Application of the results for convective mixing to a recent Fourier analysis of 87 Sr/ 86 Sr variations along the Mid-Atlantic Ridge suggests that the falloff in amplitude of variation observed with decreasing wavelength in the Mid-Atlantic Ridge data cannot be explained by convective mixing in magma chambers. Instead, it is postulated that this falloff is due to the mechanics of the production and/or the solid-state convective mixing of chemical and isotopic heterogeneities in the solid mantle. (orig.)

  1. Temporal and Directional Patterns of Nymphal Halyomorpha halys (Hemiptera: Pentatomidae) Movement on the Trunk of Selected Wild and Fruit Tree Hosts in the Mid-Atlantic Region.

    Acebes-Doria, Angelita L; Leskey, Tracy C; Bergh, J Christopher

    2017-04-01

    Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive and polyphagous herbivore that has been problematic in Mid-Atlantic fruit orchards, many of which are adjacent to woodlands containing its wild hosts. Our tree census in woodlands bordering 15 Mid-Atlantic apple orchards revealed 47 species of deciduous trees and shrubs, 76.6% of which were recorded hosts of H. halys. Tree of heaven was most common and abundant overall. Halyomorpha halys nymphs have a substantial walking dispersal capacity, and their fitness is enhanced by feeding on multiple hosts. Directional and temporal patterns of nymphal H. halys movement on selected wild hosts and apple and peach trees at the orchard-woodland interface were monitored in 2014 and 2015 using passive traps to capture nymphs walking up and down tree trunks. Weekly captures from mid-May to late September or mid-October were compared among hosts across both seasons. Despite higher total nymphal captures in 2014 than 2015, the seasonal trends for both years were similar and indicated bivoltine H. halys populations. In both years, more nymphs were intercepted while walking up than down and captures of upward- and downward-walking nymphs varied significantly among the hosts. All instars were captured, but captures of second instars predominated. Captures reflected seasonal changes in instar distribution and consisted predominantly of younger and older nymphs, early and later in the season, respectively. Results are discussed in relation to host and seasonal effects on the movement of nymphs at the orchard-woodland interface, and the implications for H. halys management. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Regional characteristics of land use in northeast and southern Blue Ridge province: Associations with acid-rain effects on surface-water chemistry

    Liegel, L.; Cassell, D.; Stevens, D.; Shaffer, P.; Church, R.

    1991-01-01

    The Direct/Delayed Response Project (DDRP) is one of several being conducted by the United States Environmental Protection Agency to assess risk to surface waters from acidic deposition in the eastern United States. In one phase of DDRP, land use, wetland, and forest cover data were collected for statistical samples of 145 northeast lakes and 35 southern Blue Ridge Province stream watersheds. Land use and other data were then extrapolated from individual to target watershed populations in both study regions. Project statistical design allows summarization of results for various subsets of the target population. The article discusses results and implications of the land-use and land-cover characterization for both regions

  3. AN APPLIED ONTOLOGY TO THE MID-ATLANTIC CABLE: HISTORICAL TO MODERN INFORMATICS CONSIDERATION FROM A MATH PERSPECTIVE KAIEM L. FRINK ELIZABETH CITY STATE UNIVERSITY(ECSU)KAIEM_FRINK@HOTMAIL.COM, DR. DEWAYNE B. BRANCH ECSU, DR. ROB RASKIN JET PROPULSIONS LABORATORY GLENDA THOMAS ECSU,KENNETH JONES ECSU

    Frink, K.; Branch, B. D.; Raskin, R.

    2009-12-01

    As early as the 1600's scientists in various fields world to address a global human need of human communication on a global basis by implementing the trans-Atlantic cable. The Mid 4Trans-Atlantic cable is one of the earliest forms of global commutation. Here may be the first evidence of informatics needs where science, data, and engineering were collaborated across disciplines to advance a world standard of living. This work investigates what applied ontology may have been consisting with the thought pattern of such expertise who conducted informatics arguably without computers, ontology’s, and a cyber infrastructure. In modern context, an applied ontology may best represent the body of intentional learning, research and collaboration among scientists to achieve a human goal. Perhaps if such intentional non-partisan work can achieve a solution such as Trans-Atlantic Cable, climate change may benefit from intentional collaborative ontology’s and systems of multi user knowledgebase or expert informatics systems. 1Bruce C. Heezen 1924 -1977 American Geologist famous for mapping the Mid Atlantic Mountain Ridge in the 1950’s. Heezen died in 1977 on a submarine cruise to study the Mid-Atlantic ridge near Ice land aboard the NR-1 submarine. 7Marie Tharp academic background is Bachelors Degree in English, Master Degree in Geology University of Michigan, and Mathematics Degree at the University of Tulsa. Tharp worked at Lamont- Doherty Earth Observatory at Columbia University. History of the Digital Divide during the 1600’s touches on the availability of information. 3Issue of Mathematics during the 1600’s would be lack of communications and assessment. The scientific communities cannot address climate change most largely due to language barriers amongst humans. Weight per meter for the cable and the ships weight capacity in the 1600’sWeight/per meter 2w/m=X1 taking into account that maximum depths or Atlantic Ocean was unknown at that time and still is.

  4. Reevaluating the age of the Walden Creek Group and the kinematic evolution of the western Blue Ridge, southern Appalachians

    Thigpen, J. Ryan; Hatcher, Robert D.; Kah, Linda C.; Repetski, John E.

    2016-01-01

    An integrated synthesis of existing datasets (detailed geologic mapping, geochronologic, paleontologic, geophysical) with new paleontologic and geochemical investigations of rocks previously interpreted as part of the Neoproterozoic Walden Creek Group in southeastern Tennessee suggest a necessary reevaluation of the kinematics and structural architecture of the Blue Ridge Foothills. The western Blue Ridge of Tennessee, North Carolina, and Georgia is composed of numerous northwest-directed early and late Paleozoic thrust sheets, which record pronounced variation in stratigraphic/structural architecture and timing of metamorphism. The detailed spatial, temporal, and kinematic relationships of these rocks have remained controversial. Two fault blocks that are structurally isolated between the Great Smoky and Miller Cove-Greenbrier thrust sheets, here designated the Maggies Mill and Citico thrust sheets, contain Late Ordovician-Devonian conodonts and stable isotope chemostratigraphic signatures consistent with a mid-Paleozoic age. Geochemical and paleontological analyses of Walden Creek Group rocks northwest and southeast of these two thrust sheets, however, are more consistent with a Late Neoproterozoic (550–545 Ma) depositional age. Consequently, the structural juxtaposition of mid-Paleozoic rocks within a demonstrably Neoproterozoic-Cambrian succession between the Great Smoky and Miller Cove-Greenbrier thrust sheets suggests that a simple foreland-propagating thrust sequence model is not applicable in the Blue Ridge Foothills. We propose that these younger rocks were deposited landward of the Ocoee Supergroup, and were subsequently plucked from the Great Smoky fault footwall as a horse, and breached through the Great Smoky thrust sheet during Alleghanian emplacement of that structure.

  5. Determining the Extent of Hydrothermal Interaction on the Southern Costa Rica Rift Ridge Flank During the Past 8 Ma from Joint Inversion of Geophysical Data

    Wilson, D. J.; Moorkamp, M.; Hobbs, R. W.; Peirce, C.; Harris, R. N.; Morgan, J. V.

    2017-12-01

    Advective hydrothermal systems preferentially develop in zones of high porosity and permeability, driven by a local heat source. Associated chemical reactions lead to changes in the bulk physical properties, so variations in velocity and density, and the relationship connecting them, may provide a record of alteration by hydrothermal fluids. Oceanic crust accreted at intermediate rate ridges displays a range of characteristics between those typical for fast and slow spreading rates so changes in crustal porosity and permeability are sensitive to the interplay between tectonic stretching, magmatic supply and plate motions. Hence, changes in spreading style and sediment cover will influence the extent of the hydrothermal interaction that occurs and the mode of heat loss as evidenced by heat flow measurements. Using a variety of geophysical data we determine where hydrothermal circulation has been active in young oceanic crust that was accreted at an intermediate spreading rate. Results from traveltime tomography along a 300 km profile across the southern flank of the Costa Rica Rift reveal several variations in the P-wave velocity structure of the upper crust (layer 2). Following an initial increase in P-wave velocity near the ridge axis there is a section of the model 80 km in length that has lower P-wave velocity (up to 0.5 km s-1) compared to adjacent crust. This section has shallower bathymetry, by up to 500 m, than predicted by the subsidence curve and the top basement surface is rougher with a greater amount of faulting and larger throws. This zone is preceded by crust with significantly faster P-wave velocities (up to 1.0 km s-1) that was sampled by DSDP/ODP 504B. We characterise these changes in the shallow crustal structure by jointly inverting travel-time data and gravity data with deeper control from coincident magnetotelluric data. Using a cross-gradient approach allows us to search for models with a structural match, thus determining the relationship

  6. Anomalous intraseasonal events in the thermocline ridge region of Southern Tropical Indian Ocean and their regional impacts

    Jayakumar, A.; Gnanaseelan, C.

    2012-03-01

    The present study explores the mechanisms responsible for the strong intraseasonal cooling events in the Thermocline Ridge region of the southwestern Indian Ocean. Air sea interface and oceanic processes associated with Madden Julian Oscillation are studied using an Ocean General Circulation Model and satellite observations. Sensitivity experiments are designed to understand the ocean response to intraseasonal forcing with a special emphasis on 2002 cooling events, which recorded the strongest intraseasonal perturbations during the last well-observed decade. This event is characterized by anomalous Walker circulation over the tropical Indian Ocean and persistent intraseasonal heat flux anomaly for a longer duration than is typical for similar events (but without any favorable preconditioning of ocean basic state at the interannual timescale). The model heat budget analysis during 1996 to 2007 revealed an in-phase relationship between atmospheric fluxes associated with Madden Julian Oscillation and the subsurface oceanic processes during the intense cooling events of 2002. The strong convection, reduced shortwave radiation and increased evaporation have contributed to the upper ocean heat loss in addition to the slower propagation of active phase of convection, which supported the integration of longer duration of forcing. The sensitivity experiments revealed that dynamic response of ocean through entrainment at the intraseasonal timescale primarily controls the biological response during the event, with oceanic interannual variability playing a secondary role. This study further speculates the role of oceanic intraseasonal variability in the 2002 droughts over Indian subcontinent.

  7. Sea-level records from the U.S. mid-Atlantic constrain Laurentide Ice Sheet extent during Marine Isotope Stage 3.

    Pico, T; Creveling, J R; Mitrovica, J X

    2017-05-30

    The U.S. mid-Atlantic sea-level record is sensitive to the history of the Laurentide Ice Sheet as the coastline lies along the ice sheet's peripheral bulge. However, paleo sea-level markers on the present-day shoreline of Virginia and North Carolina dated to Marine Isotope Stage (MIS) 3, from 50 to 35 ka, are surprisingly high for this glacial interval, and remain unexplained by previous models of ice age adjustment or other local (for example, tectonic) effects. Here, we reconcile this sea-level record using a revised model of glacial isostatic adjustment characterized by a peak global mean sea level during MIS 3 of approximately -40 m, and far less ice volume within the eastern sector of the Laurentide Ice Sheet than traditional reconstructions for this interval. We conclude that the Laurentide Ice Sheet experienced a phase of very rapid growth in the 15 kyr leading into the Last Glacial Maximum, thus highlighting the potential of mid-field sea-level records to constrain areal extent of ice cover during glacial intervals with sparse geological observables.

  8. Structure of the oceanic lithosphere and upper mantle north of the Gloria Fault in the eastern mid-Atlantic by receiver function analysis

    Hannemann, Katrin; Krüger, Frank; Dahm, Torsten; Lange, Dietrich

    2017-10-01

    Receiver functions (RF) have been used for several decades to study structures beneath seismic stations. Although most available stations are deployed on shore, the number of ocean bottom station (OBS) experiments has increased in recent years. Almost all OBSs have to deal with higher noise levels and a limited deployment time (˜1 year), resulting in a small number of usable records of teleseismic earthquakes. Here we use OBSs deployed as midaperture array in the deep ocean (4.5-5.5 km water depth) of the eastern mid-Atlantic. We use evaluation criteria for OBS data and beamforming to enhance the quality of the RFs. Although some stations show reverberations caused by sedimentary cover, we are able to identify the Moho signal, indicating a normal thickness (5-8 km) of oceanic crust. Observations at single stations with thin sediments (300-400 m) indicate that a probable sharp lithosphere-asthenosphere boundary (LAB) might exist at a depth of ˜70-80 km which is in line with LAB depth estimates for similar lithospheric ages in the Pacific. The mantle discontinuities at ˜410 km and ˜660 km are clearly identifiable. Their delay times are in agreement with PREM. Overall the usage of beam-formed earthquake recordings for OBS RF analysis is an excellent way to increase the signal quality and the number of usable events.

  9. Assessing the Roles of Iron, Macronutrients and Wet deposition in Controlling Phytoplankton Growth in Seasonally Oligotrophic Waters of the Mid-Atlantic Bight

    Sedwick, P.; Mulholland, M. R.; Najjar, R.; Bernhardt, P. W.; Price, L. M.; Sohst, B. M.; Sookhdeo, C.; Widner, B.

    2016-02-01

    The role of iron supply in regulating phytoplankton production in high-nutrient, low-chlorophyll ocean regions has been well established. Less clear, however, is the importance of iron for phytoplankton processes in other oceanic settings, such as coastal and oligotrophic waters, where differential changes in the supply and removal of dissolved iron (dFe) can result in limitation or co-limitation of growth due to iron deficiency. One such region of interest is the Mid-Atlantic Bight (MAB), where previous field experiments have provided some evidence of co-limitation of algal growth by nitrogen and iron. In summer 2014 we conducted field sampling and shipboard experiments to assess the role of iron and macronutrient availability in controlling primary production in seasonally oligotrophic waters over the MAB continental slope, with a focus on the the impacts of wet deposition. Our results indicate that nitrogen was the proximate limiting nutrient, with a secondary limitation imposed by availability of phosphorus; we found no evidence for a deficiency in dFe, which was present at concentrations in the range 0.3-0.9 nM. Phytoplankton growth was clearly stimulated by the addition of natural rainwater, suggesting that summer rain events stimulate primary production in the MAB by contributing new nitrogen (primarily as ammonium) and phosphorus, whilst maintaining iron-replete conditions.

  10. Seasonality and flux estimates of dissolved organic carbon in tidal wetlands and estuaries in the U.S. Mid- Atlantic Bight and Gulf of Mexico from ocean color

    Cao, F.; Tzortziou, M.; Hu, C.; Najjar, R.

    2016-02-01

    Tidal wetlands and estuaries are dynamic features of coastal ocean and play critical roles in the global carbon cycle. Exchanges of dissolved organic carbon (DOC) between tidal wetlands and adjacent estuaries have important implications for carbon sequestration in tidal wetlands as well as biogeochemical cycling of wetlands derived material in the coastal zones. Recent studies demonstrated that the absorption coefficients of chromophoric dissolved organic matter at λ= 275 and 295 nm, which can be derived from satellite ocean color observations, can be used to accurately retrieve dissolved organic carbon (DOC) in some coastal waters. Based on a synthesis of existing field observations collected covering wide spatial and temporal variability in the Mid-Atlantic Bight and the Gulf of Mexico, here we developed and validated new empirical models to estimate coastal DOC from remotely sensed bio-optical properties of the surface water. We focused on the interfaces between tidal wetland-estuary and estuary-shelf water domains. The DOC algorithms were applied to SeaWiFs and MODIS observations to generate long-term climatological DOC distributions from 1998 to 2014. Empirical orthogonal function analysis revealed strong seasonality and spatial gradients in the satellite retrieved DOC in the tidal wetlands and estuaries. Combined with field observations and biogeochemical models, satellite retrievals can be used to scale up carbon fluxes from individual marshes and sub-estuaries to the whole estuarine system, and improve understanding of biogeochemical exchanges between terrestrial and aquatic ecosystems.

  11. Review of hydrodynamic and transport models and data collected near the mid-Atlantic low-level radioactive waste disposal sites

    Onishi, Y.; Hibler, L.F.; Sherwood, C.R.

    1987-08-01

    The objectives of this study were to (1) briefly review and evaluate available simulation models that may be used to predict the distribution of low-level radioactive waste (LLW) from the 2800-m and 3800-m Low Level Radioactive Disposal Sites in the Mid-Atlantic Continental Slope and Rise on a regional (a few hundred kilometers square) scale, (2) identify pertinent physical, biological, and geological oceanographic data in or near those LLW disposal sites, and (3) determine minimum data requirements for regional modeling. With suitable model modifications such as turbulence closure, enhanced sediment transport, radionuclide transport, and/or curvilinear coordinate system setup, the FLESCOT model, the FLOWER model, and Blumberg's model would be appropriate candidates for regional radionuclide modeling to predict the transport and dispersion of LLW disposed in the 2800-m and 3800-m sites. Although the RMA10 model does not incorporate a turbulence closure scheme, this model, with some modifications, is also an appropriate candidate for regional radionuclide modeling. FLESCOT is currently the only one that solves distributions of flow, turbulence, salinity, water temperature, sediments, dissolved contaminants, and sediment-sorbed contaminants. Thus, the FLESCOT model is recommended to be applied to the 2800-m and 3800-m sites to predict the transport and accumulation of LLW on a regional scale

  12. Geoelectric hazard maps for the Mid-Atlantic United States: 100 year extreme values and the 1989 magnetic storm

    Love, Jeffrey J.; Lucas, Greg M.; Kelbert, Anna; Bedrosian, Paul A.

    2018-01-01

    Maps of extreme value geoelectric field amplitude are constructed for the Mid‐Atlantic United States, a region with high population density and critically important power grid infrastructure. Geoelectric field time series for the years 1983–2014 are estimated by convolving Earth surface impedances obtained from 61 magnetotelluric survey sites across the Mid‐Atlantic with historical 1 min (2 min Nyquist) measurements of geomagnetic variation obtained from a nearby observatory. Statistical models are fitted to the maximum geoelectric amplitudes occurring during magnetic storms, and extrapolations made to estimate threshold amplitudes only exceeded, on average, once per century. For the Mid‐Atlantic region, 100 year geoelectric exceedance amplitudes have a range of almost 3 orders of magnitude (from 0.04 V/km at a site in southern Pennsylvania to 24.29 V/km at a site in central Virginia), and they have significant geographic granularity, all of which is due to site‐to‐site differences in magnetotelluric impedance. Maps of these 100 year exceedance amplitudes resemble those of the estimated geoelectric amplitudes attained during the March 1989 magnetic storm, and, in that sense, the March 1989 storm resembles what might be loosely called a “100 year” event. The geoelectric hazard maps reported here stand in stark contrast with the 100 year geoelectric benchmarks developed for the North American Electric Reliability Corporation.

  13. Dissolved inorganic carbon, total alkalinity, nutrients, and other variables collected from profile and discrete observations using Niskin bottle and other instruments from NOAA Ship Henry B. Bigelow in Gulf of Maine, Georges Bank, and Mid-Atlantic Bight from 2015-05-20 to 2015-06-02 (NCEI Accession 0157024)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains profile discrete measurements of dissolved inorganic carbon, total alkalinity, nutrients, and chlorophyll a in Mid-Atlantic Bight and...

  14. Dissolved inorganic carbon, total alkalinity, pH, nutrients, and other variables collected from surface discrete observations using flow-through pump and other instruments from NOAA Ship Henry B. Bigelow on the Northeast U.S. Shelf (Gulf of Maine and Mid-Atlantic Bight) from 2013-03-17 to 2013-05-09 (NCEI Accession 0154386)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains surface discrete measurements of dissolved inorganic carbon, total alkalinity, pH and nutrients in the Mid-Atlantic Bight and Gulf of...

  15. Population Genomics Reveals Seahorses (Hippocampus erectus) of the Western Mid-Atlantic Coast to Be Residents Rather than Vagrants

    Boehm, J. T.; Waldman, John; Robinson, John D.; Hickerson, Michael J.

    2015-01-01

    Understanding population structure and areas of demographic persistence and transients is critical for effective species management. However, direct observational evidence to address the geographic scale and delineation of ephemeral or persistent populations for many marine fishes is limited. The Lined seahorse (Hippocampus erectus) can be commonly found in three western Atlantic zoogeographic provinces, though inhabitants of the temperate northern Virginia Province are often considered tropical vagrants that only arrive during warm seasons from the southern provinces and perish as temperatures decline. Although genetics can locate regions of historical population persistence and isolation, previous evidence of Virginia Province persistence is only provisional due to limited genetic sampling (i.e., mitochondrial DNA and five nuclear loci). To test alternative hypotheses of historical persistence versus the ephemerality of a northern Virginia Province population we used a RADseq generated dataset consisting of 11,708 single nucleotide polymorphisms (SNP) sampled from individuals collected from the eastern Gulf of Mexico to Long Island, NY. Concordant results from genomic analyses all infer three genetically divergent subpopulations, and strongly support Virginia Province inhabitants as a genetically diverged and a historically persistent ancestral gene pool. These results suggest that individuals that emerge in coastal areas during the warm season can be considered “local” and supports offshore migration during the colder months. This research demonstrates how a large number of genes sampled across a geographical range can capture the diversity of coalescent histories (across loci) while inferring population history. Moreover, these results clearly demonstrate the utility of population genomic data to infer peripheral subpopulation persistence in difficult-to-observe species. PMID:25629166

  16. Population genomics reveals seahorses (Hippocampus erectus of the western mid-Atlantic coast to be residents rather than vagrants.

    J T Boehm

    Full Text Available Understanding population structure and areas of demographic persistence and transients is critical for effective species management. However, direct observational evidence to address the geographic scale and delineation of ephemeral or persistent populations for many marine fishes is limited. The Lined seahorse (Hippocampus erectus can be commonly found in three western Atlantic zoogeographic provinces, though inhabitants of the temperate northern Virginia Province are often considered tropical vagrants that only arrive during warm seasons from the southern provinces and perish as temperatures decline. Although genetics can locate regions of historical population persistence and isolation, previous evidence of Virginia Province persistence is only provisional due to limited genetic sampling (i.e., mitochondrial DNA and five nuclear loci. To test alternative hypotheses of historical persistence versus the ephemerality of a northern Virginia Province population we used a RADseq generated dataset consisting of 11,708 single nucleotide polymorphisms (SNP sampled from individuals collected from the eastern Gulf of Mexico to Long Island, NY. Concordant results from genomic analyses all infer three genetically divergent subpopulations, and strongly support Virginia Province inhabitants as a genetically diverged and a historically persistent ancestral gene pool. These results suggest that individuals that emerge in coastal areas during the warm season can be considered "local" and supports offshore migration during the colder months. This research demonstrates how a large number of genes sampled across a geographical range can capture the diversity of coalescent histories (across loci while inferring population history. Moreover, these results clearly demonstrate the utility of population genomic data to infer peripheral subpopulation persistence in difficult-to-observe species.

  17. An Alternative to Channel-Centered Views of the Landscape for Understanding Modern Streams in the Mid-Atlantic Piedmont Region, Eastern USA

    Merritts, D. J.; Walter, R. C.; Rahnis, M. A.; Oberholtzer, W.

    2008-12-01

    Stream channels generally are the focus of conceptual models of valley bottom geomorphology. The channel-centered model prevalent in the tectonically inactive eastern U. S. invokes meandering stream channels migrating laterally across valley floors, eroding one bank while depositing relatively coarse sediment in point bars on the other. According to this model, overbank deposition during flooding deposits a veneer of fine sediment over the gravel substrate. Erosion is considered normal, and the net volume of sediment is relatively constant with time. A dramatic change in conditions-land-clearing during European settlement--led to widespread aggradation on valley bottoms. This historic sedimentation was incorporated in the channel-centered view by assuming that meandering streams were overwhelmed by the increased sediment load and rapidly aggraded vertically. Later, elevated stream channels cut through these deposits because of decreased sediment supply and increased stormwater runoff accompanying urbanization. This view can be traced to early ideas of stream equilibrium in which incoming sediment supply and runoff determine stream-channel form. We propose a different conceptual model. Our trenching and field work along hundreds of km of stream length in the mid-Atlantic Piedmont reveal no point bars prior to European settlement. Instead, a polygenetic valley-bottom landscape underlies the drape of historic sediment. The planar surface of this veneer gives the appearance of a broad floodplain generated by long-term meandering and overbank deposition, but the "floodplain" is a recent aggradational surface from regional base-level rise due to thousands of early American dams that spanned valley bottoms. As modern streams incise into the historic fine-grained slackwater sediment, they expose organic-rich hydric soils along original valley bottom centers; talus, colluvium, bedrock, and saprolite with forest soils along valley margins; and weathered Pleistocene (and

  18. Seismic anisotropy in the upper mantle beneath the MAGIC array, mid-Atlantic Appalachians: Constraints from SKS splitting and quasi-Love wave propagation

    Aragon, J. C.; Long, M. D.; Benoit, M. H.; Servali, A.

    2016-12-01

    North America's eastern passive continental margin has been modified by several cycles of supercontinent assembly. Its complex surface geology and distinct topography provide evidence of these events, while also raising questions about the extent of deformation in the continental crust, lithosphere, and mantle during past episodes of rifting and mountain building. The Mid-Atlantic Geophysical Integrative Collaboration (MAGIC) is an EarthScope and GeoPRISMS-funded project that involves a collaborative effort among seismologists, geodynamicists, and geomorphologists. One component of the project is a broadband seismic array consisting of 28 instruments in a linear path from coastal Virginia to western Ohio, which operated between October 2013 and October 2016. A key science question addressed by the MAGIC project is the geometry of past lithospheric deformation and present-day mantle flow beneath the Appalachians, which can be probed using observations of seismic anisotropy Here we present observations of SKS splitting and quasi-Love wave arrivals from stations of the MAGIC array, which together constrain seismic anisotropy in the upper mantle. SKS splitting along the array reveals distinct regions of upper mantle anisotropy, with stations in and to the west of the range exhibiting fast directions parallel to the strike of the mountains. In contrast, weak splitting and null SKS arrivals dominate eastern stations in the coastal plain. Documented Love-to-Rayleigh wave scattering for surface waves originating the magnitude 8.3 Illapel, Chile earthquakes in September 2015 provides complementary constraints on anisotropy. These quasi-Love wave arrivals suggest a pronounced change in upper mantle anisotropy at the eastern edge of present-day Appalachian topography. Together, these observations increase our understanding of the extent of lithospheric deformation beneath North America associated with Appalachian orogenesis, as well as the pattern of present-day mantle flow

  19. Using ecological indicators and a decision support system for integrated ecological assessment at two national park units in the Mid-Atlantic region, U.S.A.

    Mahan, Carolyn G.; Young, John A.; Miller, Bruce; Saunders, Michael C.

    2014-01-01

    We implemented an integrated ecological assessment using a GIS-based decision support system model for Upper Delaware Scenic and Recreational River (UPDE) and Delaware Water Gap National Recreation Area (DEWA)—national park units with the mid-Atlantic region of the United States. Our assessment examined a variety of aquatic and terrestrial indicators of ecosystem components that reflect the parks’ conservation purpose and reference condition. Our assessment compared these indicators to ecological thresholds to determine the condition of park watersheds. Selected indicators included chemical and physical measures of water quality, biologic indicators of water quality, and landscape condition measures. For the chemical and physical measures of water quality, we used a water quality index and each of its nine components to assess the condition of water quality in each watershed. For biologic measures of water quality, we used the Ephemeroptera, Plecoptera, Trichoptera aquatic macroinvertebrate index and, secondarily, the Hilsenhoff aquatic macroinvertebrate index. Finally, for the landscape condition measures of our model, we used percent forest and percent impervious surface. Based on our overall assessment, UPDE and DEWA watersheds had an ecological assessment score of 0.433 on a −1 to 1 fuzzy logic scale. This score indicates that, in general, the natural resource condition within watersheds at these parks is healthy or ecologically unimpaired; however, we had only partial data for many of our indicators. Our model is iterative and new data may be incorporated as they become available. These natural parks are located within a rapidly urbanizing landscape—we recommend that natural resource managers remain vigilant to surrounding land uses that may adversely affect natural resources within the parks.

  20. Using Ecological Indicators and a Decision Support System for Integrated Ecological Assessment at Two National Park Units in the Mid-Atlantic Region, USA

    Mahan, Carolyn G.; Young, John A.; Miller, Bruce J.; Saunders, Michael C.

    2015-02-01

    We implemented an integrated ecological assessment using a GIS-based decision support system model for Upper Delaware Scenic and Recreational River (UPDE) and Delaware Water Gap National Recreation Area (DEWA)—national park units with the mid-Atlantic region of the United States. Our assessment examined a variety of aquatic and terrestrial indicators of ecosystem components that reflect the parks' conservation purpose and reference condition. Our assessment compared these indicators to ecological thresholds to determine the condition of park watersheds. Selected indicators included chemical and physical measures of water quality, biologic indicators of water quality, and landscape condition measures. For the chemical and physical measures of water quality, we used a water quality index and each of its nine components to assess the condition of water quality in each watershed. For biologic measures of water quality, we used the Ephemeroptera, Plecoptera, Trichoptera aquatic macroinvertebrate index and, secondarily, the Hilsenhoff aquatic macroinvertebrate index. Finally, for the landscape condition measures of our model, we used percent forest and percent impervious surface. Based on our overall assessment, UPDE and DEWA watersheds had an ecological assessment score of 0.433 on a -1 to 1 fuzzy logic scale. This score indicates that, in general, the natural resource condition within watersheds at these parks is healthy or ecologically unimpaired; however, we had only partial data for many of our indicators. Our model is iterative and new data may be incorporated as they become available. These natural parks are located within a rapidly urbanizing landscape—we recommend that natural resource managers remain vigilant to surrounding land uses that may adversely affect natural resources within the parks.

  1. Dependence of waterbirds and shorebirds on shallow-water habitats in the Mid-Atlantic coastal region: An ecological profile and management recommendations

    Erwin, R.M.

    1996-01-01

    Waterbirds (waterfowl, colonially nesting wading and seabirds, ospreys [Pandion haliaetus], and bald eagles [Haliaeetus leucocephalus]) and shorebirds (sandpipers, plovers, and relatives) may constitute a large fraction of the top level carnivore trophic component in many shallow-water areas of the mid-Atlantic region. The large biomass of many species (>1 kg body mass for the two raptors and some waterfowl) and enormous populations (e.g., >1 million shorebirds in late May in parts of Delaware Bay) reveal the importance of waterbirds as consumers and as linkages in nutrient flux in many shallow-water habitats. Salt and brackish marsh shallow-water habitats, including marsh pannes and tidal pools and creeks as well as constructed impoundments, are used intensively during most months of the year; in fall and winter, mostly by dabbling ducks, in spring and summer by migrant shorebirds and breeding colonial wading birds and seabirds. In adjacent estuaries, the intertidal flats and littoral zones of shallow embayments are heavily used by shorebirds, raptors, and colonial waterbirds in the May to September periods, with use by duck and geese heaviest from October to March. With the regional degradation of estuarine habitats and population declines of many species of waterbirds in the past 20 yr, some management recommendations relevant to shallow waters include: better protection, enhancement, and creation of small bay islands (small and isolated to preclude most mammalian predators) for nesting and brooding birds, especially colonial species; establishment of sanctuaries from human disturbance (e.g., boating, hunting) both in open water (waterfowl) and on land, better allocation of sandy dredged materials to augment islands or stabilize eroding islands; improvement in water management of existing impoundments to ensure good feeding, resting, and nesting opportunities for all the waterbirds, support for policies to preclude point and nonpoint source runoff of chemicals

  2. Downscaling, 2-way Nesting, and Data Assimilative Modeling in Coastal and Shelf Waters of the U.S. Mid-Atlantic Bight and Gulf of Maine

    Wilkin, J.; Levin, J.; Lopez, A.; Arango, H.

    2016-02-01

    Coastal ocean models that downscale output from basin and global scale models are widely used to study regional circulation at enhanced resolution and locally important ecosystem, biogeochemical, and geomorphologic processes. When operated as now-cast or forecast systems, these models offer predictions that assist decision-making for numerous maritime applications. We describe such a system for shelf waters of the Mid-Atlantic Bight (MAB) and Gulf of Maine (GoM) where the MARACOOS and NERACOOS associations of U.S. IOOS operate coastal ocean observing systems that deliver a dense observation set using CODAR HF-radar, autonomous underwater glider vehicles (AUGV), telemetering moorings, and drifting buoys. Other U.S. national and global observing systems deliver further sustained observations from moorings, ships, profiling floats, and a constellation of satellites. Our MAB and GoM re-analysis and forecast system uses the Regional Ocean Modeling System (ROMS; myroms.org) with 4-dimensional Variational (4D-Var) data assimilation to adjust initial conditions, boundary conditions, and surface forcing in each analysis cycle. Data routinely assimilated include CODAR velocities, altimeter satellite sea surface height (with coastal corrections), satellite temperature, in situ CTD data from AUGV and ships (NMFS Ecosystem Monitoring voyages), and all in situ data reported via the WMO GTS network. A climatological data assimilative analysis of hydrographic and long-term mean velocity observations specifies the regional Mean Dynamic Topography that augments altimeter sea level anomaly data and is also used to adjust boundary condition biases that would otherwise be introduced in the process of downscaling from global models. System performance is described with respect to the impact of satellite, CODAR and in situ observations on analysis skill. Results from a 2-way nested modeling system that adds enhanced resolution over the NSF OOI Pioneer Array in the central MAB are also

  3. Watershed-scale impacts of stormwater green infrastructure on hydrology, nutrient fluxes, and combined sewer overflows in the mid-Atlantic region.

    Pennino, Michael J; McDonald, Rob I; Jaffe, Peter R

    2016-09-15

    Stormwater green infrastructure (SGI), including rain gardens, detention ponds, bioswales, and green roofs, is being implemented in cities across the globe to reduce flooding, combined sewer overflows, and pollutant transport to streams and rivers. Despite the increasing use of urban SGI, few studies have quantified the cumulative effects of multiple SGI projects on hydrology and water quality at the watershed scale. To assess the effects of SGI, Washington, DC, Montgomery County, MD, and Baltimore County, MD, were selected based on the availability of data on SGI, water quality, and stream flow. The cumulative impact of SGI was evaluated over space and time by comparing watersheds with and without SGI, and by assessing how long-term changes in SGI impact hydrologic and water quality metrics over time. Most Mid-Atlantic municipalities have a goal of achieving 10-20% of the landscape drain runoff through SGI by 2030. Of these areas, Washington, DC currently has the greatest amount of SGI (12.7% of the landscape drained through SGI), while Baltimore County has the lowest (7.9%). When controlling for watersheds size and percent impervious surface cover, watersheds with greater amounts of SGI have less flashy hydrology, with 44% lower peak runoff, 26% less frequent runoff events, and 26% less variable runoff. Watersheds with more SGI also show 44% less NO3(-) and 48% less total nitrogen exports compared to watersheds with minimal SGI. There was no significant reduction in phosphorus exports or combined sewer overflows in watersheds with greater SGI. When comparing individual watersheds over time, increases in SGI corresponded to non-significant reductions in hydrologic flashiness compared to watersheds with no change in SGI. While the implementation of SGI is somewhat in its infancy in some regions, cities are beginning to have a scale of SGI where there are statistically significant differences in hydrologic patterns and water quality. Copyright © 2016 The Authors

  4. Monitoring Groundwater Variations from Satellite Gravimetry and Hydrological Models: A Comparison with in-situ Measurements in the Mid-Atlantic Region of the United States

    Ruya Xiao

    2015-01-01

    Full Text Available Aimed at mapping time variations in the Earth’s gravity field, the Gravity Recovery and Climate Experiment (GRACE satellite mission is applicable to access terrestrial water storage (TWS, which mainly includes groundwater, soil moisture (SM, and snow. In this study, SM and accumulated snow water equivalent (SWE are simulated by the Global Land Data Assimilation System (GLDAS land surface models (LSMs and then used to isolate groundwater anomalies from GRACE-derived TWS in Pennsylvania and New York States of the Mid-Atlantic region of the United States. The monitoring well water-level records from the U.S. Geological Survey Ground-Water Climate Response Network from January 2005 to December 2011 are used for validation. The groundwater results from different combinations of GRACE products (from three institutions, CSR, GFZ and JPL and GLDAS LSMs (CLM, NOAH and VIC are compared and evaluated with in-situ measurements. The intercomparison analysis shows that the solution obtained through removing averaged simulated SM and SWE of the three LSMs from the averaged GRACE-derived TWS of the three centers would be the most robust to reduce the noises, and increase the confidence consequently. Although discrepancy exists, the GRACE-GLDAS estimated groundwater variations generally agree with in-situ observations. For monthly scales, their correlation coefficient reaches 0.70 at 95% confidence level with the RMSE of the differences of 2.6 cm. Two-tailed Mann-Kendall trend test results show that there is no significant groundwater gain or loss in this region over the study period. The GRACE time-variable field solutions and GLDAS simulations provide precise and reliable data sets in illustrating the regional groundwater storage variations, and the application will be meaningful and invaluable when applied to the data-poor regions.

  5. Non-Fluvial Controls of Erosion, Sediment Transport and Fluvial Morphology in a mid-Atlantic Piedmont Watershed, White Clay Creek, Pennsylvania, U.S.A.

    McCarthy, K.; Affinito, R. A.; Pizzuto, J. E.; Stotts, S.; Henry, T.; Krauthauser, M.; O'Neal, M. A.

    2017-12-01

    Quantifying contemporary sediment budgets is essential for restoration and ecosystem management of mid-Atlantic watersheds, but relevant processes and controls are poorly understood. In the 153 km2 White Clay Creek watershed in southeastern Pennsylvania, longitudinal profiles reflect migration of knickpoints though bedrock over Quaternary timescales. In bank exposures along stream valleys, saprolite, bedrock, and matrix-supported cobbly and bouldery diamicton (likely colluvial) commonly underlie finer-grained clay, silt, sand, and gravel deposits of valley floor depositional environments. Overbank sedimentation rates were quantified by measuring the thickness of sediment deposited over the roots of floodplain trees. The sampled trees range in age from 25-270 years with median sediment accumulation rates of approximately 2 mm/yr (range 0-10 mm/yr). Rates of bank retreat (measured from historical aerial imagery or root-exposure dendrochronology) vary from 6-36 cm/yr, with median rates of 10 cm/yr. While bank erosion rates are subject to a variety of controls, including channel curvature, the density of riparian trees, and freeze-thaw processes, the strongest influence appears to be the grain size and thickness of bouldery diamicton exposed along the toes of retreating banks. Cobbles and boulders supplied by eroding diamicton also mantle the bed of the channel, such that 33- 80% of the bed material remains immobile at bankfull stage. A conceptual model of fluvial processes and sediment budgets for these channels must account for the watershed's history of changing climate, tectonics, and land use, requiring mapping of bedrock, colluvium, former mill dam sediments, and other non-alluvial deposits and controls. Efforts to apply hydraulic geometry principles (requiring a precise adjustment to contemporary hydraulic and sediment regime) or to treat these channels as traditional "threshold" rivers are unlikely to be successful.

  6. Inter-Rifting and Inter-Seismic Strain Accumulation in a Propagating Ridge System: A Geodetic Study from South Iceland

    Travis, M. E.; La Femina, P. C.; Geirsson, H.

    2012-12-01

    The Mid-Atlantic Ridge, a slow spreading (~19 mm/yr) mid-ocean ridge boundary between the North American and Eurasian plates, is exposed subaerially in Iceland as the result of ridge-hotspot interaction. Plate spreading in Iceland is accommodated along neovolcanic zones comprised of central volcanoes and their fissure swarms. In south Iceland plate motion is partitioned between the Western Volcanic Zone (WVZ) and Eastern Volcanic Zone (EVZ). The EVZ is propagating to the southwest, while the WVZ is dying out from the northeast. Plate motion across both systems has been accommodated by repeated rifting events and fissure eruptions. In this study we investigate whether the WVZ is active and accumulating strain, and how strain is partitioned between the WVZ and EVZ. We also test how strain is accumulating along fissure swarms within the EVZ (i.e. is strain accumulation localized to one fissure swarm, or are multiple systems active?). We use GPS data and elastic block models run using the program DEFNODE to investigate these issues. GPS data are processed using the GIPSY-OASIS II software, and have been truncated to the 2000.5-2011 time period to avoid co-seismic displacement from the two June 2000 South Iceland Seismic Zone earthquakes. We also truncate the time series for sites within 20 km of Eyjafjallajökull to the beginning of 2010 to eliminate deformation associated with the March 2010 eruption of that volcano. We correct for co-seismic displacement from the two May 2008 SISZ earthquakes, inflation at Hekla volcano and the horizontal component of glacial isostatic rebound (GIA). Our best-fit model for inter-rifting and inter-seismic elastic strain accumulation suggests 80-90% of spreading is accommodated in the EVZ with the other 10-20% accommodated by the WVZ. The best-fit location of the EVZ is between Veidivotn and Lakigigar in an area of no Holocene volcanic activity. We suggest the WVZ is only active at Hengill and its associated fissure swarm. Geologic and

  7. Beach-ridge sedimentology as an archive of terrestrial climate change: Insights from a geochemical and stratigraphic study of the Tijucas Strandplain, southern Brazil

    Krask, J. L.; Hein, C. J.; Galy, V.; FitzGerald, D.; Henrique de Fontoura Klein, A.

    2017-12-01

    Whereas millennial-scale variations in climate forcing drives changes in terrestrial processes, which are in turn directly linked to fluvial sediment loads (e.g., weathering and erosion), the impact of decadal- to centennial- scale climate fluctuations on downstream coastal sedimentation patterns and landscape evolution remains unclear. Specifically, the connection between long-term (decades or more) precipitation seasonality and sediment export from river systems has not been established. This study examines the manner in which sub-millennial-scale fluctuations in precipitation over river catchments may be recorded in coastal progradational sedimentary archives. The 5-km wide Tijucas Strandplain (southern Brazil) formed over the last 5800 years through the rapid reworking of sediment discharged from the Tijucas River in a regime of falling sea level. In an overall regime shift from sand- to mud- dominance (linked to a long-term reduction in wave energy caused by bay shoaling) are nearly 70 distinct transitions between shore-parallel sand- and mud- dominated facies. Bulk organic carbon and terrestrial plant-wax fatty acid stable hydrogen (δD) and carbon (δ13C) isotopic measurements from sediments from select sandy and muddy ridges across the plain reveal that these two sedimentological regimes are geochemically distinct. Specifically, waxes from sediments deposited during periods of sandy progradation had δD values, on average, >10 ‰ higher than those from mud-dominated periods, indicating that these sedimentary units reflect different hydroclimatic conditions within the river drainage basin at the time of deposition. Comparison of plant wax isotopic signatures of river, bay, and beach sediments during the current period of mud-dominated progradation reveals a close correlation with earlier periods of mud deposition within the Tijucas Strandplain. Thus, decadal- to centennial- scale sedimentologic transitions within the plain are interpreted to reflect climate

  8. Target loads of atmospheric sulfur deposition for the protection and recovery of acid-sensitive streams in the Southern Blue Ridge Province.

    Sullivan, Timothy J; Cosby, Bernard J; Jackson, William A

    2011-11-01

    An important tool in the evaluation of acidification damage to aquatic and terrestrial ecosystems is the critical load (CL), which represents the steady-state level of acidic deposition below which ecological damage would not be expected to occur, according to current scientific understanding. A deposition load intended to be protective of a specified resource condition at a particular point in time is generally called a target load (TL). The CL or TL for protection of aquatic biota is generally based on maintaining surface water acid neutralizing capacity (ANC) at an acceptable level. This study included calibration and application of the watershed model MAGIC (Model of Acidification of Groundwater in Catchments) to estimate the target sulfur (S) deposition load for the protection of aquatic resources at several future points in time in 66 generally acid-sensitive watersheds in the southern Blue Ridge province of North Carolina and two adjoining states. Potential future change in nitrogen leaching is not considered. Estimated TLs for S deposition ranged from zero (ecological objective not attainable by the specified point in time) to values many times greater than current S deposition depending on the selected site, ANC endpoint, and evaluation year. For some sites, one or more of the selected target ANC critical levels (0, 20, 50, 100μeq/L) could not be achieved by the year 2100 even if S deposition was reduced to zero and maintained at that level throughout the simulation. Many of these highly sensitive streams were simulated by the model to have had preindustrial ANC below some of these target values. For other sites, the watershed soils contained sufficiently large buffering capacity that even very high sustained levels of atmospheric S deposition would not reduce stream ANC below common damage thresholds. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Tornado Strikes Southern Maryland

    2002-01-01

    Evening light catches the tops of towering thunderheads over the Mid-Atlantic states on April 28, 2002. The powerful storms spawned several tornados, one of which was classified as an F4 tornado. The powerful tornado touched down in the southern Maryland town of La Plata, destroying most of the historic downtown. The twister-one of the strongest ever to hit the state-beat a 24-mile swath running west to east through the state and claimed at least three lives. The image above was taken by the Geostationary Operational Environmental Satellite (GOES) at 7:15 PM Eastern Daylight Savings Time. A large version of the animation shows more detail. (5.9 MB Quicktime) Image courtesy National Oceanic and Atmospheric Administration (NOAA) and the GOES Project Science Office. Animation by Robert Simmon, NASA GSFC.

  10. A landscape indicator approach to the identification and articulation of the consequences of land-cover change in the Mid-Atlantic Region, 1973-2001

    Slonecker, E. Terrence; Milheim, Lesley E.; Claggett, Peter

    2009-01-01

    Landscape indicators, derived from land-use and land-cover data, hydrology, nitrate deposition, and elevation data, were used by Jones and others (2001a) to calculate the ecological consequences of land-cover change. Nitrate loading and physical bird habitat were modeled from 1973 and 1992 land-cover and other spatial data for the Mid-Atlantic region. Utilizing the same methods, this study extends the analysis another decade with the use of the 2001 National Land Cover Dataset. Land-cover statistics and trends are calculated for three time periods: 1973-1992, 1992-2001 and 1973-2001. In addition, high-resolution aerial photographs (1 meter or better ground-sample distance) were acquired and analyzed for thirteen pairs of adjacent USGS 7.5 minute quadrangle maps in areas where distinct positive or negative changes to nitrogen loading and bird habitat were previously calculated. During the entire 30 year period, the data show that there was extensive loss of agriculture and forest area and a major increase in urban land-cover classes. However, the majority of the conversion of other classes to urban occurred during the 1992-2001 period. During the 1973-1992 period, there was only moderate increase in urban area, while there was an inverse relationship between agricultural change and forest change. In general, forest gain and agricultural loss was found in areas of improving landscape indicators, and forest loss and agricultural gain was found to occur in areas of declining indicators related to habitat and nitrogen loadings, which was generally confirmed by the aerial photographic analysis. In terms of the specific model results, bird habitat, which is mainly related to the extent of forest cover, declined overall with forest extent, but was also affected more in the decline of habitat quality. Nitrate loading, which is mainly related to agricultural land cover actually improved from 1992-2001, and in the overall study, mainly due to the conversion of agriculture to

  11. Vertical datum conversion process for the inland and coastal gage network located in the New England, Mid-Atlantic, and South Atlantic-Gulf hydrologic regions

    Rydlund, Jr., Paul H.; Noll, Michael L.

    2017-03-07

    Datum conversions from the National Geodetic Vertical Datum of 1929 to the North American Vertical Datum of 1988 among inland and coastal gages throughout the hydrologic regions of New England, the Mid-Atlantic, and the South Atlantic-Gulf have implications among river and storm surge forecasting, general commerce, and water-control operations. The process of data conversions may involve the application of a recovered National Geodetic Vertical Datum of 1929–North American Vertical Datum of 1988 offset, a simplistic datum transformation using VDatum or VERTCON software, or a survey, depending on a gaging network datum evaluation, anticipated uncertainties for data use among the cooperative water community, and methods used to derive the conversion. Datum transformations from National Geodetic Vertical Datum of 1929 to North American Vertical Datum of 1988 using VERTCON purport errors of ± 0.13 foot at the 95 percent confidence level among modeled points, claiming more consistency along the east coast. Survey methods involving differential and trigonometric leveling, along with observations using Global Navigation Satellite System technology, afford a variety of approaches to establish or perpetuate a datum during a survey. Uncertainties among leveling approaches are generally quality category and ≥0.1 foot for Level II or III quality categories (defined by the U.S. Geological Survey) by observation and review of experienced practice. The conversion process is initiated with an evaluation of the inland and coastal gage network datum, beginning with altitude datum components and the history of those components queried through the U.S. Geological Survey Groundwater Site Inventory database. Subsequent edits to the Groundwater Site Inventory database may be required and a consensus reached among the U.S. Geological Survey Water Science Centers to identify the outstanding workload categorized as in-office datum transformations or offset applications versus out

  12. Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

    Shimeld, John; Li, Qingmou; Chian, Deping; Lebedeva-Ivanova, Nina; Jackson, Ruth; Mosher, David; Hutchinson, Deborah R.

    2016-01-01

    The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity–depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km2. The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity–depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity–depth profiles for each seismic trace. A thickness of 12–13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity–depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares

  13. Exploring tectonomagmatic controls on mid-ocean ridge faulting and morphology with 3-D numerical models

    Howell, S. M.; Ito, G.; Behn, M. D.; Olive, J. A. L.; Kaus, B.; Popov, A.; Mittelstaedt, E. L.; Morrow, T. A.

    2016-12-01

    Previous two-dimensional (2-D) modeling studies of abyssal-hill scale fault generation and evolution at mid-ocean ridges have predicted that M, the ratio of magmatic to total extension, strongly influences the total slip, spacing, and rotation of large faults, as well as the morphology of the ridge axis. Scaling relations derived from these 2-D models broadly explain the globally observed decrease in abyssal hill spacing with increasing ridge spreading rate, as well as the formation of large-offset faults close to the ends of slow-spreading ridge segments. However, these scaling relations do not explain some higher resolution observations of segment-scale variability in fault spacing along the Chile Ridge and the Mid-Atlantic Ridge, where fault spacing shows no obvious correlation with M. This discrepancy between observations and 2-D model predictions illuminates the need for three-dimensional (3-D) numerical models that incorporate the effects of along-axis variations in lithospheric structure and magmatic accretion. To this end, we use the geodynamic modeling software LaMEM to simulate 3-D tectono-magmatic interactions in a visco-elasto-plastic lithosphere under extension. We model a single ridge segment subjected to an along-axis gradient in the rate of magma injection, which is simulated by imposing a mass source in a plane of model finite volumes beneath the ridge axis. Outputs of interest include characteristic fault offset, spacing, and along-axis gradients in seafloor morphology. We also examine the effects of along-axis variations in lithospheric thickness and off-axis thickening rate. The main objectives of this study are to quantify the relative importance of the amount of magmatic extension and the local lithospheric structure at a given along-axis location, versus the importance of along-axis communication of lithospheric stresses on the 3-D fault evolution and morphology of intermediate-spreading-rate ridges.

  14. Abundant Hydrothermal Venting in the Southern Ocean Near 62°S/159°E on the Australian-Antarctic Ridge

    Baker, E. T.; Hahm, D.; Rhee, T. S.; Park, S. H.; Lupton, J. E.; Walker, S. L.; Choi, H.

    2014-12-01

    Circum-Antarctic Ridges (CARs) comprise almost one-third of the global Mid-Ocean Ridge, yet remain terra incognita for hydrothermal activity and chemosynthetic ecosystems. The InterRidge Vents Database lists only 3 confirmed (visualized) and 35 inferred (plume evidence) active sites along the ~21,000 km of CARs. Here, we report on a multi-year effort to locate and characterize hydrothermal activity on two 1st-order segments of the Australian-Antarctic Ridge that are perhaps more isolated from other known vent fields than any other vent site on the Mid-Ocean Ridge. KR1 is a 300-km-long segment near 62°S/159°E, and KR2 a 90-km-long segment near 60°S/152.5°E. We used profiles collected by Miniature Autonomous Plume Recorders (MAPRs) on rock corers in March and December of 2011 to survey each segment, and an intensive CTD survey in Jan/Feb 2013 to pinpoint sites and sample plumes on KR1. Optical and oxidation-reduction potential (ORP, aka Eh) 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 13 sites, some within a few km of each other. The densest site concentration on KR1 occurred along a relatively inflated, 90-km-long section near the segment center. CTD tows covered 20 km of the eastern, most inflated portion of this area, finding two 6-km-long zones centered near 158.6°E and 158.8°E with multiple plume anomalies. Three ORP anomalies within 50 m of the seafloor indicate precise venting locations. We call this area the Mujin "Misty Harbor" vent field. Vent frequency sharply decreases away from Mujin. 3He/heat ratios determined from 20 plume samples in the Mujin field were mostly <0.015 fM/J, indicative of chronic venting, but 3 samples, 0.021-0.034 fM/J, are ratios typical of a recent eruption. The spatial density of hydrothermal activity along KR1 and KR2 is similar to other intermediate-rate spreading ridges. We calculate the plume incidence (ph) along

  15. Observation of a Gelatinous Octopod, Haliphron atlanticus, along the Southern West Mariana Ridge: A Unique Cephalopod of Continental Slope and Mesopelagic Communities

    Michael J. Miller

    2018-01-01

    Full Text Available The circumglobal deep-sea gelatinous giant octopod, Haliphron atlanticus, reaches 4 m in length and uses both benthic and pelagic habitats in the upper 3000 m of the ocean during different life history stages, but it is rarely observed due to the deep-depths where it typically lives. It has been collected in trawls and observed a few times near continental margins or islands and has been identified in the stomach contents of deep-diving predators such as sperm whales and blue sharks or detected as body fragments after predation events. An individual H. atlanticus (~1 m in total length was video-recorded at 12:21 for about 3 minutes in front of the Shinkai 6500 submersible at 586–599 m (6.5°C, salinity 34.4 along the West Mariana Ridge. It made no escape attempt as the submersible approached and it moved slowly up or down in front of the submersible. It was over the outer seamount-slope (bottom depth ~3208 m ~50 km west of seamounts (≥1529 m summits, but how it fits into the mesopelagic food web along the ridge is unclear. More information is needed to understand the role of H. atlanticus in oceanic food webs and if it typically lives along seamount ridges.

  16. Carbon isotopes and concentrations in mid-oceanic ridge basalts

    Pineau, F.; Javoy, M.

    1983-01-01

    In order to estimate carbon fluxes at mid-ocean ridges and carbon isotopic compositions in the convective mantle, we have studied carbon concentrations and isotopic compositions in tholeiitic glasses from the FAMOUS zone (Mid-Atlantic Ridge at 36 0 N) and East Pacific Rise from 21 0 N (RITA zone) to 20 0 S. These samples correspond essentially to the whole spectrum of spreading rates (2-16 cm/yr). The contain: -CO 2 vesicles in various quantities (3-220 ppm C) with delta 13 C between -4 and -9per mille relative to PDB, in the range of carbonatites and diamonds. - Carbonate carbon (3-100 ppm C) with delta 13 C between -2.6 and -20.0per mille relative to PDB. - Dissolved carbon at a concentration of 170+-10 ppm under 250 bar pressure with delta 13 C from -9 to -21per mille relative to PDB. This dissolved carbon, not contained in large CO 2 vesicles, corresponds to a variety of chemical forms among which part of the above carbonates, microscopic CO 2 bubbles and graphite. The lightest portions of this dissolved carbon are extracted at low temperatures (400-600 0 C) whereas the CO 2 from the vesicles is extracted near fusion temperature. These features can be explained by outgassing processes in two steps from the source region of the magma: (1) equilibrium outgassing before the second percolation threshold, where micron size bubbles are continuously reequilibrated with the magma; (2) distillation after the second percolation threshold when larger bubbles travel faster than magma concentrations to the surface. The second step may begin at different depths apparently related to the spreading rate, shallower for fast-spreading ridges than for slow-spreading ridges. (orig./WL)

  17. Microbial Community Structure of Deep-sea Hydrothermal Vents on the Ultraslow Spreading Southwest Indian Ridge

    Jian Ding

    2017-06-01

    Full Text Available Southwest Indian Ridge (SWIR is a typical oceanic ultraslow spreading ridge with intensive hydrothermal activities. The microbial communities in hydrothermal fields including primary producers to support the entire ecosystem by utilizing geochemical energy generated from rock-seawater interactions. Here we have examined the microbial community structures on four hydrothermal vents from SWIR, representing distinct characteristics in terms of temperature, pH and metal compositions, by using Illumina sequencing of the 16S small subunit ribosomal RNA (rRNA genes, to correlate bacterial and archaeal populations with the nature of the vents influenced by ultraslow spreading features. Epsilon-, Gamma-, Alpha-, and Deltaproteobacteria and members of the phylum Bacteroidetes and Planctomycetes, as well as Thaumarchaeota, Woesearchaeota, and Euryarchaeota were dominant in all the samples. Both bacterial and archaeal community structures showed distinguished patterns compared to those in the fast-spreading East Pacific Ridge or the slow-spreading Mid-Atlantic Ridge as previously reported. Furthermore, within SWIR, the microbial communities are highly correlated with the local temperatures. For example, the sulfur-oxidizing bacteria were dominant within bacteria from low-temperature vents, but were not represented as the dominating group recovered from high temperature (over 300°C venting chimneys in SWIR. Meanwhile, Thaumarchaeota, the ammonium oxidizing archaea, only showed high relative abundance of amplicons in the vents with high-temperature in SWIR. These findings provide insights on the microbial community in ultraslow spreading hydrothermal fields, and therefore assist us in the understanding of geochemical cycling therein.

  18. Corrigendum to "Depth-varying seismogenesis on an oceanic detachment fault at 13°20‧N on the Mid-Atlantic Ridge" [Earth Planet. Sci. Lett. 479 (2017) 60-70

    Craig, Timothy J.; Parnell-Turner, Ross

    2018-06-01

    The microseismic hypocenters plotted in our study, derived in Parnell-Turner et al. (2017), used data collected by instrumentation from the NERC Ocean-Bottom Instrumentation Facility (Minshull et al., 2005) under the auspices of NERC projects NE/J022551/1, NE/J02029X/1 and NE/J021741/1 led by Tim Reston, Christine Peirce and Christopher MacLeod, during cruises JC102 and JC109 led by Christine Peirce. The raw seismic data from the OBS deployment are available from the NERC's British Oceanographic Data Centre (https://www.bodc.ac.uk), or by contacting the NERC grant-holders directly.

  19. Volcanogenic-hydrothermal iron-rich materials from the southern part of the Central Indian Ocean Basin

    Iyer, S; Gupta, S; Charan, S; Mills, O.P.

    . This may further be corroborated by the E–W elongation of some of the N–S-oriented seamounts, caused by the addition of magmatic materials and are thus indicative of more than one episode of volcanism. There are additional evidences which indicate volcanic...-brown material from the Japan Basin. Mar. Geol. 129, 331–336. Aumento, F., Mitchell, W.S., 1975. Magnetic spherules from the Mid-Atlantic Ridge. Geology 3, 407–410. Barrett, T.J., Friedrichsen, H., 1982. Elemental and isotopic composition of some metalliferous...

  20. Ca/Al of plagioclase-hosted melt inclusions as an indicator for post-entrapment processes at mid-ocean ridges?

    Zhang, H.T.; Yang, Y.M.; Yan, Q.S.; Shi, Z.F.; Zhu, Z.W.; Su, W.C.; Qin, C.J.; Ye, J.

    2016-07-01

    The composition of melt inclusions in basalts erupted at mid-ocean ridges may be modified by post-entrapment processes, so the present composition of melt inclusions may not represent their original composition at the time of entrapment. By combining the melt inclusion composition in samples from the South Mid-Atlantic Ridge at 19°S analyzed in this study, and from the Petrological Database, we found that post-entrapment crystallization processes resulted in higher Ca/Al, Mg#[100×atomic Mg2+/(Mg2++Fe2+)], MgO and FeO contents, and lower CaO and Al2O3 contents of plagioclase-hosted melt inclusions relative to those hosted in olivine. In addition, melt inclusions hosted in plagioclase with anorthite content larger than 80mol.% had been modified more readily than others. By discussing the relationships between Ca/Al and fractional crystallization, post-entrapment crystallization, and the original melt composition, we propose that Ca/Al can be regarded as an indicator of the effect of post-entrapment processes on melt inclusion composition. Specifically, i) when Ca/Al<0.78, melt inclusion compositions corrected for fractional crystallization to Mg#=72 can represent the primary magma at mid-ocean ridges; ii) when 0.781.0, the compositions of melt inclusions do not reflect the original melt composition nor preserve information about the mantle source. According to these criteria, plagioclase-hosted melt inclusions with Ca/Al>1.0 in basalts from the South Mid-Atlantic Ridge at19°S cannot represent the composition of the melt at the moment of their entrapment. (Author)

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

    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 (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 the older-looking, slightly faulted volcanic terrain that floors the non-transform fracture zone valleys. These observations document the asymmetric nature of seafloor spreading near ridge-transform intersections. An important implication is that the crust and lithosphere across different portions of the fracture zone will have different geological characteristics. Across the active transform zone two lithosphere plate edges formed at ridge-transform corners are faulted against one another. In the non

  2. Ca/Al of plagioclase-hosted melt inclusions as an indicator for post-entrapment processes at mid-ocean ridges?

    Zhang, H.T.; Yang, Y.M.; Yan, Q.S.; Shi, Z.F.; Zhu, Z.W.; Su, W.C.; Qin, C.J.; Ye, J.

    2016-01-01

    The composition of melt inclusions in basalts erupted at mid-ocean ridges may be modified by post-entrapment processes, so the present composition of melt inclusions may not represent their original composition at the time of entrapment. By combining the melt inclusion composition in samples from the South Mid-Atlantic Ridge at 19°S analyzed in this study, and from the Petrological Database, we found that post-entrapment crystallization processes resulted in higher Ca/Al, Mg#[100×atomic Mg2+/(Mg2++Fe2+)], MgO and FeO contents, and lower CaO and Al2O3 contents of plagioclase-hosted melt inclusions relative to those hosted in olivine. In addition, melt inclusions hosted in plagioclase with anorthite content larger than 80mol.% had been modified more readily than others. By discussing the relationships between Ca/Al and fractional crystallization, post-entrapment crystallization, and the original melt composition, we propose that Ca/Al can be regarded as an indicator of the effect of post-entrapment processes on melt inclusion composition. Specifically, i) when Ca/Al 1.0, the compositions of melt inclusions do not reflect the original melt composition nor preserve information about the mantle source. According to these criteria, plagioclase-hosted melt inclusions with Ca/Al>1.0 in basalts from the South Mid-Atlantic Ridge at19°S cannot represent the composition of the melt at the moment of their entrapment. (Author)

  3. Mineralogy and geochemistry of triassic carbonatites in the Matcha alkaline intrusive complex (Turkestan-Alai Ridge, Kyrgyz Southern Tien Shan), SW Central Asian orogenic belt

    Vrublevskii, V. V.; Morova, A. A.; Bukharova, O. V.; Konovalenko, S. I.

    2018-03-01

    Postorogenic intrusions of essexites and alkaline and nepheline syenites in the Turkestan-Alai segment of the Kyrgyz Southern Tien Shan coexist with dikes and veins of carbonatites dated at ∼220 Ma by the Ar-Ar and Rb-Sr age methods. They are mainly composed of calcite and dolomite (60-85%), as well as sodic amphibole, phlogopite, clinopyroxene, microcline, albite, apatite, and magnetite, with accessory niobate, ilmenite, Nb-rutile, titanite, zircon, baddeleyite, monazite-(Ce), barite, and sulfides. The rocks share mineralogical and geochemical similarity with carbonatites that originated by liquid immiscibility at high temperatures above 500 °C. Alkaline silicate and salt-carbonate melts are derived from sources with mainly negative bulk εNd(t) ∼ from -11 to 0 and high initial 87Sr/86Sr ratios (∼0.7061-0.7095) which may be due to mixing of PREMA and EM-type mantle material. Pb isotopic ratios in accessory pyrrhotite (206Pb/204Pb = 18.38; 207Pb/204Pb = 15.64; 208Pb/204Pb = 38.41) exhibit an EM2 trend. The intrusions bear signatures of significant crustal contamination as a result of magma genesis by syntexis and hybridism. Concordant isotope composition changes of δ13C (-6.5 to -1.9‰), δ18O (9.2-23‰), δD (-58 to -41‰), and δ34S (12.6-12.8‰) in minerals and rocks indicate inputs of crustal material at the stage of melting and effect of hot fluids released during dehydration of metamorphosed oceanic basalts or sediments. The observed HFSE patterns of the oldest alkaline gabbro may be due to interaction of the primary mafic magma with IAB-type material. The isotope similarity of alkaline rocks with spatially proximal basalts of the Tarim large igneous province does not contradict the evolution of the Turkestan-Alai Triassic magmatism as the "last echo" of the Tarim mantle plume.

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

    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

  5. Does presence of a mid-ocean ridge enhance biomass and biodiversity?

    Imants G Priede

    Full Text Available In contrast to generally sparse biological communities in open-ocean settings, seamounts and ridges are perceived as areas of elevated productivity and biodiversity capable of supporting commercial fisheries. We investigated the origin of this apparent biological enhancement over a segment of the North Mid-Atlantic Ridge (MAR using sonar, corers, trawls, traps, and a remotely operated vehicle to survey habitat, biomass, and biodiversity. Satellite remote sensing provided information on flow patterns, thermal fronts, and primary production, while sediment traps measured export flux during 2007-2010. The MAR, 3,704,404 km(2 in area, accounts for 44.7% lower bathyal habitat (800-3500 m depth in the North Atlantic and is dominated by fine soft sediment substrate (95% of area on a series of flat terraces with intervening slopes either side of the ridge axis contributing to habitat heterogeneity. The MAR fauna comprises mainly species known from continental margins with no evidence of greater biodiversity. Primary production and export flux over the MAR were not enhanced compared with a nearby reference station over the Porcupine Abyssal Plain. Biomasses of benthic macrofauna and megafauna were similar to global averages at the same depths totalling an estimated 258.9 kt C over the entire lower bathyal north MAR. A hypothetical flat plain at 3500 m depth in place of the MAR would contain 85.6 kt C, implying an increase of 173.3 kt C attributable to the presence of the Ridge. This is approximately equal to 167 kt C of estimated pelagic biomass displaced by the volume of the MAR. There is no enhancement of biological productivity over the MAR; oceanic bathypelagic species are replaced by benthic fauna otherwise unable to survive in the mid ocean. We propose that globally sea floor elevation has no effect on deep sea biomass; pelagic plus benthic biomass is constant within a given surface productivity regime.

  6. Radiogenic isotopes in enriched mid-ocean ridge basalts from Explorer Ridge, northeast Pacific Ocean

    Cousens, Brian; Weis, Dominique; Constantin, Marc; Scott, Steve

    2017-09-01

    Extreme gradients in topography related to variations in magma supply are observed on the Southern Explorer Ridge (SER), part of the northern Juan de Fuca ridge system. We report radiogenic isotope (Pb, Sr, Nd, Hf) and geochemical data for twenty-four basalt whole-rock and glass samples collected from the length of the SER and from Explorer Deep, a rift to the north of the SER. Lavas from the SER form a north-south geochemical gradient, dominated by E-MORB at the northern axial high, and range from T-MORB to N-MORB towards the southern deepest part of the ridge. Linear relationships between incompatible element ratios and isotopic ratios in MORB along the ridge are consistent with mixing of magmas beneath the ridge to generate the geographic gradient from E- to N-MORB. The E-MORB have high Sr and Pb, and low Nd and Hf isotopic ratios, typical of enriched mantle that includes a FOZO or HIMU isotopic component. The West Valley and Endeavour segments of the northern Juan de Fuca ridge also include this isotopic component, but the proportion of the FOZO or HIMU component is more extreme in the SER basalts. The FOZO or HIMU component may be garnet-bearing peridotite, or a garnet pyroxenite embedded in peridotite. Recycled garnet pyroxenite better explains the very shallow SER axial high, high Nb/La and La/Sm, and the ;enriched; isotopic compositions.

  7. Great Lakes/Mid Atlantic HSRC

    Federal Laboratory Consortium — The University of Michigan, Michigan State University, and Howard University combined forces to pursue cooperative efforts in multi-disciplinary hazardous substance...

  8. Mid-Atlantic Microbial Pathogenesis Meeting

    2005-12-01

    rheumatic fever, yet little is understood about the regulation of streptococcal genes involved in disease processes and survival in the host. Genome...of brucellosis, a disease that is characterized by abortion and infertility in ruminant animals and undulant fever in humans. In the natural hosts...were presented at this session. 15. SUBJECT TERMS bacteria, pathogenesis, microbiology, virulence, disease 16. SECURITY CLASSIFICATION OF: 17

  9. Petrological systematics of mid-ocean ridge basalts: Constraints on melt generation beneath ocean ridges

    Langmuir, Charles H.; Klein, Emily M.; Plank, Terry

    Mid-ocean ridge basalts (MORB) are a consequence of pressure-release melting beneath ocean ridges, and contain much information concerning melt formation, melt migration and heterogeneity within the upper mantle. MORB major element chemical systematics can be divided into global and local aspects, once they have been corrected for low pressure fractionation and interlaboratory biases. Regional average compositions for ridges unaffected by hot spots ("normal" ridges) can be used to define the global correlations among normalized Na2O, FeO, TiO2 and SiO2 contents, CaO/Al2O3 ratios, axial depth and crustal thickness. Back-arc basins show similar correlations, but are offset to lower FeO and TiO2 contents. Some hot spots, such as the Azores and Galapagos, disrupt the systematics of nearby ridges and have the opposite relationships between FeO, Na2O and depth over distances of 1000 km. Local variations in basalt chemistry from slow- and fast-spreading ridges are distinct from one another. On slow-spreading ridges, correlations among the elements cross the global vector of variability at a high angle. On the fast-spreading East Pacific Rise (EPR), correlations among the elements are distinct from both global and slow-spreading compositional vectors, and involve two components of variation. Spreading rate does not control the global correlations, but influences the standard deviations of axial depth, crustal thickness, and MgO contents of basalts. Global correlations are not found in very incompatible trace elements, even for samples far from hot spots. Moderately compatible trace elements for normal ridges, however, correlate with the major elements. Trace element systematics are significantly different for the EPR and the mid-Atlantic Ridge (MAR). Normal portions of the MAR are very depleted in REE, with little variability; hot spots cause large long wavelength variations in REE abundances. Normal EPR basalts are significantly more enriched than MAR basalts from normal

  10. Geophysical studies of aseismic ridges in northern Indian Ocean-crustal structure and isostatic models

    Sreejith, K.M.

    . The important conclusions derived from this study are as follows. 1. The Comorin Ridge extends for about 500 km in NNW-SSE direction in north central Indian Ocean, close to the southern tip of India and western continental margin of Sri Lanka. The ridge... topography has variable reliefs along its strike and uneven gradients on both sides of the ridge flanks. The southern part of the ridge (between 1.5°N and 3°N) has an elevation of up to 0.5 km from the adjacent seafloor of about 4 km deep; in the central...

  11. Ridge Regression Signal Processing

    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.

  12. Insights on the evolution of mid-ocean basins: the Atlantis Basin of southern Azores

    Alves, T.; Bouriak, S.; Volkonskaya, A.; Monteiro, J.; Ivanov, M.

    2003-04-01

    Single-channel seismic reflection and sidescan (OKEAN) data acquired in an unstudied region of the North Atlantic give important insights on the evolution of mid-ocean basins. Located on the eastern flank of the Mid-Atlantic Ridge, south of the Azores Islands, the study area contains more than 1,000 ms two-way travel-time of sediments with a similar seismic stratigraphy to that of ODP sites 950-952 in the Madeira Abyssal Plain. Processed thickness values correspond to a maximum thickness of about 1450 m and an average thickness of more than 500 m based on velocity data from ODP sites 950-952. The structure of the surveyed area and its location in relation to the Madeira Abyssal Plain and Mid-Atlantic Ridge indicate the existence, south of Azores, of two distinct sedimentary basins separated by major structural lineaments (Azores-Gibraltar and Atlantis Fracture Zones) and by seamount chains (Cruiser-Great Meteor Chain, Plato-Atlantis Chain). The basement of the sedimentary basins is irregular, showing multiple dome-shaped volcanic structures identical to those in the Norwegian-Greenland Sea and Madeira Abyssal Plain. However, half-graben/graben basement blocks predominate east of 30ºW underneath a moderately deformed overburden. The complex structure observed most likely reflects changes in the direction and velocity of ocean spreading plus variations in the regional thermal gradients induced by local hot spots. In parallel, some of the sub-surface structures identified next to basin-bounding Fracture Zones may have resulted from transtensional and transpressional tectonism.

  13. Ridge and Furrow Fields

    Møller, Per Grau

    2016-01-01

    Ridge and furrow is a specific way of ploughing which makes fields of systematic ridges and furrows like a rubbing washboard. They are part of an overall openfield system, but the focus in this paper is on the functionality of the fields. There are many indications that agro-technological reasons...... systems and the establishment of basic structures like villages (with churches) and townships and states (in northern Europe). The fields can be considered as a resilient structure lasting for 800 years, along with the same basic physical structures in society....

  14. Vertical structure, biomass and topographic association of deep-pelagic fishes in relation to a mid-ocean ridge system

    Sutton, T. T.; Porteiro, F. M.; Heino, M.; Byrkjedal, I.; Langhelle, G.; Anderson, C. I. H.; Horne, J.; Søiland, H.; Falkenhaug, T.; Godø, O. R.; Bergstad, O. A.

    2008-01-01

    The assemblage structure and vertical distribution of deep-pelagic fishes relative to a mid-ocean ridge system are described from an acoustic and discrete-depth trawling survey conducted as part of the international Census of Marine Life field project MAR-ECO . The 36-station, zig-zag survey along the northern Mid-Atlantic Ridge (MAR; Iceland to the Azores) covered the full depth range (0 to >3000 m), from the surface to near the bottom, using a combination of gear types to gain a more comprehensive understanding of the pelagic fauna. Abundance per volume of deep-pelagic fishes was highest in the epipelagic zone and within the benthic boundary layer (BBL; 0-200 m above the seafloor). Minimum fish abundance occurred at depths below 2300 m but above the BBL. Biomass per volume of deep-pelagic fishes over the MAR reached a maximum within the BBL, revealing a previously unknown topographic association of a bathypelagic fish assemblage with a mid-ocean ridge system. With the exception of the BBL, biomass per volume reached a water column maximum in the bathypelagic zone between 1500 and 2300 m. This stands in stark contrast to the general "open-ocean" paradigm that biomass decreases exponentially from the surface downwards. As much of the summit of the MAR extends into this depth layer, a likely explanation for this mid-water maximum is ridge association. Multivariate statistical analyses suggest that the dominant component of deep-pelagic fish biomass over the northern MAR was a wide-ranging bathypelagic assemblage that was remarkably consistent along the length of the ridge from Iceland to the Azores. Integrating these results with those of previous studies in oceanic ecosystems, there appears to be adequate evidence to conclude that special hydrodynamic and biotic features of mid-ocean ridge systems cause changes in the ecological structure of deep-pelagic fish assemblages relative to those at the same depths over abyssal plains. Lacking terrigenous input of

  15. Cowley Ridge wind plant experiences best production year ever

    Anon.

    2000-01-01

    The Cowley Ridge wind plant in southern Alberta in its fifth year of operation generated 63,380 MWh of electricity, exceeding its annual goal by about 15 per cent. December was one of the highest production months ever. During December the plant operated an an average of 62 per cent capacity throughout the month. The annual average is 35 per cent of capacity

  16. Preliminary Analysis of the Knipovich Ridge Segmentation - Influence of Focused Magmatism and Ridge Obliquity on an Ultraslow Spreading System

    Okino, K.; Curewitz, D.; Asada, M.; Tamaki, K.

    2002-12-01

    Bathymetry, gravity and deep-tow sonar image data are used to define the segmentation of a 400 km long portion of the ultraslow-spreading Knipovich Ridge in the Norwegian-Greenland Sea, Northeast Atlantic Ocean. Discrete volcanic centers marked by large volcanic constructions and accompanying short wavelength mantle Bouguer anomaly (MBA) lows generally resemble those of the Gakkel Ridge and the easternmost Southwest Indian Ridge (SWIR). These magmatically robust segment centers are regularly spaced about 85-100 km apart along the ridge, and are characterized by accumulated hummocky terrain, high relief, off-axis seamount chains and significant MBA lows. We suggest that these eruptive centers correspond to areas of enhanced magma flux, and that their spacing reflects the geometry of underlying mantle upwelling cells. The large-scale thermal structure of the mantle primarily controls discrete and focused magmatism, and the relatively wide spacing of these segments may reflect cool mantle beneath the ridge. Segment centers along the southern Knipovich Ridge are characterized by lower relief and smaller MBA anomalies than along the northern section of the ridge. This suggests that ridge obliquity is a secondary control on ridge construction on the Knipovich Ridge, as the obliquity changes from 35° to 49° from north to south, respectively, while spreading rate and axial depth remain approximately constant. The increased obliquity may contribute to decreased effective spreading rates, lower upwelling magma velocity and melt formation, and limited horizontal dike propagation near the surface. We also identify small, magmatically weaker segments with low relief, little or no MBA anomaly, and no off axis expression. We suggest that these segments are either fed by lateral melt migration from adjacent magmatically stronger segments or represent smaller, discrete mantle upwelling centers with short-lived melt supply.

  17. Preliminary analysis of the Knipovich Ridge segmentation: influence of focused magmatism and ridge obliquity on an ultraslow spreading system

    Okino, Kyoko; Curewitz, Daniel; Asada, Miho; Tamaki, Kensaku; Vogt, Peter; Crane, Kathleen

    2002-09-01

    Bathymetry, gravity and deep-tow sonar image data are used to define the segmentation of a 400 km long portion of the ultraslow-spreading Knipovich Ridge in the Norwegian-Greenland Sea, Northeast Atlantic Ocean. Discrete volcanic centers marked by large volcanic constructions and accompanying short wavelength mantle Bouguer anomaly (MBA) lows generally resemble those of the Gakkel Ridge and the easternmost Southwest Indian Ridge. These magmatically robust segment centers are regularly spaced about 85-100 km apart along the ridge, and are characterized by accumulated hummocky terrain, high relief, off-axis seamount chains and significant MBA lows. We suggest that these eruptive centers correspond to areas of enhanced magma flux, and that their spacing reflects the geometry of underlying mantle upwelling cells. The large-scale thermal structure of the mantle primarily controls discrete and focused magmatism, and the relatively wide spacing of these segments may reflect cool mantle beneath the ridge. Segment centers along the southern Knipovich Ridge are characterized by lower relief and smaller MBA anomalies than along the northern section of the ridge. This suggests that ridge obliquity is a secondary control on ridge construction on the Knipovich Ridge, as the obliquity changes from 35° to 49° from north to south, respectively, while spreading rate and axial depth remain approximately constant. The increased obliquity may contribute to decreased effective spreading rates, lower upwelling magma velocity and melt formation, and limited horizontal dike propagation near the surface. We also identify small, magmatically weaker segments with low relief, little or no MBA anomaly, and no off-axis expression. We suggest that these segments are either fed by lateral melt migration from adjacent magmatically stronger segments or represent smaller, discrete mantle upwelling centers with short-lived melt supply.

  18. Serpentinization of mantle-derived peridotites at mid-ocean ridges: Mesh texture development in the context of tectonic exhumation

    Rouméjon, Stéphane; Cannat, Mathilde

    2014-06-01

    At slow spreading ridges, axial detachment faults exhume mantle-derived peridotites and hydrothermal alteration causes serpentinization in a domain extending more than 1 km next to the fault. At the microscopic scale, serpentinization progresses from a microfracture network toward the center of olivine relicts and forms a mesh texture. We present a petrographic study (SEM, EBSD, and Raman) of the serpentine mesh texture in a set of 278 abyssal serpentinized peridotites from the Mid-Atlantic and Southwest Indian Ridges. We show that serpentinization initiated along two intersecting sets of microfractures that have consistent orientations at the sample scale, and in at least one studied location, at the 100 m scale. We propose that these microfractures formed in fresh peridotites due to combined thermal and tectonic stresses and subsequently served as channels for serpentinizing fluids. Additional reaction-induced cracks developed for serpentinization extents <20%. The resulting microfracture network has a typical spacing of ˜60 µm but most serpentinization occurs next to a subset of these microfractures that define mesh cells 100-400 µm in size. Apparent mesh rim thickness is on average 33 ± 19 µm corresponding to serpentinization extents of 70-80%. Published laboratory experiments suggest that mesh rims formation could be completed in a few years (i.e., quasi instantaneous at the plate tectonic timescale). The depth and extent of the serpentinization domain in the detachment fault's footwall are probably variable in time and space and as a result we expect that the serpentine mesh texture at slow spreading ridges forms at variable rates with a spatially heterogeneous distribution.

  19. Geology along the Blue Ridge Parkway in Virginia

    Carter, Mark W.; Southworth, C. Scott; Tollo, Richard P.; Merschat, Arthur J.; Wagner, Sara; Lazor, Ava; Aleinikoff, John N.

    2017-01-01

    Detailed geologic mapping and new SHRIMP (sensitive high-resolution ion microprobe) U-Pb zircon, Ar/Ar, Lu-Hf, 14C, luminescence (optically stimulated), thermochronology (fission-track), and palynology reveal the complex Mesoproterozoic to Quaternary geology along the ~350 km length of the Blue Ridge Parkway in Virginia. Traversing the boundary of the central and southern Appalachians, rocks along the parkway showcase the transition from the para-autochthonous Blue Ridge anticlinorium of northern and central Virginia to the allochthonous eastern Blue Ridge in southern Virginia. From mile post (MP) 0 near Waynesboro, Virginia, to ~MP 124 at Roanoke, the parkway crosses the unconformable to faulted boundary between Mesoproterozoic basement in the core of the Blue Ridge anticlinorium and Neoproterozoic to Cambrian metasedimentary and metavolcanic cover rocks on the western limb of the structure. Mesoproterozoic basement rocks comprise two groups based on SHRIMP U-Pb zircon geochronology: Group I rocks (1.2-1.14 Ga) are strongly foliated orthogneisses, and Group II rocks (1.08-1.00 Ga) are granitoids that mostly lack obvious Mesoproterozoic deformational features.Neoproterozoic to Cambrian cover rocks on the west limb of the anticlinorium include the Swift Run and Catoctin Formations, and constituent formations of the Chilhowee Group. These rocks unconformably overlie basement, or abut basement along steep reverse faults. Rocks of the Chilhowee Group are juxtaposed against Cambrian rocks of the Valley and Ridge province along southeast- and northwest-dipping, high-angle reverse faults. South of the James River (MP 64), Chilhowee Group and basement rocks occupy the hanging wall of the nearly flat-lying Blue Ridge thrust fault and associated splays.South of the Red Valley high-strain zone (MP 144.5), the parkway crosses into the wholly allochthonous eastern Blue Ridge, comprising metasedimentary and meta-igneous rocks assigned to the Wills Ridge, Ashe, and Alligator

  20. The Mozambique Ridge: a document of massive multistage magmatism

    Fischer, Maximilian D.; Uenzelmann-Neben, Gabriele; Jacques, Guillaume; Werner, Reinhard

    2017-01-01

    The Mozambique Ridge, a prominent basement high in the southwestern Indian Ocean, consists of four major geomorphological segments associated with numerous phases of volcanic activity in the Lower Cretaceous. The nature and origin of the Mozambique Ridge have been intensely debated with one hypothesis suggesting a Large Igneous Province origin. High-resolution seismic reflection data reveal a large number of extrusion centres with a random distribution throughout the southern Mozambique Ridge and the nearby Transkei Rise. Intrabasement reflections emerge from the extrusion centres and are interpreted to represent massive lava flow sequences. Such lava flow sequences are characteristic of eruptions leading to the formation of continental and oceanic flood basalt provinces, hence supporting a Large Igneous Province origin of the Mozambique Ridge. We observe evidence for widespread post-sedimentary magmatic activity that we correlate with a southward propagation of the East African Rift System. Based on our volumetric analysis of the southern Mozambique Ridge we infer a rapid sequential emplacement between ˜131 and ˜125 Ma, which is similar to the short formation periods of other Large Igneous Provinces like the Agulhas Plateau.

  1. Volcanism and hydrothermalism on a hotspot-influenced ridge: Comparing Reykjanes Peninsula and Reykjanes Ridge, Iceland

    Pałgan, Dominik; Devey, Colin W.; Yeo, Isobel A.

    2017-12-01

    Current estimates indicate that the number of high-temperature vents (one of the primary pathways for the heat extraction from the Earth's mantle) - at least 1 per 100 km of axial length - scales with spreading rate and should scale with crustal thickness. But up to present, shallow ridge axes underlain by thick crust show anomalously low incidences of high-temperature activity. Here we compare the Reykjanes Ridge, an abnormally shallow ridge with thick crust and only one high-temperature vent known over 900 km axial length, to the adjacent subaerial Reykjanes Peninsula (RP), which is characterized by high-temperature geothermal sites confined to four volcanic systems transected by fissure swarms with young (Holocene) volcanic activity, multiple faults, cracks and fissures, and continuous seismic activity. New high-resolution bathymetry (gridded at 60 m) of the Reykjanes Ridge between 62°30‧N and 63°30‧N shows seven Axial Volcanic Ridges (AVR) that, based on their morphology, geometry and tectonic regime, are analogues for the volcanic systems and fissure swarms on land. We investigate in detail the volcano-tectonic features of all mapped AVRs and show that they do not fit with the previously suggested 4-stage evolution model for AVR construction. Instead, we suggest that AVR morphology reflects the robust or weak melt supply to the system and two (or more) eruption mechanisms may co-exist on one AVR (in contrast to 4-stage evolution model). Our interpretations indicate that, unlike on the Reykjanes Peninsula, faults on and around AVRs do not cluster in orientation domains but all are subparallel to the overall strike of AVRs (orthogonal to spreading direction). High abundance of seamounts shows that the region centered at 62°47‧N and 25°04‧W (between AVR-5 and -6) is volcanically robust while the highest fault density implies that AVR-1 and southern part of AVR-6 rather undergo period of melt starvation. Based on our observations and interpretations we

  2. Southern Appalachian Regional Seismic Network

    Chiu, S.C.C.; Johnston, A.C.; Chiu, J.M. [Memphis State Univ., TN (United States). Center for Earthquake Research and Information

    1994-08-01

    The seismic activity in the southern Appalachian area was monitored by the Southern Appalachian Regional Seismic Network (SARSN) since late 1979 by the Center for Earthquake Research and Information (CERI) at Memphis State University. This network provides good spatial coverage for earthquake locations especially in east Tennessee. The level of activity concentrates more heavily in the Valley and Ridge province of eastern Tennessee, as opposed to the Blue Ridge or Inner Piedmont. The large majority of these events lie between New York - Alabama lineament and the Clingman/Ocoee lineament, magnetic anomalies produced by deep-seated basement structures. Therefore SARSN, even with its wide station spacing, has been able to define the essential first-order seismological characteristics of the Southern Appalachian seismic zone. The focal depths of the southeastern U.S. earthquakes concentrate between 8 and 16 km, occurring principally beneath the Appalachian overthrust. In cross-sectional views, the average seismicity is shallower to the east beneath the Blue Ridge and Piedmont provinces and deeper to the west beneath the Valley and Ridge and the North American craton. Results of recent focal mechanism studies by using the CERI digital earthquake catalog between October, 1986 and December, 1991, indicate that the basement of the Valley and Ridge province is under a horizontal, NE-SW compressive stress. Right-lateral strike-slip faulting on nearly north-south fault planes is preferred because it agrees with the trend of the regional magnetic anomaly pattern.

  3. Southern Appalachian Regional Seismic Network

    Chiu, S.C.C.; Johnston, A.C.; Chiu, J.M.

    1994-08-01

    The seismic activity in the southern Appalachian area was monitored by the Southern Appalachian Regional Seismic Network (SARSN) since late 1979 by the Center for Earthquake Research and Information (CERI) at Memphis State University. This network provides good spatial coverage for earthquake locations especially in east Tennessee. The level of activity concentrates more heavily in the Valley and Ridge province of eastern Tennessee, as opposed to the Blue Ridge or Inner Piedmont. The large majority of these events lie between New York - Alabama lineament and the Clingman/Ocoee lineament, magnetic anomalies produced by deep-seated basement structures. Therefore SARSN, even with its wide station spacing, has been able to define the essential first-order seismological characteristics of the Southern Appalachian seismic zone. The focal depths of the southeastern U.S. earthquakes concentrate between 8 and 16 km, occurring principally beneath the Appalachian overthrust. In cross-sectional views, the average seismicity is shallower to the east beneath the Blue Ridge and Piedmont provinces and deeper to the west beneath the Valley and Ridge and the North American craton. Results of recent focal mechanism studies by using the CERI digital earthquake catalog between October, 1986 and December, 1991, indicate that the basement of the Valley and Ridge province is under a horizontal, NE-SW compressive stress. Right-lateral strike-slip faulting on nearly north-south fault planes is preferred because it agrees with the trend of the regional magnetic anomaly pattern

  4. Using bathymetry and reflective seismic profiles to tests a suspected link between melt flux and cumulative fault heave at mid-ocean ridges

    Haughton, G.; Murton, B. J.; Le Bas, T.; Henstock, T.

    2017-12-01

    The interplay between magma supply and spreading rate is believed to play a major role in determining large scale seafloor morphology. Here we use bathymetry to test this relationship in areas with similar spreading rates and differing magma supplies. By using open source bathymetry data we have developed a repeatable, automated method for categorising seafloor cumulative fault heave and then attempt to identify the controlling variables. We measure the total apparent fault heave along axis and off-axis at 29°N and 60°N on the Mid-Atlantic Ridge then compare this to proxies for deformation and magma supply. Two approaches are adopted for identifying faults: one using bathymetry and the other spreading-parallel seismic reflection data. The first re-examines the orthogonally spreading Broken Spur segment (26°N) spreading at 23 mm yr-1 (full rate). The other examines the Reykjanes Ridge (60°N) spreading obliquely at 21 mm yr-1 (full rate), which may be influenced by the Icelandic hotspot. Each have contrasting residual depth and structure, with the former being typical of slow spreading ridges, with marked axial valleys, whereas the latter is more typical of fast spreading ridge morphology, with smooth axial rise. We find that high total heave (indicating high tectonic spreading) on the Broken Spur segment does not correlate with high mantle Bouguer anomalies (indicating thin crust and low melt flux). From this we hypothesise that total heave on the large scale at the Broken Spur segment is not controlled by crustal thickness or melt supply. At the Raykjanes Ridge, V-shaped ridges have thicker crust (measured seismically) which converge south of Iceland. These are thought to reflect transient (every 4-6 Myrs) pulses of hot mantle radiating away from the Iceland plume. We find ridge-symmetrical variation in fault heave but with a lower frequency (6-8 Myrs) and longer wavelength (3-7 Myrs) than the V-shaped ridges. Our analysis shows that plume pulses do not

  5. Iron-Oxidizing Bacteria Found at Slow-Spreading Ridge: a Case Study of Capelinhos Hydrothermal Vent (Lucky Strike, MAR 37°N)

    Henri, P. A.; Rommevaux, C.; Lesongeur, F.; Emerson, D.; Leleu, T.; Chavagnac, V.

    2015-12-01

    Iron-oxidizing bacteria becomes increasingly described in different geological settings from volcanically active seamounts, coastal waters, to diffuse hydrothermal vents near seafloor spreading centers [Emerson et al., 2010]. They have been mostly identified and described in Pacific Ocean, and have been only recently found in hydrothermal systems associated to slow spreading center of the Mid-Atlantic Ridge (MAR) [Scott et al., 2015]. During the MoMARSAT'13 cruise at Lucky Strike hydrothermal field (MAR), a new hydrothermal site was discovered at about 1.5 km eastward from the lava lake and from the main hydrothermal vents. This active venting site, named Capelinhos, is therefore the most distant from the volcano, features many chimneys, both focused and diffuses. The hydrothermal end-member fluids from Capelinhos are different from those of the other sites of Lucky Strike, showing the highest content of iron (Fe/Mn≈3.96) and the lowest chlorinity (270 mmol/l) [Leleu et al., 2015]. Most of the chimneys exhibit rust-color surfaces and bacterial mats near diffuse flows. During the MoMARSAT'15 cruise, an active chimney, a small inactive one, and rust-color bacterial mat near diffuse flow were sampled at Capelinhos. Observations by SEM of the hydrothermal samples revealed the presence of iron oxides in an assemblage of tubular "sheaths", assembled "stalks", helical "stalks" and amorphous aggregates. These features are similar to those described from the Loihi iron-mats deposits and argue for the occurrence of iron-oxidizing bacteria. Cultures under micro-aerobic and neutral pH conditions allowed us to isolate strains from the small inactive chimney. Pyrosequencing of the 16S rRNA gene of the isolates and environmental samples will soon be performed, which should confirm the presence of iron-oxidizing bacteria and reveal the organization of bacterial communities in this original and newly discovered hydrothermal site of the slow spreading Mid-Atlantic Ridge. Emerson

  6. Ridge Orientations of the Ridge-Forming Unit, Sinus Meridiani, Mars-A Fluvial Explanation

    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

  7. Water content within the oceanic upper mantle of the Southwest Indian Ridge: a FTIR analysis of orthopyroxenes of abyssal peridotites

    Li, W.; Li, H.; Tao, C.; Jin, Z.

    2013-12-01

    Water can be present in the oceanic upper mantle as structural OH in nominally anhydrous minerals. Such water has marked effects on manlte melting and rheology properties. However, the water content of MORB source is mainly inferred from MORB glass data that the water budget of oceanic upper mantle is poorly constrained. Here we present water analysis of peridotites from different sites on the Southwest Indian Ridge. The mineral assemblages of these peridotites are olivine, orthopyroxene, clinopyroxene and spinel. As the peridotites have been serpentinized to different degrees, only water contents in orthopyroxnene can be better determined by FTIR spectrometry. The IR absorption bands of all measured orthopyroxenes can be devided into four different groups: (1)3562-3596 cm-1, (2)3515-3520 cm-1, (3)3415-3420 cm-1, (4)3200-3210 cm-1. The positions of these absorption bands are in good agreement with perivious reports. Hydrogen profile measurements performed on larger opx grains in each suite of samples show no obvious variations between core and rims regions, indicating that diffusion of H in orthopyroxene is insignificant. Preliminary measured water contents of orthopyroxene differ by up to one order of magnitude. Opx water contents (80-220 ppm) of most samples are within the range of those found in mantle xenoliths of contentinal settings [1]. Opx water contents of one sample (VM-21V-S9-D5-2: 38-64 ppm) are similar to those from Gakkel Ridge abyssal peridotites (25-60 ppm) [2] but higher than those from Mid-Atlantic Ridge ODP-Leg 209(~15 ppm) [3]. Two other samples show high water concentrations (VM-19ΙΙΙ-S3-TVG2-4: 260-275 ppm, Wb-18-b: 190-265 ppm) which compare well with those from Mid-Atlantic Ridge ODP-Leg 153(160-270 ppm) [4]. Most opx water contents decrease with increasing depletion degree (spl Cr#) consistent with an incompatible behavior of water during partial melting. Recalculated bulk water contents (27-117 ppm) of these peridotites overlap

  8. Influence of elevation and forest type on community assemblage and species distribution of shrews in the central and southern Appalachian mountains

    W. Mark Ford; Timothy S. McCay; Michael A. Menzel; W. David Webster; Cathryn H. Greenberg; John F. Pagels; Joseph F. Merritt; Joseph F. Merritt

    2005-01-01

    We analyzed shrew community data from 398,832 pitfall trapnights at 303 sites across the upper Piedmont, Blue Ridge, northern Ridge and Valley, southern Ridge and Valley, Cumberland Plateau and Allegheny Mountains and Plateau sections of the central and southern Appalachian Mountains from Alabama to Pennsylvania. The objectives of our research were to describe regional...

  9. Variability of Fe isotope compositions of hydrothermal sulfides and oxidation products at mid-ocean ridges

    Li, Xiaohu; Wang, Jianqiang; Chu, Fengyou; Wang, Hao; Li, Zhenggang; Yu, Xing; Bi, Dongwei; He, Yongsheng

    2018-04-01

    Significant Fe isotopic fractionation occurs during the precipitation and oxidative weathering of modern seafloor hydrothermal sulfides, which has an important impact on the cycling of Fe isotopes in the ocean. This study reports the Fe-isotope compositions of whole-rock sulfides and single-mineral pyrite collected from hydrothermal fields at the South Mid-Atlantic Ridge (SMAR) and the East Pacific Rise (EPR) and discusses the impacts of precipitation and late-stage oxidative weathering of sulfide minerals on Fe isotopic fractionation. The results show large variation in the Fe-isotope compositions of the sulfides from the different hydrothermal fields on the mid-oceanic ridges, indicating that relatively significant isotope fractionation occurs during the sulfide precipitation and oxidative weathering processes. The Fe-isotope compositions of the sulfides from the study area at the SMAR vary across a relatively small range, with an average value of 0.01‰. This Fe-isotope composition is similar to the Fe-isotope composition of mid-oceanic ridge basalt, which suggests that Fe was mainly leached from basalt. In contrast, the Fe-isotope composition of the sulfides from the study area at the EPR are significantly enriched in light Fe isotopes (average value - 1.63‰), mainly due to the kinetic fractionation during the rapid precipitation process of hydrothermal sulfide. In addition, the pyrite from different hydrothermal fields is enriched in light Fe isotopes, which is consistent with the phenomenon in which light Fe isotopes are preferentially enriched during the precipitation of pyrite. The red oxides have the heaviest Fe-isotope compositions (up to 0.80‰), indicating that heavy Fe isotopes are preferentially enriched in the oxidation product during the late-stage oxidation process. The data obtained from this study and previous studies show a significant difference between the Fe-isotope compositions of the sulfides from the SMAR and EPR. The relatively heavy

  10. Measuring mandibular ridge reduction

    Steen, W.H.A.

    1984-01-01

    This thesis investigates the mandibular reduction in height of complete denture wearers and overdenture wearers. To follow this reduction in the anterior region as well as in the lateral sections of the mandible, an accurate and reproducible measuring method is a prerequisite. A radiologic technique offers the best chance. A survey is given of the literature concerning the resorption process after the extraction of teeth. An oblique cephalometric radiographic technique is introduced as a promising method to measure mandibular ridge reduction. The reproducibility and the accuracy of the technique are determined. The reproducibility in the positioning of the mandible is improved by the introduction of a mandibular support which permits a precise repositioning of the edentulous jaw, even after long periods of investigation. (Auth.)

  11. Modes and implications of mantle and lower-crust denudation at slow-spreading mid-ocean ridges

    Schroeder, Timothy John

    Slow-spreading mid-ocean ridges (Cann, 1993, Cannat, 1993). Extension at mid-ocean ridges is most commonly manifested by slip on high angle (˜60°) normal faults that dip into, and define the rift valley walls (Smith and Cann, 1993). Less commonly, extension occurs by long periods of slip along low-angle normal faults that penetrate to structurally deep levels of oceanic lithosphere and denude gabbro and/or pendotite to the seafloor in domal massifs termed "oceanic core complexes" (Dick et al., 1981; Dick et al., 1991; Tucholke et al., 1998; Mutter and Karson, 1992; Cann et al., 1997; MacLeod et al., 2002). This dissertation addresses processes and implications of tectonic extension at two oceanic core complexes. Atlantis Massif (30°N, Mid-Atlantic Ridge) is formed dominantly of serpentinized peridotite with lesser gabbro, and Atlantis Bank (57°E, Southwest Indian Ridge) is dominated by gabbro. Localization of brittle strain at Atlantis Massif occurred by reaction-softening processes associated with metasomatic alteration of peridotite and serpentmite to amphibole-, chlorite- and talc-bearing assemblages. Ductile strain at Atlantis Massif and Atlantis Bank is localized into intervals of highly-fractionated, oxide-rich gabbro. Two-oxide geothermometry of gabbro indicates that it was not penetratively deformed below ˜500°C. Denuded peridotite at Atlantis Massif is host to hydrothermal circulation driven in part by exothermic serpentinization reactions. Serpentinization decreases the seismic velocity of peridotite and leads to acquisition of a magnetic signature. Venting of highly-alkaline, methane- and hydrogen-rich serpentinization-derived fluids leads to lithification of seafloor carbonate ooze by precipitation of carbonate cement in a zone of mixing with "normal" seawater. This process may be the primary depositional mechanism of ophicalcite deposits and likely occurs wherever peridotite is exposed near the Earth's surface and is fractured to permit water

  12. Ocean Ridges and Oxygen

    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

  13. The Subduction of an Exhumed and Serpentinized Magma-Poor Basement Beneath the Northern Lesser Antilles Reveals the Early Tectonic Fabric at Slow-Spreading Mid-Oceanic Ridges

    Marcaillou, B.; Klingelhoefer, F.; Laurencin, M.; Biari, Y.; Graindorge, D.; Jean-Frederic, L.; Laigle, M.; Lallemand, S.

    2017-12-01

    Multichannel and wide-angle seismic data as well as heat-flow measurements (ANTITHESIS cruise, 2016) reveal a 200x200km patch of magma-poor oceanic basement in the trench and beneath the outer fore-arc offshore of Antigua to Saint Martin in the Northern Lesser Antilles. These data highlight an oceanic basement with the following features: 1/ Absence of any reflection at typical Moho depth and layer2/layer3 limit depths. 2/ High Velocity Vp at the top (>5.5 km/s), low velocity gradient with depth (serpentinized at the slow-spreading mid-Atlantic Ridge 80 Myr ago, is currently subducting beneath the Northern Lesser Antilles. During the exhumation, early extension triggers penetrative shear zones sub-parallel to the ridge and to the transform fault. Eventually, this early extension generates sliding along the so-called detachment fault, while the other proto-detachment abort. Approaching the trench, the plate bending reactivates these weak zones in normal faults and fluid pathways promoting deep serpentinisation and localizing tectonic deformation at the plate interface. These subducting fluid-rich mechanically weak mantle rocks rise questions about their relation to the faster slab deepening, the lower seismic activity and the pervasive tectonic partitioning in this margin segment.

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

    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

  15. Seafloor Tectonic Fault Fabric and the Evolution of the Walvis Ridge-Rio Grande Rise Hot Spot Twins in the South Atlantic

    Sager, W. W.; Engfer, D.; Thoram, S.; Koppers, A. A. P.; Class, C.

    2015-12-01

    Walvis Ridge (WR) and Rio Grande Rise (RGR) are Cretaceous-Cenozoic large igneous provinces (LIPs) formed by the Tristan-Gough hot spot interacting with the Mid-Atlantic Ridge (MAR). Although hot spot-ridge interaction has long been considered a primary factor controlling WR-RGR morphology, details are fuzzy owing to sparse geophysical data. We examined tectonic fabric revealed in satellite altimetry-derived gravity data to infer details about RGR-WR evolution. Plate tectonic reconstructions indicate that the main RGR plateau and large N-S plateau in the eastern WR erupted at the same point at ~90 Ma. Over the next ~8 Myr, these conjunct LIPs formed a "V" shape with a basin in between. Curved fracture zones within the basin imply the two LIPs formed around a microplate. The prominent rift in the middle of RGR formed nearly perpendicular to the RGR-WR intersection, suggesting an extensional microplate boundary. Hot spot eruptions continued at the MAR, emplacing the eastern WR and two main RGR plateaus until ~60 Ma. During this period, the N-S trending Eastern Rio Grande Rise (ERGR) was erupted along the MAR. Both the ERGR and WR formed bathymetric lineaments parallel to seafloor fault fabric and were likely connected. This resulted in WR seamounts with a "tadpole" shape, the head being small to medium seamounts on the WR track and the tails being low, spreading-fabric-parallel ridges extending up to ~150 km northward. Similar, small seamounts are found in the contemporaneous ERGR. Another critical observation is that the WR-RGR formed at a large crustal discontinuity (~700 km at anomaly C33, ~84 Ma) at one or more fracture zone offsets. By late Cenozoic time (anomaly C5, ~10 Ma), the offset was reduced by half while several new fracture zones formed at the junction between RGR and WR. This implies a connection between ridge reorganization and RGR-WR volcanism that may have resulted from the fracture zones becoming oblique to the spreading direction as Euler poles

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

    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.

  17. Expedition 357 Preliminary Report: Atlantis Massif Serpentinization and Life

    Früh-Green, GL; Orcutt, BN; Green, S; Cotterill, C; McCaig, AM; Expedition 357 Scientists,

    2016-01-01

    International Ocean Discovery Program (IODP) Expedition 357 successfully cored an east–west transect across the southern wall of Atlantis Massif on the western flank of the Mid-Atlantic Ridge to study the links between serpentinization processes and microbial activity in the shallow subsurface of highly altered ultramafic and mafic sequences that have been uplifted to the seafloor along a major detachment fault zone. The primary goals of this expedition were to (1) examine the role of serpent...

  18. Circumventing shallow air contamination in Mid Ocean Ridge Basalts

    Mukhopadhyay, Sujoy; Parai, Rita; Tucker, Jonathan; Middleton, Jennifer; Langmuir, Charles

    2016-04-01

    Noble gases in mantle-derived basalts provide a rich portrait of mantle degassing and surface-interior volatile exchange. However, the ubiquity of shallow-level air contamination frequently obscures the mantle noble gas signal. In a majority of samples, shallow air contamination dominates the noble gas budget. As a result, reconstructing the variability in heavy noble gas mantle source compositions and inferring the history of deep recycling of atmospheric noble gases is difficult. For example, in the gas-rich popping rock 2ΠD43, 129Xe/130Xe ratios reach 7.7±0.23 in individual step-crushes, but the bulk composition of the sample is close to air (129Xe/130Xe of 6.7). Here, we present results from experiments designed to elucidate the source of shallow air contamination in MORBs. Step-crushes were carried out to measure He, Ne, Ar and Xe isotopic compositions on two aliquots of a depleted popping glass that was dredged from between the Kane and Atlantis Fracture Zones of the Mid-Atlantic Ridge in May 2012. One aliquot was sealed in ultrapure N2 after dredge retrieval, while the other aliquot was left exposed to air for 3.5 years. The bulk 20Ne/22Ne and 129Xe/130Xe ratios measured in the aliquot bottled in ultrapure N2 are 12.3 and 7.6, respectively, and are nearly identical to the estimated mantle source values. On the other hand, step crushes in the aliquot left exposed to air for several years show Ne isotopic compositions that are shifted towards air, with a bulk 20Ne/22Ne of 11.5; the bulk 129Xe/130Xe, however, was close to 7.6. These results indicate that lighter noble gases exchange more efficiently between the bubbles trapped in basalt glass and air, suggesting a diffusive or kinetic mechanism for the incorporation of the shallow air contamination. Importantly, in Ne-Ar or Ar-Xe space, step-crushes from the bottled aliquot display a trend that can be easily fit with a simple two-component hyperbolic mixing between mantle and atmosphere noble gases. Step

  19. Microfracturing and fluid pathways in serpentinizing abyssal peridotites along the Southwest Indian Ridge (62°-65°E)

    Rouméjon, S.; Cannat, M.; Agrinier, P.; Godard, M.; Andreani, M.

    2013-12-01

    conditions associated with this serpentinization history and to discuss the nature of serpentinizing fluids, based on a comparison with published work on serpentinites from the Mid-Atlantic Ridge. δ18O values decrease from 5.98‰ to 1.91‰, from mesh texture serpentine to the later recrystallized serpentines. These values probably correspond to temperatures on the order of 200-300°C and to a progressive equilibration with serpentinizing fluid values due to increasing water-rock ratios. Fluid-rock interactions produce serpentine minerals that are enriched in fluid-mobile elements (B, As, Sb, U, Cu) compared to primary minerals in the peridotites and present occasional Eu anomalies that may reflect variable redox conditions during serpentinization.

  20. Mid-ocean ridge serpentinite in the Puerto Rico Trench: Accretion, alteration, and subduction of Cretaceous seafloor in the Atlantic Ocean

    Klein, F.; Marschall, H.; Bowring, S. A.; Horning, G.

    2016-12-01

    Serpentinite is believed to be one of the main carriers of water and fluid mobile elements into subduction zones, but direct evidence for serpentinite subduction has been elusive. The Antilles island arc is one of only two subduction zones worldwide that recycles slow-spreading oceanic lithosphere where descending serpentinite is both exposed by faulting and directly accessible on the seafloor. Here we examined serpentinized peridotites dredged from the North Wall of the Puerto Rico Trench (NWPRT) to assess their formation and alteration history and discuss geological ramifications resulting from their emplacement and subduction. Lithospheric accretion and serpentinization occurred, as indicated by U-Pb geochronology of hydrothermally altered zircon, at the Cretaceous Mid-Atlantic Ridge (CMAR). In addition to lizardite-rich serpentinites with pseudomorphic textures after olivine and pyroxene typical for static serpentinization at slow spreading mid-ocean ridges, recovered samples include non-pseudomorphic antigorite-rich serpentinites that are otherwise typically associated with peridotite at convergent plate boundaries. Antigorite-serpentinites have considerably lower Fe(III)/Fetot and lower magnetic susceptibilities than lizardite-serpentinites with comparable Fetot contents. Rare earth element (REE) contents of lizardite-serpentinites decrease linearly with increasing Fe(III)/Fetot of whole rock samples, suggesting that oxidation during seafloor weathering of serpentinite releases REEs to seawater. Serpentinized peridotites recorded multifaceted igneous and high- to low-temperature hydrothermal processes that involved extensive chemical, physical, and mineralogical modifications of their peridotite precursors with strong implications for our understanding of the accretion, alteration, and subduction of slow-spreading oceanic lithosphere.

  1. Remedial Investigation Report on Chestnut Ridge Operable Unit 2 (Filled Coal Ash Pond/Upper McCoy Branch) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Volume 1. Main Text

    1994-08-01

    This document is a report on the remedial investigation (RI) of Chestnut Ridge Operable Unit (OU) 2 at the Oak Ridge Y-12 Plant. Chestnut Ridge OU 2 consists of Upper McCoy Branch (UMB), the Filled Coal Ash Pond (FCAP), and the area surrounding the Sluice Channel formerly associated with coal ash disposal in the FCAP. Chestnut Ridge OU 2 is located within the U.S. Department of Energy's (DOE's) Oak Ridge Reservation in Anderson County, Tennessee, approximately 24 miles west of Knoxville. The pond is an 8.5-acre area on the southern slope of Chestnut Ridge, 0.5 mile south of the main Y-12 Plant and geographically separated from the Y-12 Plant by Chestnut Ridge. The elevation of the FCAP is ∼ 950 ft above mean sea level (msl), and it is relatively flat and largely vegetated. Two small ponds are usually present at the northeast and northwest comers of the FCAP. The Sluice Channel Area extends ∼1000 ft from the northern margin of the FCAP to the crest of Chestnut Ridge, which has an elevation of ∼1100 ft above msl. The Sluice Channel Area is largely vegetated also. McCoy Branch runs from the top of Chestnut Ridge across the FCAP into Rogers Quarry and out of the quarry where it runs a short distance into Milton Hill Lake at McCoy Embayment, termed UMB. The portion south of Rogers Quarry, within Chestnut Ridge OU 4, is termed Lower McCoy Branch. The DOE Oak Ridge Y-12 Plant disposed of coal ash from its steam plant operations as a slurry that was discharged into an ash retention impoundment; this impoundment is the FCAP. The FCAP was built in 1955 to serve as a settling basin after coal ash slurried over Chestnut Ridge from the Y-12 Plant. The FCAP was constructed by building an earthen dam across the northern tributary of McCoy Branch. The dam was designed to hold 20 years of Y-12 steam plant ash. By July 1967, ash had filled up the impoundment storage behind the dam to within 4 ft of the top

  2. Remedial Investigation Report on Chestnut Ridge Operable Unit 2 (Filled Coal Ash Pond/Upper McCoy Branch) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Volume 1. Main Text

    1994-08-01

    This document is a report on the remedial investigation (RI) of Chestnut Ridge Operable Unit (OU) 2 at the Oak Ridge Y-12 Plant. Chestnut Ridge OU 2 consists of Upper McCoy Branch (UMB), the Filled Coal Ash Pond (FCAP), and the area surrounding the Sluice Channel formerly associated with coal ash disposal in the FCAP. Chestnut Ridge OU 2 is located within the U.S. Department of Energy`s (DOE`s) Oak Ridge Reservation in Anderson County, Tennessee, approximately 24 miles west of Knoxville. The pond is an 8.5-acre area on the southern slope of Chestnut Ridge, 0.5 mile south of the main Y-12 Plant and geographically separated from the Y-12 Plant by Chestnut Ridge. The elevation of the FCAP is {approximately} 950 ft above mean sea level (msl), and it is relatively flat and largely vegetated. Two small ponds are usually present at the northeast and northwest comers of the FCAP. The Sluice Channel Area extends {approximately}1000 ft from the northern margin of the FCAP to the crest of Chestnut Ridge, which has an elevation of {approximately}1100 ft above msl. The Sluice Channel Area is largely vegetated also. McCoy Branch runs from the top of Chestnut Ridge across the FCAP into Rogers Quarry and out of the quarry where it runs a short distance into Milton Hill Lake at McCoy Embayment, termed UMB. The portion south of Rogers Quarry, within Chestnut Ridge OU 4, is termed Lower McCoy Branch. The DOE Oak Ridge Y-12 Plant disposed of coal ash from its steam plant operations as a slurry that was discharged into an ash retention impoundment; this impoundment is the FCAP. The FCAP was built in 1955 to serve as a settling basin after coal ash slurried over Chestnut Ridge from the Y-12 Plant. The FCAP was constructed by building an earthen dam across the northern tributary of McCoy Branch. The dam was designed to hold 20 years of Y-12 steam plant ash. By July 1967, ash had filled up the impoundment storage behind the dam to within 4 ft of the top.

  3. The Mid-Atlantic Regional Wetland Conservation Effects Assessment Project

    Megan Lang; Greg McCarty; Mark Walbridge; Patrick Hunt; Tom Ducey; Clinton Church; Jarrod Miller; Laurel Kluber; Ali Sadeghi; Martin Rabenhorst; Amir Sharifi; In-Young Yeo; Andrew Baldwin; Margaret Palmer; Tom Fisher; Dan Fenstermaher; Sanchul Lee; Owen McDonough; Metthea Yepsen; Liza McFarland; Anne Gustafson; Rebecca Fox; Chris Palardy; William Effland; Mari-Vaughn Johnson; Judy Denver; Scott Ator; Joseph Mitchell; Dennis Whigham

    2016-01-01

    Wetlands impart many important ecosystem services, including maintenance of water quality, regulation of the climate and hydrological flows, and enhancement of biodiversity through the provision of food and habitat. The conversion of natural lands to agriculture has led to broad scale historic wetland loss, but current US Department of Agriculture conservation programs...

  4. Fleet Readiness Center Mid-Atlantic Worker Cost Comparison

    2012-06-01

    Depreciation ........................................................................................33  VI.  METHODOLOGY ...Nussbaum is professor at the Department of Operations Reserach at the Naval Postgraduate School in Monterey, California (Nussbaum, 2000). 24 THIS PAGE...data received from FRCMA Oceana. 38 THIS PAGE INTENTIONALLY LEFT BLANK 39 VI. METHODOLOGY A. LIMITS OF RESEARCH Most financial and managerial

  5. Potential stream density in Mid-Atlantic US watersheds.

    Elmore, Andrew J; Julian, Jason P; Guinn, Steven M; Fitzpatrick, Matthew C

    2013-01-01

    Stream network density exerts a strong influence on ecohydrologic processes in watersheds, yet existing stream maps fail to capture most headwater streams and therefore underestimate stream density. Furthermore, discrepancies between mapped and actual stream length vary between watersheds, confounding efforts to understand the impacts of land use on stream ecosystems. Here we report on research that predicts stream presence from coupled field observations of headwater stream channels and terrain variables that were calculated both locally and as an average across the watershed upstream of any location on the landscape. Our approach used maximum entropy modeling (MaxEnt), a robust method commonly implemented to model species distributions that requires information only on the presence of the entity of interest. In validation, the method correctly predicts the presence of 86% of all 10-m stream segments and errors are low (stream density and compare our results with the National Hydrography Dataset (NHD). We find that NHD underestimates stream density by up to 250%, with errors being greatest in the densely urbanized cities of Washington, DC and Baltimore, MD and in regions where the NHD has never been updated from its original, coarse-grain mapping. This work is the most ambitious attempt yet to map stream networks over a large region and will have lasting implications for modeling and conservation efforts.

  6. Mid-Atlantic Offshore Wind Interconnection and Transmission (MAOWIT)

    Kempton, Willett [Univ. of Delaware, Newark, DE (United States)

    2016-04-05

    This project has carried out a detailed analysis to evaluate the pros and cons of offshore transmission, a possible method to decrease balance-of-system costs and permitting time identified in the DOE Office Wind Strategic Plan (DOE, 2011). It also addresses questions regarding the adequacy of existing transmission infrastructure and the ability of existing generating resources to provide the necessary Ancillary Services (A/S) support (spinning and contingency reserves) in the ISO territory. This project has completed the tasks identified in the proposal: 1. Evaluation of the offshore wind resource off PJM, then examination of offshore wind penetrations consistent with U.S. Department of Energy’s (DOE) targets and with their assumed resource size (DOE, 2011). 2. Comparison of piecemeal radial connections to the Independent System Operator (ISO) with connections via a high-voltage direct current (HVDC) offshore network similar to a team partner. 3. High-resolution examination of power fluctuations at each node due to wind energy variability 4. Analysis of wind power production profiles over the Eastern offshore region of the regional ISO to assess the effectiveness of long-distance, North- South transmission for leveling offshore wind energy output 5. Analysis of how the third and fourth items affect the need for ISO grid upgrades, congestion management, and demand for Ancillary Services (A/S) 6. Analysis of actual historic 36-hr and 24-hr forecasts to solve the unit commitment problem and determine the optimal mix of generators given the need to respond to both wind variability and wind forecasting uncertainties.

  7. Bathymetry and oceanic flow structure at two deep passages crossing the Lomonosov Ridge

    Björk, Göran; Jakobsson, Martin; Assmann, Karen; Andersson, Leif G.; Nilsson, Johan; Stranne, Christian; Mayer, Larry

    2018-01-01

    The Lomonosov Ridge represents a major topographical feature in the Arctic Ocean which has a large effect on the water circulation and the distribution of water properties. This study presents detailed bathymetric survey data along with hydrographic data at two deep passages across the ridge: a southern passage (80-81° N), where the ridge crest meets the Siberian continental slope, and a northern passage around 84.5° N. The southern channel is characterized by smooth and flat bathymetry around 1600-1700 m with a sill depth slightly shallower than 1700 m. A hydrographic section across the channel reveals an eastward flow with Amundsen Basin properties in the southern part and a westward flow of Makarov Basin properties in the northern part. The northern passage includes an approximately 72 km long and 33 km wide trough which forms an intra-basin in the Lomonosov Ridge morphology (the Oden Trough). The eastern side of the Oden Trough is enclosed by a narrow and steep ridge rising 500-600 m above a generally 1600 m deep trough bottom. The deepest passage (the sill) is 1470 m deep and located on this ridge. Hydrographic data show irregular temperature and salinity profiles indicating that water exchange occurs as midwater intrusions bringing water properties from each side of the ridge in well-defined but irregular layers. There is also morphological evidence that some rather energetic flows may occur in the vicinity of the sill. A well expressed deepening near the sill may be the result of seabed erosion by bottom currents.

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

    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

  9. European temperature responses to blocking and ridge regional patterns

    Sousa, Pedro M.; Trigo, Ricardo M.; Barriopedro, David; Soares, Pedro M. M.; Santos, João A.

    2018-01-01

    Blocking occurrence and its impacts on European temperature have been studied in the last decade. However, most previous studies on blocking impacts have focused on winter only, disregarding its fingerprint in summer and differences with other synoptic patterns that also trigger temperature extremes. In this work, we provide a clear distinction between high-latitude blocking and sub-tropical ridges occurring in three sectors of the Euro-Atlantic region, describing their climatology and consequent impacts on European temperature during both winter and summer. Winter blocks (ridges) are generally associated to colder (warmer) than average conditions over large regions of Europe, in some areas with anomalies larger than 5 °C, particularly for the patterns occurring in the Atlantic and Central European sectors. During summer, there is a more regional response characterized by above average temperature for both blocking and ridge patterns, especially those occurring in continental areas, although negative temperature anomalies persist in southernmost areas during blocking. An objective analysis of the different forcing mechanisms associated to each considered weather regime has been performed, quantifying the importance of the following processes in causing the temperature anomalies: horizontal advection, vertical advection and diabatic heating. While during winter advection processes tend to be more relevant to explain temperature responses, in summer radiative heating under enhanced insolation plays a crucial role for both blocking and ridges. Finally, the changes in the distributions of seasonal temperature and in the frequencies of extreme temperature indices were also examined for specific areas of Europe. Winter blocking and ridge patterns are key drivers in the occurrence of regional cold and warm extreme temperatures, respectively. In summer, they are associated with substantial changes in the frequency of extremely warm days, but with different signatures in

  10. Oak Ridge Leadership Computing Facility (OLCF)

    Federal Laboratory Consortium — The Oak Ridge Leadership Computing Facility (OLCF) was established at Oak Ridge National Laboratory in 2004 with the mission of standing up a supercomputer 100 times...

  11. Oak Ridge Geochemical Reconnaissance Program

    Arendt, J.W.

    1977-03-01

    The Oak Ridge reconnaissance program is responsible for the geochemical survey in a 12-state area covering Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, Minnesota, Wisconsin, Michigan, Iowa, Indiana, and Illinois as part of the National Uranium Resource Evaluation Program. The program concept is outlined and the planning and organization of the program is discussed

  12. Discovery and Distribution of Black Smokers on the Western Galapagos Spreading Center: Implications for Spatial and Temporal Controls on High Temperature Venting at Ridge/Hotspot Intersections

    Haymon, R. M.; Anderson, P. G.; Baker, E. T.; Resing, J. A.; White, S. M.; MacDonald, K. C.

    2006-12-01

    flows of visually-similar ages (estimated to be tens-to-hundreds of years old). Possibly a volcanic pulse may have activated the hotspot- affected western GSC, and powered contemporaneous hydrothermal vents that now are waning. It may be that hotspots produce episodes of near-synchronous, extensive ridge volcanism and hydrothermal activity, followed by periods of quiescence. This idea is consistent with: the episodic eruption histories of Hawaii and Iceland; variably anomalous hydrothermal plume incidence (low on RR, SEIR, GSC; high on Mid-Atlantic Ridge near Azores hotspot); models of episodic melt extraction from mantle plumes; and evidence for magma propagation along hotspot-influenced ridges. Our hypothesis potentially can be tested by studies of gene flow between animal communities located on either side of the Galapagos hotspot, and by dating of GSC hydrothermal chimneys and the lava flows on which they are constructed.

  13. InRidge program: Preliminary results from the first cruise

    Mukhopadhyay, R.; Murthy, K.S.R.; Iyer, S.D.; Rao, M.M.M.; Banerjee, R.; Subrahmanyam, A.S.; Shirodkar, P.V.; Ghose, I.

    The first cruise under India's own Ridge research initiative, InRidge collected new data on bathymetry, free-air gravity and magnetic anomalies across the ridge axis between the Vema and Zhivago transform faults in the Central Indian Ridge...

  14. The beach ridges of India: A review

    Kunte, P.D.; Wagle, B.G.

    , and is presented in a consolidated form. Beach ridges of the east and west coast of India are grouped in thirteen-beach ridge complexes based on their association. Review indicates that the beach ridges of India are not older than the Holocene age...

  15. कार्ल्सवर्ग पर्वतश्रेणी के तलछट की विशेषता

    Valsangkar, A.B.

    The sediment coverage in the Carlsberg Ridge is similar in appearance to those in the Mid-Atlantic Ridge. The Carlsberg Ridge sediments show that their sources are continental, biogenic and diagenetic. The sedimentation rate determined by Th232...

  16. Effects of Cocos Ridge Collision on the Western Caribbean: Is there a Panama Block?

    Kobayashi, D.; La Femina, P. C.; Geirsson, H.; Chichaco, E.; Abrego M, A. A.; Fisher, D. M.; Camacho, E. I.

    2011-12-01

    It has been recognized that the subduction and collision of the Cocos Ridge, a 2 km high aseismic ridge standing on >20 km thick oceanic crust of the Cocos plate, drives upper plate deformation in southern Central America. Recent studies of Global Positioning System (GPS) derived horizontal velocities relative to the Caribbean Plate showed a radial pattern centered on the Cocos Ridge axis where Cocos-Caribbean convergence is orthogonal, and margin-parallel velocities to the northwest. Models of the full three-dimensional GPS velocity field and earthquake slip vectors demonstrate low mechanical coupling along the Middle America subduction zone in Nicaragua and El Salvador, and a broad zone of high coupling beneath the Osa Peninsula, where the Cocos Ridge intersects the margin. These results suggest that Cocos Ridge collision may be the main driver for trench-parallel motion of the fore arc to the northwest and for uplift and shortening of the outer fore arc in southern Central America, whereby thickened and hence buoyant Cocos Ridge crust acts as an indenter causing the tectonic escape of the fore arc. These studies, however, were not able to constrain well the pattern of surface deformation east-southeast of the ridge axis due to a lack of GPS stations, and Cocos Ridge collision may be responsible for the kinematics and deformation of the proposed Panama block. Recent reinforcement of the GPS network in southeastern Costa Rica and Panama has increased the spatial and temporal resolution of the network and made it possible to further investigate surface deformation of southern Central America and the Panama block. We present a new regional surface velocity field for Central America from geodetic GPS data collected at 11 recently-installed and 178 existing episodic, semi-continuous, and continuous GPS sites in Nicaragua, Costa Rica, and Panama. We investigate the effects of Cocos Ridge collision on the Panama block through kinematic block modeling. Published

  17. Fluvial Channel Networks as Analogs for the Ridge-Forming Unit, Sinus Meridiani, Mars

    Wilkinson, M. J.; du Bois, J. B.

    2010-01-01

    Fluvial models have been generally discounted as analogs for the younger layered rock units of Sinus Meridiani. A fluvial model based on the large fluvial fan provides a possibly close analog for various features of the sinuous ridges of the etched, ridge-forming unit (RFU) in particular. The close spacing of the RFU ridges, their apparently chaotic orientations, and their organization in dense networks all appear unlike classical stream channel patterns. However, drainage patterns on large fluvial fans low-angle, fluvial aggradational features, 100s of km long, documented worldwide by us provide parallels. Some large fan characteristics resemble those of classical floodplains, but many differences have been demonstrated. One major distinction relevant to the RFU is that channel landscapes of large fans can dominate large areas (1.2 million km2 in one S. American study area). We compare channel morphologies on large fans in the southern Sahara Desert with ridge patterns in Sinus Meridiani (fig 1). Stream channels are the dominant landform on large terrestrial fans: they may equate to the ubiquitous, sinuous, elongated ridges of the RFU that cover areas region wide. Networks of convergent/divergent and crossing channels may equate to similar features in the ridge networks. Downslope divergence is absent in channels of terrestrial upland erosional landscapes (fig. 1, left), whereas it is common to both large fans (fig. 1, center) and RFU ridge patterns (fig 1, right downslope defined as the regional NW slope of Sinus Meridiani). RFU ridge orientation, judged from those areas apparently devoid of impact crater control, is broadly parallel with the regional slope (arrow, fig. 1, right), as is mean orientation of major channels on large fans (arrow, fig. 1, center). High densities per unit area characterize fan channels and martian ridges reaching an order of magnitude higher than those in uplands just upstream of the terrestrial study areas fig. 1. In concert with

  18. Bose enhancement and the ridge

    Altinoluk, Tolga [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, 15706 Santiago de Compostela, Galicia (Spain); Armesto, Néstor, E-mail: nestor.armesto@usc.es [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, 15706 Santiago de Compostela, Galicia (Spain); Beuf, Guillaume [Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel); Kovner, Alex [Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269-3046 (United States); Lublinsky, Michael [Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel)

    2015-12-17

    We point out that Bose enhancement in a hadronic wave function generically leads to correlations between produced particles. We show explicitly, by calculating the projectile density matrix in the Color Glass Condensate approach to high-energy hadronic collisions, that the Bose enhancement of gluons in the projectile leads to azimuthal collimation of long range rapidity correlations of the produced particles, the so-called ridge correlations.

  19. Bose enhancement and the ridge

    Tolga Altinoluk

    2015-12-01

    Full Text Available We point out that Bose enhancement in a hadronic wave function generically leads to correlations between produced particles. We show explicitly, by calculating the projectile density matrix in the Color Glass Condensate approach to high-energy hadronic collisions, that the Bose enhancement of gluons in the projectile leads to azimuthal collimation of long range rapidity correlations of the produced particles, the so-called ridge correlations.

  20. Oak Ridge National Laboratory Review

    Krause, C.; Pearce, J.; Zucker, A. (eds.)

    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.

  1. Wetland Survey of Selected Areas in the Oak Ridge Y-12 Plant Area of Responsibilty, Oak Ridge, Tennessee

    Rosensteel.

    1997-01-01

    This document was prepared to summarize wetland surveys performed in the Y- 1 2 Plant area of responsibility in June and July 1994. Wetland surveys were conducted in three areas within the Oak Ridge Y- 12 Plant area of responsibility in June and July 1994: the Upper East Fork Poplar Creek (UEFPC) Operable Unit (OU), part of the Bear Creek Valley OU (the upper watershed of Bear Creek from the culvert under Bear Creek Road upstream through the Y-12 West End Environmental Management Area, and the catchment of Bear Creek North Tributary 1), and part of Chestnut Ridge OU 2 (the McCoy Branch area south of Bethel Valley Road). Using the criteria and methods set forth in the Wetlands Delineation Manual, 18 wetland areas were identified in the 3 areas surveyed; these areas were classified according to the system developed by Cowardin. Fourteen wetlands and one wetland/pond area that are associated with disturbed or remnant stream channels and seeps were identified in the UEFPC OU. Three wetlands were identified in the Bear Creek Valley OU portion of the survey area. One wetland was identified in the riparian zone of McCoy Branch in the southern portion of Chestnut Ridge OU 2

  2. Variational Ridging in Sea Ice Models

    Roberts, A.; Hunke, E. C.; Lipscomb, W. H.; Maslowski, W.; Kamal, S.

    2017-12-01

    This work presents the results of a new development to make basin-scale sea ice models aware of the shape, porosity and extent of individual ridges within the pack. We have derived an analytic solution for the Euler-Lagrange equation of individual ridges that accounts for non-conservative forces, and therefore the compressive strength of individual ridges. Because a region of the pack is simply a collection of paths of individual ridges, we are able to solve the Euler-Lagrange equation for a large-scale sea ice field also, and therefore the compressive strength of a region of the pack that explicitly accounts for the macro-porosity of ridged debris. We make a number of assumptions that have simplified the problem, such as treating sea ice as a granular material in ridges, and assuming that bending moments associated with ridging are perturbations around an isostatic state. Regardless of these simplifications, the ridge model is remarkably predictive of macro-porosity and ridge shape, and, because our equations are analytic, they do not require costly computations to solve the Euler-Lagrange equation of ridges on the large scale. The new ridge model is therefore applicable to large-scale sea ice models. We present results from this theoretical development, as well as plans to apply it to the Regional Arctic System Model and a community sea ice code. Most importantly, the new ridging model is particularly useful for pinpointing gaps in our observational record of sea ice ridges, and points to the need for improved measurements of the evolution of porosity of deformed ice in the Arctic and Antarctic. Such knowledge is not only useful for improving models, but also for improving estimates of sea ice volume derived from altimetric measurements of sea ice freeboard.

  3. Hydrothermal plume anomalies over the southwest Indian ridge: magmatic control

    Yue, X.; Li, H.; Tao, C.; Ren, J.; Zhou, J.; Chen, J.; Chen, S.; Wang, Y.

    2017-12-01

    Here we firstly reported the extensive survey results of the hydrothermal activity along the ultra-slow spreading southwest Indian ridge (SWIR). The study area is located at segment 27, between the Indomed and Gallieni transform faults, SWIR. The seismic crustal thickness reaches 9.5km in this segment (Li et al., 2015), which is much thicker than normal crustal. The anomaly thickened crust could be affected by the Crozet hotspot or highly focused melt delivery from the mantle. The Duanqiao hydrothermal field was reported at the ridge valley of the segment by Tao et al (2009). The Deep-towed Hydrothermal Detection System (DHDS) was used to collect information related with hydrothermal activity, like temperature, turbidity, oxidation-reduction potential (ORP) and seabed types. There are 15 survey lines at the interval of 2 to 3 km which are occupied about 1300 km2 in segment 27. After processing the raw data, including wiping out random noise points, 5-points moving average processing and subtracting the ambient, we got anomalous Nephelometric Turbidity Units values (ΔNTU). And dE/dt was used to identify the ORP anomalous as the raw data is easily influenced by electrode potentials drifting (Baker et al., 2016). According to the results of water column turbidity and ORP distributions, we confirmed three hydrothermal anomaly fields named A1, A2 and A3. The three fields are all located in the western part of the segment. The A1 field lies on the ridge valley, west side of Duanqiao field. The A2 and A3 field lie on the northern and southern of the ridge valley, respectively. We propose that recent magmatic activity probably focus on the western part of segment 27.And the extensive distribution of hydrothermal plume in the segment is the result of the discrete magma intrusion. References Baker E T, et al. How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of hydrothermal discharge locations. EPSL, 2016, 449:186-196. Li J

  4. Rainfall declines over Queensland from 1951-2007 and links to the Subtropical Ridge and the SAM

    Cottrill, D A; Ribbe, J

    2010-01-01

    Much of southern and eastern Australia including Queensland have experienced rainfall declines over recent decades affecting agricultural production and accelerating water infrastructure development. Rainfall declines from southern Australia have now been directly related to changes in the Southern Annular Mode (SAM) and the subtropical ridge. In southern and coastal Queensland, the rainfall declines have occurred mostly in the austral summer and autumn. Observations from this region reveal the rainfall decline is correlated to an increase in the mean sea level pressure (MSLP) at many stations. The largest increases in MSLP are over southeast Queensland and coastal regions, where some of the largest rainfall declines occur. This study indicates the subtropical ridge as one of the main factors in the rainfall decline over this region. SAM is also likely to be important, although its seasonal influence, apart from winter, is harder to determine.

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

    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

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

    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.

  7. Geophysical Investigation of Upper Mantle Anomalies of the Australian-Antarctic Ridge

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

    2017-12-01

    Australian-Antarctic Ridge (AAR) is situated between the Pacific-Antarctic Ridge (PAR) and Southeast Indian Ridge (SEIR), extending eastward from the Australian-Antarctic Discordance (AAD). Much of the AAR has been remained uncharted until 2011 because of its remoteness and harsh weather conditions. Since 2011, four multidisciplinary expeditions initiated by the Korea Polar Research Institute (KOPRI) have surveyed the little-explored eastern ends of the AAR and investigated the tectonics, geochemistry, and hydrothermal activity of this intermediate spreading system. Recent isotope studies using the new basalt samples from the AAR have led to the new hypothesis of the Southern Ocean mantle domain (SOM), which may have originated from the super-plume activity associated with the Gondwana break-up. In this study, we characterize the geophysics of the Southern Ocean mantle using the newly acquired shipboard bathymetry and available geophysical datasets. First, we computed residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography along the AAR in order to obtain a geological proxy for regional variations in magma supply. The results of these 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 central ridge segments of the AAR. Interestingly, the along-axis depths of the entire AAR are significantly shallower than the neighboring ridge systems and the global ridges of intermediate spreading rates. Such shallow depths are also correlated with regional negative geoid anomalies. Furthermore, recent mantle tomography models consistently showed that the upper mantle (< 250 km) below the AAR has low S-wave velocities, suggesting that it may be hotter than the nearby ridges. Such regional-scale anomalies of the

  8. Metallogenesis along the Indian Ocean Ridge System

    Banerjee, R.; Ray, Dwijesh

    including India. Among these studies majority were concentrated around the Central Indian Ridge and the Southwest Indian Ridge areas, while a few observations were made around the rest of the areas in the IORS. The findings of these studies are discussed...

  9. Sex Determination from Fingerprint Ridge Density | Gungadin ...

    This study was conducted with an aim to establish a relationship between sex and fingerprint ridge density. The fingerprints were taken from 500 subjects (250 males and 250 females) in the age group of 18-60 years. After taking fingerprints, the ridges were counted in the upper portion of the radial border of each print for all ...

  10. Geomagnetic Paleointensity Variations as a Cheap, High-Resolution Geochronometer for Recent Mid-Ocean Ridge Processes

    DYMENT, J.; HEMOND, C.

    2001-12-01

    The sequence of geomagnetic field reversals is widely used to date events younger than 160 Ma, with a resolution of a million years. In oceanic domains, Vine and Matthews (1963) magnetic anomalies have been successfully used for more than 35 years. The major limitation of this chronometer is its low temporal resolution, especially for the recent times: the youngest polarity reversal, between Brunhes normal and Matuyama reversed periods, is dated ~800 ka. Studies of pelagic sedimentary cores have shown the existence of consistent variations of the geomagnetic field intensity within this period. If accurately dated, these variations may refine the magnetic geochronometer to a much higher resolution of 10-100 ka. Recent studies have demonstrated that the "tiny wiggles" of lower amplitude and shorter wavelength superimposed to the Vine and Matthews anomalies are of geomagnetic origin and correspond to the paleointensity variations identified on sediment cores. Using a large set of magnetic data acquired in 1996 on the Mid-Atlantic Ridge at 21° N (surface and submersible magnetic anomalies, natural remanent magnetization and absolute paleointensities measured on samples), we have shown that the oceanic crust confidently records the geomagnetic intensity variations. It was unfortunately impossible to date the samples, made of basalt too depleted in K2O and in trace elements required by the various methods of radiochronology. In 2000 we have collected a similar data set at the Central Indian Ridge axis at 19° S (surface, deep-tow, and submersible magnetic anomalies, natural remanent magnetization and absolute paleointensities measured on samples). This area offers the advantages of 1) a faster spreading rate, and therefore a higher temporal resolution of the geomagnetic signal, and 2) the presence of moderately enriched basalt as a consequence of the interaction of the ridge with the nearby Reunion hotspot, making possible radiochronologic dating. Our first evaluation

  11. Coastal lagoons and beach ridges as complementary sedimentary archives for the reconstruction of Holocene relative sea-level changes

    Sander, Lasse; Hede, Mikkel Ulfeldt; Fruergaard, Mikkel

    2016-01-01

    Coastal lagoons and beach ridges are genetically independent, though non-continuous, sedimentary archives. We here combine the results from two recently published studies in order to produce an 8000-year-long record of Holocene relative sea-level changes on the island of Samsø, southern Kattegat,...

  12. Ridge interaction features of the Line Islands

    Konter, J. G.; Koppers, A. A. P.; Storm, L. P.

    2016-12-01

    The sections of Pacific absolute plate motion history that precede the Hawaii-Emperor and Louisville chains are based on three chains: the Line Islands-Mid-Pacific Mountains, the Hess Rise-Shatsky Rise, and the Marshall Islands-Wake Islands (Rurutu hotspot). Although it has been clear that the Line Islands do not define a simple age progression (e.g. Schlanger et al., 1984), the apparent similarity to the Emperor Seamount geographic trend has been used to extend the overall Hawaii-Emperor track further into the past. However, we show here that plate tectonic reconstructions suggest that the Mid-Pacific Mountains (MPMs) and Line Islands (LIs) were erupted near a mid-ocean ridge, and thus these structures do not reflect absolute plate motion. Moverover, the morphology and geochemistry of the volcanoes show similarities with Pukapuka Ridge (e.g. Davis et al., 2002) and the Rano Rahi seamounts, presumed to have a shallow origin. Modern 40Ar/39Ar ages show that the LIs erupted at various times along the entire volcanic chain. The oldest structures formed within 10 Ma of plate formation. Given the short distance to the ridge system, large aseismic volcanic ridges, such as Necker Ridge and Horizon Guyot may simply reflect a connection between MPMs and the ridge, similar to the Pukapuka Ridge. The Line Islands to the south (including Karin Ridge) define short subchains of elongated seamounts that are widespread, resembling the Rano Rahi seamount field. During this time, the plate moved nearly parallel to the ridge system. The change from few large ridges to many subchains may reflect a change in absolute plate motion, similar to the Rano Rahi field. Here, significant MPMs volcanism is no longer connected to the ridge along plate motion. Similar to Pukapuka vs. Rano Rahi, the difference in direction between plate motion and the closest ridge determines whether larger ridges or smaller seamount subchains are formed. The difference between the largest structures (MPMs and LIs

  13. Oak Ridge Reservation environmental report for 1991

    Mucke, P.C.

    1992-10-01

    The Oak Ridge Reservation Environmental Report for 1991 is the 21st in a series that began in 1971. The report documents the annual results of a comprehensive program to estimate the impact of the US Department of Energy (DOE) Oak Ridge operations upon human health and the environment. The report is organized into ten sections that address various aspects of effluent monitoring, environmental surveillance, dose assessment, waste management, and quality assurance. A compliance summary gives a synopsis of the status of each facility relative to applicable state and federal regulations. Data are included for the following: Oak Ridge Y-12 Plant; Oak Ridge National Laboratory (ORNL); and Oak Ridge K-25 Site. Effluent monitoring and environmental surveillance programs are intended to serve as effective indicators of contaminant releases and ambient contaminant concentrations that have the potential to result in adverse impacts to human health and the environment

  14. The ESASSI-08 cruise in the South Scotia Ridge region: An inverse model property-transport analysis over the Ridge

    Palmer, Margarita; Gomis, Damià; Del Mar Flexas, Maria; Jordà, Gabriel; Naveira-Garabato, Alberto; Jullion, Loic; Tsubouchi, Takamasa

    2010-05-01

    The ESASSI-08 oceanographic cruise carried out in January 2008 was the most significant milestone of the ESASSI project. ESASSI is the Spanish component of the Synoptic Antarctic Shelf-Slope Interactions (SASSI) study, one of the core projects of the International Polar Year. Hydrographical and biochemical (oxygen, CFCs, nutrients, chlorophyll content, alkalinity, pH, DOC) data were obtained along 11 sections in the South Scotia Ridge (SSR) region, between Elephant and South Orkney Islands. One of the aims of the ESASSI project is to determine the northward outflow of cold and ventilated waters from the Weddell Sea into the Scotia Sea. For that purpose, the accurate estimation of mass, heat, salt, and oxygen transport over the Ridge is requested. An initial analysis of transports across the different sections was first obtained from CTD and ADCP data. The following step has been the application of an inverse method, in order to obtain a better estimation of the net flow for the different water masses present in the region. The set of property-conservation equations considered by the inverse model includes mass, heat and salinity fluxes. The "box" is delimited by the sections along the northern flank of the SSR, between Elephant Island and 50°W, the southern flank of the Ridge, between 51.5°W and 50°W, the 50°W meridian and a diagonal line between Elephant Island and 51.5°W, 61.75°S. Results show that the initial calculations of transports suffered of a significant volume imbalance, due to the inherent errors of ship-ADCP data, the complicated topography and the presence of strong tidal currents in some sections. We present the post-inversion property transports across the rim of the box (and their error bars) for the different water masses.

  15. Oak Ridge rf Test Facility

    Gardner, W.L.; Hoffman, D.J.; McCurdy, H.C.; McManamy, T.J.; Moeller, J.A.; Ryan, P.M.

    1985-01-01

    The rf Test Facility (RFTF) of Oak Ridge National Laboratory (ORNL) provides a national facility for the testing and evaluation of steady-state, high-power (approx.1.0-MW) ion cyclotron resonance heating (ICRH) systems and components. The facility consists of a vacuum vessel and two fully tested superconducting development magnets from the ELMO Bumpy Torus Proof-of-Principle (EBT-P) program. These are arranged as a simple mirror with a mirror ratio of 4.8. The axial centerline distance between magnet throat centers is 112 cm. The vacuum vessel cavity has a large port (74 by 163 cm) and a test volume adequate for testing prototypic launchers for Doublet III-D (DIII-D), Tore Supra, and the Tokamak Fusion Test Reactor (TFTR). Attached to the internal vessel walls are water-cooled panels for removing the injected rf power. The magnets are capable of generating a steady-state field of approx.3 T on axis in the magnet throats. Steady-state plasmas are generated in the facility by cyclotron resonance breakdown using a dedicated 200-kW, 28-GHz gyrotron. Available rf sources cover a frequency range of 2 to 200 MHz at 1.5 kW and 3 to 18 MHz at 200 kW, with several sources at intermediate parameters. Available in July 1986 will be a >1.0-MW, cw source spanning 40 to 80 MHz. 5 figs

  16. Ca isotope fractionation and Sr/Ca partitioning associated with anhydrite formation at mid-ocean ridge hydrothermal systems: An experimental approach

    Syverson, D. D.; Scheuermann, P.; Pester, N. J.; Higgins, J. A.; Seyfried, W. E., Jr.

    2016-12-01

    throughout Earth's history. 1 Tivey, M. K. Generation of Seafloor Hydrothermal Deposits. Oceanography 20, 50-66 (2007).2 Amini, M. et al. Calcium isotope (δ44/40Ca) fractionation along hydrothermal pathways, Logatchev field (Mid-Atlantic Ridge, 14°45'N). Geochimica et Cosmochimica Acta 72, 4107-4122 (2008).

  17. Magdalena Ridge Observatory Interferometer: Status Update

    Creech-Eakman, M. J; Bakker, E. J; Buscher, D. F; Coleman, T. A; Haniff, C. A; Jurgenson, C. A; Klinglesmith, III, D. A; Parameswariah, C. B; Romero, V. D; Shtromberg, A. V; Young, J. S

    2006-01-01

    The Magdalena Ridge Observatory Interferometer (MROI) is a ten element optical and near-infrared imaging interferometer being built in the Magdalena mountains west of Socorro, NM at an altitude of 3230 m...

  18. A deep structural ridge beneath central India

    Agrawal, P. K.; Thakur, N. K.; Negi, J. G.

    A joint-inversion of magnetic satellite (MAGSAT) and free air gravity data has been conducted to quantitatively investigate the cause for Bouguer gravity anomaly over Central Indian plateaus and possible fold consequences beside Himalayan zone in the Indian sub-continent due to collision between Indian and Eurasian plates. The appropriate inversion with 40 km crustal depth model has delineated after discriminating high density and magnetisation models, for the first time, about 1500 km long hidden ridge structure trending NW-SE. The structure is parallel to Himalayan fold axis and the Indian Ocean ridge in the Arabian Sea. A quantitative relief model across a representative anomaly profile confirms the ridge structure with its highest point nearly 6 km higher than the surrounding crustal level in peninsular India. The ridge structure finds visible support from the astro-geoidal contours.

  19. Origin of lavas from the Ninetyeast Ridge, Eastern Indian Ocean: An evaluation of fractional crystallization models

    Ludden, J.N.; Thompson, G.; Bryan, W.B.; Frey, F.A.

    1980-08-10

    Ferrobasalts from DSDP sites 214 and 216 on the Ninetyeast Ridge are characterized by high absolute iron (FeO>12.9 wt %), FeO/MgO>1.9, and TiO/sub 2/>2.0 wt %. Their trace element abundances indicate a tholeiitic affinity; however, they are distinct from midocean ridge incompatible element-depleted tholeiites owing to higher contents of Ba, Zr, and Sr and flat to slightly light-REE-enriched, chondrite-normalized REE patterns. Calculations using major and trace element abundances and phase compositions are generally consistent with a model relating most major elements and phase compositions in site 214 and 216 ferrobasalts by fractionation of clinopyroxene and plagio-class. However, some incompatible element abundances for site 216 basalts are not consistent with the fractional crystallization models. Baslats from site 214 can be related to andesitic rocks from the same site by fractionating clinopyroxene, plagioclase and titanomagnetite. Site 254 basalts, at the southern end of the Ninetyeast Ridge, and island tholeiites in the southern Indian Ocean (Amsterdam-St. Paul or Kerguelen-Heard volcanic provinces) possibly represent the most recent activity associated with a hot spot forming the Ninetyeast Ridge. These incompatible-element-enriched tholeiites have major element compositions consistent with those expected for a parental liquid for the site 214 and 216 ferrobasalts. However, differences in the trace element contents of the basalts from the Ninetyeast Ridge sites are not consistent with simple fractional crystallization derivation but require either a complex melting model or a heterogeneous mantle source.

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

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

    2011-01-01

    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; 1δ 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 H2O 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.

  1. Oak Ridge Reservation environmental report for 1989

    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

  2. Oak Ridge Reservation environmental report for 1989

    Jacobs, V.A.; Wilson, A.R. (eds.)

    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.

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

    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

  4. Preliminary results from the first InRidge cruise to the central Indian Ridge

    Mukhopadhyay, R.; Murthy, K.S.R.; Iyer, S.D.; Rao, M.M.M.; Banerjee, R.; Subrahmanyam, A.S.; Shirodkar, P.V.; Ghose, I.; Ganesan, P.; Rao, A.K.; Suribabu, A.; Ganesh, C.; Naik, G.P.

    stream_size 1 stream_content_type text/plain stream_name Inter_Ridge_News_7_40.pdf.txt stream_source_info Inter_Ridge_News_7_40.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  5. An aerial radiological survey of the Oak Ridge Reservation, Oak Ridge, Tennessee

    Maurer, R.J.

    1993-04-01

    An aerial radiological survey of the Oak Ridge Reservation (ORR) and surrounding area in Oak Ridge, Tennessee, was conducted during the period March 30 to April 14,1992. The purpose of the survey was to measure and document the terrestrial radiological environment of the Oak Ridge Reservation for use in environmental management programs and emergency response planning. The aerial survey was flown at an altitude of 150 feet (46 meters) along a series of parallel lines 250 feet (76 meters) apart and included X-10 (Oak Ridge National Laboratory), K-25 (former Gaseous Diffusion Plant), Y-12 (Weapons Production Plant), the Freels Bend Area and Oak Ridge Institute for Science and Education, the East Fork Poplar Creek (100-year floodplain extending from K-25 to Y-12), Elza Gate (former uranium ore storage site located in the city of Oak Ridge), Parcel A, the Clinch River (river banks extending from Melton Hill Dam to the city of Kingston), and the CSX Railroad Tracks (extending from Y-12 to the city of Oak Ridge). The survey encompassed approximately 55 square miles (1 41 square kilometers) of the Oak Ridge Reservation and surrounding area

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

    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

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

    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.

  8. Alveolar Ridge Carcinoma. Two Cases Report

    Pupo Triguero, Raul J; Vivar Bauza, Miriam; Alvarez Infante, Elisa

    2008-01-01

    Two cases with alveolar ridge carcinoma due to prosthetist traumatism are discussed in this paper, after 9 and 10 years of using dental prosthesis. Both patients began with disturbance in the alveolar ridge. The clinical examination and biopsy showed a well differenced carcinoma. The treatment was radical surgery and radiotherapy in the first patient, and conservative surgery with radiotherapy in the second case .The patients had xerostomia after radiotherapy and the woman had difficulties with mastication. The advantages and disadvantages of the treatment were discussed, focused on the prevention and treatment for oral

  9. ORLANDO - Oak Ridge Large Neutrino Detector

    Bugg, W.; Cohn, H.; Efremenko, Yu.; Fazely, A.; Gabriel, T.; Kamyshkov, Yu.; Plasil, F.; Svoboda, R.

    1999-01-01

    We discuss a proposal for construction of an Oak Ridge LArge Neutrino DetectOr (ORLANDO) to search for neutrino oscillations at the Spallation Neutron Source (SNS). A 4 MW SNS is proposed to be built at the Oak Ridge National Laboratory with the first stage to be operative around 2006. It will have two target stations, which makes it possible with a single detector to perform a neutrino oscillation search at two different distances. Initial plans for the placement of the detector and the discovery potential of such a detector are discussed

  10. Normalization Ridge Regression in Practice I: Comparisons Between Ordinary Least Squares, Ridge Regression and Normalization Ridge Regression.

    Bulcock, J. W.

    The problem of model estimation when the data are collinear was examined. Though the ridge regression (RR) outperforms ordinary least squares (OLS) regression in the presence of acute multicollinearity, it is not a problem free technique for reducing the variance of the estimates. It is a stochastic procedure when it should be nonstochastic and it…

  11. Geology of the Syncline Ridge area related to nuclear waste disposal, Nevada Test Site, Nye County, Nevada

    Hoover, D.L.; Morrison, J.N.

    1980-01-01

    The Syncline Ridge area is in the western part of Yucca Flat, Nye Co., Nev. Drill holes, geophysical surveys, mapping, and laboratory studies during 1976 through 1978 were used to investigate argillite in unit J (Mississippian) of the Eleana Formation (Devonian and Mississippian) as a possible nuclear waste repository site. Argillite in unit J has a minimum stratigraphic thickness of at least 700 m. The argillite underlies most of the Syncline Ridge area east of the Eleana Range, and is overlain by Quaternary alluvium and the Tippipah Limestone of Syncline Ridge. At the edges of the Syncline Ridge area, alluvium and volcanic rocks overlie the argillite. The argillite is underlain by more than 1000 m of quartzite, siliceous argillite, and minor limestone in older units of the Eleana Formation. These older units crop out in the Eleana Range. The area is divided into southern, central, and northern structural blocks by two lateral faults. The southern and central blocks either have volumes of argillite too small for a repository site, or have irregular-shaped volumes caused by Mesozoic high-angle faults that make the structure too complex for a repository site. The northern block appears to contain thick argillite within an area of 6 to 8 km 2 . The postvolcanic history of the Syncline Ridge area indicates that the area has undergone less deformation than other areas in Yucca Flat. Most of the late Tertiary and Quaternary deformation consisted of uplift and eastward tilting in the Syncline Ridge area. Preliminary engineering geology investigations indicate that although the competency of the argillite is low, the argillite may be feasible for construction of a nuclear waste disposal facility. Physical, thermal, chemical, and mineralogical properties of the argillite appear to be within acceptable limits for a nuclear waste repository

  12. Benthic megafaunal community structure of cobalt-rich manganese crusts on Necker Ridge

    Morgan, Nicole B.; Cairns, Stephen; Reiswig, Henry; Baco, Amy R.

    2015-10-01

    In the North Pacific Ocean, the seamounts of the Hawaiian Archipelago and the Mid-Pacific Mountains are connected by Necker Ridge, a 600 km-long feature spanning a depth range of 1400-4000 m. The Necker Ridge is a part of a large area of the central and western Pacific under consideration for cobalt-rich manganese crust mining. We describe the fauna and community structure of the previously unsampled Necker Ridge based on explorations with the submersible Pisces IV. On five pinnacles and a portion of the Ridge ranging from 1400 to 2000 m deep, 27 transects were recorded using HD video, and voucher specimens were collected to aid in species identification. The video was analyzed to identify and count the megafauna found on each transect and to characterize the substrate. Diversity increased from south to north along the feature. There was a significant difference in community structure between southern and northern pinnacles, with southern pinnacles dominated by crinoids of the Family Charitometridae and northern pinnacles dominated by octocorals, especially the Families Isididae and Chrysogorgiidae. DistLM demonstrated a correlation between community structure on the pinnacles and at least six environmental variables, including latitude, sediment cover, and oxygen concentration, but not including depth. The discontinuous and patchy nature of these distinct megafaunal communities highlights growing evidence that cobalt-rich seamounts are highly heterogeneous habitats, and that managing seamounts may require more complex regulations than treating them as a single ecological unit. These results suggest that extensive community analysis should occur at a given site to determine management priority areas, prior to consideration of that site for exploitation of natural resources.

  13. Wrinkle Ridges and Young Fresh Crater

    2002-01-01

    (Released 10 May 2002) The Science Wrinkle ridges are a very common landform on Mars, Mercury, Venus, and the Moon. These ridges are linear to arcuate asymmetric topographic highs commonly found on smooth plains. The origin of wrinkle ridges is not certain and two leading hypotheses have been put forth by scientists over the past 40 years. The volcanic model calls for the extrusion of high viscosity lavas along linear conduits. This thick lava accumulated over these conduits and formed the ridges. The other model is tectonic and advocates that the ridges are formed by compressional faulting and folding. Today's THEMIS image is of the ridged plains of Lunae Planum located between Kasei Valles and Valles Marineris in the northern hemisphere of the planet. Wrinkle ridges are found mostly along the eastern side of the image. The broadest wrinkle ridges in this image are up to 2 km wide. A 3 km diameter young fresh crater is located near the bottom of the image. The crater's ejecta blanket is also clearly seen surrounding the sharp well-defined crater rim. These features are indicative of a very young crater that has not been subjected to erosional processes. The Story The great thing about the solar system is that planets are both alike and different. They're all foreign enough to be mysterious and intriguing, and yet familiar enough to be seen as planetary 'cousins.' By comparing them, we can learn a lot about how planets form and then evolve geologically over time. Crinkled over smooth plains, the long, wavy raised landforms seen here are called 'wrinkle ridges,' and they've been found on Mars, Mercury, Venus, and the Moon - that is, on rocky bodies that are a part of our inner solar system. We know from this observation that planets (and large-enough moons) follow similar processes. What we don't know for sure is HOW these processes work. Scientists have been trying to understand how wrinkle ridges form for 40 years, and they still haven't reached a conclusion. That

  14. Ridge regression estimator: combining unbiased and ordinary ridge regression methods of estimation

    Sharad Damodar Gore

    2009-10-01

    Full Text Available Statistical literature has several methods for coping with multicollinearity. This paper introduces a new shrinkage estimator, called modified unbiased ridge (MUR. This estimator is obtained from unbiased ridge regression (URR in the same way that ordinary ridge regression (ORR is obtained from ordinary least squares (OLS. Properties of MUR are derived. Results on its matrix mean squared error (MMSE are obtained. MUR is compared with ORR and URR in terms of MMSE. These results are illustrated with an example based on data generated by Hoerl and Kennard (1975.

  15. Large fault fabric of the Ninetyeast Ridge implies near-spreading ridge formation

    Sager, W.W.; Paul, C.F.; Krishna, K.S.; Pringle, M.S.; Eisin, A.E.; Frey, F.A.; Rao, D.G.; Levchenko, O.V.

    of the high ridge. At 26°S, prominent NE-SW 97 oriented lineations extend southwest from the ridge. Some appear to connect with N-S fracture 98 zone troughs east of NER, implying that the NE-SW features are fracture zone scars formed after 99 the change... to the 105 ridge (Fig. 3). This is especially true for NER south of ~4°S. Where KNOX06RR crossed a 106 gravity lineation, negative gradient features correspond to troughs whereas positive gradient 107 features result from igneous basement highs (Fig. 3...

  16. Meteorological tower data for the Yucca Alluvial (YA) site and Yucca Ridge (YR) site: Final data report, July 1983-October 1984

    Church, H.W.; Freeman, D.L.; Boro, K.; Egami, R.T.

    1987-11-01

    The purpose of the NNWSI meteorological data collection program was to support environmental evaluations of site suitability for a nuclear waste repository. This is the last of a series of data summaries for the NNWSI Alluvial and Ridge Sites in southern Nevada. 3 refs., 3 figs., 6 tabs

  17. On the Antarctic Slope Front and Current crossing of the South Scotia Ridge

    Orsi, A. H.; Palmer, M.; Gomis, D.; Flexas, M. M.; Kim, Y.-S.; Jordà, G.; Wiederwohl, C.; Álvarez, M.

    2012-04-01

    To unveil the contorted path followed by the Antarctic Slope Current connecting the Weddell and Scotia Seas, hydrographic stations with unprecedented spatial resolution were occupied on a series of sections across the slope and multiple channels in the double-pronged western portion of the South Scotia Ridge. Fieldwork consisted of two cruises from the ESASSI (January 2008) and ACROSS (February 2009) programs, the Spanish and USA/Argentina components of the International Polar Year core project SASSI (Synoptic Antarctic Shelf-Slope Interaction study). In this region the Antarctic Slope Current can be located by the pronounced in-shore deepening of isopycnals over the continental slope, rendering the strong subsurface temperature and salinity gradients characteristic of the Antarctic Slope Front. Before reaching the gaps in the southern Ridge near 51°W and 50°W, the ASC carries about 3 Sv of upper layer waters, but it splits into shallow and deep branches upon turning north through these two gaps. The shallower branch enters the Hesperides Trough at 51°W, then shows a tight cyclonic loop back to that longitude roughly following the slope's 700-m isobath, and turns again westward through a similar gap in the northern Ridge. In the Scotia Sea the westward-flowing Antarctic Slope Current is found as far west as the Elephant Island along slightly deeper levels of slope (1100 m) before it is blocked by the Antarctic Circumpolar Current south of the Shackleton Fracture Zone (56°W). The deeper branch of the ASC in the Powell Basin crosses the southern Ridge near 50°W and roughly follows the 1600-m isobath before entering the Scotia Sea through the Hesperides Gap farther to the east (49°W). Thereafter the deeper waters carried westward by this branch become undistinguishable from those circulating farther offshore. Repeat cross-slope sections at both southern and northern flanks of the South Scotia Ridge showed significant temporal variability in the characteristics

  18. Internal doses in Oak Ridge. The Internet beams

    Passchier, W.F.

    1997-01-01

    A brief overview is given of the information, presented by the Radiation Internal Dose Information Center (RIDIC) of the Oak Ridge Associated Universities in Oak Ridge, TN, USA, via Internet (www.orau.gov/ehsd/ridic.htm)

  19. Efficiency of local surface plasmon polariton excitation on ridges

    Radko, Ilya; Bozhevolnyi, Sergey I.; Boltasseva, Alexandra

    2008-01-01

    We investigate experimentally and numerically the efficiency of surface plasmon polariton excitation by a focused laser beam using gold ridges. The dependence of the efficiency on geometrical parameters of ridges and wavelength dependence are examined. The experimental measurements accomplished...

  20. DEVELOPMENT OF A RIDGE PROFILE WEEDER

    ES Obe

    1980-03-01

    driven rotating horizontal short shaft which is connected by universal joints to two gangs of rotary hoe weeders. With the short shaft nearly at the bottom of a furrow between two ridges, the gangs of weeders lie on the sides of ...

  1. Oak Ridge Reservation Waste Management Plan

    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

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

    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.

  3. Alveolar ridge augmentation by osteoinduction in rats

    Pinholt, E M; Bang, G; Haanaes, H R

    1990-01-01

    The purpose of this study was to evaluate bone substitutes for alveolar ridge augmentation by osteoinduction. Allogenic, demineralized, and lyophilized dentin and bone was tested for osteoinductive properties in order to establish an experimental model for further studies. Implantations were perf...

  4. Oak Ridge Reservation Waste Management Plan

    Turner, J.W. [ed.

    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.

  5. 25 MV tandem accelerator at Oak Ridge

    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

  6. Oak Ridge reservation land-use plan

    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.

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

    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 ∼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

  8. Petrography of basalts from the Carlsberg ridge

    Banerjee, R.; Iyer, S.D.

    Petrographic characteristics of basalts collected from a segment of the Carlsberg Ridge (lat. 3 degrees 35'N to 3 degrees 41'N; long. 64 degrees 05'E to 64 degrees 09'E) show typical pillow lava zonations with variable concentrations of plagioclase...

  9. The Northern Central Indian Ridge: Geology and tectonics of fracture zones-dominated spreading ridge segments

    Drolia, R.K.; Iyer, S.D.; Chakraborty, B.; Kodagali, V.N.; Ray, Dwijesh; Misra, S.; Andrade, R.; Sarma, K.V.L.N.S.; Rajasekhar, R.P.; Mukhopadhyay, R.

    Multi-beam and single-beam bathymetric, gravity and magnetic data, across seven ridge segments (length varying between 37 and 84 km), offset by six transform discontinuities (ranging in dislocation length between 48 and 344 km) of the Northern...

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

    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

  11. Some improved classification-based ridge parameter of Hoerl and ...

    Some improved classification-based ridge parameter of Hoerl and Kennard estimation techniques. ... This assumption is often violated and Ridge Regression estimator introduced by [2]has been identified to be more efficient than ordinary least square (OLS) in handling it. However, it requires a ridge parameter, K, of which ...

  12. Does the lateral intercondylar ridge disappear in ACL deficient patients?

    van Eck, C.F.; Martins, C.A.Q.; Vyas, S.M.; Celentano, U.; van Dijk, C.N.; Fu, F.H.

    2010-01-01

    The aim of this study was to determine whether there is a difference in the presence of the lateral intercondylar ridge and the lateral bifurcate ridge between patients with sub-acute and chronic ACL injuries. We hypothesized that the ridges would be present less often with chronic ACL deficiency.

  13. Thickness of Knox Group overburden on Central Chestnut Ridge, Oak Ridge Reservation

    Staub, W.P.; Hopkins, R.A.

    1984-05-01

    The thickness of residual soil overlying the Knox Group along Central Chestnut Ridge was estimated by a conventional seismic refraction survey. The purpose of this survey was to identify sites on the Department of Energy's Oak Ridge Reservation where ample overburden exists above the water table for the shallow land burial of low-level radioactive waste. The results of the survey suggest that the upper slopes of the higher ridges in the area have a minimum of 16 to 26 m (52 to 85 ft) of overburden and that the crests of these ridges may have more than 30 m (100 ft). Therefore, it is unlikely that sound bedrock would be encountered during trench excavation [maximum of 10 m (32 ft)] along Central Chestnut Ridge. Also, the relatively low seismic wave velocities measured in the overburden suggest that the water table is generally deep. On the basis of these preliminary results, Central Chestnut Ridge appears to be suitable for further site characterization for the shallow land burial of low-level radioactive waste. 3 references, 5 figures, 1 table

  14. The Mysterious Southern Torque

    McDowell, M. S.

    2004-05-01

    Something weird happened to twist the southern hemisphere out of alignment with the northern, as evidenced by the positions of the mountain ranges of North and South America, the Atlantic MAR, and the closure of West Africa to North America - all smooth were the torque reversed. What happened, and when, and why? We identify a number of global "cracks" of almost exactly the same length and direction, with some, even more peculiarly, turning the same angle, and proceeding an equal distance in the new direction. The Emperor-Hawaiian chain, the Louisville chain and the west coast of North America, as examples, are essentially parallel. Their northerly legs follow the angle of the axis of orbital ellipse. But then they all make equal 45 degree easterly bends, to 17.5 NW, and continue on, still parallel, for very similar distances. It is the same at the north coast of South America, and the mid-section of the MAR from 46W to 12W. It is the distance from the Cameroons to Kenya, from the south end of the Red Sea to the SE Indian Ridge at the Nema Fracture zone, from west to east of the Nazca plate.What is all this? Coincidence? Seeing things? Researchers have attributed plate motion or hot spot motion or both or absolutely none, to all of the above. Geophysicists have dated the surfaces from Archean to Pleistocene by all possible scientific means, certainly no possible correlation can be made. Yet we postulate the physical reality can be demonstrated. It is so global a phenomenon that it is well beyond what a hot spot or a plate could do. Even a really tremendous impact would have trouble making such precise geometric arrangements. So what is it - perhaps the angle of rotation, or the inertia of northern hemisphere mass above the geoid? And if so, then, what changed it? It would seem that some huge imbalance occurred. Suppose the whole bottom blew out of the southern hemisphere, and the center of mass drastically altered. Suppose some unknown universal force changed our

  15. Southern blotting.

    Brown, T

    2001-05-01

    Southern blotting is the transfer of DNA fragments from an electrophoresis gel to a membrane support (the properties and advantages of the different types of membrane, transfer buffer, and transfer method are discussed in detail), resulting in immobilization of the DNA fragments, so the membrane carries a semipermanent reproduction of the banding pattern of the gel. After immobilization, the DNA can be subjected to hybridization analysis, enabling bands with sequence similarity to a labeled probe to be identified. This appendix describes Southern blotting via upward capillary transfer of DNA from an agarose gel onto a nylon or nitrocellulose membrane, using a high-salt transfer buffer to promote binding of DNA to the membrane. With the high-salt buffer, the DNA becomes bound to the membrane during transfer but not permanently immobilized. Immobilization is achieved by UV irradiation (for nylon) or baking (for nitrocellulose). A Support Protocol describes how to calibrate a UV transilluminator for optimal UV irradiation of a nylon membrane. An alternate protocol details transfer using nylon membranes and an alkaline buffer, and is primarily used with positively charged nylon membranes. The advantage of this combination is that no post-transfer immobilization step is required, as the positively charged membrane binds DNA irreversibly under alkaline transfer conditions. The method can also be used with neutral nylon membranes but less DNA will be retained. A second alternate protocol describes a transfer method based on a different transfer-stack setup. The traditional method of upward capillary transfer of DNA from gel to membrane described in the first basic and alternate protocols has certain disadvantages, notably the fact that the gel can become crushed by the weighted filter papers and paper towels that are laid on top of it. This slows down the blotting process and may reduce the amount of DNA that can be transferred. The downward capillary method described in

  16. Unfaulting the Sardarapat Ridge, Southwest Armenia

    Wetmore, P.; Connor, C.; Connor, L. J.; Savov, I. P.; Karakhanyan, A.

    2012-12-01

    Armenia is located near the core of contractional deformation associated with the collision between the Arabian and Eurasian tectonic plates. Several studies of this region, including portions of adjacent Georgia, Iran, and Turkey, have indicated that 1-2 mm/yr of intra-plate, north-south shortening is primarily accommodated by a network of E-W trending thrust faults, and NW-trending (dextral) and NE-trending (sinistral) strike-slip faults. One proposed fault in this network, the Sardarapat Fault (SF), was investigated as part of a regional seismic hazard assessment ahead of the installation of a replacement reactor at the Armenian Nuclear Power Plant (ANPP). The SF is primarily defined by the Sardarapat Ridge (SR), which is a WNW-trending, 40-70 m high topographic feature located just north of the Arax River and the Turkey-Armenia border. The stratigraphy comprising this ridge includes alluvium overlying several meters of lacustrine deposits above a crystal-rich basaltic lava flow that yields an Ar-Ar age of 0.9 +/- 0.02 Ma. The alluvial sediments on the ridge contain early Bronze age (3832-3470 BP) artifacts at an elevation 25 m above those of the surrounding alluvial plane. This has lead to the suggestion that the SR is bound to the south (the steepest side) by the SF, which is uplifting the ridge at a rate of 0.7 mm/yr. However, despite the prominence and trend of the ridge there are no unequivocal observations, such as scarps or exposures of fault rocks, to support the existence of the SF. The goal of the investigation of the SR area was to test various models for the formation of the ridge including faulting and combined volcanic and erosional processes. We therefore collected gravimetric, magnetic, magneto-tellurics (MT), and transient electromagnetic (TEM) data across an area of ~400 km2, and used correlations of stratigraphic data from coreholes drilled proximal to the study area to define the geometry of the contact between the basement and basin fill to

  17. Model selection in kernel ridge regression

    Exterkate, Peter

    2013-01-01

    Kernel ridge regression is a technique to perform ridge regression with a potentially infinite number of nonlinear transformations of the independent variables as regressors. This method is gaining popularity as a data-rich nonlinear forecasting tool, which is applicable in many different contexts....... The influence of the choice of kernel and the setting of tuning parameters on forecast accuracy is investigated. Several popular kernels are reviewed, including polynomial kernels, the Gaussian kernel, and the Sinc kernel. The latter two kernels are interpreted in terms of their smoothing properties......, and the tuning parameters associated to all these kernels are related to smoothness measures of the prediction function and to the signal-to-noise ratio. Based on these interpretations, guidelines are provided for selecting the tuning parameters from small grids using cross-validation. A Monte Carlo study...

  18. Oak Ridge National Laboratory Waste Management Plan

    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

  19. ORNL (Oak Ridge National Laboratory) 89

    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.

  20. ORNL [Oak Ridge National Laboratory] 89

    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

  1. Oak Ridge National Laboratory Waste Management Plan

    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.

  2. Global survey of lunar wrinkle ridge formation times

    Yue, Z.; Michael, G. G.; Di, K.; Liu, J.

    2017-11-01

    Wrinkle ridges are a common feature of the lunar maria and record subsequent contraction of mare infill. Constraining the timing of wrinkle ridge formation from crater counts is challenging because they have limited areal extent and it is difficult to determine whether superposed craters post-date ridge formation or have alternatively been uplifted by the deformation. Some wrinkle ridges do allow determination to be made. This is possible where a ridge shows a sufficiently steep boundary or scarp that can be identified as deforming an intersecting crater or the crater obliterates the relief of the ridge. Such boundaries constitute only a small fraction of lunar wrinkle ridge structures yet they are sufficiently numerous to enable us to obtain statistically significant crater counts over systems of structurally related wrinkle ridges. We carried out a global mapping of mare wrinkle ridges, identifying appropriate boundaries for crater identification, and mapping superposed craters. Selected groups of ridges were analyzed using the buffered crater counting method. We found that, except for the ridges in mare Tranquilitatis, the ridge groups formed with average ages between 3.5 and 3.1 Ga ago, or 100-650 Ma after the oldest observable erupted basalts where they are located. We interpret these results to suggest that local stresses from loading by basalt fill are the principal agent responsible for the formation of lunar wrinkle ridges, as others have proposed. We find a markedly longer interval before wrinkle ridge formation in Tranquilitatis which likely indicates a different mechanism of stress accumulation at this site.

  3. Alveolar ridge keratosis - a retrospective clinicopathological study

    2013-01-01

    Background Alveolar ridge keratosis (ARK) is a distinct, benign clinicopathological entity, characterized by a hyperkeratotic plaque or patch that occurs on the alveolar edentulous ridge or on the retromolar trigone, considered to be caused by chronic frictional trauma. The aim of this retrospective study is to present the clinicopathological features of 23 consecutive cases of ARK. Material and methods The 23 biopsy samples of ARK were selected and pathological features were revised (keratosis, acanthosis, surface architecture, and inflammation). Factors such as the patient’s gender, age, anatomical location, tobacco and alcohol use were analyzed. Results Sixteen out of the 23 cases studied were men and 7 women with a mean age of 55.05 (age ranged from 17 to 88 years). Thirteen cases had a history of tobacco habit, amongst whom, 4 also presented alcohol consumption. All the cases presented only unilateral lesions. Nineteen cases involved the retromolar trigone while 4 cases involved edentulous alveolar ridges. When observed microscopically, the lesions were mainly characterized by moderate to important hyperorthokeratosis. Inflammation was scanty or absent. In four of the cases, the presence of melanin pigment in the superficial corium or in the cytoplasm of macrophages was detected. None of the cases showed any features of dysplasia. Conclusion Our results reveal that ARK is a benign lesion. However, the high prevalence of smokers amongst the patients might suggest that some potentially malignant disorders such as tobacco associated leukoplakia may clinically mimic ARK. PMID:23587097

  4. Alveolar ridge rehabilitation to increase full denture retention and stability

    Mefina Kuntjoro

    2010-12-01

    Full Text Available Background: Atrophic mandibular alveolar ridge generally complicates prostetic restoration expecially full denture. Low residual alveolar ridge and basal seat can cause unstable denture, permanent ulcer, pain, neuralgia, and mastication difficulty. Pre-proshetic surgery is needed to improve denture retention and stability. Augmentation is a major surgery to increase vertical height of the atrophic mandible while vestibuloplasty is aimed to increase the denture bearing area. Purpose: The augmentation and vestibuloplasty was aimed to provide stability and retentive denture atrophic mandibular alveolar ridge. Case: A 65 years old woman patient complained about uncomfortable denture. Clinical evaluate showed flat ridge in the anterior mandible, flabby tissue and candidiasis, while residual ridge height was classified into class IV. Case management: Augmentation using autograph was conducted as the mandible vertical height is less than 15 mm. Autograph was used to achieve better bone quantity and quality. Separated alveolar ridge was conducted from left to right canine region and was elevated 0.5 mm from the previous position to get new ridge in the anterior region. The separated alveolar ridge was fixated by using T-plate and ligature wire. Three months after augmentation fixation appliances was removed vestibuloplasty was performed to increase denture bearing area that can make a stable and retentive denture. Conclusion: Augmentation and vestibuloplasty can improve flat ridge to become prominent.Latar belakang: Ridge mandibula yang atrofi pada umumnya mempersulit pembuatan restorasi prostetik terutama gigi tiruan lengkap (GTL. Residual alveolar ridge dan basal seat yang rendah menyebabkan gigi tiruan menjadi tidak stabil, menimbulkan ulser permanen, nyeri, neuralgia, dan kesulitan mengunyah. Tujuan: Augmentasi dan vestibuloplasti pada ridge mandibula yang atrofi dilakukan untuk menciptakan gigi tiruan yang stabil dan retentive. Kasus: Pasien wanita

  5. An aerial radiological survey of the Oak Ridge Reservation and surrounding area, Oak Ridge, Tennessee

    Maurer, R.J.

    1989-09-01

    An aerial radiological survey of the Oak Ridge Reservation (ORR) and surrounding area in Oak Ridge, Tennessee, was conducted from September 12--29, 1989. The purpose of the survey was to measure and document the site's terrestrial radiological environment for use in effective environmental management and emergency response planning. The aerial survey was flown at an altitude of 91 meters (300 feet) along a series of parallel lines 152 meters (500 feet) apart. The survey encompassed an area of 440 square kilometers (170 square miles) as defined by the Tennessee Valley Authority Map S-16A of the entire Oak Ridge Reservation and adjacent area. The results of the aerial survey are reported as inferred exposure rates at 1 meter above ground level (AGL) in the form of a radiation contour map. Typical background exposure rates were found to vary from 5 to 14 microroentgens per hour (μR/h). The man-made radionuclides, cobalt-60, cesium-137, and protactinium-234m (a radioisotope indicative of depleted uranium), were detected at several facilities on the site. In support of the aerial survey, ground-based exposure rate and soil sample measurements were obtained at several locations within the survey boundary. In addition to the large scale aerial survey, two special flyovers were requested by the Department of Energy. The first request was to conduct a survey of a 1-mile x 2-mile area in south Knoxville, Tennessee. The area had been used previously to store contaminated scrap metals from operations at the Oak Ridge site. The second request was to fly several passes over a 5-mile length of railroad tracks leading from the Oak Ridge Y-12 Plant, north through the city of Oak Ridge. The railroad tracks had been previously used in the transport of cesium-137

  6. Multibeam collection for CE16007: Multibeam data collected aboard Celtic Explorer from 2016-04-08 to 2016-04-22, Galway, Ireland to St. John's, Canada

    National Oceanic and Atmospheric Administration, Department of Commerce — Coverage includes a swath of multibeam data with focus on a previously unidentified seabed feature in the Mid-Atlantic Ridge. The survey was conducted between 08/04...

  7. Dynamics of the Seychelles-Chagos Thermocline Ridge

    Bulusu, S.

    2016-02-01

    The southwest tropical Indian Ocean (SWTIO) features a unique, seasonal upwelling of the thermocline also known as the Seychelles-Chagos Thermocline Ridge (SCTR). More recently, this ridge or "dome"-like feature in the thermocline depth at (55°E-65°E, 5°S-12°S) in the SWTIO has been linked to interannual variability in the semi-annual Indian Ocean monsoon seasons as well as the Madden-Julian Oscillation (MJO) and El Niño Southern Oscillation (ENSO). The SCTR is a region where the MJO is associated with strong SST variability. Normally more cyclones are found generated in this SCTR region when the thermocline is deeper, which has a positive relation to the arrival of a downwelling Rossby wave from the southeast tropical Indian Ocean. Previous studies have focused their efforts solely on sea surface temperature (SST) because they determined salinity variability to be low, but with the Soil Moisture and Ocean Salinity (SMOS), and Aquarius salinity missions new insight can be shed on the effects that the seasonal upwelling of the thermocline has on Sea Surface Salinity (SSS). Seasonal SSS anomalies these missions will reveal the magnitude of seasonal SSS variability, while Argo depth profiles will show the link between changes in subsurface salinity and temperature structure. A seasonal increase in SST and a decrease in SSS associated with the downwelling of the thermocline have also been shown to occasionally generate MJO events, an extremely important part of climate variability in the Indian ocean. Satellite derives salinity and Argo data can help link changes in surface and subsurface salinity structure to the generation of the important MJO events. This study uses satellite derived salinity from Soil Moisture and Ocean Salinity (SMOS), and Aquarius to see if these satellites can yield new information on seasonal and interannual surface variability. In this study barrier layer thickness (BLT) estimates will be derived from satellite measurements using a

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

    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.

  9. Using fire to restore pine/hardwood ecosystems in the Southern Appalachians of North Carolina

    James M. Vose; Wayne T. Swank; Barton D. Clinton; Ronald L. Hendrick; Amy E. Major

    1997-01-01

    In the Southern Appalachians, mixed pine/hardwood ecosystems occupy the most xeric sites (i.e., south/west aspect ridge sites). They are typically comprised of varying proportions of pitch pine (Pinus rigida), Virginia pine (Pinus virginiana), and/or shortleaf pine (Pinus echinata) and a mixture of hardwoods, including scarlet oak (Quercus coccinea), chestnut oak (...

  10. Pre prosthetic reconstruction of alveolar ridge

    Prabhuji Munivenkatappa Lakshmaiahenkatesh

    2011-01-01

    Full Text Available Dento-alveolar bony defects are common and occur due to a variety of causes, such as, pulpal pathology, traumatic tooth extraction, advanced periodontal disease, implant failure, tumor or congenital anomalies. These defects often cause a significant problem in dental treatment and rehabilitation. Many techniques exist for effective soft and hard tissue augmentation. The approach is largely based on the extent of the defect and specific procedures to be performed for the implant or prosthetic rehabilitation. This article presents case reports of soft and hard tissue ridge augmentation.

  11. Oak Ridge Reservation environmental report for 1991

    Mucke, P.C.

    1992-10-01

    The first two volumes of this report present data and supporting narratives regarding the impact of the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) on its surrounding environs and the public during 1991. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a ''stand-alone'' report for the reader who does not want to review in detail all of the 1991 data for the ORR. This volume, Volume 2, includes the detailed data formats that ensure all the environmental data are represented. Narratives are not included. The information in Vol. 2 is addressed and analyzed in Vol. 1

  12. Oak Ridge Reservation environmental report for 1992

    Koncinski, W.S.

    1993-09-01

    The two volumes of this report present data and supporting narratives regarding the impact of the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) on its environs and the public during 1992. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a ''stand-alone'' report for the reader who does not want to review in detail all of the 1992 data for the ORR. This volume (volume 2) includes the detailed data in formats that ensure all the environmental data are presented. Narratives are not included in Vol. 2

  13. The rise and fall of the ridge

    Sorensen, Paul [Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2011-04-01

    Recent data from heavy ion collisions at RHIC show unexpectedly large near-angle correlations that broaden longitudinally with centrality. The amplitude of this ridge-like correlation rises rapidly with centrality, reaches a maximum, and then falls in the most central collisions. In this talk we explain how this behavior can be easily understood in a picture where final momentum-space correlations are driven by initial coordinate space density fluctuations. We propose {nu}{sub n}{sup 2}/{epsilon}{sub n,part}{sup 2} as a useful way to study these effects and explain what it tells us about the collision dynamics.

  14. Oak Ridge TNS Program: a status report

    Roberts, M.

    1978-01-01

    The Oak Ridge TNS activities have been directed at characterizing the design space between TFTR and EPR with a fundamental emphasis on higher beta plasma systems than previously projected, i.e., anti β approximately 5 to 10% as compared to 1 to 3%. Based on the results of the FY 1977 System Studies, our activities this year are directed toward preconceptual design with particular emphasis placed on reducing the technological requirements through innovations in plasma engineering. Examples of the new innovations include microwave assisted start up to reduce power requirements and a reduced TF ripple constraint by more refined ripple loss calculations, to increase engineering feasibility through simpler, more maintainable designs

  15. Gakkel Ridge: A window to ancient asthenosphere

    Snow, J.; Hellebrand, E.; Dick, H.; Liu, C.; Stracke, A.

    2008-12-01

    We are accustomed to thinking of the ambient mantle as being a well-stirred reservoir, which contains at most regions of stored subducted slabs and "plums" containing lithophile trace element enrichments. What is forgotten in all of this is that the main process of formation of heterogeneities is a negative one - generating 10x more depleted mantle at any given moment than it does oceanic crust. Because the volume of lithosphere subducted over Earth history is so large, it has always been assumed that the process of subduction and convective mixing re-homogenizes the depleted and enriched reservoirs about as fast as it produces them. What if it doesn't? Our primary means of studying mantle heterogeneity however is basalts. Direct study of the mantle entails observations on xenoliths, ophiolites and orogenic lherzolites, and abyssal peridotites. The latter have the inherent problems of being melting residues, associated with fracture zones, are highly serpentinized and rare. The arctic ridge system gives us a unique perspective on the mantle, and samples we have recovered there are relatively free from these problems. Due to the slow spreading rate, which apparently severely limits the melt productivity, the thickest crust in the Arctic ridge system is approximately "normal". The most common crust is about half thickness and there are large expanses with no crust at all, in the sense of Hess, 1962, exposing mantle peridotite in the floor of extensive rift zones. We have shown Os isotopic evidence for the survival of ancient depletion signatures in Gakkel abyssal peridotites that apparently were not destroyed by subduction, convective stirring or resetting during magma genesis (Liu, et al., 2008). Additionally, preliminary Nd isotopic evidence suggests at least a 400Ma intact prehistory for these samples. Apparently, the low melt productivity on Gakkel Ridge has allowed the Gakkel mantle rocks to escape significant resetting due to melt interaction. This implies a

  16. Oak Ridge Reservation environmental report for 1992

    Koncinski, W.S.

    1993-09-01

    The two volumes of this report present data and supporting narratives regarding the impact of the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) on its environs and the public during 1992. This Volume (Volume 1) includes all narrative descriptions, summaries, and conclusions and is intended to be a ''stand-alone'' report for the reader who does not want to review in detail all of the 1992 data for the ORR. Volume 2 includes the detailed data in formats that ensure all the environmental data are represented. Narratives are not included in Vol. 2

  17. Oak Ridge Leadership Computing Facility Position Paper

    Oral, H Sarp [ORNL; Hill, Jason J [ORNL; Thach, Kevin G [ORNL; Podhorszki, Norbert [ORNL; Klasky, Scott A [ORNL; Rogers, James H [ORNL; Shipman, Galen M [ORNL

    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.

  18. Multimode Interference: Identifying Channels and Ridges in Quantum Probability Distributions

    O'Connell, Ross C.; Loinaz, Will

    2004-01-01

    The multimode interference technique is a simple way to study the interference patterns found in many quantum probability distributions. We demonstrate that this analysis not only explains the existence of so-called "quantum carpets," but can explain the spatial distribution of channels and ridges in the carpets. With an understanding of the factors that govern these channels and ridges we have a limited ability to produce a particular pattern of channels and ridges by carefully choosing the ...

  19. Remedial investigation report on Waste Area Grouping 5 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Volume 4: Appendix C, Risk assessment

    1995-03-01

    Waste Area Grouping (WAG) 5 is part of Oak Ridge National Laboratory (ORNL) and is located on the United States Department of Energy's Oak Ridge Reservation (DOE-ORR). The site lies southeast of Haw Ridge in Melton Valley and comprises approximately 32 ha (80 ac) [12 ha (30 ac) of forested area and the balance in grassed fields]. The western and southern boundaries of WAG are contiguous with the WAG 2 area which includes White Oak Creek and Melton Branch and associated floodplains. Waste Area Grouping 5 consists of several contaminant source areas for the disposal of low-level radioactive, transuranic (TRU), and fissile wastes (1959 to 1973) as well as inorganic and organic chemical wastes. Wastes were buried in trenches and auger holes. Radionuclides from buried wastes are being transported by shallow groundwater to Melton Branch and White Oak Creek. Different chemicals of potential concern (COPCS) were identified (e.g., cesium-137, strontium-90, radium-226, thorium-228, etc.); other constituents and chemicals, such as vinyl chloride, bis(2-ethylhexyl)phthalate, trichloroethene, were also identified as COPCS. Based on the results of this assessment contaminants of concern (COCS) were subsequently identified. The human health risk assessment methodology used in this risk assessment is based on Risk Assessment Guidance for Superfund (RAGS) (EPA 1989). First, the data for the different media are evaluated to determine usability for risk assessment. Second, through the process of selecting COPCS, contaminants to be considered in the BHHRA are identified for each media, and the representative concentrations for these contaminants are determined. Third, an assessment of exposure potential is performed, and exposure pathways are identified. Subsequently, exposure is estimated quantitatively, and the toxicity of each of the COPCs is determined. The results of the exposure and toxicity assessments are combined and summarized in the risk characterization section

  20. 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

    King, David A. [Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States). Independent Environmental Assessment and Verification Program

    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

  1. 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

    King, David A.

    2012-01-01

    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

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

    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

  3. Comprehensive integrated planning: A process for the Oak Ridge Reservation, Oak Ridge, Tennessee

    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

  4. Comprehensive integrated planning: A process for the Oak Ridge Reservation, Oak Ridge, Tennessee

    NONE

    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.

  5. Greenland Fracture Zone-East Greenland Ridge(s) revisited: Indications of a C22-change in plate motion?

    Døssing, Arne; Funck, T.

    2012-01-01

    a reinterpretation of the Greenland Fracture Zone -East Greenland Ridge based on new and existing geophysical data. Evidence is shown for two overstepping ridge segments (Segments A and B) of which Segment A corresponds to the already known East Greenland Ridge while Segment B was not detected previously......Changes in the lithospheric stress field, causing axial rift migration and reorientation of the transform, are generally proposed as an explanation for anomalously old crust and/or major aseismic valleys in oceanic ridge-transform-ridge settings. Similarly, transform migration of the Greenland...... Fracture Zone and separation of the 200-km-long, fracture-zone-parallel continental East Greenland Ridge from the Eurasia plate is thought to be related to a major change in relative plate motions between Greenland and Eurasia during the earliest Oligocene (Chron 13 time). This study presents...

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

    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

  7. Analytical study of doubly excited ridge states

    Wong, H.Y.

    1988-01-01

    Two different non-separable problems are explored and analyzed. Non-perturbative methods need to be used to handle them, as the competing forces involved in these problems are equally strong and do not yield to a perturbative analysis. The first one is the study of doubly excited ridge states of atoms, in which two electrons are comparably excited. An analytical wavefunction for such states is introduced and is used to solve the two-electron Hamiltonian in the pair coordinates called hyperspherical coordinates variationally. The correlation between the electrons is built in analytically into the structure of the wavefunction. Sequences of ridge states out to very high excitation are computed and are organized as Rydberg series converging to the double ionization limit. Numerical results of such states in He and H - are compared with other theoretical calculations where available. The second problem is the analysis of the photodetachment of negative ions in an electric field via the frame transformation theory. The presence of the electron field requires a transformation from spherical to cylindrical symmetry for the outgoing photoelectron. This gives an oscillatory modulating factor as the effect of the electric field on cross-sections. All of this work is derived analytically in a general form applicable to the photodetachment of any negative ion. The expressions are applied to H - and S - for illustration

  8. Oak Ridge National Laboratory Waste Management Plan

    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

  9. Tubular Initial Conditions and Ridge Formation

    M. S. Borysova

    2013-01-01

    Full Text Available The 2D azimuth and rapidity structure of the two-particle correlations in relativistic A+A collisions is altered significantly by the presence of sharp inhomogeneities in superdense matter formed in such processes. The causality constraints enforce one to associate the long-range longitudinal correlations observed in a narrow angular interval, the so-called (soft ridge, with peculiarities of the initial conditions of collision process. This study's objective is to analyze whether multiform initial tubular structures, undergoing the subsequent hydrodynamic evolution and gradual decoupling, can form the soft ridges. Motivated by the flux-tube scenarios, the initial energy density distribution contains the different numbers of high density tube-like boost-invariant inclusions that form a bumpy structure in the transverse plane. The influence of various structures of such initial conditions in the most central A+A events on the collective evolution of matter, resulting spectra, angular particle correlations and vn-coefficients is studied in the framework of the hydrokinetic model (HKM.

  10. Behavior of Cell on Vibrating Micro Ridges

    Haruka Hino

    2015-06-01

    Full Text Available The effect of micro ridges on cells cultured at a vibrating scaffold has been studied in vitro. Several parallel lines of micro ridges have been made on a disk of transparent polydimethylsiloxane for a scaffold. To apply the vibration on the cultured cells, a piezoelectric element was attached on the outside surface of the bottom of the scaffold. The piezoelectric element was vibrated by the sinusoidal alternating voltage (Vp-p < 16 V at 1.0 MHz generated by a function generator. Four kinds of cells were used in the test: L929 (fibroblast connective tissue of C3H mouse, Hepa1-6 (mouse hepatoma, C2C12 (mouse myoblast, 3T3-L1 (mouse fat precursor cells. The cells were seeded on the micro pattern at the density of 2000 cells/cm2 in the medium containing 10% FBS (fetal bovine serum and 1% penicillin/ streptomycin. After the adhesion of cells in several hours, the cells are exposed to the ultrasonic vibration for several hours. The cells were observed with a phase contrast microscope. The experimental results show that the cells adhere, deform and migrate on the scaffold with micro patterns regardless of the ultrasonic vibration. The effects of the vibration and the micro pattern depend on the kind of cells.

  11. a comparative study of some robust ridge and liu estimators

    Dr A.B.Ahmed

    estimation techniques such as Ridge and Liu Estimators are preferable to Ordinary Least Square. On the other hand, when outliers exist in the data, robust estimators like M, MM, LTS and S. Estimators, are preferred. To handle these two problems jointly, the study combines the Ridge and Liu Estimators with Robust.

  12. Some Improved Classification-Based Ridge Parameter Of Hoerl And ...

    Of Hoerl And Kennard Estimation Techniques. 1Adewale F. Lukmanand 1Kayode Ayinde. 1 Department of Statistics, ... ordinary least square (OLS) in handling it. However, it requires a ridge parameter, K, of which many have ... handle the problem of multicollinearity. They suggested the addition of ridge parameter K to the ...

  13. Effects of ridge and furrow rainfall harvesting system on Elymus ...

    ARL

    2012-05-10

    May 10, 2012 ... A ridge-furrow rainfall harvesting system (RFRHS) was designed to increase the available soil water for .... The solar energy passed through the plastic-film and heated up the air and the surface soil of ridge and then the heat was trapped by the greenhouse effect (Zhou et al., 2009). Meanwhile, the.

  14. Nonlinear Forecasting With Many Predictors Using Kernel Ridge Regression

    Exterkate, Peter; Groenen, Patrick J.F.; Heij, Christiaan

    This paper puts forward kernel ridge regression as an approach for forecasting with many predictors that are related nonlinearly to the target variable. In kernel ridge regression, the observed predictor variables are mapped nonlinearly into a high-dimensional space, where estimation of the predi...

  15. Site characterization of the West Chestnut Ridge site

    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

  16. Oak Ridge Reservation Annual Site environmental report summary for 1994

    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

  17. Clinical management of highly resorbed mandibular ridge without fibrous tissue

    Veeramalai N Devaki

    2012-01-01

    Full Text Available Alveolar ridge atrophy poses a clinical challenge toward the fabrication of successful prosthesis. Resorption of mandibular denture bearing areas results in unstable non-retentive dentures associated with pain and discomfort. This article describes rehabilitation procedure of a patient with resorbed ridge with maximal areas of coverage to improve support and neutral zone arrangement of teeth to improve stability of denture.

  18. Strong signatures of high-latitude blocks and subtropical ridges in winter PM10 over Europe

    Ordonez, C.; Garrido-Perez, J. M.; Garcia-Herrera, R.

    2017-12-01

    Atmospheric blocking is associated with persistent, slow-moving high pressure systems that interrupt the eastward progress of extratropical storm systems at middle and high latitudes. Subtropical ridges are low latitude structures manifested as bands of positive geopotential height anomalies extending from sub-tropical latitudes towards extra-tropical regions. We have quantified the impact of blocks and ridges on daily PM10 (particulate matter ≤ 10 µm) observations obtained from the European Environment Agency's air quality database (AirBase) for the winter period of 2000-2010. For this purpose, the response of the PM10 concentrations to the location of blocks and ridges with centres in two main longitudinal sectors (Atlantic, ATL, 30˚-0˚ W; European, EUR, 0˚-30˚ E) is examined. EUR blocking is associated with a collapse of the boundary layer as well as reduced wind speeds and precipitation occurrence, yielding large positive anomalies which average 12 µg m-3 over the whole continent. Conversely, the enhanced zonal flow around 50˚-60˚ N and the increased occurrence of precipitation over northern-central Europe on days with ATL ridges favour the ventilation of the boundary layer and the impact of washout processes, reducing PM10 concentrations on average by around 8 µg m-3. The presence of EUR blocks is also concurrent with an increased probability of exceeding the European air quality target (50 µg m-3 for 24-h averaged PM10) and the local 90th percentiles for this pollutant at many sites, while the opposite effect is found for ridges. In addition, the effect of synoptic persistence on the PM10 concentrations is particularly strong for EUR blocks. Finally, we have found that the effect of both synoptic patterns can partly control the interannual variability of winter mean PM10 at many sites of north-western and central Europe, with coefficients of determination (R2) exceeding 0.80 for southern Germany. These results indicate that the response of the

  19. On the mean squared error of the ridge estimator of the covariance and precision matrix

    van Wieringen, Wessel N.

    2017-01-01

    For a suitably chosen ridge penalty parameter, the ridge regression estimator uniformly dominates the maximum likelihood regression estimator in terms of the mean squared error. Analogous results for the ridge maximum likelihood estimators of covariance and precision matrix are presented.

  20. Crustal structure and tectonics of the Ninetyeast Ridge from seismic and gravity studies

    Krishna, K.S.; Neprochnov, Y.P.; Rao, D.G.; Grinko, B.N.

    Seismic reflection and refraction, gravity, and bathymetric data across and along the central part of the Ninetyeast Ridge were analyzed to determine the crustal structure of the ridge and to understand its tectonics. The ridge in the study area...

  1. Optical dating of dune ridges on Rømø

    Madsen, Anni Tindahl; Murray, A. S.; Andersen, Thorbjørn Joest

    2007-01-01

    The application of optically stimulated luminescence (OSL) to the dating of recent aeolian sand ridges on Rømø, an island off the southwest coast of Denmark, is tested. These sand ridges began to form approximately 300 years ago, and estimates of the ages are available from historical records....... Samples for OSL dating were taken ~0.5 m below the crests of four different dune ridges; at least five samples were recovered from each ridge to test the internal consistency of the ages. Additional samples were recovered from the low lying areas in the swales and from the scattered dune formations......-defined building phases separated by inactive periods and the first major ridge formed ~235 years ago. This study demonstrates that optical dating can be successfully applied to these young aeolian sand deposits, and we conclude that OSL dating is a powerful chronological tool in studies of coastal change....

  2. Papillary fibroelastoma arising from the coumadin ridge

    Mahim Malik

    2017-06-01

    Full Text Available Cardiac papillary fibroelastomas (CPF are rare cardiac tumors, mostly found on the valvular surfaces in the heart. These tumors are frond like in nature and are benign, intracardiac masses, rarely causing any hemodynamic disturbances. However, excision of these masses is indicated due to their propensity to embolize. We present a case report of the tumor found on the coumadin ridge, causing transient ischemic attacks in a patient. We performed complete excision of the tumor via median sternotomy on cardiopulmonary bypass support with cardiac arrest. The diagnosis was confirmed by histological examination. The patient had an uneventful postoperative course and was discharghed on postoperative day 4. She has had complete resolution of her symptoms post excision. The diagnosis of the mass was confirmed on histological examination.

  3. Oak Ridge Reservation environmental report for 1988

    Prince, N.L.

    1989-05-01

    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 1988. 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 1988 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 Volume 2. The tables in Volume 2 are addressed in Volume 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Volume 1

  4. Model Selection in Kernel Ridge Regression

    Exterkate, Peter

    Kernel ridge regression is gaining popularity as a data-rich nonlinear forecasting tool, which is applicable in many different contexts. This paper investigates the influence of the choice of kernel and the setting of tuning parameters on forecast accuracy. We review several popular kernels......, including polynomial kernels, the Gaussian kernel, and the Sinc kernel. We interpret the latter two kernels in terms of their smoothing properties, and we relate the tuning parameters associated to all these kernels to smoothness measures of the prediction function and to the signal-to-noise ratio. Based...... on these interpretations, we provide guidelines for selecting the tuning parameters from small grids using cross-validation. A Monte Carlo study confirms the practical usefulness of these rules of thumb. Finally, the flexible and smooth functional forms provided by the Gaussian and Sinc kernels makes them widely...

  5. Current glaciation of the Chikhachev ridge (South-Eastern Altai and its dynamics after maximum of the Little Ice Age

    D. A. Ganyushkin

    2016-01-01

    Full Text Available Glaciation of the Chikhachev ridge (South-Eastern Altai remains poorly known: field observations were not performed since the mid-twentieth century, available schemes and estimates of the glaciation and its scale made on the basis of remote sensing cover only a part of the glaciers, reconstructions of the Little Ice Age (LIA glaciations are absent. This research was based on interpretation of the satellite images: Landsat-4 (1989, Landsat-7 (2001, and Spot-5 (2011, as well as with the use of data of the field season of 2015. Characteristics of glaciations of the Chikhachev ridge as the whole and of its individual centers (Talduair massif, Mongun-Taiga-Minor massif, and southern part of the Chikhachev ridge were determined for the first time. Recent glaciation is represented by 7 glaciers with their total area of 1.12 km2 in the Talduair massif, by 5 glaciers with total area of 0.75 km2 in the Mongun-Taiga-Minor massif, and by 85 glaciers with total area of 29 km2 in the southern part of the Chikhachev ridge. Since the LIA maximum, areas of glaciers decreased by 61% in the Talduair massif, by 74% in the Mongun-Taiga-Minor massif, by 56% in the southern part of the Chikhachev ridge with simultaneous lifting of the firn line by 50 m, 65 m, and 70 m, respectively.The largest rates of the glacier contractions were determined for the period 1989–2011. Different mechanisms of the glacier retreats were shown by the example of the glacier complexes Burgastyn-Gol (one-sided retreat and disintegration and the Grigorjev glacier (gradual retreat of the tongue. Retreat of the Grigorjev glacier has been reconstructed for the period from the LIA maximum until 2015. Average rate of the retreat increased from 1,6 m/year in 1957–1989 up to 11,3 m/year in 2011–2015. The present-day scales of the glaciers and rates of their retreating do not significantly differ from estimations made by other researchers for the nearest centers of glaciation of the

  6. Melton Valley Storage Tanks Capacity Increase Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    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

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

    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

  8. Oak Ridge Health Studies phase 1 report, Volume 1: Oak Ridge Phase 1 overview

    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.

  9. Oak Ridge Health Studies phase 1 report, Volume 1: Oak Ridge Phase 1 overview

    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

  10. Oak Ridge National Laboratory Technology Logic Diagram

    1993-09-01

    The Oak Ridge National Laboratory Technology Logic Diagram (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 ampersand D), remedial action (RA), and WM activities. The TLD consists of three fundamentally separate volumes: Vol. 1, Technology Evaluation; Vol. 2, Technology Logic Diagram and Vol. 3, Technology EvaLuation Data Sheets. Part A of Vols. 1 and 2 focuses on RA. Part B of Vols. 1 and 2 focuses on the D ampersand D of contaminated facilities. Part C of Vols. 1 and 2 focuses on WM. Each part of Vol. 1 contains an overview of the TM, an explanation of the problems facing the volume-specific program, a review of identified technologies, and rankings of technologies applicable to the site. Volume 2 (Pts. A. B. and C) contains the logic linkages among EM goals, environmental problems, and the various technologies that have the potential to solve these problems. Volume 3 (Pts. A. B, and C) contains the TLD data sheets. This volume provides the technology evaluation data sheets (TEDS) for ER/WM activities (D ampersand D, RA and WM) 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 is given for the technologies in Vol. 2

  11. Oak Ridge National Laboratory Technology Logic Diagram

    1993-09-01

    The Oak Ridge National Laboratory Technology Logic Diagram (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 ampersand D), remedial action (RA), and WM activities. The TLD consists of three fundamentally separate volumes: Vol. 1 (Technology Evaluation), Vol. 2 (Technology Logic Diagram), and Vol. 3 (Technology Evaluation Data Sheets). Part A of Vols. 1 and 2 focuses on D ampersand D. Part B of Vols. 1 and 2 focuses on RA of contaminated facilities. Part C of Vols. 1 and 2 focuses on WM. Each part of Vol. 1 contains an overview of the TLD, an explanation of the program-specific responsibilities, a review of identified technologies, and the ranking os remedial technologies. Volume 2 (Pts. A, B, and C) contains the logic linkages among EM goals, environmental problems, and the various technologies that have the potential to solve these problems. Volume 3 (Pts. A, B, and C) contains the TLD data sheets. The focus of Vol. 1, Pt. B, is RA, and it has been divided into six chapters. The first chapter is an introduction, which defines problems specific to the ER Program for ORNL. Chapter 2 provides a general overview of the TLD. Chapters 3 through 5 are organized into necessary subelement categories: RA, characterization, and robotics and automation. The final chapter contains regulatory compliance information concerning RA

  12. Structural evolution of the Ural-Tian Shan junction: A view from Karatau ridge, South Kazakhstan

    Alexeiev, D.V.; Cook, H.E.; Buvtyshkin, V.M.; Golub, L.Y.

    2009-01-01

    The deformation history of the Late Palaeozoic Ural-Tian Shan junction is discussed for the example of the Karatau ridge in southern Kazakhstan. Three deformation events are recognized. The Late Carboniferous D1 event is characterized by Laramide-style thrust-and-fold structures on the southern margin of Kazakhstan with shortening in a NE-SW direction. The Latest Permian and Triassic D2 event is controlled by compression in an east-west direction, which reflects collisional deformation in the Urals. The main structures are submeridional folds and north-west-striking sinistral strike-slip faults. The Triassic D3 event with shortening in a north-south direction reflects collision of the Turan microcontinent against the southern margin of Kazakhstan. The main structures are north-west-striking dextral strike-slip faults. Our new data provides important clues for the reconstruction of pre-Cretaceous structures between the Urals and the Tian Shan. ?? 2008 Acad??mie des sciences.

  13. Tiger team assessment of the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    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

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

    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

  16. Microgravity survey of the Oak Ridge K-25 Site, Oak Ridge, Tennessee

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

    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.

  18. Geomorphological investigation of multiphase glacitectonic composite ridge systems in Svalbard

    Lovell, Harold; Benn, Douglas I.; Lukas, Sven; Spagnolo, Matteo; Cook, Simon J.; Swift, Darrel A.; Clark, Chris D.; Yde, Jacob C.; Watts, Tom

    2018-01-01

    Some surge-type glaciers on the High-Arctic archipelago of Svalbard have large glacitectonic composite ridge systems at their terrestrial margins. These have formed by rapid glacier advance into proglacial sediments during the active surge phase, creating multicrested moraine complexes. Such complexes can be formed during single surge advances or multiple surges to successively less-extensive positions. The few existing studies of composite ridge systems have largely relied on detailed information on internal structure and sedimentology to reconstruct their formation and links to surge processes. However, natural exposures of internal structure are commonly unavailable, and the creation of artificial exposures is often problematic in fragile Arctic environments. To compensate for these issues, we investigate the potential for reconstructing composite ridge system formation based on geomorphological evidence alone, focusing on clear morphostratigraphic relationships between ridges within the moraine complex and relict meltwater channels/outwash fans. Based on mapping at the margins of Finsterwalderbreen (in Van Keulenfjorden) and Grønfjordbreen (in Grønfjorden), we show that relict meltwater channels that breach outer parts of the composite ridge systems are in most cases truncated upstream within the ridge complex by an inner pushed ridge or ridges at their ice-proximal extents. Our interpretation of this relationship is that the entire composite ridge system is unlikely to have formed during the same glacier advance but is instead the product of multiple advances to successively less-extensive positions, whereby younger ridges are emplaced on the ice-proximal side of older ridges. This indicates that the Finsterwalderbreen composite ridge system has been formed by multiple separate advances, consistent with the cyclicity of surges. Being able to identify the frequency and magnitude of former surges is important as it provides insight into the past behaviour of

  19. Stratigraphic variations and secondary porosity within the Maynardville Limestone in Bear Creek Valley, Y-12 Plant, Oak Ridge, Tennessee

    Goldstrand, P.M.

    1995-05-01

    To evaluate groundwater and surface water contamination and migration near the Oak Ridge Y-12 plant, a Comprehensive Groundwater Monitoring Plan was developed. As part of the Maynardville exit pathways monitoring program, monitoring well clusters were ii installed perpendicular to the strike of the Maynardville Limestone, that underlies the southern part of the Y-12 Plant and Bear Creek Valley (BCV). The Maynardville Project is designed to locate potential exit pathways of groundwater, study geochemical characteristics and factors affecting the occurrence and distribution of water-bearing intervals, and provide hydrogeologic information to be used to reduce the potential impacts of contaminants entering the Maynardville Limestone

  20. Segmentation along the Queen Charlotte Fault: The long-lived influence of plate-motion rotation and Explorer Ridge fracture zones

    Miller, N. C.; Walton, M. A. L.; Brothers, D. S.; Haeussler, P. J.; Ten Brink, U. S.; Conrad, J. E.; Kluesner, J.; Andrews, B. D.

    2017-12-01

    step marks the southern extent of rupture during the 2012 Mw 7.8 and 1949 M 8.1 Haida Gwaii earthquakes, suggesting that it forms a rupture barrier. Between 54—56 N, ridge-QCF intersections mark other major rupture boundaries, and, in some places, are associated with small pull-apart basins, suggesting that relic step overs continue to control segmentation along the QCF.

  1. Recent coastal evolution in a carbonate sandy environments and relation to beach ridge formation: the case of Anegada, British Virgin Islands

    Cescon, Anna Lisa; Cooper, J. Andrew G.; Jackson, Derek W. T.

    2014-05-01

    In a changing climate context coastal areas will be affected by more frequent extreme events. Understanding the relationship between extreme events and coastal geomorphic response is critical to future adaptation plans. Beach ridge landforms commonly identified as hurricane deposits along tropical coasts in Australia and in the Caribbean Sea. However their formative processes in such environments are still not well understood. In particular, the role of different extreme wave events (storm waves, tsunami waves and extreme swell), in generating beach ridges is critical to their use as palaeotempestology archives. Anegada Island is a carbonate platform situated in the British Virgin Island between the Atlantic Ocean and the Caribbean Sea. Pleistocene in age, Anegada is surrounded by the Horseshoe fringing coral reef. Two Holocene sandy beach ridge plains are present on the western part of the island. The north beach ridge plain is Atlantic facing and has at least 30 ridges; the south beach ridge plain is Caribbean Sea facing and contains 10 ridges. Historical aerial photos enabled the shoreline evolution from 1953 to 2012 to be studied. Three different coastal domains are associate with the beach ridge plains: strong east-west longshore transport affects the north coastline, the south-west coastline from West End to Pomato Point represents an export corridor for these sediments and finally, along the southern coastline, from Pomato Point to Settling Point the area presents a depositional zone with little to no change in the last 70 years. The link between the extreme wave events that have affected Anegada Island in the last 70 years and beach ridge creation is discussed. Hurricane Donna crossed over Anegada Island in 1960: its geomorphological signature is tracked in the shoreline change analysis and its implication in beach ridge formation is discussed. Anegada Island has also been impacted by tsunami waves (Atwater et al., 2012) and a comparative discussion of the

  2. Uplift, Emergence, and Subsidence of the Gorda Escarpment Basement Ridge Offshore Cape Mendocino, CA

    Hoover, Susan M.; Tréhu, Anne M.

    2017-12-01

    The Gorda Escarpment is a topographic step that characterizes the south side of the Mendocino Transform Fault east of 126oW and forms the northern edge of the Vizcaino Block. Seismic reflection data suggest that the basement beneath the northern edge of the Vizcaino is composed of east-west trending slivers of oceanic crust that form a 15 km wide band of buried ridges we call the Gorda Escarpment Basement Ridge (GEBR) to distinguish it from the northwest-trending basement structure that characterizes most of the Vizcaino Block. The history of uplift and subsidence of the GEBR is reconstructed by combining the seismic reflection profiles with age and lithological constraints from ODP Site 1022, gravity cores, and grab samples from the northern face of the Escarpment recovered using a remotely operated vehicle. Uplift of the GEBR began prior to 6 Ma, and it was above sea level 3.7-2.5 Ma. GEBR uplift and emergence coincided with sediment deposition on the southern flank of the GEBR that we interpret as indicative of strong upwelling and turbulence in the lee of a shallow ridge and island chain. A bright reflection, interpreted to be a sill, is observed south of the shallowest part of the GEBR. We speculate that this sill may reflect a larger, hidden intrusion at depth and that thermal expansion of the crust combined with tectonic forces to drive enhanced uplift of this segment of the plate boundary. The GEBR has been subsiding since 2.7 Ma, and its shallowest point is now 1,400 m below sea level.

  3. 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 TENNESSEE TECHNOLOGY PARK, OAK RIDGE, TENNESSEE

    David A. King

    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. The goal is to obtain all media no-further-investigation (NFI) determinations for the subject parcels considering existing soils. To augment the existing soils-only NFI determinations, samples of groundwater, surface water, soil, and sediment were collected to support all media NFI decisions. The only updates presented here are those that were made after the original issuance of the NFI documents. In the subject parcel where the soils NFI determination was not completed for approval (Parcel 21d), the full process has been performed to address the soils as well. 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 NFI

  4. Aerodynamic roughness length related to non-aggregated tillage ridges

    M. Kardous

    2005-11-01

    Full Text Available Wind erosion in agricultural soils is dependent, in part, on the aerodynamic roughness length (z0 produced by tillage ridges. Although previous studies have related z0 to ridge characteristics (ridge height (RH and spacing (RS, these relationships have not been tested for tillage ridges observed in the North African agricultural fields. In these regions, due to climate and soil conditions, small plowing tools are largely used. Most of these tools produce non-aggregated and closely-spaced small ridges. Thus, experiments were conducted in a 7-m long wind tunnel to measure z0 for 11 ridge types covering the range of geometric characteristics frequently observed in south Tunisia. Experimental results suggest that RH2/RS is the first order parameter controlling z0. A strong relationship between z0 and RH2/RS is proposed for a wide range of ridge characteristics.

  5. Hydrodynamic role of longitudinal ridges in a leatherback turtle swimming

    Bang, Kyeongtae; Kim, Jooha; Lee, Sang-Im; Choi, Haecheon

    2015-11-01

    The leatherback sea turtle (Dermochelys coriacea), the fastest swimmer and the deepest diver among marine turtles, has five longitudinal ridges on its carapace. These ridges are the most remarkable morphological features distinguished from other marine turtles. To investigate the hydrodynamic role of these ridges in the leatherback turtle swimming, we model a carapace with and without ridges by using three dimensional surface data of a stuffed leatherback turtle in the National Science Museum, Korea. The experiment is conducted in a wind tunnel in the ranges of the real leatherback turtle's Reynolds number (Re) and angle of attack (α). The longitudinal ridges function differently according to the flow condition (i.e. Re and α). At low Re and negative α that represent the swimming condition of hatchlings and juveniles, the ridges significantly decrease the drag by generating streamwise vortices and delaying the main separation. On the other hand, at high Re and positive α that represent the swimming condition of adults, the ridges suppress the laminar separation bubble near the front part by generating streamwise vortices and enhance the lift and lift-to-drag ratio. Supported by the NRF program (2011-0028032).

  6. Constraints on the neutrino emission from the Galactic Ridge with the ANTARES telescope

    S. Adrián-Martínez

    2016-09-01

    Full Text Available A highly significant excess of high-energy astrophysical neutrinos has been reported by the IceCube Collaboration. Some features of the energy and declination distributions of IceCube events hint at a North/South asymmetry of the neutrino flux. This could be due to the presence of the bulk of our Galaxy in the Southern hemisphere. The ANTARES neutrino telescope, located in the Mediterranean Sea, has been taking data since 2007. It offers the best sensitivity to muon neutrinos produced by galactic cosmic ray interactions in this region of the sky. In this letter a search for an extended neutrino flux from the Galactic Ridge region is presented. Different models of neutrino production by cosmic ray propagation are tested. No excess of events is observed and upper limits for different neutrino flux spectral indices Γ are set. For Γ=2.4 the 90% confidence level flux upper limit at 100 TeV for one neutrino flavour corresponds to Φ01f(100 TeV=2.0⋅10−17 GeV−1cm−2s−1sr−1. Under this assumption, at most two events of the IceCube cosmic candidates can originate from the Galactic Ridge. A simple power-law extrapolation of the Fermi-LAT flux to account for IceCube High Energy Starting Events is excluded at 90% confidence level.

  7. Aquatic Natural Areas Analysis and Evaluation: Oak Ridge Reservation

    Baranski, Dr. Michael J. [Catawba College

    2011-04-01

    This report presents an assessment of the natural area value of eight Aquatic Natural Areas (ANAs) and seven Aquatic Reference Areas (ARAs) on the Oak Ridge Reservation (ORR) in Anderson and Roane Counties in east Tennessee. It follows a previous study in 2009 that analyzed and evaluated terrestrial natural areas on the Reservation. The purpose of both studies was to evaluate and rank those specially designated areas on the Reservation that contain sensitive species, special habitats, and natural area value. Natural areas receive special protections through established statutes, regulations, and policies. The ORR contains 33,542 acres (13,574 ha) administered by the Department of Energy. The surface waters of the Reservation range from 1st-order to 5th-order streams, but the majority of the streams recognized as ANAs and ARAs are 1st- and 2nd-order streams. East Fork Poplar Creek is a 4th-order stream and the largest watershed that drains Reservation lands. All the waters of the Reservation eventually reach the Clinch River on the southern and western boundaries of the ORR. All available information was collected, synthesized, and evaluated. Field observations were made to support and supplement the available information. Geographic information system mapping techniques were used to develop several quantitative attributes about the study areas. Narrative descriptions of each ANA and ARA and tables of numerical data were prepared. Criteria for assessment and evaluation were developed, and eight categories of factors were devised to produce a ranking system. The evaluation factors used in the ranking system were: (A) size of area, (B) percentage of watershed protected, (C) taxa present with protected status, (D) overall biotic diversity, (E) stream features, (F) water quality and use support ratings, (G) disturbance regime, and (H) other factors. Each factor was evaluated on a 5-point ranking scale (0-4), and each area received a composite score, where 32 was the

  8. Sulfide geochronlogy along the Southwest Indian Ridge

    Yang, W.; Tao, C.; Li, H.; Liang, J.; Liao, S.

    2017-12-01

    Dragon Flag and Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones in the ultraslow-spreading Southwest Indian Ridge (SWIR). Ten subsamples from active and inactive vents of Dragon Flag hydrothermal field and twenty-eight subsamples from Duanqiao hydrothermal field were dated using the 230Th/238U method. Four main episodes of hydrothermal activity of Duanqiao were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. And sulfide samples from the nearby Dragon Flag filed at the same time and the results show that the ages of most sulfides from Dragon Flag field range from 1.496(±0.176) to 5.416 (±0.116) kyrs with the oldest age estimated at 15.997 (±0.155) kyrs Münch et al. (2001) reconstructed the evolution history of Mt. Jourdanne hydrothermal field. The age dating results indicate activity in two episodes, at 70-40 and 27-13 kyrs. The hydrothermal activity in Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. All these results suggest that hydrothermal activity of Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. Mt. Jourdanne is situated on an axial volcanic ridge which has both volcanic and tectonic activity. This is necessary to develop the heat source and pathways for the fluid convection, which enables the hydrothermal circulation. Hydrothermal activity in Dragon Flag Field is located next to the detachment fault termination. The detachment fault system provides a pathway for hydrothermal convection. Such style of heat source can contribute to continuous hydrothermal activity for over 1000 years. Duanqiao field is located near the central volcano and there is a hot

  9. 76 FR 26252 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2011-05-06

    ... development, University of Maryland MSE Study, Surfclam Ocean Quahog Excessive Share Project, and ACL/AM... meeting date. Dated: May 3, 2011. Tracey L. Thompson, Acting Director, Office of Sustainable Fisheries...

  10. 78 FR 52508 - Mid-Atlantic Fishery Management Council; Public Meeting

    2013-08-23

    ... Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meeting. SUMMARY: The...) will meet to develop recommendations for Georges Bank yellowtail flounder accountability measures...

  11. 76 FR 45253 - Meeting of the Mid-Atlantic/Northeast Visibility Union Executive Board

    2011-07-28

    ... Contact: Kromeklia Bryant, Ozone Transport Commission (OTC), 444 North Capitol Street NW., Suite 638, Washington, DC 20001; (202) 508-3840; e-mail: [email protected] ; Web site: http://www.otcair.org/manevu... e-mail: [email protected] or via the MANE- VU Web site at http://www.otcair.org/manevu/ . Dated: July...

  12. 78 FR 5421 - Mid-Atlantic Fishery Management Council (MAFMC); Meetings

    2013-01-25

    ... 5 p.m. there will be a Scoping Hearing for the Deep Sea Corals Amendment. On Thursday February 14--A presentation on the new Council Web site will be held from 9 a.m. until 9:30 a.m. The Council will hold its... Fishery Management Plan (Deep Sea Corals Amendment) and review alternatives to be included in the...

  13. Coastal sensitivity to sea level rise : a focus on the mid-atlantic region

    2009-01-15

    The focus of this product is to identify and review the potential impacts of future sea-level rise based on present scientific understanding. To do so, this product evaluates : several aspects of sea-level rise impacts to the natural environment and ...

  14. ENVIRONMENTAL AUDITING: AN INTEGRATED ENVIRONMENTAL ASSESSMENT OF THE U.S. MID-ATLANTIC REGION

    Many of today's environmental problems are regional in scope and their effects overlap and interact. We developed a simple method to provide an integrated assessment of environmental conditions and estimate cumulative impacts across a large region, by combining data on land-cove...

  15. An Ecological Assessment of the United States Mid-Atlantic Region: A Landscape Atlas

    K. Bruce Jones; Kurt H. Riitters; James D. Wickham; Roger D. Tankersley; Robert V. O' Neill; Deborah J. Chaloud; Elizabeth R. Smith; Anne C. Neale

    1997-01-01

    Environmental quality affects our health, our quality of life, the sustainability of our economies, and the futures of our children. Yet pressures from an increasing population coupled with the need for economic development and an improved standard of living often have multiple effects on our natural resources. So just as a person with a less-than-healthy lifestyle is...

  16. 75 FR 29725 - Mid-Atlantic Fishery Management Council; Public Hearings

    2010-05-27

    ...) The implementation of catch share systems for the squid fisheries to further refine the existing management process; the biological and socio-economic outcomes of a catch share system and how such outcomes... collection processes if a catch share system is implemented; and (2) The need for additional fishery...

  17. Stream water temperature limits occupancy of salamanders in mid-Atlantic protected areas

    Grant, Evan H. Campbell; Wiewel, Amber N. M.; Rice, Karen C.

    2014-01-01

    Stream ecosystems are particularly sensitive to urbanization, and tolerance of water-quality parameters is likely important to population persistence of stream salamanders. Forecasted climate and landscape changes may lead to significant changes in stream flow, chemical composition, and temperatures in coming decades. Protected areas where landscape alterations are minimized will therefore become increasingly important for salamander populations. We surveyed 29 streams at three national parks in the highly urbanized greater metropolitan area of Washington, DC. We investigated relationships among water-quality variables and occupancy of three species of stream salamanders (Desmognathus fuscus, Eurycea bislineata, and Pseudotriton ruber). With the use of a set of site-occupancy models, and accounting for imperfect detection, we found that stream-water temperature limits salamander occupancy. There was substantial uncertainty about the effects of the other water-quality variables, although both specific conductance (SC) and pH were included in competitive models. Our estimates of occupancy suggest that temperature, SC, and pH have some importance in structuring stream salamander distribution.

  18. 78 FR 17358 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2013-03-21

    ... Organizational Reports, the New England and South Atlantic Liaison Reports, the Executive Director's Report, the... December 2012 and February 2013 minutes, receive Organizational Reports, the New England and South Atlantic... recommendation on the workshop results to include control dates, roll-over provisions, GRAs, port meetings, etc...

  19. 77 FR 70149 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2012-11-23

    ... will be a Public Listening Session from 5 p.m. until 6 p.m. on Wednesday evening with discussion of..., review top themes from the Visioning Project, and discuss objectives, strategies, and tactics for one... review the outcomes from Monday and discuss objectives, strategies, and tactics for up to three strategic...

  20. 77 FR 59593 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2012-09-28

    ... Strategic Planning Working Group will meet. 5 p.m. until 6 p.m.--There will be a Public Listening Session... a presentation regarding the Management Strategy Evaluation (MSA) Summer Flounder Study. 10 a.m... the Visioning Project, and discuss objectives, strategies, and tactics for three to four strategic...

  1. Leadership Styles of Chief Financial Officers in Higher Education in the Mid-Atlantic Region

    Benson, Patricia

    2017-01-01

    The purpose of this research was to explore the factors that contribute to a chief financial officer's (CFO) success and demise within a higher education setting. Relatively little attention has been given to the study of leadership in educational institutions (Vroom, 1983). Leadership defines what the future should look like, aligns people with…

  2. 75 FR 3897 - Mid-Atlantic Fishery Management Council; Public Meetings

    2010-01-25

    ... the Hyatt Regency Chesapeake Bay Hotel, 100 Heron Blvd, Cambridge, MD 21613; telephone: (410) 901... Council will hear the Scientific and Statistical Committee (SSC) Report. 1 p.m. until 2 p.m. -- The...

  3. FUZZY DECISION ANALYSIS FOR INTEGRATED ENVIRONMENTAL VULNERABILITY ASSESSMENT OF THE MID-ATLANTIC REGION

    A fuzzy decision analysis method for integrating ecological indicators is developed. This is a combination of a fuzzy ranking method and the Analytic Hierarchy Process (AHP). The method is capable ranking ecosystems in terms of environmental conditions and suggesting cumula...

  4. An Integrated Environmental Assessment of the US Mid-Atlantic Region

    James D. Wickham; K.B. Jones; Kurt H. Riitters; R.V. O' Neill; R.D. Tankersley; E.R. Smith; A.C. Neale; D.J. Chaloud

    1999-01-01

    Many of today's environmental problems are in scope and their effects overlap and interact. We developed a simple method to provide an integrated assessment of environmental conditions and estimate cumulative impacts across a large region, by combining data on land-cover, population, roads, streams, air pollution, and topography. The integrated assessment...

  5. Fuzzy Decision Analysis for Integrated Environmental Vulnerability Assessment of the Mid-Atlantic Region

    Liem T. Tran; C. Gregory Knight; Robert V. O' Neill; Elizabeth R. Smith; Kurt H. Riitters; James D. Wickham

    2002-01-01

    A fuzzy decision analysis method for integrating ecological indicators was developed. This was a combination of a fuzzy ranking method and the analytic hierarchy process (AHP). The method was capable of ranking ecosystems in terms of environmental conditions and suggesting cumulative impacts across a large region. Using data on land cover, population, roads, streams,...

  6. Chemical composition and cycling of dissolved organic matter in the Mid-Atlantic Bight

    Aluwihare, Lihini I.; Repeta, Daniel J.; Chen, Robert F.

    This study focuses on the chemical characterization of high molecular-weight dissolved organic matter (HMW DOM) isolated from the Middle Atlantic Bight in April 1994 and March 1996. Using proton nuclear magnetic resonance spectroscopy ( 1HNMR) and monosaccharide analysis we compared both spatial and temporal variations in the chemical structure of HMW DOM across this region. Our analyses support the presence of at least two compositionally distinct components to HMW DOM. The major component is acyl polysaccharide (APS), a biopolymer rich in carbohydrates, acetate and lipid, accounting for between 50% and 80% of the total high molecular-weight dissolved organic carbon (HMW DOC) in surface samples. APS is most abundant in fully marine, surface-water samples, and is a product of autochthonous production. Organic matter with spectral properties characteristic of humic substances is the second major component of HMW DOM. Humic substances are most abundant (up to 49% of the total carbon) in samples collected from estuaries, near the coast, and in deep water, suggesting both marine and perhaps terrestrial sources. Radiocarbon analyses of neutral monosaccharides released by the hydrolysis of APS have similar and modern (average 71‰) Δ 14C values. Radiocarbon data support our suggestion that these sugars occur as part of a common macromolecule, with an origin via recent biosynthesis. Preliminary radiocarbon data for total neutral monosaccharides isolated from APS at 300 and 750 m show this fraction to be substantially enriched relative to total HMW DOC and DOC. The relatively enriched radiocarbon values of APS at depth suggest APS is rapidly transported into the deep ocean.

  7. 77 FR 47820 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    2012-08-10

    ... discuss data needs and modeling strategies. Although non-emergency issues not contained in this agenda may... Science, will hold a workshop entitled ``Modeling Protogynous Hermaphrodite Fishes.'' DATES: The workshop...-5255. SUPPLEMENTARY INFORMATION: This workshop will address the need for improved stock assessment...

  8. Outdoor education in the Mid-Atlantic states: an assessment of market segmentation

    Stephanie L. Young; Megan L. Hash; Roy Ramthun

    2007-01-01

    Programs that emphasize experiential learning in outdoor settings have a long history in the United States and have been offered by a wide range of organizations. This study focused on programming that included environmental education, experiential education, and outdoor education. The purpose of this study was to examine the range of services and programs that offer...

  9. 75 FR 27990 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2010-05-19

    ... Monitoring Committee's recommendations and SSC advice for 2011 quota levels and associated management... setting processes; and, discuss the mechanics of how the August specification setting process will be...

  10. 77 FR 49782 - Mid-Atlantic Fishery Management Council (MAFMC); Public Hearings

    2012-08-17

    ... hour after the hearing start time, the hearing may be closed. Some GPS navigation units may provide... prior to the hearing date. Dated: August 14, 2012. Tracey L. Thompson, Acting Deputy Director, Office of...

  11. 77 FR 22285 - Mid-Atlantic Fishery Management Council; Public Hearings

    2012-04-13

    ... halfway through a hearing or later, the hearing may be closed. Some GPS navigation units may provide.... Dated: April 10, 2012. Tracey L. Thompson, Acting Director, Office of Sustainable Fisheries, National...

  12. H11649: NOS Hydrographic Survey , Mid-Atlantic Corridor, Maryland, 2007-11-18

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Oceanic and Atmospheric Administration (NOAA) has the statutory mandate to collect hydrographic data in support of nautical chart compilation for safe...

  13. H11873: NOS Hydrographic Survey , Mid-Atlantic Corridor, Maryland, 2008-12-18

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Oceanic and Atmospheric Administration (NOAA) has the statutory mandate to collect hydrographic data in support of nautical chart compilation for safe...

  14. Enabling the Commercial Space Transportation Industry at the Mid-Atlantic Regional Spaceport

    2011-09-01

    global recession. This 5 growth is attributed to increased globalization, technology improvements, deregulation , access to previously closed...for space flight. This Final Rule requires insurance and training to ensure all crew members are aware that space flight is inherently dangerous (FAA...overflight (See Figure 7). Minimal land overflight is an important cost advantage when insuring launches. WFF maintains an aeronautical research airport

  15. H11198: NOS Hydrographic Survey , Mid-Atlantic Corridor, New Jersey, 2003-12-03

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Oceanic and Atmospheric Administration (NOAA) has the statutory mandate to collect hydrographic data in support of nautical chart compilation for safe...

  16. 75 FR 11129 - Mid-Atlantic Fishery Management Council; Atlantic Mackerel, Butterfish, Atlantic Bluefish, Spiny...

    2010-03-10

    ...) announces its intention to prepare, in cooperation with NMFS, an EA in accordance with the National..., 2009, the Council announced its intention to prepare, in cooperation with NMFS, an EIS in accordance... numerous Fishery Management Action Team (FMAT) Omnibus Amendment Committee, and full Council meetings...

  17. 76 FR 72906 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2011-11-28

    ... Council will receive a presentation on Fishery Management Councils: Decision-making, Communication, and... Council will conduct its regular Business Session, receive Organizational Reports, Council Liaison Reports... Biedron of Cornell University on Fishery Management Councils: Decision-making, Communication, and Social...

  18. 75 FR 26920 - Mid-Atlantic Fishery Management Council; Spiny Dogfish Amendment 3 Scoping Process

    2010-05-13

    ... scoping comments on the two additional issues, which relate to Essential Fish Habitat (EFH) designations... appropriate habitat conservation and enhancement recommendations, revisions to the descriptions of prey species and their habitats, and a list of research and information needs. It could also identify Habitat...

  19. 77 FR 33443 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting

    2012-06-06

    ...-Atlantic Fishery Management Council's (Council) Summer Flounder, Scup, Black Sea Bass, and Bluefish... Summer Flounder, Scup, Black Sea Bass, and Bluefish. Although non-emergency issues not contained in this...

  20. 78 FR 57620 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    2013-09-19

    ... sea bass, and bluefish management measures for 2014-15 (2014 for Bluefish) in conjunction with the Atlantic States Marine Fisheries Commission's (ASMFC) Summer Flounder, Scup, Black Sea Bass, and Bluefish... Bluefish Board will review the Scientific and Statistical Committee (SSC), the associated Monitoring...