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Sample records for narrow submarine canyon

  1. Influence of San Gabriel submarine canyon on narrow-shelf sediment dynamics, southern California

    USGS Publications Warehouse

    Karl, Herman A.

    1980-01-01

    A conceptual model attributes the PTC to modification of shelf circulation patterns by San Gabriel Canyon. Surface waves diverge over the canyon head resulting in differential wave set up at the shore face. This forces back turbid nearshore water for a distance of a few kilometers toward the canyon. At some point on the shelf, seaward nearshore flow overlaps offshore currents generated or modified by internal waves focused onto the shelf by the canyon and/or turbulent eddies produced by flow separation in currents moving across the canyon axis. At times, these subtle processes overprint tidal and wind-driven currents and thereby create the PTC. The model suggests that canyons heading several kilometers from shore can have a regulatory effect on narrow-shelf sediment dynamics.

  2. Geomorphic process fingerprints in submarine canyons

    USGS Publications Warehouse

    Brothers, Daniel S.; ten Brink, Uri S.; Andrews, Brian D.; Chaytor, Jason D.; Twichell, David C.

    2013-01-01

    Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A) are used to examine linkages between morphological domains and the generation and evolution of submarine sediment flows. For example, canyon reaches of the upper continental slope are characterized by steep, linear and/or convex longitudinal profiles, whereas reaches farther down canyon have distinctly concave longitudinal profiles. The transition between these geomorphic domains is inferred to represent the downslope transformation of debris flows into erosive, canyon-flushing turbidity flows. Over geologic timescales this process appears to leave behind a predictable geomorphic fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may be a proxy for the volume of sediment released during geomorphically significant failures along the upper continental slope. Focused studies of slope-sourced submarine canyons may provide new insights into the relationships between fine-scale canyon morphology and down-canyon changes in sediment flow dynamics.

  3. An experimental approach to submarine canyon evolution

    NASA Astrophysics Data System (ADS)

    Lai, Steven Y. J.; Gerber, Thomas P.; Amblas, David

    2016-03-01

    We present results from a sandbox experiment designed to investigate how sediment gravity flows form and shape submarine canyons. In the experiment, unconfined saline gravity flows were released onto an inclined sand bed bounded on the downstream end by a movable floor that was used to increase relief during the experiment. In areas unaffected by the flows, we observed featureless, angle-of-repose submarine slopes formed by retrogressive breaching processes. In contrast, areas influenced by gravity flows cascading across the shelf break were deeply incised by submarine canyons with well-developed channel networks. Normalized canyon long profiles extracted from successive high-resolution digital elevation models collapse to a single profile when referenced to the migrating shelf-slope break, indicating self-similar growth in the relief defined by the canyon and intercanyon profiles. Although our experimental approach is simple, the resulting canyon morphology and behavior appear similar in several important respects to that observed in the field.

  4. Plunge Pools in Hawaiian Submarine Canyons

    NASA Astrophysics Data System (ADS)

    Caress, D. W.; Greene, H. G.; Greene, H. G.; Paull, C. K.; Ussler, W.; Clague, D.; Moore, J. G.; Maher, N. H.

    2001-12-01

    Many submarine canyon systems include well-defined intra-canyon depressions. Often, these depressions are found at the base of scarps along the canyon thalweg, with morphologic characteristics similar to subarial plunge pools formed at waterfalls. One plausible mechanism for the origin of these features is scouring during submarine debris flows. Other processes which can plausibly contribute to the formation of re-entrants and depressions in submarine canyons include erosion by spring sapping, slumping, collapse following gas expulsion or subsurface dissolution, and channel damming by mass wasting of canyon walls. The Monterey Bay Aquarium Research Institution conducted ROV dives around the Hawaiian Islands during a spring 2001 expedition of the R/V Western Flyer and ROV Tiburon. Three ROV dives investigated submarine canyons on the north (windward) sides of Molokai and Hawaii that exhibit well-developed intra-canyon depressions. These depressions ranged from 10 m deep and 150 m across to 90 m deep and 750 m across. The headwall scarps ranged from 20 m to 350 m. ROV video observations combined with rock and sediment sampling allowed us to characterize the depressions' detailed morphology, relate the morphology to the underlying geology, and view the genesis of these features in the context of the origin and evolution of the canyon systems as a whole. Our observations support the hypothesis that these intra-canyon depressions, or plunge pools, are formed through scouring during submarine debris flows. In all cases the down-canyon depression sills are dams composed of debris piles, with angular rubble exposed on the depression side and sand covering the down-canyon side. The Molokai plunge pool is draped with mud and silt, suggesting no recent activity. However, the Kohala plunge pools show clear signs of recent scour and no sediment cover. The headwalls above the plunge pools expose layered volcanoclastic and lava flow units, with more resistant layers frequently forming vertical or overhanging walls. We interpret these canyons as being largely formed through retrogressive (headward) erosion and slope failure. Periodic rockfalls and debris flows following undercutting of the headwalls scours the depressions, builds the pool dams, and both lengthens and deepens the canyons. >http://www.mbari.org/education/cruises/Hawaii/

  5. Seismic expression of Late Quaternary Banda submarine canyon and fan offshore northern Baja California

    SciTech Connect

    Legg, M.R.

    1987-05-01

    High-resolution seismic reflection profiles obtained throughout the inner California continental borderland offshore northwestern Baja California, Mexico, show the presence of numerous modern submarine canyons and associated fans. One set of these, the Banda submarine canyon/fan, is of relatively recent origin, as demonstrated by onlap of the basal fan sediments against an acoustically transparent, presumably hemipelagic deposit. Late Quaternary sedimentation rates inferred from isotopically dated piston core samples place the age of the postulated hemipelagic unit at approximately 650,000 years ago. The Banda submarine canyon heads within the Bahia Todos Santo and passes through a narrow gorge between Punta Banda and Islas Todos Santos. It is proposed that this submarine canyon and fan system formed entirely during late Quaternary time, following the breach of the Punta Banda ridge during a late Pleistocene high sea level stand. The presence of an ancient, buried channel exiting to the north out of Bahia Todos Santos probably marks the head of an earlier submarine canyon which acted as the conduit of clastic sediments from Valle Maneadero to the deep borderland basins. The now active Banda submarine canyon pirated the supply of terrigenous clastics from this older canyon. The active Agua Blanca fault zone cuts across the head of Banda submarine canyon, suggesting that tectonic movements may have played a role in the development of the Banda submarine canyon and fan system.

  6. Flow dynamics around downwelling submarine canyons

    NASA Astrophysics Data System (ADS)

    Spurgin, J. M.; Allen, S. E.

    2014-10-01

    Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (northwestern Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby and Burger numbers were used to determine the significance of Coriolis acceleration and stratification (respectively) and their impacts on flow dynamics. A new non-dimensional parameter (χ) was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10-day model period; however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation, and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. The offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m). Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate), as well as stronger vorticity within the canyon. Results from previous studies are explained within this new dynamic framework.

  7. Flow dynamics around downwelling submarine canyons

    NASA Astrophysics Data System (ADS)

    Spurgin, J. M.; Allen, S. E.

    2014-05-01

    Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (Northwest Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby number and Burger number were used to determine the significance of Coriolis acceleration and stratification (respectively) and their impacts on flow dynamics. A new non-dimensional parameter (χ) was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10 day model period, however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. Offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m). Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate) as well as stronger vorticity within the canyon. Results from previous studies were explained within this new dynamic framework.

  8. Wilmington Submarine Canyon: a marine fluvial-like system.

    USGS Publications Warehouse

    McGregor, B.; Stubblefield, W.L.; Ryan, William B. F.; Twichell, D.C.

    1982-01-01

    Midrange sidescan sonar data show that a system of gullies and small channels feeds into large submarine canyons on the Middle Atlantic Continental Slope of the US. The surveyed canyons all have relatively flat floors, but they have different channel morphologies. Wilmington Canyon has a meandering channel that extends down the Continental Slope and across the Continental Rise, whereas two canyons south of Wilmington Canyon have straight channels that trend directly downslope onto the rise. The morphology of these submarine canyon systems is remarkably similar to that of terrestrial fluvial systems.-Authors

  9. An Experimental Study of Submarine Canyon Evolution on Continental Slopes

    NASA Astrophysics Data System (ADS)

    Lai, S. Y.; Gerber, T. P.; Amblas, D.

    2013-12-01

    Submarine canyons define the morphology of many continental slopes and are conduits for the transport of sediment from shallow to deep water. Though the origin and evolution of submarine canyons is still debated, there is general agreement that sediment gravity flows play an important role. Here we present results from a simple, reduced-scale sandbox experiment designed to investigate how sediment gravity flows generate submarine canyons. In the experiments, gravity flows were modeled using either sediment-free or turbid saline currents. Unconfined flows were released onto an inclined bed of sand bounded on the downstream end by a movable floor that was incrementally lowered during the course of an experiment to produce an escarpment. This design was developed to represent the growth of relief across the continental slope. To monitor canyon evolution on the slope, we placed an overhead DSLR camera to record vivid time-lapse videos. At the end of each experimental stage we scanned the topography by imaging a series of submerged laser stripes, each projected from a motor-driven transverse laser sheet, onto a calibrated Cartesian coordinate system to produce high resolution bathymetry without draining the ambient water. In areas unaffected by the flows, we observe featureless, angle-of-repose submarine slopes formed by retrogressive breaching processes. In contrast, areas influenced by gravity flows cascading across the shelf break are deeply incised by submarine canyons with well-developed channel networks. Our results show that downslope gravity flows and submarine falling base level are both required to produce realistic canyon morphologies at laboratory scale. Though our mechanism for generating relief may be a rather crude analogue for the processes driving slope evolution, we hope our novel approach can stimulate new questions about the coevolution of canyons and slopes and motivate further experimental work to address them.

  10. Regional impact of submarine canyons during seasonal upwelling

    NASA Astrophysics Data System (ADS)

    Connolly, Thomas P.; Hickey, Barbara M.

    2014-02-01

    A numerical model of the northern California Current System along the coasts of Washington and British Columbia is used to quantify the impact of submarine canyons on upwelling from the continental slope onto the shelf. Comparisons with an extensive set of observations show that the model adequately represents the seasonal development of near-bottom density, as well as along-shelf currents that are critical in governing shelf-slope exchange. Additional model runs with simplified coastlines and bathymetry are used to isolate the effects of submarine canyons. Near submarine canyons, equatorward flow over the outer shelf is correlated with dense water at canyon heads and subsequent formation of closed cyclonic eddies, which are both associated with cross-shelf ageostrophic forces. Lagrangian particles tracked from the slope to midshelf show that canyons are associated with upwelling from depths of 140-260 m. Source depths for upwelling are shallower than 150 m at locations away from canyons and in a model run with bathymetry that is uniform in the along-shelf direction. Water upwelled through canyons is more likely to be found near the bottom over the shelf. Onshore fluxes of relatively saline water through submarine canyons are large enough to increase volume-averaged salinity over the shelf by 0.1-0.2 psu during the early part of the upwelling season. The nitrate input from the slope to the Washington shelf associated with canyons is estimated to be 30-60% of that upwelled to the euphotic zone by local wind-driven upwelling.

  11. Origin of Izu-Bonin forearc submarine canyons

    SciTech Connect

    Fujioka, Kantaro ); Yoshida, Haruko )

    1990-06-01

    Submarine canyons on the Izu-Bonin forearc are morphologically divided from north to south into four types based on their morphology, long profiles, and seismic profiles: Mikura, Aogashima, Sofu, and Chichijima types, respectively. These types of canyons are genetically different from each other. Mikura group is formed by the faults related to bending of the subducting Philippine Sea Plate. Aogashima type genetically relates to the activity of large submarine calderas that supply large amounts of volcaniclastic material to the consequent forearc slope. The third, Sofu group, is thought to be formed by the large-scale mega mass wasting in relation to the recent movement of the Sofugan tectonic line. The last, Chichijima group, is formed by collision of the Uyeda Ridge and the Ogasawara Plateau on the subducting Pacific Plate with Bonin Arc. Long profiles of four types of submarine canyons also support this.

  12. Anatomy of La Jolla submarine canyon system; offshore southern California

    USGS Publications Warehouse

    Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

    2013-01-01

    An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (< 10 cm) turbidites, they are inferred to be part of a veneer of recent sediment covering pre-canyon host sediments that underpin the terraces. The combined use of state of the art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

  13. Geology and biology of Oceanographer submarine canyon.

    USGS Publications Warehouse

    Valentine, P.C.; Uzmann, J.R.; Cooper, R.A.

    1980-01-01

    Santonian beds more than 100 m thick are the oldest rocks collected from the canyon. Quaternary silty clay veneers the canyon walls in many places and is commonly burrowed by benthic organisms that cause extensive erosion of the canyon walls, especially in the depth zone (100-1300 m) inhabited by the crabs Geryon and Cancer. Bioerosion is minimal on high, near-vertical cliffs of sedimentary rock, in areas of continual sediment movement, and where the sea floor is paved by gravel. A thin layer of rippled, unconsolidated silt and sand is commonly present on the canyon walls and in the axis. Shelf sediments are transported from Georges Bank over the E rim and in the Canyon by the SW drift and storm currents; tidal currents and internal waves move the sediment downcanyon along the walls and axis.- from Authors

  14. Morpho-sedimentary features and sediment dispersal of the Fangliao Submarine Canyon in the active margin offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, Y. H.; Chiang, C. S.; Yu, H. S.

    2009-04-01

    Using newly collected multi-channel seismic profiles and bathymetric data this paper characterizes morphology and relates it to structural and sedimentary processes in the Fangliao Submarine Canyon and contrasts with the nearby Kaoping Canyon about 20 km in distance by the sediment dispersal in terms of source to sink. The Fangliao Canyon consists of three distinct morphologic parts: an upper canyon, a lower canyon and a distal submarine fan. The upper canyon indents into and begins at the shelf edge and extends downsope in a relatively straight course for a distance of about 22 km and ends at water depth of about 600 where the canyon turns sharply to the southwest. The deflection of canyon course is caused by the presence of a structural high of diapiric mud ridge. The lower canyon runs southwestwards along the western edge of the elongate ridge for a distance of about 45 km and is in water depth of about of 900 m where the canyon mouth opens and sediments disperse laterally and downslope, forming a relatively small submarine fan of about 400 square kilometers. The upper canyon is represented by a relatively narrow (3-4.5 km), V-shaped valley with canyon relief less than 300 m. Seismic profiles reveal terminations of parallel reflectors against steep canyon walls and slumping and sliding features, suggesting erosional canyon down-cutting. In the lower canyon, the canyon width increases to 12 km wide and canyon relief greater than 400 meters, indicating intense down-cutting of canyon floor and lateral erosion of canyon walls. However, the cross-sectional morphology is characterized by varying V-and U-shaped valleys. Relatively flat reflectors onlap the canyon floor and result in U-shaped cross sections, indicating combined effects of erosion and deposition. The distal submarine fan is a low-relief depositional feature probably resulting from channelized and overbank deposition. Although under the same conditions of climate, sea-level changes and tectonics of the SW Taiwan margin the Fangliao Canyon differs greatly from the nearby Kaoping Canyon in terms of sediment dispersal. The sediment source of the Fangliao Canyon is mainly derived from the canyon head indenting the shelf edge where neither major rivers nor deltas are close to or present, resulting in limited sediment supply from the shelf to the canyon head. Therefore, the Fangliao Canyon serves as a sediment pathway fed by limited sediments from the shelf edge, allowing to transport sediments for a relatively short distance of about 70 km and depositing them at the upper continental slope in water depth of about 1000 m, forming a small fan, the ultimate sediment sink. In contrast, the head of Kaoping canyon is connected to the Kaoping River, a small mountainous river with a high sediment yield. Recurrent hyperpycnal flows during the flood seasons are transporting great amounts of sediments to the Kaoping canyon head to generate powerful down-slope sediment flows, transporting sediments for a long distance of about 260 km across the entire continental slope and reaching the deep-sea Manila Trench, the ultimate sediment sink. Without continuous and large supply of sediments to the canyon head the Fangliao Canyon can be considered as a sediment pathway with limited capacity for transporting shallow marine sediments to the deep sea. Key words: submarine canyon, morphology, sediment dispersal, seismics,Taiwan

  15. Role of submarine canyons in shaping the rise between Lydonia and Oceanographer canyons, Georges Bank

    USGS Publications Warehouse

    McGregor, B.A.

    1985-01-01

    Three large submarine canyons, Oceanographer, Gilbert, and Lydonia, indent the U.S. Atlantic continental shelf and, with four additional canyons, dissect the continental slope in the vicinity of Georges Bank. On the upper rise, these canyons merge at a water depth of approximately 3100 m to form only two valleys. Differences in channel morphology of the canyons on the upper rise imply differences in relative activity, which is inconsistent with observations in the canyon heads. At present, Lydonia Canyon incises the upper rise more deeply than do the other canyons: however, seismic-reflection profiles show buried channels beneath the rise, which suggests that these other six canyons were periodically active during the Neogene. The rise morphology and the thickness of inferred Neogene- and Quaternary-age sediments on the rise are attributed to the presence and activity of the canyons. The erosional and depositional processes and the morphology of these canyons are remarkably similar to those of fluvial systems. Bear Seamount, which has approximately 2000 m of relief on the rise, has acted as a barrier to downslope sediment transport since the Late Cretaceous. Sediment has piled up on the upslope side, whereas much less sediment has accumulated in the "lee shadow" on the downslope side. Seismic-reflection profile data show that Lydonia Canyon has not eroded down to the volcanic rock of Bear Seamount. ?? 1985.

  16. Giant submarine canyons: is size any clue to their importance in the rock record?

    USGS Publications Warehouse

    Normark, William R.; Carlson, Paul R.

    2003-01-01

    Submarine canyons are the most important conduits for funneling sediment from continents to oceans. Submarine canyons, however, are zones of sediment bypassing, and little sediment accumulates in the canyon until it ceases to be an active conduit. To understand the potential importance in the rock record of any given submarine canyon, it is necessary to understand sediment-transport processes in, as well as knowledge of, deep-sea turbidite and related deposits that moved through the canyons. There is no straightforward correlation between the final volume of the sedimentary deposits and size o fthe associated submarine canyons. Comparison of selected modern submarine canyons together with their deposits emphasizes the wide range of scale differences between canyons and their impact on the rock record. Three of the largest submarine canyons in the world are incised into the Beringian (North American) margin of the Bering Sea. Zhemchug Canyon has the largest cross-section at the shelf break and greatest volume of incision of slope and shelf. The Bering Canyon, which is farther south in the Bering Sea, is first in length and total area. In contrast, the largest submarine fans-e.g., Bengal, Indus, and Amazon-have substantially smaller, delta-front submarine canyons that feed them; their submarine drainage areas are one-third to less than one-tenth the area of Bering Canyon. some very large deep-sea channells and tubidite deposits are not even associated with a significant submarine canyon; examples include Horizon Channel in the northeast Pacific and Laurentian Fan Valley in the North Atlantic. Available data suggest that the size of turbidity currents (as determined by volume of sediment transported to the basins) is also not a reliable indicator of submarine canyon size.

  17. Cyclone-induced hyperpycnal turbidity currents in a submarine canyon

    NASA Astrophysics Data System (ADS)

    Liu, James T.; Wang, Yu-Huai; Yang, Rick J.; Hsu, Ray T.; Kao, Shuh-Ji; Lin, Hui-Ling; Kuo, Fang Hsu

    2012-04-01

    Density currents such as turbidity currents are major transport agents in various terrestrial, lacustrine, and marine environments worldwide. However, a gap exists between those who study the deposits by turbidity currents (turbidite) on a field scale, and those who study turbidity currents using small-scale laboratory experiments and theoretical/numerical models. We report two typhoon-triggered hyperpycnal turbidity current events observed in a submarine canyon. Our findings verify turbidite sequences with the characteristics of suspended sediment carried by passing turbidity currents that displayed distinct waxing and waning phases. Our study also confirms the direct link between typhoon-triggered hyperpycnal flows in a small mountainous river and turbidity currents in a nearby submarine canyon that transport sediment to the deep-sea efficiently.

  18. Submarine canyons: multiple causes and long-time persistence

    SciTech Connect

    Shepard, F.P.

    1981-06-01

    Submarine canyons are of composite origin and that many of the hypotheses suggested in the past were partly correct but did not appreciate that coordination of other processes was required. Thus there is growing evidence that, in the history of many canyons, there was a period in which subaerial erosion was an important precursor, but that present features are predominantly the result of marine erosion. Those advocating turbidity currents as the unique cause of canyons failed to appreciate that debris flows down the incipient valleys, as well as other types of landslides, could be an almost equally important factor in marine erosion. The great effect of biologic activity on the rock walls of incipient canyons has been almost completely neglected in explanations, and various types of currents such as those of the tides have been left largely out of the picture. Perhaps the most important feature absent in these various hypotheses has been the realization that canyons may well be the result of a long period of formation, much longer than the short episodes of Pleistocene glacial sea-level lowering usually considered explanation enough of these giant features which commonly cut into hard crystalline rock. New information is showing that the canyons may date back to at least the Cretaceous. (JMT)

  19. Erosion and submarine canyons on the insular shelf edge south of Iceland

    NASA Astrophysics Data System (ADS)

    Kjartansson, E.

    2005-12-01

    Iceland is surrounded by a clearly defined insular shelf that is usually more than 100 km wide. The depth of the shelf edge is usually between 150 and 300 meters. South of Myrdalur in south Iceland, the shelf is much narrower, around 20 km at the narrowest point. This is probably caused by renewed volcanism in the region during the quaternary. This has caused southward extension of the shoreline and, in combination with quaternary glaciation, a great increase in sediment transported across the shelf. This increase in sediment results in turbidity currents that are strong enough to erode the shelf slope, carving submarine canyons that reach 300 km south of the shelf edge to a depth of 2400 meters in the Iceland Basin. This erosion appears to have removed a few tens of kilometers from the outside of the shelf. The bathymetry of the shelf slope and submarine canyons has been mapped using data that has been recorded using a Simrad EM-300 multibeam sonar onboard the Icelandic research vessel Arni Fridriksson. The morphology of the shelf slope in this region differs from other parts of the Icelandic insular shelf slope. It shows a distinct dendric pattern similar to what is observed onshore where the topography is created by erosion caused by rainfall and its drainage. Two of the submarine canyons originate in the vicinity of two major glacial rivers of the region, Markarfljot and Kudafljot. Reflections from the bottom of these canyons are considerably stronger than from surrounding areas. The third canyon originates near Reynisdjup which coincides with the location of the catastrophic glacial outburst flood that was caused by the eruption of Katla volcano in 1918. The floor of this canyon shows minor contrast in sonar reflection strength, compared to the surrounding ocean bottom. This may indicate that this part of the canyon system is active episodically during floods related to eruptions by Katla. Katla has had significant eruptions approximately every 50 years throughout most of the historical period. A fresh-looking landslide is seen at the shelf edge near Reynisdjup. A direct connection of the submarine canyons to the Maury channel further south and east in the Iceland Basin has not been found yet.

  20. Submarine canyons as important habitat for cetaceans, with special reference to the Gully: A review

    NASA Astrophysics Data System (ADS)

    Moors-Murphy, Hilary B.

    2014-06-01

    There has been much research interest in the use of submarine canyons by cetaceans, particularly beaked whales (family Ziphiidae), which appear to be especially attracted to canyon habitats in some areas. However, not all submarine canyons are associated with large numbers of cetaceans and the mechanisms through which submarine canyons may attract cetaceans are not clearly understood. This paper reviews some of the cetacean associations with submarine canyons that have been anecdotally described or presented in scientific literature and discusses the physical, oceanographic and biological mechanisms that may lead to enhanced cetacean abundance around these canyons. Particular attention is paid to the Gully, a large submarine canyon and Marine Protected Area off eastern Canada for which there exists some of the strongest evidence available for submarine canyons as important cetacean habitat. Studies demonstrating increased cetacean abundance in the Gully and the processes that are likely to attract cetaceans to this relatively well-studied canyon are discussed. This review provides some limited evidence that cetaceans are more likely to associate with larger canyons; however, further studies are needed to fully understand the relationship between the physical characteristics of canyons and enhanced cetacean abundance. In general, toothed whales (especially beaked whales and sperm whales) appear to exhibit the strongest associations with submarine canyons, occurring in these features throughout the year and likely attracted by concentrating and aggregating processes. By contrast, baleen whales tend to occur in canyons seasonally and are most likely attracted to canyons by enrichment and concentrating processes. Existing evidence thus suggests that at least some submarine canyons are important foraging areas for cetaceans, and should be given special consideration for cetacean conservation and protection.

  1. Origin of Florida Canyon and the role of spring sapping on the formation of submarine box canyons

    USGS Publications Warehouse

    Paull, Charles K.; Spiess, Fred N.; Curray, Joseph R.; Twichell, David C.

    1990-01-01

    Florida Canyon, one of a series of major submarine canyons on the southwestern edge of the Florida Platform, was surveyed using GLORIA, SeaBeam, and Deep-Tow technologies, and it was directly observed during three DSRV Alvin dives. Florida Canyon exhibits two distinct morphologies: a broad V-shaped upper canyon and a deeply entrenched, flat-floored, U-shaped lower canyon. The flat- floored lower canyon extends 20 km into the Florida Platform from the abyssal Gulf. The lower canyon ends abruptly at an ∼3 km in diameter semicircular headwall that rises 750 m with a >60° slope angle to the foot of the upper canyon. The sides of the lower canyon are less steep than its headwall and are characterized by straight faces that occur along preferred orientations and indicate a strong joint control. The upper canyon is characterized by a gently sloping, straight V-shaped central valley cut into a broad terrace. The flat floor of the upper canyon continues as terraces along the upper walls of the lower canyon. On the flanks of the upper canyon, there are five >50-m-deep, >0.5-km-wide, closed sink-hole-like depressions which indicate subsurface dissolution within the platform. The origin of the lower canyon is difficult to explain with traditional models of submarine canyon formation by external physical processes. The movement of ground water, probably with high salinities and reduced compounds along regional joints, may have focused the corrosive force of submarine spring sapping at the head of the lower canyon to produce the canyon's present shape.

  2. Ascension Submarine Canyon, California - Evolution of a multi-head canyon system along a strike-slip continental margin

    USGS Publications Warehouse

    Nagel, D.K.; Mullins, H.T.; Greene, H. Gary

    1986-01-01

    Ascension Submarine Canyon, which lies along the strike-slip (transform) dominated continental margin of central California, consists of two discrete northwestern heads and six less well defined southeastern heads. These eight heads coalesce to form a single submarine canyon near the 2700 m isobath. Detailed seismic stratigraphic data correlated with 19 rock dredge hauls from the walls of the canyon system, suggest that at least one of the two northwestern heads was initially eroded during a Pliocene lowstand of sea level ???3.8 m.y. B.P. Paleogeographic reconstructions indicate that at this time, northwestern Ascension Canyon formed the distal channel of nearby Monterey Canyon and has subsequently been offset by right-lateral, strike-slip faulting along the San Gregorio fault zone. Some of the six southwestern heads of Ascension Canyon may also have been initially eroded as the distal portions of Monterey Canyon during late Pliocene-early Pleistocene sea-level lowstands (???2.8 and 1.75 m.y. B.P.) and subsequently truncated and offset to the northwest. There have also been a minimum of two canyon-cutting episodes within the past 750,000 years, after the entire Ascension Canyon system migrated to the northwest past Monterey Canyon. We attribute these late Pleistocene erosional events to relative lowstands of sea level 750,000 and 18,000 yrs B.P. The late Pleistocene and Holocene evolution of the six southeastern heads also appears to have been controlled by structural uplift of the Ascension-Monterey basement high at the southeastern terminus of the Outer Santa Cruz Basin. We believe that uplift of this basement high sufficiently oversteepened submarine slopes to induce gravitational instability and generate mass movements that resulted in the erosion of the canyon heads. Most significantly, though, our results and interpretations support previous proposals that submarine canyons along strike-slip continental margins can originate by tectonic trunction and lateral offset. ?? 1986.

  3. Hudson Submarine Canyon Head Offshore New York and New Jersey: A Dynamic Interface

    NASA Astrophysics Data System (ADS)

    Rona, P.; Guida, V.; Sullivan, M.; Haag, S.; Macelloni, L.; Sweeney, E.; Scranton, M.; Hobbs, J.; Asper, V.

    2007-12-01

    Hudson Canyon is the largest submarine canyon on the U. S. Atlantic continental margin. Having completed a surface ship multi-beam bathymetric map of the Hudson Canyon region (resolution 100m; http://pubs.usgs.gov/of/2004/1441/index/html), we report preliminary results of mapping portions of the canyon head (75 square km, water depth 200-500 m) using the Eagle Ray autonomous underwater vehicle (Explorer 27- BO1-2200 AUV, ISE Ltd.) of the University of Southern Mississippi. The AUV was equipped with a Simrad EM2000 multi-beam sonar system and flown 50 m above the seafloor for resolution (3 m), and with a CTD to map water column properties. Shipboard CTD casts were also made and water sampled from the shelf break (depth 200 m) to the upper continental rise (3000 m) for detection of methane. The canyon head is of interest as an essential fish habitat (squid, hake, tilefish, and lobster) that may contribute to sustain a regional fishery and that may conduct sediment to the ocean basin. A shallow trough, the Hudson Shelf Valley, extends ~185 km across the continental shelf connecting the mouth of the Hudson River to the canyon head where it indents the seaward edge of the shelf. The canyon head bifurcates with branch 1 (6 km-long) oriented NW-SE aligned with the Shelf Valley, and branch 2 (4 km-long) oriented N-S. The two branches merge into a segment 10 km-long oriented NW-SE aligned with branch 1. Branch 1 has symmetric walls with mean inclinations of 10 degrees and smooth seafloor, suggesting that it is presently inactive and accumulating a cover of hemipelagic sediment. In contrast, the walls of both the N-S branch 2 and of the contiguous NW-SE segment are asymmetric. The walls of the NW-SE segment have a mean inclination of 15 degrees and exhibit semicircular escarpments 800-900 m long and 600-700 m wide, separated by narrow ravines perpendicular to the canyon axis. Slump blocks with sharp rims occur where N-S branch 1 joins the NW- SE segment. Two circular depressions (diameter 100 and 300 m; relief c.15 m; depths 345 m and 390 m) occur at the base of the SW wall of the segment and may be collapse features related to gas discharge evidenced by a high methane anomaly at the shelf edge. The head of Hudson Canyon encompasses diverse habitats and is a dynamic interface between shelf and slope processes. We thank NOAA's National Undersea Research Program for support.

  4. Deep-sea scavenging amphipod assemblages from the submarine canyons of the Western Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Duffy, G. A.; Horton, T.; Billett, D. S. M.

    2012-11-01

    Submarine canyons have often been identified as hotspots of secondary production with the potential to house distinct faunal assemblages and idiosyncratic ecosystems. Within these deep-sea habitats, assemblages of scavenging fauna play a vital role in reintroducing organic matter from large food falls into the wider deep-sea food chain. Free-fall baited traps were set at different depths within three submarine canyons on the Iberian Margin. Amphipods from the traps were identified to species level and counted. Scavenging amphipod assemblages were compared at different depths within each canyon and between individual canyon systems. Using data from literature, abyssal plain assemblages were compared to submarine canyon assemblages. Samples from canyons were found to contain common abyssal plain species but in greater than expected abundances. It is proposed that this is a result of the high organic carbon input into canyon systems owing to their interception of sediment from the continental shelf and input from associated estuarine systems. Community composition differed significantly between the submarine canyons and abyssal plains. The cause of this difference cannot be attributed to one environmental variable due to the numerous inherent differences between canyons and abyssal plains.

  5. Deep-sea scavenging amphipod assemblages from the submarine canyons of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Duffy, G. A.; Horton, T.; Billett, D. S. M.

    2012-06-01

    Submarine canyons have often been identified as hotspots of secondary production with the potential to house distinct faunal assemblages and idiosyncratic ecosystems. Within these deep-sea habitats, assemblages of scavenging fauna play a vital role in reintroducing organic matter from large food falls into the wider deep-sea food chain. Free-fall baited traps were set at different depths within three submarine canyons on the Iberian Margin. Amphipods from the traps were identified to species level and counted. Scavenging amphipod assemblages were compared at different depths within each canyon, between individual canyon systems, and between the abyssal plain and submarine canyon sites. Samples from canyons were found to contain common abyssal plain species but in greater than expected abundances. Community composition differed significantly between the submarine canyons and abyssal plains. It is proposed that this is a result of the high organic carbon input into canyon systems owing to their interception of sediment from the continental shelf and input from associated estuarine systems.

  6. Hanging canyons of Haida Gwaii, British Columbia, Canada: Fault-control on submarine canyon geomorphology along active continental margins

    NASA Astrophysics Data System (ADS)

    Harris, Peter T.; Barrie, J. Vaughn; Conway, Kim W.; Greene, H. Gary

    2014-06-01

    Faulting commonly influences the geomorphology of submarine canyons that occur on active continental margins. Here, we examine the geomorphology of canyons located on the continental margin off Haida Gwaii, British Columbia, that are truncated on the mid-slope (1200-1400 m water depth) by the Queen Charlotte Fault Zone (QCFZ). The QCFZ is an oblique strike-slip fault zone that has rates of lateral motion of around 50-60 mm/yr and a small convergent component equal to about 3 mm/yr. Slow subduction along the Cascadia Subduction Zone has accreted a prism of marine sediment against the lower slope (1500-3500 m water depth), forming the Queen Charlotte Terrace, which blocks the mouths of submarine canyons formed on the upper slope (200-1400 m water depth). Consequently, canyons along this margin are short (4-8 km in length), closely spaced (around 800 m), and terminate uniformly along the 1400 m isobath, coinciding with the primary fault trend of the QCFZ. Vertical displacement along the fault has resulted in hanging canyons occurring locally. The Haida Gwaii canyons are compared and contrasted with the Sur Canyon system, located to the south of Monterey Bay, California, on a transform margin, which is not blocked by any accretionary prism, and where canyons thus extend to 4000 m depth, across the full breadth of the slope.

  7. Recent sea beam mapping of Ascension-Monterey Submarine Canyon System

    SciTech Connect

    Greene, H.G. )

    1990-06-01

    Extensive Sea Beam and Bathymetric Swatch Survey System (BS{sup 3}) data covering the Ascension-Monterey Submarine Canyon system and adjoining areas and canyons were collected offshore central California. Many discovered geomorphological features lead to significant new geologic conclusions about the formation and processes of submarine canyons in general and disclose unique sedimentary and tectonic features of the Ascension-Monterey Canyon system. The highly detailed bathymetric maps constructed from the Sea Beam data indicate that the seafloor topographic pattern is influenced by sedimentary and tectonic processes; both remain active along the central California margin. Interpretations of MOAA composite maps, final raw Sea Beam bathymetric maps, and three-dimensional physiographic renditions from bathymetric data indicate a diverse and complex geomorphology for the Ascension-Monterey Submarine Canyon system and adjoining region. Five distinct geomorphologic provinces and four well-defined geographic areas are mapped. Canyons cut by faults and canyon walls actively undergoing mass wasting are prominently displayed in the Sea Beam data. Sedimentary processes illustrating canyon channel capture and the formation of extensive mega-sedimentary wave fields where the canyons debouch onto the abyssal plain are spectacularly well defined. This new tool of seafloor mapping is contributing significant data for the geological interpretation of continental margins and seafloor in the world's oceans.

  8. Holocene sedimentary activity in a non-terrestrially coupled submarine canyon: Cook Strait Canyon system, New Zealand

    NASA Astrophysics Data System (ADS)

    Mountjoy, J. J.; Micallef, A.; Stevens, C. L.; Stirling, M. W.

    2014-06-01

    The Cook Strait Canyon system, located between the North and South islands of New Zealand, is a large (1800 km2), multi-branching, shelf-indenting canyon on an active subduction margin. The canyon comes within 1 km of the coast, but does not intercept fluvial or littoral sediment systems and is therefore defined as a non-terrestrially coupled system. Sediment transport associated with a strong tidal stream, and seafloor disturbance related to numerous high-activity faults, is known from previous studies. Little is known, however, about the rates of sedimentary activity in the canyon and the processes driving it. A substantial dataset of EM300 multibeam bathymetry, gravity cores, 3.5 kHz seismic reflection profiles, camera and video transects and current meter data have been collected across the region between 2002 and 2011. The canyon system therefore provides an excellent study area for understanding sediment transport in a non-coupled submarine canyon system. Analysis of the data reveals a two-staged sediment transport system where: (1) oceanographic (tidal) processes mobilise sediment from the continental shelf and transport it to depocentres in the upper-central canyons, and (2) tectonic (earthquake) processes remobilise sediment that is transported through the lower canyon to the deep ocean. Tidal boundary-layer currents within the canyon reach velocities up to 0.53 m/s and are capable of mobilising fine sand in the central reach of the upper canyons. The velocity is higher at the canyon rim and capable of mobilising coarse sand. Sediment depocentres resulting from this tidally forced sediment transport have a well formed geomorphology within the mid-upper canyon arms of Cook Strait and Nicholson Canyons. Pseudo-static stability modelling, supported by sediment core analysis, indicates that sediment accumulated in the upper canyons fails during seismic events approximately every 100 years. The 100 year return period ground shaking-level (peak ground acceleration, ignoring the effect of the water column above the seabed) at this site is estimated to be 0.23g. Fresh rock outcrops and bed-scour in the lower canyon floor indicate that remobilised material is transported to the deep ocean. The processes identified here are likely to be analogous to those occurring in many non-coupled shelf-indenting canyons on active margins globally, and provide a framework within which the biological response to geomorphic processes in submarine canyons can be assessed.

  9. Submarine canyons: hotspots of benthic biomass and productivity in the deep sea

    PubMed Central

    De Leo, Fabio C.; Smith, Craig R.; Rowden, Ashley A.; Bowden, David A.; Clark, Malcolm R.

    2010-01-01

    Submarine canyons are dramatic and widespread topographic features crossing continental and island margins in all oceans. Canyons can be sites of enhanced organic-matter flux and deposition through entrainment of coastal detrital export, dense shelf-water cascade, channelling of resuspended particulate material and focusing of sediment deposition. Despite their unusual ecological characteristics and global distribution along oceanic continental margins, only scattered information is available about the influence of submarine canyons on deep-sea ecosystem structure and productivity. Here, we show that deep-sea canyons such as the Kaikoura Canyon on the eastern New Zealand margin (42°01′ S, 173°03′ E) can sustain enormous biomasses of infaunal megabenthic invertebrates over large areas. Our reported biomass values are 100-fold higher than those previously reported for deep-sea (non-chemosynthetic) habitats below 500 m in the ocean. We also present evidence from deep-sea-towed camera images that areas in the canyon that have the extraordinary benthic biomass also harbour high abundances of macrourid (rattail) fishes likely to be feeding on the macro- and megabenthos. Bottom-trawl catch data also indicate that the Kaikoura Canyon has dramatically higher abundances of benthic-feeding fishes than adjacent slopes. Our results demonstrate that the Kaikoura Canyon is one of the most productive habitats described so far in the deep sea. A new global inventory suggests there are at least 660 submarine canyons worldwide, approximately 100 of which could be biomass hotspots similar to the Kaikoura Canyon. The importance of such deep-sea canyons as potential hotspots of production and commercial fisheries yields merits substantial further study. PMID:20444722

  10. Does littoral sand bypass the head of Mugu Submarine Canyon? - a modeling study

    USGS Publications Warehouse

    Xu, Jingping; Elias, Edwin; Kinsman, Nicole

    2011-01-01

    A newly developed sand-tracer code for the process-based model Delft3D (Deltares, The Netherlands) was used to simulate the littoral transport near the head of the Mugu Submarine Canyon in California, USA. For westerly swells, which account for more than 90% of the wave conditions in the region, the sand tracers in the downcoast littoral drift were unable to bypass the canyon head. A flow convergence near the upcoast rim of the canyon intercepts the tracers and moves them either offshore onto the shelf just west of the canyon rim (low wave height conditions) or into the canyon head (storm wave conditions). This finding supports the notion that Mugu Canyon is the true terminus of the Santa Barbara Littoral Cell.

  11. Submarine canyon and slope processes of the U.S. Atlantic continental margin

    USGS Publications Warehouse

    McGregor, B.A.

    1983-01-01

    Two regions on the U.S. Atlantic continental margin were surveyed using single-channel, seismic-reflection profiling techniques: the Mid-Atlantic Continental Slope and Rise seaward of New Jersey in the vicinity of Baltimore Canyon and the Continental Slope and upper Rise just north of Cape Hatteras. Submarine canyons are the dominant morphologic feature in both areas. The Continental Slope in the Baltimore Canyon area has a general sea-floor gradient of 3?-4? and a width of approximately 40 km, whereas the study area north of Cape Hatteras has a general sea-floor gradient of approximately 9? and a width of 20 km. The dominant slope process differs in each area. In the Baltimore Canyon area, subbottom reflectors suggest that sediment deposition with progradation of the slope is related to canyon processes. In the study area north of Cape Hatteras, the canyons appear erosional and mass wasting is the dominant erosional process. Dominant slope processes appear to be correlated with the width and sea-floor gradient of the Continental Slope. Although the absolute age of the canyons is difficult to determine without rotary-drill cores for stratigraphic control, Baltimore Canyon is suggested to be older than the shelf-indenting canyon just north of Cape Hatteras. An anomalously large ridge flanking Baltimore Canyon on the upper rise appears to be related to canyon depositional and erosional processes.

  12. Clast-contact conglomerates in submarine canyons: possible subaqueous sieve deposits

    SciTech Connect

    Fitzgerald, M.S.

    1987-05-01

    Thick, coarse, clast-contact conglomerates in submarine canyon fill have previously been attributed to rock-fall, grain-flow, or winnowing processes. However, these processes do not adequately explain some thick conglomeratic sequences. The proposed process of subaqueous sieve deposition could account for these clast-contact conglomerates. Subaerial sieve deposition has been documented on small-scale fan models and on alluvial fans. A subaerial sieve deposit begins as a debris flow which at some point freezes up. The matrix is then lost by subsequent filtration or outflow, and the emplacement of a clast-contact gravel ensues. A subaqueous sieve deposit would be slightly modified in that the matrix would not be lost by filtration into the submarine canyon floor, but rather by outflow at the terminus of the lobe immediately after deposition, or possibly from the top and/or sides of the freezing flow mass during transport. Besides forming in submarine canyons, subaqueous sieve deposits might also occur in paralic, submarine fan channel, and base-of-the-slope settings. In substantiating the existence of subaqueous sieve deposits, the sedimentary structures and grain-size data from recent sieve deposits on alluvial fans are compared to those of ancient submarine canyon deposits. Numerous similarities are found supporting this new method of deposition. Some discrepancies are encountered, but these are expected due to modifications caused by an aqueous medium.

  13. Submarine canyons and channels in the Lower St. Lawrence Estuary (Eastern Canada): Morphology, classification and recent sediment dynamics

    NASA Astrophysics Data System (ADS)

    Normandeau, Alexandre; Lajeunesse, Patrick; St-Onge, Guillaume

    2015-07-01

    Series of submarine canyons and channels observed in the Lower St. Lawrence Estuary (LSLE) provide an opportunity to analyze in great detail the morphology, spatial distribution and modern activity of such systems in a relatively shallow (≤ 300 m) semi-enclosed basin. Based on their geomorphology and physical settings, the canyons and channels were classified into four categories according to their feeding sources (ancient or recent): glacially-fed, river-fed, longshore drift-fed and sediment-starved systems. Their activity was interpreted based on geomorphological characteristics such as the presence of bedforms related to gravity flows, backscatter intensity, axial incision and the presence of rapidly deposited layers in surficial sediments. River-fed deltas were interpreted as inactive, mainly because suspended sediment concentrations at river mouths are low, preventing the generation of hyperpycnal currents or delta-lip failures related to high sediment supply. Longshore drift-fed canyons, present where the coastal shelf narrows, were found to be episodically active probably due to earthquakes or extreme storm events. Unlike other longshore drift-fed canyons observed elsewhere in the world, they are active infrequently because of the modern low rates of sediment supply to their heads. The most active canyons are the sediment-starved type and were observed near Pointe-des-Monts. Their activity is probably due to slope failures and to the presence of strong hydrodynamic processes. Therefore, sediment supply is not the main mechanism responsible for modern canyon and channel activity in the LSLE. However, sediment supply has been an important factor during the formation of the submarine channels and canyons. Their quasi-exclusive occurrence on the Québec North Shore is attributed to its larger watershed and important sedimentary delivery during deglaciation. The Québec North Shore watershed is 20 times greater than the Québec South Shore watershed, which favored the transport of greater volumes of sediment during the early-Holocene. Moreover, the slope proximity to the shore led to the formation of longshore-drift fed systems on the North Shore when sediment supplied to rivers were transferred on a narrow shelf.

  14. Sediment dynamics and post-glacial evolution of the continental shelf around the Blanes submarine canyon head (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Durn, Ruth; Canals, Miquel; Lastras, Galderic; Micallef, Aaron; Amblas, David; Pedrosa-Pmies, Rut; Sanz, Jos Luis

    2013-11-01

    The Blanes submarine canyon (BC) deeply incises the Catalan continental shelf in the NW Mediterranean Sea. As a consequence of the closeness (only 4 km) of its head to the coastline and the mouth of the Tordera River, the canyon has a direct influence on the shelf dispersal system as it collects large amounts of sediment, mainly during high-energy events. Multibeam bathymetry, backscatter imagery and very-high resolution seismic reflection profiles have allowed characterizing the morphology of the continental shelf around the canyon head, also identifying sediment sources and transport pathways into the canyon. The morphological data have also been used to reconstruct the evolution of the continental shelf during the last sea-level transgression so that the current understanding of shelf-to-canyon sediment exchanges through time could be improved. The continental shelf surrounding the BC consists of both depositional and erosional or non-depositional areas. Depositional areas display prominent sediment bodies, a generally smooth bathymetry and variable backscatter. These include: (i) an area of modern coarse-grained sediment accumulation that comprises the inner shelf; (ii) a modern fine-grained sedimentation area on the middle shelf offshore Tossa de Mar; and (iii) a modern sediment depleted area that covers most of the middle and outer shelf to the west of the canyon head. Erosional and non-depositional areas display a rough topography and high backscatter, and occur primarily to the east of the canyon head, where the arrival of river-fed inputs is very small. In agreement with this pattern, the continental shelf north and west of the canyon head likely is the main source of shelf sediment into the canyon. To the north, a pattern of very high backscatter extends from the coastline to the canyon head, suggesting the remobilization and off-shelf export of fines. Additionally, relict near-shore sand bodies developed over the Barcelona shelf that extend to the canyon head rim constitute a source of coarse sediment. High-energy processes, namely river floods and coastal storms, are the main controls over the river-shelf-canyon sediment exchange. River floods increase the delivery of terrigenous particles to the coastal system. Storms, mainly from the east, remobilize the sediment temporarily accumulated on the shelf towards the canyon head, so that the finer fractions are preferentially removed and a coarse lag is normally left on the shelf floor. Exceptionally, very strong storms also remove the coarse fractions from the shelf drive them into the canyon. Processes like dense shelf water cascading, which is much more intense in canyons to the north of BC, and the Northern Current also contribute to the transport of suspended sediment from far distant northern sources. During the last post-glacial transgression the BC had a strong influence on the evolution of the inner continental margin, as it interrupted the shelf sediment dispersal system by isolating the shelves to its north and south, named La Planassa and Barcelona shelves, respectively. The detailed study of the geomorphology and uppermost sediment cover of the continental shelf surrounding the Blanes submarine canyon yields insight into the past and present shelf sediment dynamics and the shelf-to-canyon sediment exchanges. The continental shelf near the canyon head consists of mosaic where erosional, or non-depositional, and depositional zones coexist. East of the canyon and offshore Tossa de Mar, the modern sediment deposition is mostly confined to the inner and middle shelf, whilst most of the La Planassa shelf is sediment depleted with numerous relict morphosedimentary features cropping out. Rocky outcrops, narrow ridges and relict coarse sand deposits suggesting erosion or non-deposition of fine sediments in modern times occupy the middle and outer shelf floor east and northeast of the canyon head. In contrast, north and west of the canyon head, the middle and outer shelf comprises several large relict sand bodies that point out to long-term deposition. However, the lack of modern sediments on top of these bodies supports active erosion or by-pass in present times. The morphology of the continental shelf near the canyon head records the imprint of the main factors controlling the shelf sediment-dispersal system and provides evidence for the main sources and transport pathways of sediment from the shelf into the canyon. The depletion of fine sediments on the continental shelf, as evidenced by backscatter data, suggests that the Blanes Canyon acts as a sediment trap collecting the finest fractions resuspended primarily from the adjacent shelf to the north. The main processes that control the shelf-to-canyon transfer of sediment are eastern storms, which enhance the off-shelf export of mainly fine sediment from the shelf. Particularly severe storms are also able to remobilize and transport coarse sediment from the shelf and also from the relict sand bodies into the canyon. Other processes, such as DSWC and the Northern Current, contribute to a lesser extent to the transport of sediment along the shelf and into the canyon. During the last post-glacial transgression, the BC played a crucial role in the shaping of the continental shelf surrounding it by cutting the littoral drift of sediment between the shelf areas to the north and south, thus severely modifying the across- and along-shelf sediment pathways. As a result, to the east of the canyon, the poor development of transgressive deposits indicates the prevalence of erosion and non-deposition associated to a limited sediment supply and an effective action of the littoral drift leading to a south-westward transport of sediment towards the canyon head. To the north and west of the canyon the morphology of the continental shelf changed significantly during the sea-level rise. At the early stage of the transgression, the sediment supplied by the Tordera River was discharged directly into the canyon, thus preventing deposition over the shelf. Later, the progressive sea-level rise favoured the development of large depositional bodies on the Barcelona shelf favoured by the increase of accommodation space and the augmenting distance between the river mouth and the canyon head. A drastic change in the configuration of the shelf occurred when the sea-level raised enough to flood the entire continental shelf. The along-shelf sediment transport between the shelf areas to the north and south of the canyon head was then restored and new sediment bodies were formed between the coastline and the canyon tip. At present, these sediment bodies constitute the primary source of coarse sediment into the BC. These results confirm that the Blanes submarine canyon head is highly dynamic and sensitive to a variety of processes that enhance the transport of sediment from the shelf into the canyon, particularly during major storms.

  15. Headless submarine canyons and fluid flow on the toe of the Cascadia accretionary complex

    USGS Publications Warehouse

    Orange, D.L.; McAdoo, B.G.; Moore, J.C.; Tobin, H.; Screaton, E.; Chezar, H.; Lee, H.; Reid, M.; Vail, R.

    1997-01-01

    Headless submarine canyons with steep headwalls and shallowly sloping floors occur on both the second and third landward vergent anticlines on the toe of the Cascadia accretionary complex off central Oregon (45 ??N, 125?? 30??W). In September 1993, we carried out a series of nine deep tow camera sled runs and nine ALVIN dives to examine the relationship between fluid venting, structure and canyon formation. We studied four canyons on the second and third landward vergent anticlines, as well as the apparently unfailed intercanyon regions along strike. All evidence of fluid expulsion is associated with the canyons; we found no evidence of fluid flow between canyons. Even though all fluid seeps are related to canyons, we did not find seeps in all canyons, and the location of the seeps within the canyons differed. On the landward facing limb of the second landward vergent anticline a robust cold seep community occurs at the canyon's inflection point. This seep is characterized by chemosynthetic vent clams, tube worms and extensive authigenic carbonate. Fluids for this seep may utilize high-permeability flow paths either parallel to bedding within the second thrust ridge or along the underlying thrust fault before leaking into the overriding section. Two seaward facing canyons on the third anticlinal ridge have vent clam communities near the canyon mouths at approximately the intersection between the anticlinal ridge and the adjacent forearc basin. No seeps were found along strike at the intersection of the slope basin and anticlinal ridge. We infer that the lack of seepage along strike and the presence of seeps in canyons may be related to fluid flow below the forearc basin/slope unconformity (overpressured by the impinging thrust fault to the west?) directed toward canyons at the surface.

  16. Event-driven sediment flux in Hueneme and Mugu submarine canyons, southern California

    USGS Publications Warehouse

    Xu, J. P.; Swarzenski, P.W.; Noble, M.; Li, A.-C.

    2010-01-01

    Vertical sediment fluxes and their dominant controlling processes in Hueneme and Mugu submarine canyons off south-central California were assessed using data from sediment traps and current meters on two moorings that were deployed for 6 months during the winter of 2007. The maxima of total particulate flux, which reached as high as 300+ g/m2/day in Hueneme Canyon, were recorded during winter storm events when high waves and river floods often coincided. During these winter storms, wave-induced resuspension of shelf sediment was a major source for the elevated sediment fluxes. Canyon rim morphology, rather than physical proximity to an adjacent river mouth, appeared to control the magnitude of sediment fluxes in these two submarine canyon systems. Episodic turbidity currents and internal bores enhanced sediment fluxes, particularly in the lower sediment traps positioned 30 m above the canyon floor. Lower excess 210Pb activities measured in the sediment samples collected during periods of peak total particulate flux further substantiate that reworked shelf-, rather than newly introduced river-borne, sediments supply most of the material entering these canyons during storms.

  17. Submarine canyons as the preferred habitat for wood-boring species of Xylophaga (Mollusca, Bivalvia)

    NASA Astrophysics Data System (ADS)

    Romano, C.; Voight, J. R.; Company, J. B.; Plyuscheva, M.; Martin, D.

    2013-11-01

    Submarine canyons are often viewed as natural “debris concentrators” on the seafloor. Organic substrates may be more abundant inside than outside canyon walls. To determine the effects of the presence these substrates in the Blanes submarine canyon (NW Mediterranean) and its adjacent western open slope, we deployed wood to study colonizing organisms. Three replicate pine and oak cubes (i.e. most common trees inland) were moored at 900, 1200, 1500 and 1800 m depth and collected after 3, 9 and 12 months. Wood from inside the canyon was significantly more heavily colonized by the five morphotypes of wood-boring bivalves than was wood on the adjacent open slope. Xylophaga sp. A dominated all wood types and locations, with peak abundance at 900 and 1200 m depth. Its growth rate was highest (0.070 mm d-1) during the first three months and was faster (or it recruits earlier) in pine than in oak. Size distribution showed that several recruitment events may have occurred from summer to winter. Xylophaga sp. B, appeared first after 9 months and clearly preferred pine over oak. As the immersion time was the same, this strongly supported a specific association between recruiters and type of substrate. Three morphotypes, pooled as Xylophaga spp. C, were rare and seemed to colonize preferentially oak inside the canyon and pine in the adjacent open slope. Individuals of Xylophaga were more abundant inside the canyon than in nearby off-canyon locations. Blanes Canyon may serve as a long-term concentrator of land-derived vegetal fragments and as a consequence sustain more animals. Are the species richness and abundance of wood-boring bivalves higher inside the canyon than on the adjacent open slope? Do the composition and density of the wood-boring bivalves change with deployment time and depth, as well as on the type of the sunken wood? What is the growth rate of the dominant wood-boring species?

  18. Axial Channel Morphology Fill and Movement Within Submarine Canyons off California

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Caress, D. W.; Ussler, W.; Lundsten, E.; Thomas, H.

    2008-12-01

    Axial channels of seven submarine canyons off California have recently been investigated with ultrahigh resolution multibeam surveys. Vibracores collected from remotely operated vehicles (ROVs) provide ground truth data on the materials within the axis of six of these canyons. Acoustic beacons were used to track movement of the seafloor within the axis of Monterey Canyon. Multibeam bathymetry (0.15 m vertical precision and 1.0 m horizontal resolution at 50 m survey altitude) and chirp seismic-reflection profiles (0.11 m vertical resolution) were collected from an autonomous underwater vehicle (AUV). Inertial navigation combined with Doppler velocity sonar allows the AUV to navigate the sinuous canyons at 3 kt on a pre-programmed route ~50 m above the seafloor. Submarine canyons that head near the shoreline (Monterey, Hueneme, Mugu, Redondo and La Jolla) contain similar wave-like bedforms with 20-100 m wavelengths and amplitudes up to 2.5 m oriented roughly perpendicular to the channel axis. These bedforms are asymmetric in profile with a steep down-canyon face and crescent-shaped, concave down-canyon. They are observed throughout the surveys (80-800 m water depth) and appear to form genetically similar packages (0.1 to 3 km long) that terminate upslope at a somewhat higher topographic step. Generally, bedform groups are found within the axial channel, but occasionally extend up the canyon walls. ROV-collected vibracores show that the wave-like bedforms comprise recent, coarse-grained gravity flow deposits, suggesting these canyons are active. In contrast, two submarine canyons with heads on the outer shelf (Soquel and Santa Monica) lack these wave-like bedforms and have relatively smooth axial channel floors. Vibracores show these canyons are filled with generally uniform fine-grained sediments, suggesting they are inactive. Apparently wave-like bedforms are common features of active submarine canyons. To assess whether sediment within a canyon floor is moved by traction currents or mass transport, three acoustic beacons were deployed in Monterey Canyon (~290 m water depth) in February 2007. The beacons were placed in 50-cm-high ~45 kg concrete monuments. These boulder-sized monuments were buried leaving only the top of the beacon extending ~6 cm above the seafloor. The position of these beacons was re-surveyed 8 times between February 2007 and July 2008. While the beacons did not move between most surveys, two down-canyon shifts of ~150 m and >1,200 m were measured. The episodic movement of the buried monuments suggests that the seafloor was remobilized to more than 50-cm- depth during sediment transport events. Four repeat AUV multibeam surveys were also conducted during the first half of 2007. These surveys show that the wave-shaped bedforms occur in the canyon axis down to at least 1,100 m water depth. Because the buried monuments have moved more than two wavelengths down- canyon during an individual event, identification and tracking of individual bedforms between events has proven to be difficult. Apparently, these wave-shaped bedforms are produced during brief, discrete mass transport events.

  19. Small-scale turbidity currents in a big submarine canyon

    USGS Publications Warehouse

    Xu, Jingping; Barry, James P.; Paull, Charles K.

    2013-01-01

    Field measurements of oceanic turbidity currents, especially diluted currents, are extremely rare. We present a dilute turbidity current recorded by instrumented moorings 14.5 km apart at 1300 and 1860 m water depth. The sediment concentration within the flow was 0.017%, accounting for 18 cm/s gravity current speed due to density excess. Tidal currents of ?30 cm/s during the event provided a "tailwind" that assisted the down-canyon movement of the turbidity current and its sediment plume. High-resolution velocity measurements suggested that the turbidity current was likely the result of a local canyon wall slumping near the 1300 m mooring. Frequent occurrences, in both space and time, of such weak sediment transport events could be an important mechanism to cascade sediment and other particles, and to help sustain the vibrant ecosystems in deep-sea canyons.

  20. Multibeam bathymetric survey of the Ipala Submarine Canyon, Jalisco, Mexico (20°N): The southern boundary of the Banderas Forearc Block?

    NASA Astrophysics Data System (ADS)

    Urías Espinosa, J.; Bandy, W. L.; Mortera Gutiérrez, C. A.; Núñez Cornú, Fco. J.; Mitchell, N. C.

    2016-03-01

    The Middle America Trench bends sharply northward at 20°N. This, along with the close proximity of the Rivera-North America Euler pole to the northern end of this trench, sharply increases the obliquity of subduction at 20°N. By analogy with other subduction zones with similar sharply changing obliquity, significant trench parallel extension is expected to exist in the forearc region near the bend. To evaluate this possibility, multibeam bathymetric, seafloor backscatter and sub-bottom seismic reflection data were collected in this area during the MORTIC08 campaign of the B.O. El Puma. These data image in detail a large submarine canyon (the Ipala Canyon) extending from the coast at 20°05‧N to the Middle America Trench at 19°50‧N. This canyon is 114 km long and is fed by sediments originating from two, possibly three, small rivers: the Ipala, Tecolotlán and Maria Garza. This canyon deeply incises (up to 600 m) the entire continental slope and at least the outer part of the shelf. Within the canyon, we observe meanders and narrow channels produced by turbidity flows indicating that the canyon is active. In the marginal areas of the canyon slumps, rills, and uplifts suggest that mass movements and fluid flow have had a major impact on the seafloor morphology. The seafloor bathymetry, backscatter images and sub-bottom reflection profiles evidence the tectonic processes occurring in this area. Of particular interest, the canyon is deflected by almost 90° at three locations, the deflections all having a similar azimuth of between 125° and 130°. Given the prominence and geometry of this canyon, along with its tectonic setting, we propose that the presence of the canyon is related to extension produced by the sharp change in the plate convergence. If so, the canyon may lie along the southeast boundary of a major forearc block (the Banderas Forearc Block).

  1. Characterization and classification of the erosional shapes of submarine canyon systems

    NASA Astrophysics Data System (ADS)

    Vachtman, D.; Mitchell, N. C.

    2009-04-01

    Canyons and gullies are an integral part of slope morphology on most continental margins. The submarine systems extend out for up to a thousand kilometres from the continental margin, forming branched networks whose origin is not well understood. The gradual accumulation of world-wide bathymetric and seismic data on continental margins provides a basis for the classification of slope morphology and consequent erosional and depositional processes which contribute to the formation of the shapes of the submarine systems network. Discussion and development of models for analysis of erosional shapes of submarine networks along continental margins has been confusing and controversial. Since canyon systems may cross both shelf and slope, so that limiting discussion to parts of the system can be problematic. Turbidity currents are generally credited with the excavation of submarine canyons and with transporting sediment down the canyon to the base of the continental slopes to the marine basin. However, studies indicate that turbidity currents are not necessarily the initial cause of the valley formation and, similar to subaerial river valleys, submarine systems are formed by various processes. The valleys of the sea floor appear to have had several origins, producing distinctive types; submarine features may include numerous tributaries entering from both sides, and relief comparable to major land canyons. This study aims to establish to what extent the same origin can be applied to the hundreds of canyons found around various coasts of the world along convergent, divergent and transform continental margins. In the detailed manner, we use examples of available evidence for subaerial erosion and bathymetric data that correspond to different slope curvatures and display unique canyon branching-system morphology. The methodology for quantative classification of canyon systems is based on the bathymetric data and involves 2-D depiction of tributary-like channel networks and the establishment of their spacing, paths of the tributaries and channel patterns. Additionally, we examine main channel and tributary cross-sections with emphasis on the position of the river channel thalwegs, along with the 3-D analysis of shapes of various morphological elements and bedforms. These are performed so that differences in canyon morphology can be related statistically to the properties of downslope progression of slope profile, slope shape and curvature, as well as the competence of the transport mechanism with increasing distance from sediment source. This is in analogy to both subaerial fluvial systems and erosional processes at the shelf break. Quantitative methodologies based on computational geometry used in this study have the potential to construct deductive spatial models of sequences of topological structures, spatial relationships of "non-connected" objects, and integration of objects and space, which might open ways of re-thinking traditional parameter-based approaches for classification of the erosional shapes and processes of submarine canyon systems.

  2. Modelling bottom trawling-generated sediment flows in La Fonera submarine canyon (Northwestern Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Payo-Payo, Marta; Silva Jacinto, Ricardo; Lastras, Galderic; Canals, Miquel; Puig, Pere; Martín, Jacobo; Sanchez-Vidal, Anna; Rabineau, Marina

    2015-04-01

    Bottom-trawling is one of the anthropogenic activities with a stronger and more widespread impact on the seafloor. Physical processes involved in sediment resuspension due to trawling and the resulting sediment-laden flows are not fully understood. The amount and fate of remobilized sediments are of the utmost relevance for establishing present-day continental margin sediment budgets. Resuspension by bottom trawling leads to massive transfer of sediment from shallower to deeper areas practically worldwide. La Fonera submarine canyon is a large, deeply-incised active canyon in the Northwestern Mediterranean Sea. It presents complex sediment transport dynamics associated to littoral drift and extreme events such as dense shelf water cascading and severe storms. Recent studies have revealed recurrent peaks in near-bottom current speed and suspended sediment concentration in the northern flank of the canyon synchronously with trawling. Aiming at simulating sediment-loaded fluxes triggered by trawling and their interaction with the seafloor in La Fonera canyon, we have implemented a numerical process-based model developed to reproduce such flows. Mooring data have been used both to calibrate the modelled sediment fluxes. Good agreement between model and monitoring data has been found, with modelled peaks of suspended sediment concentration values exceeding 120 mg-l-1 and current speed measurements of up to 40 cm-s-1 at the mooring site. Moreover, we have quantified fishing activity over the canyon flanks through modelling and have obtained the propagation pattern of sediment flows from the fishing ground downward the canyon. Our results confirm the value of numerical models to complete and enlarge our understanding of the sedimentary transfer processes from shallow to deep in the ocean. Besides, they allow establishing quantitative comparisons between trawling impact and natural forcing on the sediments dynamics of La Fonera submarine canyon.

  3. Reconstruction of submarine canyon systems associated with proto-Stockton arch during Late Cretaceous

    SciTech Connect

    Rider, J.

    1986-04-01

    A hypothetical depositional model of the middle Great Valley gas fields of California includes the area from the Southwest Vernalis gas field in the south (T3S) to the Nicolaus gas field in the north (T12N). The model assumes that (1) the early Campanian Dobbins Shale Member was deposited at or near the shelf/slope break, and (2) the absence of the Dobbins Shale Member indicates scouring processes of active submarine canyon systems. A striking correlation exists between the proposed distribution of the Dobbins Shale Member scour channels and the position of river systems operating today in the valley. The model distinguishes six submarine canyon systems: (1) Feather River/Nicolaus, (2) American River/Florin, (3) Cosumnes River/Poppy Ridge, (4) Mokelumne River/Lodi, (5) Calaveras delta/Mulligan Hill, and (6) Stanislaus River/East Collegeville. The model implies that an extensive delta system was associated with the Calaveras River during deposition of the Dobbins Shale Member, before its erosive exit southwest of the Mulligan Hill gas field, just east of the Los Medanos, Concord, and Willow Pass fields. The presence of possible equivalents of the Dobbins Shale Member of this latter area suggests an early Campanian highland, the proto-Stockton arch. Subsequent Forbes Formation deposition appears to involve apronlike drapes or overlaps of the early Campanian canyons. However, during deposition of the Kione Formation, the canyon systems were reactivated, and canyon scour predominated, matching the scour patterns of the Dobbins Shale Member. From these ancestral canyons, younger canyons could have evolved easily.

  4. Morphology of Submarine Canyons in the Palomares Margin (East of Alboran Sea, western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Perez-Hernandez, S.; Comas, M. C.; Escutia, C.

    2009-04-01

    Morphological analysis on the Palomares Margin has been done using high-resolution swath bathymetry data collected during the MARSIBAL-06 (2006) cruise on board of the R/V BIO Hespérides. Complemented with data from GEBCO 2000 and Ifremer (Medimap Group, 2007) the data-set provides the first complete bathymetric mosaic of the Palomares Margin. The bathymetric mosaic allows to study the physiographic provinces of the Palomares Margin and to conduct, for the first time, a detailed morphological analysis of the two main sediment-transfer conduits: the Gata and the Alias-Almanzora Canyons. The Gata Canyon extends for 64km from the outer shelf to the base of the slope with a general W-E direction. A tributary system of canyons originates at the shelf break and continues on the slope until they merge at 1230m water depth. The walls of the canyons are characterized by repeated slides. Perpendicular profiles to the Canyon pathway reveal gentle transversal "V" asymmetrical shapes with a marked axial incision on the canyon floor (highs between 65 to 103m in the southern flank, and between 30-90m in the northern flank ). The transition from an erosional canyon to a deposition channel is located at 2100m water depth, and is characterized by trapezoidal shapes on transversal profiles accompanied of lower relieves (40-65m). At the mouth of the canyon-channel system no sedimentary lobes are observed. The Alias-Almanzora canyon (73km long and preferential direction W-E) is located North of the Gata Canyon and extends from the continental shelf to the base of the slope. A tributary system to the Alias- Almanzora canyon-head locates less than 150m from the coast, facing a fluvial drainage system onland. Proximal tributary canyons and gullies feed the main canyon until it merges in the continental slope at 1516m water depth. The tributary system exhibits a marked "V" shape in transverse profiles and marked axial incisions. Down slope, transversal profiles have trapezoidal shapes. Longitudinal profiles show convex-up sections along the tributary system and concave-up sections from the merge in the main canyon down slope. The transition from an erosional canyon to a depositional channel is located at 2100m water depth. The mouth of the Alias-Almanzora Canyon-channel system is characterized by distributaries channels and lobated features. Morphological analyses from these Canyons indicate they have different origin and evolution. The connection of the Alias-Almanzora Canyon to a fluvial drainage system offshore suggests the canyon formed by erosion of the continental shelf edge during sea-level low stand periods, when entrapment of sediment on deltas and reduced sediment transport through submarine canyons occurred. The Gata Canyon has instead developed by head wards erosion and gravitational instabilities. Both canyon systems are highly influenced by recent tectonics, and structural trends influence their location and changes in pathways. Contribution from Projects SAGAS CTM2005-08071-03-01 and TOPO-IBERIA CSD2006-00041 (R & D National Plan of the Ministry of Science and Technology and FEDER funding, Spain).

  5. Litter in submarine canyons off the west coast of Portugal

    NASA Astrophysics Data System (ADS)

    Mordecai, Gideon; Tyler, Paul A.; Masson, Douglas G.; Huvenne, Veerle A. I.

    2011-12-01

    Marine litter is of global concern and is present in all the world's oceans, including deep benthic habitats where the extent of the problem is still largely unknown. Litter abundance and composition were investigated using video footage and still images from 16 Remotely Operated Vehicle (ROV) dives in Lisbon, Setúbal, Cascais and Nazaré Canyons located west of Portugal. Litter was most abundant at sites closest to the coastline and population centres, suggesting the majority of the litter was land sourced. Plastic was the dominant type of debris, followed by fishing gear. Standardised mean abundance was 1100 litter items km -2, but was as high as 6600 litter items km -2 in canyons close to Lisbon. Although all anthropogenic material may be harmful to biota, debris was also used as a habitat by some macro-invertebrates. Litter composition and abundance observed in the canyons of the Portuguese margin were comparable to those seen in other deep sea areas around the world. Accumulation of litter in the deep sea is a consequence of human activities both on land and at sea. This needs to be taken into account in future policy decisions regarding marine pollution.

  6. Sedimentologic evolution of a submarine canyon in a forearc basin, Upper Cretaceous Rosario Formation, San Carlos, Mexico

    SciTech Connect

    Morris, W.R.; Busby-Spera, C.J.

    1988-06-01

    The walls, floor, and fill of a submarine canyon are well-exposed near San Carlos, Mexico, in forecarc strata of the Upper Cretaceous Rosario Formation. The submarine canyon is about 7 km wide and at least 230 m deep and has eroded a minimum of 150 m into underlying fluvial red beds. It is unclear whether subaerial or submarine processes initiated the canyon cutting; however, marine processes, especially debris flows, modified the morphology of the submarine canyon. The submarine canyon fill and overlying slope deposits form two major fining-upward sequences. The first includes a 120 m thick lower conglomerate-sandstone unit (LCSU) at the base of the canyon fill overlain by a 50-110 m thick middle mudstone-sandstone unit (MMSU). The MMSU consists predominantly of mudstone and thin-bedded sandstone, but includes a channel filled with sandstone beds that form a fining- and thinning-upward sequence. This sequence is overlain by the second major sequence, a 0-60 m thick upper conglomerate-sandstone unit (UCSU), which is confined to three channels within the submarine canyon and passes gradationally upward into slope mudstone. Each of the two major fining-upward sequences records a gradual decrease in supply of coarse-grained sediment to the submarine canyon head. The first fining-upward sequence may correspond to a lowstand and subsequent rise in global sea level or, alternatively, may have resulted from local downdropping of the basin. The second fining-upward sequence does not correspond to global sea level fluctuations but is age-correlative with a drop then rise in relative sea level recognized by other workers 300-400 km to the north in the San Diego-Ensenada area. This sea level drop is inferred to have been a regional-scale tectonic event that affect the forearc basin along its length. 18 figures, 2 tables.

  7. Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin

    NASA Astrophysics Data System (ADS)

    Richter, T. O.; de Stigter, H. C.; Boer, W.; Jesus, C. C.; van Weering, T. C. E.

    2009-02-01

    Submarine canyons represent natural conduits for preferential transport of particulate material, including anthropogenic contaminants, from coastal zones directly to the deep sea. To assess related dispersal of natural and anthropogenic lead (Pb), we analyzed Pb concentrations and stable isotope ratios in surface sediments and sediment trap particulate material from the Portuguese margin Nazaré and Setúbal/Lisbon canyons. Geochemical data are integrated with previously obtained data on near-bottom hydrodynamics and processes and pathways of sediment transport. The two canyon systems are located in close geographic proximity to each other, but represent contrasting settings in terms of sediment input and down-canyon sediment transport processes. Concentration-isotope diagrams and three-isotope plots ( 206Pb/ 207Pb vs. 208Pb/ 206Pb) suggest binary mixing between natural and anthropogenic end members. The inferred isotopic signature of pollutant Pb ( 206Pb/ 207Pb=1.143 [1.134-1.149, 95% confidence interval]) is most consistent with industrial Pb; ongoing influence from gasoline Pb additives is at most of minor importance. Two proposed natural end members most likely bracket the isotopic signature of natural Pb. Accordingly, binary mixing calculations indicate that on average 20-45% vs. 35-55% of total Pb is derived from anthropogenic sources in the Nazaré and Setúbal-Lisbon canyon systems, respectively. Enhanced anthropogenic influence in the latter area is consistent with its proximity to heavily populated and industrialized areas and with sediment input from the Tagus and Sado rivers, potential major carriers of pollutant particles. In both canyon systems, the anthropogenic component generally decreases with increasing water depth. Isotopic signatures of sediment trap particulate material are generally consistent with surface sediment data at similar water depth, but show large variability in the upper Nazaré canyon and major deviations from surface sediments in the lower canyon. In the lower canyon, Pb isotopic ratios of sediment trap particulate material mostly reflect low pelagic fluxes from the overlying water column, whereas surface sediment signatures are dominated by episodic down-canyon mass transport events. Such gravity flows appear to incorporate older (pre-industrial) material masking the isotopic signature of pollutant Pb. Large variability in the upper canyon reflects continuous sediment resuspension by bottom currents. Stronger average bottom currents are associated with higher 206Pb/ 207Pb ratios of sediment trap particulate material and hence decreased influence of pollutant Pb. This may reflect preferential resuspension of natural Pb at the canyon floor and/or additional remobilization of older, less-polluted sediment in adjacent areas such as the canyon walls.

  8. Sedimentary regime of deep submarine canyons around Fylla Banke, northeastern Labrador Sea

    NASA Astrophysics Data System (ADS)

    Paulsen, Dorthe; Kuijpers, Antoon; Seidenkrantz, Marit-Solveig; Nielsen, Tove

    2014-05-01

    Sedimentary regime of deep submarine canyons around the Fylla Banke, northeastern Labrador Sea Dorthe Paulsen (1), Antoon Kuijpers (2), Marit-Solveig Seidenkrantz (3) and Tove Nielsen (2) 1) Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K 2) Geological Survey of Denmark and Greenland (GEUS), Øster Voldgde 10, DK-1350 Copenhagen K. 3) Centre for Past Climate Studies, Department of Geoscience, Aarhus University. Hoegh-Guldbergs Gade 2, DK-8000 Aarhus C The southern end of the Davis Strait, the comparatively shallow-water area separating the Labrador Sea from the Baffin Bay, is cut by two deep submarine canyons of west Greenland, on the western and eastern side of the Fylla Banke, respectively. The purpose of this study is to investigate Late Pleistocene sedimentary processes governing the area of the two canyons in order to test if gravity flows or ocean currents are the most important factors governing canyon sedimentary processes in this region. Furthermore, an account is given on the formation of the two canyons in order to explain the significant difference between them. The study was carried out based on seismic profiles combined with bathymetric information, and a single sidescan sonar profile from one of the canyons (western canyon). Sedimentary information and an age model are derived from of a 5-m long gravity core (TTR13-AT-479G) collected from the mouth of the western canyon (southern end). The data indicates that the sedimentary regime is today highly affected by northward transport of the ocean currents and that gravity flows (southward from shallower to deep waters) are only of limited significance today. The deep southern end of the canyons are influenced by the upper parts of the deep North Atlantic Deep Water, but the majority of the sediment transport is linked to the strong northward flow of the lower parts of the West Greenland Current. For comparison the sediment transport is held up against earlier studies from the Davis Strait area, where 2D seismic profiles were carried out several places of the west coast of Greenland. These studies are from a contourite drift complex at the Davis Strait and north of Labrador Sea. A further possible process operating in maintaining active sediment transport through the canyon may be the cascading of dense winter water formed on the West Greenland shelf.

  9. Rapid Changes on Sediment Accumulation Rates within Submarine Canyons Caused By Bottom Trawling Activities

    NASA Astrophysics Data System (ADS)

    Puig, P.; Masque, P.; Martin, J.; Paradis, S.; Juan, X.; Toro, M.; Palanques, A.

    2014-12-01

    The physical disturbance of the marine sedimentary environments by commercial bottom trawling is a matter of concern. The direct physical effects of this fishing technique include scraping and ploughing of the seabed and increases of the near-bottom water turbidity by sediment resuspension. However, the quantification of the sediment that has been resuspended by this anthropogenic activity over years and has been ultimately exported across the margin remains largely unaddressed. The analysis of sediment accumulation rates from sediment cores collected along the axes of several submarine canyons in the Catalan margin (northwestern Mediterranean) has allowed to estimate the contribution of this anthropogenic activity to the present-day sediment dynamics. 210Pb chronologies, occasionally supported by 137Cs dating, indicate a rapid increase of sediment accumulation rates since the 1970s, in coincidence with a strong impulse in the industrialization of the trawling fleets of this region. Such increase has been associated to the enhanced delivery of sediment resuspended by trawlers from the shelves and upper slope regions towards the canyon's interior, and to the rapid technical development at that time, in terms of engine power and gear size. This change has been observed in La Fonera (or Palamós) Canyon at depths greater than 1700 m, while in other canyons it is restricted to shallower regions (~1000 m in depth) closer to fishing grounds. Two sampling sites from La Fonera and Foix submarine canyons that exhibited high sediment accumulation rates (0.6-0.7 cm/y) were reoccupied several years after the first chronological analyses. These two new cores reveal a second and more rapid increase of sediment accumulation rates in both canyons occurring circa 2002 and accounting for about 2 cm/y. This second change at the beginning of the XXI century has been attributed to a preferential displacement of the trawling fleet towards slope fishing grounds surrounding submarine canyons, and also to technical improvements in trawling vessels, presumably related to subsidies and aids provided by the European Commission to the fishing industry.

  10. Increasing sediment accumulation rates in La Fonera (Palams) submarine canyon axis and their relationship with bottom trawling activities

    NASA Astrophysics Data System (ADS)

    Puig, P.; Martn, J.; Masqu, P.; Palanques, A.

    2015-10-01

    Previous studies conducted in La Fonera (Palams) submarine canyon (NW Mediterranean) found that trawling activities along the canyon flanks cause resuspension and transport of sediments toward the canyon axis. 210Pb chronology supported by 137Cs dating applied to a sediment core collected at 1750 m in 2002 suggested a doubling of the sediment accumulation rate since the 1970s, coincident with the rapid industrialization of the local trawling fleet. The same canyon area has been revisited a decade later, and new data are consistent with a sedimentary regime shift during the 1970s and also suggest that the accumulation rate during the last decade could be greater than expected, approaching ~2.4 cm yr-1 (compared to ~0.25 cm yr-1 pre-1970s). These results support the hypothesis that commercial bottom trawling can substantially affect sediment dynamics and budgets on continental margins, eventually initiating the formation of anthropogenic depocenters in submarine canyon environments.

  11. A comparison of megafaunal communities in five submarine canyons off Southern California, USA

    NASA Astrophysics Data System (ADS)

    Duffy, Grant A.; Lundsten, Lonny; Kuhnz, Linda A.; Paull, Charles K.

    2014-06-01

    Remotely operated vehicle surveys were conducted in five submarine canyons off Southern California during research expeditions in 2005 and 2010. Video transects from a range of depths were analysed to produce presence/absence data of megafauna for each site. A comparison of benthic communities at various depths, locales, and canyons was performed. No significant difference was found between canyon communities based on the level of sediment transport activity, however this may be due to the unbalanced sampling of this opportunistic study. There was significant variation in biological community composition and abundance amongst water depths. These depth-related trends are in agreement with the findings of the previous studies and are likely tied to depth-correlated variables such as hydrostatic pressure, temperature, salinity, and oxygen concentration. Species richness was found to initially increase with depth before declining rapidly at the mouths of the studied canyons. Low oxygen levels in the Santa Monica Basin, into which four of the surveyed canyons empty, may explain this.

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

    USGS Publications Warehouse

    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 subtle modification by Holocene processes active during the present sea-level high-stand.

  13. Contemporary Suspended Sediment Fluxes Through the Gulf of Lion Submarine Canyons.

    NASA Astrophysics Data System (ADS)

    Palanques, A.; Puig, P.; de Madron, X. D.; Guillen, J.; Calafat, A.; Fabres, J.; Heussner, S.; Canals, M.

    2004-12-01

    The Gulf of Lion continental margin receives sediment inputs from the River Rhone as well as from some smaller rivers. From the west to the east ends of this margin, the slope is incised by numerous submarine canyons and the shelf-slope suspended sediment transfer through these canyons is not well known. In the framework of the EUROSTRATAFORM Project (EVK3-CT-2002-00079, EU Fifth Framework Programme: Energy, Environment and Sustainable Development), contemporary suspended sediment transport in the head of seven submarine canyon of the Gulf of Lion was studied by deploying moorings with Aanderaa RCM9/11 current meters equipped with turbidimeters 5 m above bottom at 300 m depth from November 2003 to May 2004. In these time period, there were several sediment transport events, but two of them were especially relevant: one in Early December 2003 and another one in late February 2004. The December event was generated by a "wet storm" during which rivers discharges increased up to one order of magnitude and a cyclonic along-shore advection of a cold, brackish and turbid stream developed in the shelf, whereas the February event was generated by a "dry storm" without associated relevant rivers discharges increases and with an advective transport of fine sediment across the shelf due to cascading of cold, dense water. During these events, the maximum suspended sediment transport took place through the Cap de Creus canyon (at the western end of the Gulf of Lion) where sediment fluxes increased up to two orders of magnitude, and also a relevant transport occurred in other western (Lacaze-Duthier) and central canyons (Herault and Petit Rhone) where sediment fluxes increased up to one order of magnitude. However sediment fluxes in the eastern canyons (Planier and Grand Rhone) did not increase during these events. Other minor sediment flux increases in winter were associated to dense water cascading. This study indicates a preferential shelf-slope sediment transfer through the central and western canyons of the Gulf of Lion and especially through the Cap de Creus canyon.

  14. Lateral advection of organic matter in cascading-dominated submarine canyons

    NASA Astrophysics Data System (ADS)

    Tesi, T.; Puig, P.; Palanques, A.; Goi, M. A.

    2010-03-01

    In the Gulf of Lions (GoL), dense water overflowing off the shelf occurs seasonally and represents the main mechanism affecting the shelf-slope exchange of particulate organic matter (OM). Most of the dense water export takes place in the south-western GoL and in particular through Cap de Creus (CdC) submarine canyon. Here, benthic instruments were deployed to collect down-canyon particulate fluxes whereas surface sediments were taken after the cascading event along the sediment dispersal system on the shelf, in CdC canyon and in the nearby Lacaze-Duthiers (LD) canyon. The chemical composition of the suspended material and surface sediments were investigated using several proxies including organic and inorganic carbon, total nitrogen, biogenic silica, ? 13C, ? 14C, and alkaline CuO oxidation products. Thermohaline anomalies and high current speed events were measured in CdC canyon since December 2004 until mid-April 2005 indicating a marked off-shelf export of dense water trough the canyon. During the cascading, mud and relatively coarse shelf and upper canyon sediments were the major component of the mass flux. Conversely, advection of fine material via nepheloid layers dominated down-slope fluxes during pre- and post-cascading. The resulting change in grain-size affected the flux of mineral-bound terrigenous OC, indicating that the down-canyon transport of land-derived OM did not occur as bulk but rather its composition is driven by sediment sorting associated with different transport mechanisms. Both surface sediments and sediment trap samples indicated that CdC canyon is well connected to the GoL terrigenous dispersal system. Conversely, our results suggest an overall limited influence of land-derived OM in LD canyon. In spite of the reduced fluvial nutrient supply, a significant pulsed input of modern marine OM was observed in April 2005 at the end of the cascading period. Both intense mixing and lack of strong water column stratification likely played a key role allowing for both diffusion of nutrients-rich waters into the euphotic zone and efficient vertical sink of marine OC. On its way toward the seafloor, this fresh pool of OC interacted with the dense plume overflowing off the shelf, becoming part of the material laterally advected to the slope.

  15. Biodiversity of macrofaunal assemblages from three Portuguese submarine canyons (NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Cunha, Marina R.; Paterson, Gordon L. J.; Amaro, Teresa; Blackbird, Sabena; de Stigter, Henko C.; Ferreira, Clarisse; Glover, Adrian; Hilário, Ana; Kiriakoulakis, Konstadinos; Neal, Lenka; Ravara, Ascensão; Rodrigues, Clara F.; Tiago, Áurea; Billett, David S. M.

    2011-12-01

    The macrofaunal assemblages from three Portuguese submarine canyons, Nazaré, Cascais and Setúbal were studied from samples collected at their upper (900-1000 m), middle (3200-3500 m) and lower sections (4200-4500 m) and at the adjacent open slopes (˜1000 m), during the HERMES cruises D297 (R.R.S. Discovery, 2005) CD179 (R.R.S. Charles Darwin, 2006) and 64PE252 (R.V. Pelagia, 2006). The taxonomic composition and patterns in biodiversity, abundance and community structure of the benthic macrofauna were described. Annelida (42.1% of total abundance; 137 species) and Arthropoda (20.6%; 162 species) were, respectively, the most abundant and the most species-rich Phyla among the 342 taxa identified during this study. Multivariate analyses showed significant differences between and within canyons and between canyons and open slope assemblages. At their upper section, canyons supported higher macrofauna abundance but slightly lower biodiversity than the adjacent slopes at similar depth. In all canyons abundance reached the highest value in the middle section and the lowest in the upper section, with marked fluctuations in Nazaré (474-4599 ind. m -2) and lower variability in Cascais (583-1125 ind. m -2). The high abundance and dominance of the assemblages in the middle section of Nazaré and Setúbal was accompanied by depressed biodiversity, while in Cascais, Hurlbert's expected species richness showed increasing values from the upper to the middle canyon, and maintained the high values at the lower section. Overall, the Nazaré Canyon showed the lowest expected species richness (ES (100): 16-39) and the Cascais Canyon the highest (39-54). There was a significant negative Kendall's correlation between total organic carbon concentrations in the superficial sediments and ES (100) and a significant positive correlation between total nitrogen and macrofauna density. The influences of organic enrichment, sediment heterogeneity and hydrodynamic regime on the abundance, diversity and community structure of the macrofauna are discussed. It is suggested that altered and localised environmental conditions in the Portuguese canyons play an important role in modifying more common abundance and diversity bathymetric patterns evident in many continental slope environments.

  16. The surface sediment distribution and sedimentary environment of the Pearl River Submarine Canyon

    NASA Astrophysics Data System (ADS)

    Han, X.; Chu, F.; Li, J.; Xu, D.; Zhang, W.

    2012-12-01

    The grain size composition, particle size parameters, clay mineral, and detrital mineral of surface sediment of this The Pearl River Submarine Canyon (the PRSC, for short) area have been measured and analyzed, which were took sampling in 2005 and 2006 in the northern South China Sea. The results show that the isolines distribution features of these parameters have very good corresponding relation with the geomorphology of the PRSC. On the continental-shelf slope break of the PRSC head (123m-1500m water depth), the close interval isolines of the surface sediment particle size percentage content and size parameters nearly parallel with the water depth isolines. The data of sand percentage content and mean grain size, sorting coefficient and skewness decreases with the increase of water depth. The other way around, the silt and clay percentage content and kurtosis value increase with deeper water. These show that in the canyon head sediment distribution was controlled by the material source (mainly comes from the Pearl River), slope and the northern South China Sea offshore current. In the main PRSC area, the surface sediment grain size composition content and grain size parameter numerical isolines have become a isoline platform which has the similar shape with the main PRSC and extended to the northeast and southwest deep sea basin. This means that the sedimentary environment of main canyon is apparently different with the head environment, that is affected by the high-temperature and high-salt the South China Sea Branch of by the Kuroshio along the 3500 m water depth isoline and alone the canyon to bending. The 25% percentage content isoline of the calcium biological and 45% percentage content isoline of the light mineral show a broadband distribution along the head and upside of the PRSC, and reduces in the entrance with the water depth isolines, apparently influenced by the South China Sea Branch of the Kuroshio. A high value area of the silt, clay mineral, light mineral, heavy mineral, silicon biological, and calcium biological appears to the entrance of the PRSC, which may be controlled by a perennial anticlockwise current. But how the materials passed through the South China Sea Branch of the Kuroshio and sediment here still is not be solved. The distribution of clay minerals close to the distribution of grain size, around the main canyon with more loose and uniform interval value isolines. It is lower of the percentage content isolines value of the Illite, Kaolinite and Chlorite in the canyon than the values around the canyon (specially at northeast, northwest, southwest ). And the Smectite percentage content has the opposite distribution, the value is higher in the canyon than out the canyon. Which means that the Traditional knowledge about ocean clay minerals distribution is influenced by the latitude is not adaptive at submarine canyon area. To sum up, the existence of the PRSC has changed the material transport mode from land to deep ocean basin in the northern South China Sea. Not only it played a transfer passageway, but also it played the role of the sorting and aggregation, which is beneficial to the formation and gathering of certain minerals. This work were supported by the NSFC (41106046), the Youth Ocean Science Fund Project, SOA(2011333) and the Basic Scientific Researching Specific Funds of SIO, SOA (JT1002)

  17. A multidisciplinary study of the role of submarine canyons off western Portugal

    NASA Astrophysics Data System (ADS)

    Vitorino, J.; Oliveira, A.; Rodrigues, A.

    2003-04-01

    A multidisciplinary research aimed to characterise the dominant aspects of the Portuguese canyon systems and their role on the shelf-deep ocean sediment exchanges is being conducted in the framework of EU project Eurostrataform. Three contrasting systems are studied: (1) the Nazaré Canyon is a narrow and deep canyon which extends from the deep ocean and completely cuts the NW Portuguese shelf, with no local riverine sources; (2) the Setubal-Lisbon canyon system affects an area marked by complex topography and coastline configuration and with riverine contributions provided by the Tagus and Sado rivers; (3) the Oporto canyon is restricted to the outer shelf, with a major local riverine source (Douro river). We present preliminary results from the ongoing program of observations, which includes multidisciplinary surveys (CTD, suspended particle matter measurments, shallow seismic) and both long- and short-term moorings. Process studies are extended with the use of system MOCASSIM, an operational system for the forecast of oceanographic conditions off the Portuguese coast, which is presently being developped at Instituto Hidrografico. The system integrates wave and circulation models and makes use of data assimilation methods to provide numerical results which are consistent with the observed conditions.

  18. Habitat heterogeneity, disturbance, and productivity work in concert to regulate biodiversity in deep submarine canyons.

    PubMed

    McClain, Craig R; Barry, James P

    2010-04-01

    Habitat heterogeneity is a major structuring agent of ecological assemblages promoting beta diversity and ultimately contributing to overall higher global diversity. The exact processes by which heterogeneity increases diversity are scale dependent and encompass variation in other well-known processes, e.g., productivity, disturbance, and temperature. Thus, habitat heterogeneity likely triggers multiple and cascading diversity effects through ecological assemblages. Submarine canyons, a pervasive feature of the world's oceans, likely increase habitat heterogeneity at multiple spatial scales similar to their terrestrial analogues. However, our understanding of how processes regulating diversity, and the potential for cascading effects within these important topographic features, remains incomplete. Utilizing remote-operated vehicles (ROVs) for coring and video transects, we quantified faunal turnover in the deep-sea benthos at a rarely examined scale (1 m-1 km). Macrofaunal community structure, megafaunal density, carbon flux, and sediment characteristics were analyzed for the soft-bottom benthos at the base of cliff faces in Monterey Canyon (northeast Pacific Ocean) at three depths. We documented a remarkable degree of faunal turnover and changes in overall community structure at scales < 100 m, and often < 10 m, related to geographic features of a canyon complex. Ultimately, our findings indicated that multiple linked processes related to habitat heterogeneity, ecosystem engineering, and bottom-up dynamics are important to deep-sea biodiversity. PMID:20462112

  19. A million miles from rivers: secondary flow in submarine canyon-fan systems.

    NASA Astrophysics Data System (ADS)

    Dorrell, Robert; Darby, Steve; Peakall, Jeff; Parsons, Dan; Sumner, Esther; Wynn, Russell

    2013-04-01

    In both subaerial and submarine meander bends, fluid flow travels in a helical spiral, as centrifugal and hydrostatic forces balance the turbulent shear stress within the flow. Understanding the sense of the secondary flow circulation is important because the near bed orientation of the fluid flow vector strongly affects sediment transport and hence meander bend morphodynamic evolution, the patterns of surface grain size sorting and therefore the character of the sedimentary deposits produced. To evaluate the conditions favouring the onset of distinctive secondary flow circulations (and in particular, to discriminate cases when the near-bed radial flow is directed towards the inner bank ('river like') or outer bank ('river reversed'), we develop a holistic analytical model incorporating centrifugal and Coriolis forces, the radial pressure gradient and the baroclinicity of the flow. This new model is validated using experimental data and used to highlight the influence on the secondary flow of the principle physical forces acting on the flow. Previous analytical studies have considered a temporally constant, two-dimensional, rotationally invariant, framework that leads to vanishing radial material flux conditions when applied to flows within bounded channels. However, we show that a three-dimensional flow framework, with non-zero radial material fluxes resultant of flow super-elevation and overspill, is required to capture the rotational structure of flow within submarine meanders. Given this three-dimensional model, we present phase-space diagrams indicating the variation of the generic vertical structure of rotational flow within submarine meanders. Our findings highlight the importance of the radial flux boundary conditions as the primary control of secondary flow dynamics of submarine meanders. Further, the new model presented here suggests that the propensity for the occurrence of "river-reversed" secondary flow in canyon-fan networks is greater than recently advocated.

  20. Flow and mixing in Ascension, a steep, narrow canyon

    NASA Astrophysics Data System (ADS)

    Gregg, M. C.; Hall, R. A.; Carter, G. S.; Alford, M. H.; Lien, R.-C.; Winkel, D. P.; Wain, D. J.

    2011-07-01

    A thin gash in the continental slope northwest of Monterey Bay, Ascension Canyon, is steep, with sides and axis both strongly supercritical to M2 internal tides. A hydrostatic model forced with eight tidal constituents shows no major sources feeding energy into the canyon, but significant energy is exchanged between barotropic and baroclinic flows along the tops of the sides, where slopes are critical. Average turbulent dissipation rates observed near spring tide during April are half as large as a two week average measured during August in Monterey Canyon. Owing to Ascension's weaker stratification, however, its average diapycnal diffusivity, 3.9 × 10-3 m2 s-1, exceeded the 2.5 × 10-3 m2 s-1 found in Monterey. Most of the dissipation occurred near the bottom, apparently associated with an internal bore, and just below the rim, where sustained cross-canyon flow may have been generating lee waves or rotors. The near-bottom mixing decreased sharply around Ascension's one bend, as did vertically integrated baroclinic energy fluxes. Dissipation had a minor effect on energetics, which were controlled by flux divergences and convergences and temporal changes in energy density. In Ascension, the observed dissipation rate near spring tide was 2.1 times that predicted from a simulation using eight tidal constituents averaged over a fortnightly period. The same observation was 1.5 times the average of an M2-only prediction. In Monterey, the previous observed average was 4.9 times the average of an M2-only prediction.

  1. The summer assemblage of large pelagic Crustacea in the Gully submarine canyon: Major patterns

    NASA Astrophysics Data System (ADS)

    MacIsaac, K. G.; Kenchington, T. J.; Kenchington, E. L. R.; Best, M.

    2014-06-01

    We describe the trawl-vulnerable crustacean micronekton and macrozooplankton of the Gully, a large, shelf-incising submarine canyon off Nova Scotia, Canada, and a Marine Protected Area. Over 68 species of pelagic crustacea were collected with an International Young Gadoid Pelagic Trawl during three annual summer surveys at one fixed station in the canyon. Depths sampled ranged from the surface to the upper bathypelagic zone, concentrated in the upper 1250 m, with a maximum depth of 1500 m. The crustacean fauna was dominated by cold temperate species typical of mid- to higher-latitudes in the North Atlantic. Meganyctiphanes norvegica and Eusergestes arcticus were particularly dominant in terms of both observed biomass and abundance above 750 m depth. At least 17 species were new records for Canadian waters. The species assemblage of the station varied primarily with depth and diel cycle, the only dominant members of the assemblage showing pronounced inter-annual variations in catch being M. norvegica and Themisto gaudichaudii, both relatively shallow living species.

  2. Modeled alongshore circulation and morphologic evolution onshore of a large submarine canyon

    NASA Astrophysics Data System (ADS)

    Hansen, J. E.; Raubenheimer, B.; List, J. H.; Elgar, S.; Guza, R. T.; Lippmann, T. C.

    2012-12-01

    Alongshore circulation and morphologic evolution observed at an ocean beach during the Nearshore Canyon Experiment, onshore of a large submarine canyon in San Diego, CA (USA), are investigated using a two-dimensional depth-averaged numerical model (Delft3D). The model is forced with waves observed in ~500 m water depth and tidal constituents derived from satellite altimetry. Consistent with field observations, the model indicates that refraction of waves over the canyon results in wave focusing ~500 m upcoast of the canyon and shadowing onshore of the canyon. The spatial variability in the modeled wave field results in a corresponding non-uniform alongshore circulation field. In particular, when waves approach from the northwest the alongshore flow converges near the wave focal zone, while waves that approach from the southwest result in alongshore flow that diverges away from the wave focal zone. The direction and magnitude of alongshore flows are determined by a balance between the (often opposing) radiation stress and alongshore pressure gradients, consistent with observations and previous results. The largest observed morphologic evolution, vertical accretion of about 1.5 m in about 3 m water depth near the wave focal zone, occurred over a one-week period when waves from the northwest reached heights of 1.8 m. The model, with limited tuning, replicates the magnitude and spatial extent of the observed accretion and indicates that net accretion of the cross-shore profile was owing to alongshore transport from converging alongshore flows. The good agreement between the observed and modeled morphology change allows for an in-depth examination of the alongshore force balance that resulted in the sediment convergence. These results indicate that, at least in this case, a depth-averaged hydrodynamic model can replicate observed surfzone morphologic change resulting from forcing that is strongly non-uniform in the alongshore. Funding was provided by the Office of Naval Research, The National Science Foundation, a Woods Hole Oceanographic Institution and United States Geological Survey joint postdoctoral fellowship, and a National Security Science and Engineering Faculty Fellowship.

  3. Slope basins, headless canyons, and submarine palaeoseismology of the Cascadia accretionary complex

    USGS Publications Warehouse

    McAdoo, B.G.; Orange, D.L.; Screaton, E.; Lee, H.; Kayen, R.

    1997-01-01

    A combination of geomorphological, seismic reflection and geotechnical data constrains this study of sediment erosion and deposition at the toe of the Cascadia accretionary prism. We conducted a series of ALVIN dives in a region south of Astoria Canyon to examine the interrelationship of fluid flow and slope failure in a series of headless submarine canyons. Elevated head gradients at the inflection point of canyons have been inferred to assist in localized failures that feed sediment into a closed slope basin. Measured head gradients are an order of magnitude too low to cause seepage-induced slope failure alone; we therefore propose transient slope failure mechanisms. Intercanyon slopes are uniformly unscarred and smooth, although consolidation tests indicate that up to several metres of material may have been removed. A sheet-like failure would remove sediment uniformly, preserving the observed smooth intercanyon slope. Earthquake-induced liquefaction is a likely trigger for this type of sheet failure as the slope is too steep and short for sediment flow to organize itself into channels. Bathymetric and seismic reflection data suggest sediment in a trench slope basin between the second and third ridges from the prism's deformation is derived locally. A comparison of the amounts of material removed from the slopes and that in the basin shows that the amount of material removed from the slopes may slightly exceed the amount of material in the basin, implying that a small amount of sediment has escaped the basin, perhaps when the second ridge was too low to form a sufficient dam, or through a gap in the second ridge to the south. Regardless, almost 80% of the material shed off the slopes around the basin is deposited locally, whereas the remaining 20% is redeposited on the incoming section and will be re-accreted.

  4. Submarine canyons of the north-western Sicilian offshore (Southern Tyrrhenian Sea): variability in morphologies, sedimentary processes and tectonic settings

    NASA Astrophysics Data System (ADS)

    Lo Iacono, Claudio; Sulli, Attilio; Agate, Mauro; Pennino, Valentina

    2013-04-01

    Swath-bathymetry and high-resolution seismic reflection records acquired during the last two decades in the northern Sicilian offshore has unveiled a dense network of submarine canyons within the depth range of 80-2100 m, displaying a relevant variability in their geometry, morphologies and sedimentary processes. The studied margin shows a young, tectonically active shelf to slope setting linking the Sicilian-Maghrebian Thrust Belt to the Tyrrhenian oceanic realm, developed during the Neogene-Quaternary time span. The aim of this study is to highlight the main governing factors that contributed to the evolution and differentiation of the northern Sicilian canyons, mainly focusing on the Gulf of Castellamare and on the Gulf of Palermo areas. Canyons range 10-62 km in length and 1-5 km in amplitude, the slope gradient along their axis ranges between 1.8 and 9 and their sinuosity index ranges between 1 and 1.7. Generally, canyons, tributaries and gullies mapped in the Gulf of Castellamare indent the shelf-edge and display sinuous to meandriform paths on a upward concave gently sloping margin, showing a relevant role of coastal/shelf sedimentary inputs in their evolution. Otherwise, canyons along the upward convex slope in the Palermo Gulf are steep and almost linear, with retrograding submarine landslides controlling their evolution and only one canyon (the Oreto Canyon) showing a proved connection with fluvial sedimentary inputs. Results suggest that the different structural settings of the Castellammare and Palermo basins, together with an inferred difference in fluvial sedimentary inputs, are responsible for the variability of the north-western Sicilian submarine canyon systems, which originated and evolved contemporary with the upper Pliocene(?)-Quaternary sedimentary succession and have probably been more active during the Quaternary glacial maxima. On a local scale, neo-tectonic features, mass-movements and fluid seeps processes are significant controlling factors on the distribution of the canyons. The present day morphology of the margin shows that the most incised canyons are those facing the prominent capes along the coast, suggesting how the interaction of bottom currents with the shelf geometry likely has controlled their recent evolution.

  5. Tidal and flood signatures of settling particles in the Gaoping submarine canyon (SW Taiwan) revealed from radionuclide and flow measurements

    USGS Publications Warehouse

    Huh, C.-A.; Liu, J.T.; Lin, H.-L.; Xu, J. P.

    2009-01-01

    Sediment transport and sedimentation processes in the Gaoping submarine canyon were studied using sediment trap and current meter moorings deployed at a location during the winter (January-March) and the summer (July-September) months in 2008. At the end of each deployment, sediment cores were also collected from the canyon floor at the mooring site. Samples from sediment traps and sediment cores were analyzed for 210Pb and 234Th by gamma spectrometry. In conjunction with particle size and flow measurements, the datasets suggest that sediment transport in the canyon is tidally-modulated in the drier winter season and flood (river)-dominated in the wetter summer season. From the magnitude and temporal variation of sediment flux in the canyon with respect to the burial flux and sediment budget on the open shelf and slope region, we reaffirm that, on annual or longer timescales, the Gaoping submarine canyon is an effective conduit transporting sediments from the Gaoping River's drainage basin (the source) to the deep South China Sea (the ultimate sink). ?? 2009 Elsevier B.V.

  6. Particle fluxes and their drivers in the Avilés submarine canyon and adjacent slope, central Cantabrian margin, Bay of Biscay

    NASA Astrophysics Data System (ADS)

    Rumín-Caparrós, A.; Sanchez-Vidal, A.; González-Pola, C.; Lastras, G.; Calafat, A.; Canals, M.

    2016-05-01

    The Avilés Canyon in the central Cantabrian margin is one of the largest submarine canyons in Europe, extending from the shelf edge at 130 m depth to 4765 m depth in the Biscay abyssal plain. In this paper we present the results of a year-round (March 2012 to April 2013) study of particle fluxes in this canyon and the adjacent continental slope. Three mooring lines equipped with automated sequential sediment traps, high-accuracy conductivity-temperature recorders and current meters allowed measuring total mass fluxes and their major components (lithogenics, calcium carbonate, opal and organic matter) in the settling material jointly with a set of environmental parameters. The integrated analysis of the data obtained from the moorings together with remote sensing images and meteorological and hydrographical data has shed light on the sources of particles and the across- and along margin mechanisms involved in their transfer to the deep. Our results allow interpreting the dynamics of the sedimentary particles in the study area. Two factors play a critical role: (i) direct delivery of river-sourced material to the narrow continental shelf, and (ii) major resuspension events caused by large waves and near bottom currents developing at the occasion of the rather frequent severe storms that are typical of the Cantabrian Sea. Wind direction and subsequent wind-driven currents largely determine the way sedimentary particles reach the canyon. While westerly winds favour the injection of sediments into the Avilés Canyon mainly by building an offshore transport in the bottom Ekman layer, easterly winds ease the offshore advection of particulate matter towards the Avilés Canyon and its adjacent western slope principally through the surface Ekman layer. Furthermore, repeated cycles of semidiurnal tides add an extra amount of energy to the prevailing bottom currents and actively contribute to keep a permanent background of suspended particles in near-bottom waters. High contents of lithogenics in settling particles at the three mooring stations confirm that riverine inputs are the principal source of particles to the Avilés Canyon, including the lowermost canyon, and the adjacent open slope. Primary production also has a strong influence on the amount and the composition of particulate matter, with more than 30% of the total mass flux being of biogenic origin (organic matter, opal and calcium carbonate).

  7. Geomorphology and sediment processes on the continental shelf and the submarine Akhziv canyon offshore north Galilee, eastern Mediterranean.

    NASA Astrophysics Data System (ADS)

    Ashqar, Lana; Bookman, Revital; Almogi-Labin, Ahuva; Ben-Avraham, Zvi

    2013-04-01

    The northern continental shelf of Israel is relatively steep and incised by submarine canyons. The Akhziv canyon is the largest and most developed and the southernmost in a series of canyons that formed off-shore Lebanon up to Beirut. The canyon is incised into the continental shelf 3 km from the northwestern Galilee coast to a depth of 1200 m. This study aims to understand processes responsible for the canyon morphology and the nature of sediment transport and accumulation mechanisms in the continental shelf and down the canyon to the deep sea. Moreover, the geological section in which the canyon is incised to, and the connection to the western Galilee fault system that transverse the continental shelf is explored for the regional perspective. Akhziv canyon consists of two main channels incised in cross-section V-shape at the upper part of the canyon that connect at 700m depth to produce a U-shaped main channel. The canyon's channels orientation implies a possible connection with the region's fault system. The high-resolution bathymetric map (the National Bathymetry Project) was used for the geomorphologic and morphometric analysis to define the connection between the canyon and the north- western Galilee streams that flow in a main east-west direction, parallel to the terrestrial fault system. Gaps in the submarine aeolian calcarenite ridge on the shallow shelf represent the continuation of terrestrial streams westward during low glacial sea level. Alluvial fans, mapped at 40m water depth, testify for sediment transport from land to the continental shelf toward the canyon head. Shallow high-resolution seismic lines (Sparker) were carried out along the continental shelf and canyon head to reveal the sub-surface structure. The seismic interpretation indicates the presence of channel incisions at depths of 10-15 m under the seafloor, with infill of young sediments which represents phases of deposition and erosion along the continental shelf. In addition, Piston cores (2-3 m) and short cores (30-50 cm) were sampled along the main axis of Akhziv canyon and thalweg, from depths of 40 m to 700 m. X-ray reflections of the cores showed the upper section is fine laminated while most of the core is homogenous. The change in sedimentation pattern was also evident from magnetic susceptibility measurements and grain size analysis. The differences in the sedimentation patterns along each core and between different cores represent the transport and accumulation dynamic processes from the terrestrial source along the canyon axis to the deep sea. The geomorphological map, the sub-surface seismic interpretation, and the sedimentary results present the relation between the Akhziv sub-marine canyon and the terrestrial system at the western Galilee. Further efforts on dating the sedimentary record will reveal the connection to the glacial-interglacial cycles and their effects on the eastern Mediterranean continental shelf.

  8. Composition and provenance of terrigenous organic matter transported along submarine canyons in the Gulf of Lion (NW Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Pasqual, Catalina; Goñi, Miguel A.; Tesi, Tommaso; Sanchez-Vidal, Anna; Calafat, Antoni; Canals, Miquel

    2013-11-01

    Previous projects in the Gulf of Lion have investigated the path of terrigenous material in the Rhone deltaic system, the continental shelf and the nearby canyon heads. This study focuses on the slope region of the Gulf of Lion to further describe particulate exchanges with ocean’s interior through submarine canyons and atmospheric inputs. Nine sediment traps were deployed from the heads to the mouths of Lacaze-Duthiers and Cap de Creus submarine canyons and on the southern open slope from October 2005 to October 2006. Sediment trap samples were analyzed by CuO oxidation to investigate spatial and temporal variability in the yields and compositional characteristics of terrigenous biomarkers such as lignin-derived phenols and cutin acids. Sediment trap data show that the Dense Shelf Water Cascading event that took place in the months of winter 2006 (January, February and March) had a profound impact on particle fluxes in both canyons. This event was responsible for the majority of lignin phenol (55.4%) and cutin acid (42.8%) inputs to submarine canyons, with lignin compositions similar to those measured along the mid- and outer-continental shelf, which is consistent with the resuspension and lateral transfer of unconsolidated shelf sediment to the canyons. The highest lithogenic-normalized lignin derived phenols contents in sediment trap samples were found during late spring and summer at all stations (i.e., 193.46 μg VP g-1 lithogenic at deep slope station), when river flow, wave energy and total particle fluxes were relatively low. During this period, lignin compositions were characterized by elevated cinnamyl to vanillyl phenol ratios (>3) at almost all stations, high p-coumaric to ferulic acid ratios (>3) and high yields of cutin acids relative to vanillyl phenols (>1), all trends that are consistent with high pollen inputs. Our results suggest marked differences in the sources and transport processes responsible for terrigenous material export along submarine canyons, mainly consisting of fluvial and shelf sediments during winter and atmospheric dust inputs during spring and summer.

  9. Internal bore seasonality and tidal pumping of subthermocline waters at the head of the Monterey submarine canyon

    NASA Astrophysics Data System (ADS)

    Walter, Ryan K.; Phelan, P. Joe

    2016-03-01

    This study utilizes more than a year of observations made in shallow waters (~30 m) at the head of the Monterey Submarine Canyon to assess variability in the physical environment and internal bore field. The interaction of the internal tide with the canyon rim results in a semidiurnal tidal period pumping of cold-water masses (subthermocline waters) onto the adjacent shelf (i.e., internal bores). These internal bores are shown to be significantly coherent with the local sea surface height with minimal spatial variability when comparing two sites near the canyon head region. During the summer months, and periods of strong regional wind-driven upwelling and shoaling of the offshore thermocline, the canyon rim sites display elevated semidiurnal temperature variance. This semidiurnal variability reaches its annual minimum during the winter months when the regional upwelling favorable winds subside and the offshore thermocline deepens. Additionally, the observed internal bores show a distinct asymmetry between the leading (gradual cooling with velocities directed onto the shelf) and trailing edges (sharp warming with velocities directed into the canyon). It appears that the semidiurnal internal tide at the canyon head is a first-order control on the delivery of subthermocline waters to the nearshore coastal environment at this location.

  10. Microbial Communities in Sunken Wood Are Structured by Wood-Boring Bivalves and Location in a Submarine Canyon

    PubMed Central

    Fagervold, Sonja K.; Romano, Chiara; Kalenitchenko, Dimitri; Borowski, Christian; Nunes-Jorge, Amandine; Martin, Daniel; Galand, Pierre E.

    2014-01-01

    The cornerstones of sunken wood ecosystems are microorganisms involved in cellulose degradation. These can either be free-living microorganisms in the wood matrix or symbiotic bacteria associated with wood-boring bivalves such as emblematic species of Xylophaga, the most common deep-sea woodborer. Here we use experimentally submerged pine wood, placed in and outside the Mediterranean submarine Blanes Canyon, to compare the microbial communities on the wood, in fecal pellets of Xylophaga spp. and associated with the gills of these animals. Analyses based on tag pyrosequencing of the 16S rRNA bacterial gene showed that sunken wood contained three distinct microbial communities. Wood and pellet communities were different from each other suggesting that Xylophaga spp. create new microbial niches by excreting fecal pellets into their burrows. In turn, gills of Xylophaga spp. contain potential bacterial symbionts, as illustrated by the presence of sequences closely related to symbiotic bacteria found in other wood eating marine invertebrates. Finally, we found that sunken wood communities inside the canyon were different and more diverse than the ones outside the canyon. This finding extends to the microbial world the view that submarine canyons are sites of diverse marine life. PMID:24805961

  11. The engineering and geological constraints of the intraslope basins and submarine canyons of the northwestern Gulf of Mexico

    SciTech Connect

    Bryant, W.R.; Yuh Liu, J.; Ponthier, J.

    1995-10-01

    It is well realized that future hydrocarbon discoveries on the upper and lower continental slope and rise off Texas and Louisiana necessitate innovative methods for the construction of platforms and pipelines in a very difficult engineering and complex geological environment. There are 105 intraslope basins and 5 major submarine canyons on the continental slope of the northwestern Gulf of Mexico, many of which may be prime targets for hydrocarbon production. Examination of the physiographic, geophysical and geotechnical characteristics of the intraslope basins of Pigmy and Vaca basins and the Alaminos submarine canyon are used as examples to typify the various engineering and geological constraints that are most likely to be encountered on the continental slope and rise and along the Sigsbee Escarpment in the northwestern Gulf of Mexico. High-resolution bathymetry identifies such constraints as high-angle intraslope basin walls, walls that exceed 40 degrees are not uncommon. Sediment slumps and other instabilities, such as long-term sediment creep and other affects of halokenesis and contemporaneous faulting, are illustrated and evaluated from high-resolution geophysics. The small canyons and large gullies that dissect the parameter flanks of Alaminos Canyon, that may be the results of both recent and old turbidity currents and debris flows, are structures that require engineering consideration in the implement of seafloor structures in, near or down slope of these features.

  12. Microbial communities in sunken wood are structured by wood-boring bivalves and location in a submarine canyon.

    PubMed

    Fagervold, Sonja K; Romano, Chiara; Kalenitchenko, Dimitri; Borowski, Christian; Nunes-Jorge, Amandine; Martin, Daniel; Galand, Pierre E

    2014-01-01

    The cornerstones of sunken wood ecosystems are microorganisms involved in cellulose degradation. These can either be free-living microorganisms in the wood matrix or symbiotic bacteria associated with wood-boring bivalves such as emblematic species of Xylophaga, the most common deep-sea woodborer. Here we use experimentally submerged pine wood, placed in and outside the Mediterranean submarine Blanes Canyon, to compare the microbial communities on the wood, in fecal pellets of Xylophaga spp. and associated with the gills of these animals. Analyses based on tag pyrosequencing of the 16S rRNA bacterial gene showed that sunken wood contained three distinct microbial communities. Wood and pellet communities were different from each other suggesting that Xylophaga spp. create new microbial niches by excreting fecal pellets into their burrows. In turn, gills of Xylophaga spp. contain potential bacterial symbionts, as illustrated by the presence of sequences closely related to symbiotic bacteria found in other wood eating marine invertebrates. Finally, we found that sunken wood communities inside the canyon were different and more diverse than the ones outside the canyon. This finding extends to the microbial world the view that submarine canyons are sites of diverse marine life. PMID:24805961

  13. Spatial scale-dependent habitat heterogeneity influences submarine canyon macrofaunal abundance and diversity off the Main and Northwest Hawaiian Islands

    NASA Astrophysics Data System (ADS)

    De Leo, Fabio C.; Vetter, Eric W.; Smith, Craig R.; Rowden, Ashley A.; McGranaghan, Matthew

    2014-06-01

    The mapping of biodiversity on continental margins on landscape scales is highly relevant to marine spatial planning and conservation. Submarine canyons are widespread topographic features on continental and island margins that enhance benthic biomass across a range of oceanic provinces and productivity regimes. However, it remains unclear whether canyons enhance faunal biodiversity on landscape scales relevant to marine protected area (MPA) design. Furthermore, it is not known which physical attributes and heterogeneity metrics can provide good surrogates for large-scale mapping of canyon benthic biodiversity. To test mechanistic hypotheses evaluating the role of different canyon-landscape attributes in enhancing benthic biodiversity at different spatial scales we conducted 34 submersible dives in six submarine canyons and nearby slopes in the Hawaiian archipelago, sampling infaunal macrobenthos in a depth-stratified sampling design. We employed multivariate multiple regression models to evaluate sediment and topographic heterogeneity, canyon transverse profiles, and overall water mass variability as potential drivers of macrobenthic community structure and species richness. We find that variables related to habitat heterogeneity at medium (0.13 km2) and large (15-33 km2) spatial scales such as slope, backscatter reflectivity and canyon transverse profiles are often good predictors of macrobenthic biodiversity, explaining 16-30% of the variance. Particulate organic carbon (POC) flux and distance from shore are also important variables, implicating food supply as a major predictor of canyon biodiversity. Canyons off the high Main Hawaiian Islands (Oahu and Moloka'i) are significantly affected by organic enrichment, showing enhanced infaunal macrobenthos abundance, whereas this effect is imperceptible around the low Northwest Hawaiian Islands (Nihoa and Maro Reef). Variable canyon alpha-diversity and high rates of species turnover (beta-diversity), particularly for polychaetes, suggest that canyons play important roles in maintaining high levels of regional biodiversity in the extremely oligotrophic system of the North Pacific Subtropical Gyre. This information is of key importance to the process of MPA design, suggesting that canyon habitats be explicitly included in marine spatial planning. The low-islands of Nihoa and Maro Reef in the NWHI showed a lack of sustained input of terrestrial and macrolagae detritus, likely having an influence on the observed low macrofaunal abundances (see further discussion of ‘canyon effects’ in Section 4.3), and showing the fundamental role of coastal landscape characteristics in determining the amount and nature of allochthonous organic matter entering the system. Total and highly-mobile invertebrate megafauna abundances were two to three times higher in the submarine canyons and slopes of the MHI contrasted with the NWHI (Vetter et al., 2010), also demonstrating the role of this larger contribution of terrestrial and coastal organic enrichment in the MHI contrasted with the NWHI.

  14. Modern accumulation rates and a budget of sediment off the Gaoping (Kaoping) River, SW Taiwan: A tidal and flood dominated depositional environment around a submarine canyon

    NASA Astrophysics Data System (ADS)

    Huh, Chih-An; Lin, Hui-Ling; Lin, Saulwood; Huang, Ya-Wen

    2009-03-01

    Ninety-two box cores collected during 2004-2006 from an area of ~ 3000 km 2 off the Gaoping (formerly spelled Kaoping) River, SW Taiwan, were analyzed for fallout radionuclides ( 210Pb, 137Cs and 7Be) to elucidate sedimentation rates and processes, and for the calculation of a sediment budget. The study area is located at an active collision margin with a narrow shelf and a submarine canyon extending essentially into the river's mouth. The results indicate fairly constant hemipelagic sedimentation in much of the open margin and for most of the time except in the inner shelf and along the axis of the canyon where sediment transport is more dynamic and is controlled by tidal current and wave activities constantly, and by fluvial floods or gravity-driven flows episodically. Sedimentation rates in the study area derived from 210Pb and constrained by 137Cs vary from 0.04 to 1.5 cm/yr, with the highest rates (> 1 cm/yr) flanking the Gaoping canyon over the upper slope (200-600 m) and the lowest rates (< 0.1 cm/yr) in the distal basin beyond the continental slope. The depocenter delineated from 210Pb-based sedimentation rates overlaps with the area covered by a flood layer resulting from super-typhoon Haitang in July 2005. Such correspondence supports the notion that the processes operating on event timescale have bearing on the formation of the sediment strata over centennial or longer timescales. From the distribution of sedimentation rates, sediment deposited in the study area annually is estimated to be 6.6 Mton/yr, accounting for less than 20% of Gaoping River's sediment load. The calculated budget, coupled with the presence of the short-lived 7Be and non-steady-state distribution of low levels of 210Pb in sediments along the canyon floor, suggests rapid transport of sediment from Gaoping River's mountainous watershed (the source) via the Gaoping (Kaoping) Submarine Canyon and adjacent channels (as the conduit and temporary sink) to the abyssal plain and the Manila Trench in the South China Sea (the ultimate sink).

  15. A delta-fed submarine ramp alternative to the canyon-fed depositional model of the Stevens submarine fan system, southeastern San Joaquin basin, Kern County, California

    SciTech Connect

    Harrison, C.P.

    1996-12-31

    Deep-marine sands of the Upper Miocene Stevens Sandstone, one of the most important hydrocarbon-producing units in the United States, were deposited by sediment-gravity flows in the Bakersfield Arch area of the southern San Joaquin basin. The Stevens Sandstone has historically been considered to be a thick turbidite succession shed off the southern Sierra Nevada as four fans in a long-lived submarine fan system fed by several large submarine canyons. Access to previously unavailable proprietary 2-D and 3-D seismic data sets, carefully calibrated by well-log and core data, permits a more complete understanding of the depositional architecture of this highly petroliferous, deep-marine depositional system. This study concludes that these units were deposited in a delta-fed, line- sourced deep-sea system, whose distribution was structurally-controlled. Seismic lines examined in this study show evidence for a large fault-controlled slump feature in the area that has been referred to as {open_quotes}Rosedale Canyon,{close_quotes} and no evidence supports the existence of submarine canyons feeding the system. The highly progradational Stevens interval consists of thick siliciclastic units separated by thin, intervening biosiliceous shales. Seismically, the upper bounding surfaces of these biosiliceous shales represent major downlap surfaces. As sands were deposited by high-density turbidity currents, the area of the present Bakersfield Arch developed into a deep-sea braid plain. Smaller-scale linear features detected on horizon slices through the 3-D seismic data cube have been interpreted in this study as braided channelform features deposited on the deep-sea braid plain. Hydrocarbon production along these linear trends may be associated with porosity and permeability variations resulting from channelized versus non-channelized sedimentation.

  16. A delta-fed submarine ramp alternative to the canyon-fed depositional model of the Stevens submarine fan system, southeastern San Joaquin basin, Kern County, California

    SciTech Connect

    Harrison, C.P. )

    1996-01-01

    Deep-marine sands of the Upper Miocene Stevens Sandstone, one of the most important hydrocarbon-producing units in the United States, were deposited by sediment-gravity flows in the Bakersfield Arch area of the southern San Joaquin basin. The Stevens Sandstone has historically been considered to be a thick turbidite succession shed off the southern Sierra Nevada as four fans in a long-lived submarine fan system fed by several large submarine canyons. Access to previously unavailable proprietary 2-D and 3-D seismic data sets, carefully calibrated by well-log and core data, permits a more complete understanding of the depositional architecture of this highly petroliferous, deep-marine depositional system. This study concludes that these units were deposited in a delta-fed, line- sourced deep-sea system, whose distribution was structurally-controlled. Seismic lines examined in this study show evidence for a large fault-controlled slump feature in the area that has been referred to as [open quotes]Rosedale Canyon,[close quotes] and no evidence supports the existence of submarine canyons feeding the system. The highly progradational Stevens interval consists of thick siliciclastic units separated by thin, intervening biosiliceous shales. Seismically, the upper bounding surfaces of these biosiliceous shales represent major downlap surfaces. As sands were deposited by high-density turbidity currents, the area of the present Bakersfield Arch developed into a deep-sea braid plain. Smaller-scale linear features detected on horizon slices through the 3-D seismic data cube have been interpreted in this study as braided channelform features deposited on the deep-sea braid plain. Hydrocarbon production along these linear trends may be associated with porosity and permeability variations resulting from channelized versus non-channelized sedimentation.

  17. Limited depth zonation among bathyal epibenthic megafauna of the Gully submarine canyon, northwest Atlantic

    NASA Astrophysics Data System (ADS)

    Kenchington, E. L.; Cogswell, A. T.; MacIsaac, K. G.; Beazley, L.; Law, B. A.; Kenchington, T. J.

    2014-06-01

    The Gully is a large submarine canyon incised into the Scotian Shelf, in the northwest Atlantic. A submersible-mounted camera was used to collect 17 km of high resolution video imagery of the soft sediment flanks and floor of the canyon between 1000 and 2500 m depth. A depth-stratified random survey design with two transects per stratum was followed. Depth strata were drawn at 1000-1500 m, 1500-2000 m and 2000-2500 m reflecting global and regional faunal boundaries. The 47,614 individuals or colonies observed on the transects were identified into 49 unique taxa drawn from 7 phyla, while 21 additional taxa were observed between the transect lines. Cnidaria was the most diverse phylum (22 taxa) on the transects, followed by the Echinodermata (15 taxa). Most fauna were sessile or sedentary suspension feeders. A species of Xenophyophorida, likely Syringammina sp., was the most abundant taxon. Cluster analysis of transects based on a Bray-Curtis (BC) matrix of species abundance identified one cluster of five transects and one independent transect - the deepest transect (2406 m average depth). A similarity profile test indicated that this structure is not random. There was a significant change in the megafaunal assemblage with depth over scales of 10s of kilometers, accounting for 65% of the variation in the BC matrix. Both total organic carbon and labile carbon were higher in cores from the 1000-1500 m stratum than at greater depth, consistent with transport of food and sediments into the canyon from shallower waters. The first principal component calculated from species abundances separated the two transects from the 1000-1500 m depth stratum from the others indicating that sediment food supply influences community structure and composition. Over small spatial scales (≤10 m), eight groups of species associations were identified. However, the associations between the species within each group were not strong with the highest correlation between the Xenophyophorida and the Pennatulacea (ρ=0.66). At this spatial scale substrate type was an important factor, with hard and soft bottom species associations being identified.

  18. Epibiotic relationships on Zygochlamys patagonica (Mollusca, Bivalvia, Pectinidae) increase biodiversity in a submarine canyon in Argentina

    NASA Astrophysics Data System (ADS)

    Schejter, Laura; López Gappa, Juan; Bremec, Claudia Silvia

    2014-06-01

    The continental slope of the southern SW Atlantic Ocean has many distinguishable deep submarine canyons, varying in depth and extension. The benthic fauna within one of them, detected in April 2005 by means of a multibeam SIMRAD EM1002 sonar, and located at 43°35‧S to 59°33‧W, 325 m depth, was studied to discuss faunal affinities with the neighbouring Patagonian scallop fishing grounds located at upper slope depths. In order to add faunal information to the previous general study, we studied the epibiotic species settled on Patagonian scallops (the dominant species in the area) collected in the reference sampling site using a 2.5-m mouth-opening dredge, 10 mm mesh size. We sampled 103 scallops with shell heights between 22 and 69 mm; epibionts were recorded on both valves. We found 53 epibiotic taxa, which were most conspicuous on the upper valve. Bryozoa was the most diverse group (34 species) while Polychaeta was the most abundant group, recorded on 94% of the scallops. Stylasteridae (2 species) and Clavulariidae (Cnidaria) conform newly recorded epibionts on Z. patagonica and the sponge Tedania (Tedaniopsis) infundibuliformis also represents a new record for the SW Atlantic Ocean.

  19. Seafloor characterization and benthic megafaunal distribution of an active submarine canyon and surrounding sectors: The case of Gioia Canyon (Southern Tyrrhenian Sea)

    NASA Astrophysics Data System (ADS)

    Pierdomenico, Martina; Martorelli, Eleonora; Dominguez-Carrió, Carlos; Gili, Josep Maria; Chiocci, Francesco Latino

    2016-05-01

    In this paper, we used multibeam bathymetry and backscatter, high-resolution seismic profiles, ROV video images and sediment samples to identify the principal morpho-sedimentary features and related megabenthic communities along the upper reach of the Gioia Canyon (depth < 600 m) and the surrounding shelf and slope areas. Interpretation of the multidisciplinary dataset was undertaken to evaluate the relationships between seafloor characteristics and faunal distribution along a submarine canyon in an active tectonic setting. The results from this study indicate that physical disturbance on the seafloor at the canyon head and surrounding shelf, related to high sedimentation rates and occasional turbidite flows, may limit the variability of megabenthic communities. Evidence of diffuse trawl marks over soft sedimentary bottoms indicates anthropogenic impact due to fishing activities, which could explain low abundances of megabenthic species observed locally. The canyon margins and flanks along the continental slope host octocorals Funiculina quadrangularis and Isidella elongata, species that are indicative of vulnerable marine ecosystems (VMEs) and relevant in terms of sustainable management priorities. At the Palmi Ridge, the occurrence of outcropping rocks and bottom currents related to the presence of Levantine Intermediate Waters, provide conditions for the development of hard-bottom assemblages, including the black coral Antipathella subpinnata and deep-sea sponges fields.

  20. A western thalweg of the Princeton Valley submarine canyon system as a reservoir and a trap near Willows, California

    SciTech Connect

    Blake, R.G. ); Bainer, R.W.

    1990-05-01

    The Princeton Valley submarine canyon system has long been an important reservoir and trapping mechanism in the northern Sacramento Valley, California. Recently a western thalweg of the system, identified north of Willows, California, has proven to be a significant trapping mechanism for gas in truncated Kione Formation sandstones. Both Upper Cretaceous Kione Formation and Paleocene Princeton Valley sandstones are exploratory objectives in the area and are productive in existing wells. The Kione Formation, a sand-rich deltaic sequence approximately 2,000 ft thick, has been truncated to the west by the Princeton Valley submarine canyon system. The canyon (gorge) has been subsequently filed with primarily impermeable shales, providing a trap for migrating gases in the truncated sands. The trend was discovered in 1977 by Shell Oil Company based on seismic and was the first substantiated evidence of a western thalweg of the Princeton Gorge in the Willows area. To date, four wells have been completed along the trend and current exploratory efforts are attempting to follow the gorge trend.

  1. Scleractinian coral recruitment patterns at Salt River submarine canyon, St. Croix, U.S. Virgin Islands

    NASA Astrophysics Data System (ADS)

    Rogers, Caroline S.; Fitz, H. Carl; Gilnack, Marcia; Beets, James; Hardin, John

    1984-10-01

    Scleractinian coral recruitment patterns were studied at depths of 9, 18, 27 and 37 m on the east and west walls of Salt River submarine canyon, St. Croix, U.S. Virgin Islands, by censusing coral juveniles which settled on experimental settling plates placed on the reef for 3 26 months as well as coral juveniles within quadrats on the reef. The most common species in the juvenile population within quadrats were Agaricia agaricites, Porites astreoides, Madracis decactis, Stephanocoenia michelinii, and A. lamarcki. The only species settling on settling plates were Agaricia spp., Madracis decactis, Porites spp., Stephanocoenia michelinii and Favia fragum. A total of 271 corals settled on 342 plates, with 51% of the juveniles on the east wall and 49% on the west wall. Of these 34% settled on horizontal surfaces and 66% on vertical surfaces. Based on results from quadrats, Agaricia agaricites and Porites astreoides had high recruitment rates relative to their abundance on the reef. In contrast, Agaricia lamarcki, Montastraea annularis, M. cavernosa and Siderastrea siderea had high amounts of cover compared to their abundance as juveniles within quadrats. The mean number of juveniles per m2 within quadrats ranged from 3 to 42. In general, there was a decrease in the mean number of juveniles and the number of species with depth. Total number of juveniles on settling plates was highest at 18 m on both walls. The largest number within quadrats was at 18 m on the east wall, followed by 9 m and 18 m on the west wall. High rates of coral recruitment tended to be associated with low algal biomass and relatively high grazing pressure by urchins and fishes.

  2. Hudson submarine canyon head offshore New York and New Jersey: A physical and geochemical investigation

    NASA Astrophysics Data System (ADS)

    Rona, Peter; Guida, Vincent; Scranton, Mary; Gong, Donglai; Macelloni, Leonardo; Pierdomenico, Martina; Diercks, Arne-R.; Asper, Vernon; Haag, Scott

    2015-11-01

    Hudson Canyon is the largest shelf-sourced canyon system off the east coast of the United States, and hosts a productive ecosystem that supports key fisheries. Here we report the results of a multi-year interdisciplinary study of the geological, geochemical, and physical oceanographic features and processes in the canyon that underpin that ecosystem. High-resolution multi-beam bathymetric and backscatter data show that the contrasting morphology of the two perpendicularly oriented branches at the head of the Hudson Canyon is indicative of different states of geomorphological activity and sediment transport. Tightly spaced ridges and gullies extend perpendicularly towards the canyon axis from the canyon walls. Numerous depressions are found at the base of the canyon walls or along the canyon axis at depths from 300 m to 600 m. Elevated concentrations of dissolved methane in the water column, where the highest density of depressions occur, suggests that methane is actively venting there. The topography and reflective floors of circular depressions in canyon walls and their association with methane maxima suggest that these represent active methane gas release-collapse pockmarks with carbonate floors. Patterns of irregular, low-relief, reflective depressions on the canyon floor may also represent methane release points, either as gas release or cold-seep features. The presence of methane maxima in a region of strong advective currents suggests continuous and substantial methane supply. Hydrographic observations in the canyon show that multiple layers of distinct inter-leaved shelf (cold, fresh) and slope (warm, salty) water masses occupy the head of the canyon during the summer. Their interactions with the canyon and with each other produce shifting fronts, internal waves, and strong currents that are influenced by canyon topography. Strong tidal currents with along-canyon-axis flow shear help to drive the advection, dispersion and mixing of dissolved materials in the water column that likely help support the rich canyon ecosystem.

  3. Submarine canyon morphologies in the Gulf of Palermo (Southern Tyrrhenian Sea) and possible implications for geo-hazard

    NASA Astrophysics Data System (ADS)

    Lo Iacono, Claudio; Sulli, Attilio; Agate, Mauro; Lo Presti, Valeria; Pepe, Fabrizio; Catalano, Raimondo

    2011-03-01

    The continental shelf and the upper slope of the Gulf of Palermo (Southern Tyrrhenian Sea) in the depth interval ranging from 50 to 1,500 m were mapped for the first time with Multi Beam echosounder and high resolution seismic. Seven submarine canyons are confined to the upper slope or indent the shelf-edge and enter the Palermo intraslope basin at a depth of around 1,300 m. The canyons evolved through concurrent top-down turbiditic processes and bottom-up retrogressive mass failures. Most of the mass failure features of the area are related to canyon-shaping processes and only few of them are not confined to the upper slope. In general, these features probably do not represent a significant tsunami hazard along the coast. The geological element that controls the evolution of the canyons and induces sediment instability corresponds to the steep slope gradient, especially in the western sector of the Gulf, where the steepest canyons are located. The structural features mapped in the Palermo offshore contributed to the regulation of mass failure processes in the area, with direct faults and antiform structures coinciding with some of the canyon heads. Furthermore, the occurrence of pockmarks and highs that probably consist of authigenic carbonates above faulted and folded strata suggests a local relationship between structural control, fluid escape processes and mass failure. This paper presents a valuable high-resolution morphologic dataset of the Gulf of Palermo, which constitutes a reliable base for evaluating the geo-hazard potential related to slope failure in the area.

  4. Spatial distribution of phytoplankton assemblages in the Nazaré submarine canyon region (Portugal): HPLC-CHEMTAX approach

    NASA Astrophysics Data System (ADS)

    Mendes, Carlos Rafael; Sá, Carolina; Vitorino, João; Borges, Carlos; Tavano Garcia, Virginia Maria; Brotas, Vanda

    2011-07-01

    The distribution and composition of phytoplankton assemblages were studied in the Nazaré submarine canyon, during an upwelling event, using high-performance liquid chromatography (HPLC) pigment analysis, complemented by microscopic qualitative observations. High chlorophyll a (Chl a) concentrations were recorded in the canyon head, near the coast, where values greater than 4 μg L - 1 were observed. In contrast, Chl a was relatively low in offshore regions, with values below 0.5 μg L - 1 . The most abundant accessory pigments were fucoxanthin, peridinin, diadinoxanthin and 19'-hexanoyloxyfucoxanthin. Pigment data information was analyzed using the CHEMTAX software to estimate the contribution of different taxonomic groups to total Chl a. North of the canyon head, an area with high concentration of peridinin-containing dinoflagellates was identified (with presence of chain-forming toxic dinoflagellates). The presence of these organisms was associated with mixed water columns and phosphate values lower than the ones south of the canyon head, where a dominance of diatoms was recorded. The rest of the study region showed a dominance of prymnesiophytes and a significant contribution of cyanobacteria at oceanic stations. This study demonstrates the usefulness of using pigment analysis to study spatial distribution of phytoplankton groups in relation to a complex physical environment.

  5. Accumulation of dioxins in deep-sea crustaceans, fish and sediments from a submarine canyon (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Castro-Jiménez, Javier; Rotllant, Guiomar; Ábalos, Manuela; Parera, Jordi; Dachs, Jordi; Company, Joan B.; Calafat, Antoni; Abad, Esteban

    2013-11-01

    Submarine canyons are efficient pathways transporting sediments and associated pollutants to deep sea. The objective of this work was to provide with the first assessment of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) levels and accumulation in deep-sea megafauna (crustacean and fish) and sediments in the Blanes submarine canyon (North-Western Mediterranean Sea). The influence of the selected species habitats (pelagic, nektobenthic, and benthic) and the trophic chain level on the accumulation of dioxins was also investigated. Bottom sediment and biota samples were collected at different depths and locations inside the canyon and in the adjacent slope outside the canyon influence. ∑2,3,7,8-PCDD/F concentrations in sediments varied from 102 to 680 pg g-1 dry weight (d.w.) (1-6 WHO98-TEQ pg g-1 d.w.). Dioxins are enriched in bottom sediments at higher depths inside the canyon and in particular in the deepest parts of the canyon axis (1700 m depth), whereas no enrichment of dioxins was verified at the deepest sediments from the adjacent open slope outside the canyon influence. The proportion of ∑2,3,7,8-PCDF (furans) to ∑2,3,7,8-PCDD (dioxins) increased for sediments with higher soot carbon content consistent with the higher affinity of PCDF for sorption onto soot carbon. Higher ∑2,3,7,8-PCDD/F levels were found in crustaceans than in fish, ranging from 220 to 795 pg g-1 lipid weight (l.w.) (13-90 WHO98-TEQ pg g-1 l.w.) and 110 to 300 pg g-1 l.w. (22-33 WHO98-TEQ pg g-1 l.w.) in crustaceans and fish, respectively. Dioxin highest concentrations were found in nektobenthic organisms, i.e., benthic organism with swimming capabilities (both fish and crustaceans). These higher levels are consistent with the higher trophic level and predicted biomagnification factors (BMFs) of nektobenthic species. The reduced availability of sediment-bound PCDD/F for benthic species mainly due to soot and organic carbon sorption of these contaminants most probably influenced this result too. While biomagnification exerts a clear influence on the total dioxin concentrations in biota, life habits seem to exert an influence in the differential congener-specific accumulation of dioxins rather than in the total concentration. Thus, pelagic species reflected the estimated congener pattern from the surface water dissolved phase and phytoplankton, whereas the dioxin pattern in benthic and nektobenthic species was more similar to the estimated pattern in the deep-water dissolved phase and the sediment. The three crustacean species considered in this study bioaccumulated higher amounts of other dioxin congeners (non-2,3,7,8-PCDD/Fs) compared to fish. An interplay of several factors, such as biota habitats, differential uptake of water column dioxin (dissolved and particle-bound fractions), and different metabolization capabilities and rates (CYP-mediated metabolism) may explain the differences observed in dioxin patterns among crustacean species and between fish and crustaceans in the Blanes submarine canyon.

  6. Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon

    NASA Astrophysics Data System (ADS)

    Martn, Jacobo; Puig, Pere; Palanques, Albert; Rib, Marta

    2014-06-01

    Commercial bottom trawling is one of the anthropogenic activities causing the biggest impact on the seafloor due to its recurrence and global distribution. In particular, trawling has been proposed as a major driver of sediment dynamics at depths below the reach of storm waves, but the issue is at present poorly documented with direct observations. This paper analyses changes in water turbidity in a tributary valley of the La Fonera (=Palams) submarine canyon, whose flanks are routinely exploited by a local trawling fleet down to depths of 800 m. A string of turbidimeters was deployed at 980 m water depth inside the tributary for two consecutive years, 2010-2011. The second year, an ADCP profiled the currents 80 m above the seafloor. The results illustrate that near-bottom water turbidity at the study site is heavily dominated, both in its magnitude and temporal patterns, by trawling-induced sediment resuspension at the fishing ground. Resuspended sediments are channelised along the tributary in the form of sediment gravity flows, being recorded only during working days and working hours of the trawling fleet. These sediment gravity flows generate turbid plumes that extend to at least 100 m above the bottom, reaching suspended sediment concentrations up to 236 mg l-1 close to the seafloor (5 m above bottom). A few hours after the end of daily trawling activities, water turbidity progressively decreases but resuspended particles remain in suspension for several hours, developing bottom and intermediate nepheloid layers that reach background levels 2 mg l-1 before trawling activities resume. The presence of these nepheloid layers was recorded in a CTD+turbidimeter transect conducted across the fishing ground a few hours after the end of a working day. These results highlight that deep bottom trawling can effectively replace natural processes as the main driving force of sediment resuspension on continental slope regions and generate increased near-bottom water turbidity that propagates from fishing grounds to wider and deeper areas via sediment gravity flows and nepheloid layer development.

  7. Transport and fluxes of terrestrial polycyclic aromatic hydrocarbons in a small mountain river and submarine canyon system.

    PubMed

    Lin, Bing-Sian; Lee, Chon-Lin; Brimblecombe, Peter; Liu, James T

    2016-08-01

    Polycyclic aromatic hydrocarbon (PAH) concentrations in the Gaoping River were investigated in the wet and dry seasons. PAH characteristics allowed us to trace the particulate matter transported in a river-sea system containing a small mountain river, continental shelf, and submarine canyon. PAH signatures of the Gaoping River showed that particles were rapidly transported from the high mountain to the Gaoping coastal areas in the wet season, even arriving at the deep ocean via the Gaoping Submarine Canyon. By contrast, in the dry season, the particles were delivered quite slowly and included mostly pyrogenic contaminants. The annual riverine flux estimates for PAHs were 2241 kg in the Gaoping river-sea system. Only 18.0 kg were associated with the dissolved phase; the rest was bound onto particles. The fluxes caused by typhoons and their effects accounted for 20.2% of the dissolved and 68.4% of the particulate PAH fluxes from the river. Normalized partition coefficients for organic carbon suggested that PAHs were rigid on the particles. Distinct source characteristics were evident for PAHs on riverine suspended particles and coastal surface sediments: the particles in the wet season (as background signals) were similar to petrogenic sources, whereas the particles in the dry season had characteristics of coal burning and vehicular emissions. The sediments in the northwestern shelf were similar to pyrogenic sources (including vehicular emissions and coal and biomass burning), whereas the sediments in the canyon and southeastern shelf arose from mixed sources, although some diesel signature was also evident. PMID:27131955

  8. Biological and physical processes in and around Astoria submarine Canyon, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Bosley, Keith L.; Lavelle, J. William; Brodeur, Richard D.; Wakefield, W. Waldo; Emmett, Robert L.; Baker, Edward T.; Rehmke, Kara M.

    2004-09-01

    Astoria Canyon represents the westernmost portion of the Columbia River drainage system, with the head of the canyon beginning just 16 km west of the mouth of the Columbia River along the northern Oregon and southern Washington coasts. During the summer of 2001, physical, chemical, and biological measurements in the canyon were taken to better understand the hydrodynamic setting of, and the feeding relationships among, the pelagic and benthic communities. Results show that currents were strongly tidal, and transport, where measured, was primarily up and into the canyon below shelf depth as previous studies in the canyon have shown. Temperature time series suggests that the largest diurnal oscillations occurred at, or were trapped near, the bottom of the canyon. Within the upper canyon, subtidal temperature was correlated with upper-level shelf-edge currents, linking subtidal upwelling events in the canyon with near-surface subtidal along-shore flow. Invertebrates, such as shrimp, euphausiids, and squid, as well as mesopelagic fishes, dominated the Isaacs-Kidd midwater trawl catches along the canyon walls. Large trawl catches were comprised mainly of hake and rockfishes (shallow trawls) and macrourids, scorpaenids, stomiids, and zoarcids (bottom trawls). Gut-content analysis of rockfishes and lanternfishes revealed substantial use of midwater prey such as euphausiids and mesopelagic fishes. The δ13C values of fishes and invertebrates reflected local primary production, as indicated by particulate organic matter (POM) δ13C values from samples collected at various depths along the axis of the canyon, as well as across the canyon at several sites. The δ15N values of fishes and invertebrates indicated lanternfishes, along with euphausiids, amphipods, shrimp and squid, may be important dietary components of higher-trophic-level fishes in both the benthic and benthopelagic food webs. The δ13C and δ15N values of Sebastes species showed significant enrichment in the adults of species that are largely piscivorous relative to the values of adults of more omnivorous species.

  9. Submarine canyons of north-western Sicily (Southern Tyrrhenian Sea): Variability in morphology, sedimentary processes and evolution on a tectonically active margin

    NASA Astrophysics Data System (ADS)

    Lo Iacono, Claudio; Sulli, Attilio; Agate, Mauro

    2014-06-01

    Swath-bathymetry, mono-channel and multi-channel seismic reflection records acquired during the last two decades on the northern Sicilian margin have unveiled a dense network of submarine canyons within the depth range of 80-2100 m. The canyons display a relevant variability in their geometry, morphology and sedimentary processes. The margin shows a young, tectonically active shelf to slope setting, linking the Sicilian-Maghrebian Thrust Belt to the Tyrrhenian oceanic realm, developed during the Neogene-Quaternary time span. The aim of this study is to highlight the main governing factors that contributed to the evolution and differentiation of the northern Sicilian canyons, mainly focusing on the Gulf of Palermo and on the Gulf of Castellammare. Tectonic control is more evident in the canyons of the Gulf of Palermo, with submarine landslides retrograding on a steep slope and mainly controlling their evolution. Otherwise, canyons, tributaries and gullies mapped in the Gulf of Castellammare developed on a less steep substrate and display sinuous to meandering paths, with a relevant role of coastal/shelf sedimentary inputs and downslope turbidity processes in their formation. Results suggest that, despite the geographically close proximity of the two study areas, the different structural settings of the Castellammare and Palermo Basins are mainly responsible for canyon variability. Data indicate likely on-going uplift and tilting movements along the Sicilian margin, influencing the development of the studied canyons, which have probably been more active during the Quaternary glacial maxima than they are in the present day.

  10. On vertical advection truncation errors in terrain-following numerical models: Comparison to a laboratory model for upwelling over submarine canyons

    NASA Astrophysics Data System (ADS)

    Allen, S. E.; Dinniman, M. S.; Klinck, J. M.; Gorby, D. D.; Hewett, A. J.; Hickey, B. M.

    2003-01-01

    Submarine canyons which indent the continental shelf are frequently regions of steep (up to 45°), three-dimensional topography. Recent observations have delineated the flow over several submarine canyons during 2-4 day long upwelling episodes. Thus upwelling episodes over submarine canyons provide an excellent flow regime for evaluating numerical and physical models. Here we compare a physical and numerical model simulation of an upwelling event over a simplified submarine canyon. The numerical model being evaluated is a version of the S-Coordinate Rutgers University Model (SCRUM). Careful matching between the models is necessary for a stringent comparison. Results show a poor comparison for the homogeneous case due to nonhydrostatic effects in the laboratory model. Results for the stratified case are better but show a systematic difference between the numerical results and laboratory results. This difference is shown not to be due to nonhydrostatic effects. Rather, the difference is due to truncation errors in the calculation of the vertical advection of density in the numerical model. The calculation is inaccurate due to the terrain-following coordinates combined with a strong vertical gradient in density, vertical shear in the horizontal velocity and topography with strong curvature.

  11. Megafauna of vulnerable marine ecosystems in French mediterranean submarine canyons: Spatial distribution and anthropogenic impacts

    NASA Astrophysics Data System (ADS)

    Fabri, M.-C.; Pedel, L.; Beuck, L.; Galgani, F.; Hebbeln, D.; Freiwald, A.

    2014-06-01

    Vulnerable Marine Ecosystems (VME) in the deep Mediterranean Sea have been identified by the General Fisheries Commission for the Mediterranean as consisting of communities of Scleractinia (Lophelia pertusa and Madrepora oculata), Pennatulacea (Funiculina quadrangularis) and Alcyonacea (Isidella elongata). This paper deals with video data recorded in the heads of French Mediterranean canyons. Quantitative observations were extracted from 101 video films recorded during the MEDSEACAN cruise in 2009 (Aamp/Comex). Qualitative information was extracted from four other cruises (two Marum/Comex cruises in 2009 and 2011 and two Ifremer cruises in 1995 and 2010) to support the previous observations in the Cassidaigne and Lacaze-Duthiers canyons. All the species, fishing impacts and litter recognized in the video films recorded from 180 to 700 m depth were mapped using GIS. The abundances and distributions of benthic fishing resources (marketable fishes, Aristeidae, Octopodidae), Vulnerable Marine Species, trawling scars and litter of 17 canyons were calculated and compared, as was the open slope between the Stoechades and Toulon canyons. Funiculina quadrangularis was rarely observed, being confined for the most part to the Marti canyon and, I. elongata was abundant in three canyons (Bourcart, Marti, Petit-Rhône). These two cnidarians were encountered in relatively low abundances, and it may be that they have been swept away by repeated trawling. The Lacaze-Duthiers and Cassidaigne canyons comprised the highest densities and largest colony sizes of scleractinian cold-water corals, whose distribution was mapped in detail. These colonies were often seen to be entangled in fishing lines. The alcyonacean Callogorgia verticillata was observed to be highly abundant in the Bourcart canyon and less abundant in several other canyons. This alcyonacean was also severely affected by bottom fishing gears and is proposed as a Vulnerable Marine Species. Our studies on anthropogenic impacts show that seafloor disturbance by benthic fishing is mainly attributable to trawling in the Gulf of Lion and to long lines where rocky substrates are present. The bauxite residue (red mud) expelled in the Cassidaigne canyon was seen to prevent fauna from settling at the bottom of the canyon and it covered much of the flanks. Litter was present in all of the canyons and especially in considerable quantities in the Ligurian Sea, where the heads of the canyons are closer to the coast. Three Marine Protected Areas and one fishing area with restricted access have recently been established and should permit the preservation of these deep ecosystems.

  12. Marine litter on the floor of deep submarine canyons of the Northwestern Mediterranean Sea: The role of hydrodynamic processes

    NASA Astrophysics Data System (ADS)

    Tubau, Xavier; Canals, Miquel; Lastras, Galderic; Rayo, Xavier; Rivera, Jesus; Amblas, David

    2015-05-01

    Marine litter represents a widespread type of pollution in the World's Oceans. This study is based on direct observation of the seafloor by means of Remotely Operated Vehicle (ROV) dives and reports litter abundance, type and distribution in three large submarine canyons of the NW Mediterranean Sea, namely Cap de Creus, La Fonera and Blanes canyons. Our ultimate objective is establishing the links between active hydrodynamic processes and litter distribution, thus going beyond previous, essentially descriptive studies. Litter was monitored using the Liropus 2000 ROV. Litter items were identified in 24 of the 26 dives carried out in the study area, at depths ranging from 140 to 1731 m. Relative abundance of litter objects by type, size and apparent weight, and distribution of litter in relation to depth and canyon environments (i.e. floor and flanks) were analysed. Plastics are the dominant litter component (72%), followed by lost fishing gear, disregarding their composition (17%), and metal objects (8%). Most of the observed litter seems to be land-sourced. It reaches the ocean through wind transport, river discharge and after direct dumping along the coastline. While coastal towns and industrial areas represent a permanent source of litter, tourism and associated activities relevantly increase litter production during summer months ready to be transported to the deep sea by extreme events. After being lost, fishing gear such as nets and long-lines has the potential of being harmful for marine life (e.g. by ghost fishing), at least for some time, but also provides shelter and a substrate on which some species like cold-water corals are capable to settle and grow. La Fonera and Cap de Creus canyons show the highest mean concentrations of litter ever seen on the deep-sea floor, with 15,057 and 8090 items km-2, respectively, and for a single dive litter observed reached 167,540 items km-2. While most of the largest concentrations were found on the canyon floors at water depths exceeding 1000 m, relatively little litter was identified on the canyon walls. The finding of litter 'hotspots' (i.e., large accumulations of litter) formed by mixtures of land- and marine-sourced litter items and natural debris such as sea urchin carcasses evidences an efficient transport to the floor of mid and lower canyon reaches at least. High-energy, down canyon near-bottom flows are known to occur in the investigated canyons. These are associated to seasonal dense shelf water cascading and severe coastal storms, which are the most energetic hydrodynamic processes in the study area thus becoming the best candidates as main carriers of debris to the deep. The fact that the investigated canyons have their heads at short distance (<4 km) from the shoreline enhances their ability to trap littoral drift currents and also to convey the signal of the above-mentioned high-energy events to the deep, including their litter load. This study contributes to assess the origin and transport mechanisms of litter to the deep sea as well as its potential impact on deep-sea ecosystems.

  13. Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia.

    PubMed

    Conlan, Kathleen E; Currie, David R; Dittmann, Sabine; Sorokin, Shirley J; Hendrycks, Ed

    2015-01-01

    Two South Australian canyons, one shelf-incising (du Couedic) and one slope-limited (Bonney) were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1) significantly differ by water mass, (H2) show significant regional differences and (H3) differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥ 1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to 1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01) among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water) (H1). Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2), over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3). However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there. At 1000-1500 m, the canyon interiors were depauperate, typical of V-shaped canyons elsewhere. The large number of species captured, given the relatively low sampling effort and focus on the larger macrofauna, support previous studies that identify the South Australian coast as a high biodiversity area. PMID:26618354

  14. Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia

    PubMed Central

    Dittmann, Sabine; Sorokin, Shirley J.; Hendrycks, Ed

    2015-01-01

    Two South Australian canyons, one shelf-incising (du Couedic) and one slope-limited (Bonney) were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1) significantly differ by water mass, (H2) show significant regional differences and (H3) differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01) among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water) (H1). Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2), over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3). However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there. At 1000–1500 m, the canyon interiors were depauperate, typical of V-shaped canyons elsewhere. The large number of species captured, given the relatively low sampling effort and focus on the larger macrofauna, support previous studies that identify the South Australian coast as a high biodiversity area. PMID:26618354

  15. Gravity anomaly caused by the mud diapirs off southwest Taiwan and its implication to the development of the submarine canyons

    NASA Astrophysics Data System (ADS)

    Doo, Wen-Bin; Hsu, Shu-Kun; Huang, Yuan-Ping; Chen, Song-Chuen

    2015-04-01

    Both the overpressure and buoyancy effects are generally used to account for the formation of submarine mud volcanoes (MVs) and mud diapirs (MDs). According to the distribution of the MDs and structural features, the compressive tectonic stress should play an important role on the formation of the MDs in the offshore area of southwest Taiwan. Onland Taiwan, the Tainan and Chungchou anticlinal structures (associated with MD) reveal positive gravity anomalies. The MDs in offshore southwest Taiwan are considered to be more active than onshore diapirs. However, the gravity nature of the submarine MDs is not clear. In 2012 and 2013, we have collected shipboard gravity data using R/V Ocean Researcher I in the offshore area of southwest Taiwan. By removing the gravimetric effect from the water-sediment interface and the regional gravity effect along the profiles, we find that the gravity contrasts of the MDs with respect to the surrounding strata are generally positive. The results seem conflict with the buoyant force that triggers the upward motion of the MDs. The positive density contrasts of the MDs can further indicate the relatively rigid rocks which influence the development of the Kaoping and the Fangliao Canyon.

  16. Cold-Water Corals and Anthropogenic Impacts in La Fonera Submarine Canyon Head, Northwestern Mediterranean Sea

    PubMed Central

    Canals, Miquel; Ballesteros, Enric; Gili, Josep-Maria; Sanchez-Vidal, Anna

    2016-01-01

    We assess the occurrence and extent of cold-water coral (CWC) species Madrepora oculata and Dendrophyllia cornigera, as well as gorgonian red coral Corallium rubrum, in La Fonera canyon head (Northwestern Mediterranean Sea), as well as human impacts taking place in their habitats. Occurrence is assessed based on Remotely Operated Vehicle (ROV) video imaging. Terrain classification techniques are applied to high-resolution swath bathymetric data to obtain semi-automatic interpretative maps to identify the relationship between coral distribution patterns and canyon environments. A total of 21 ROV immersions were carried out in different canyon environments at depths ranging between 79 and 401 m. Large, healthy colonies of M. oculata occur on abrupt, protected, often overhanging, rocky sections of the canyon walls, especially in Illa Negra branch. D. cornigera is sparser and evenly distributed at depth, on relatively low sloping areas, in rocky but also partially sedimented areas. C. rubrum is most frequent between 100 and 160 m on highly sloping rocky areas. The probable extent of CWC habitats is quantified by applying a maximum entropy model to predict habitat suitability: 0.36 km2 yield M. oculata occurrence probabilities over 70%. Similar predictive models have been produced for D. cornigera and C. rubrum. All ROV transects document either the presence of litter on the seafloor or pervasive trawling marks. Nets and longlines are imaged entangled on coral colonies. Coral rubble is observed at the foot of impacted colonies. Some colonies are partially covered by sediment that could be the result of the resuspension generated by bottom trawling on neighbouring fishing grounds, which has been demonstrated to be responsible of daily increases in sediment fluxes within the canyon. The characteristics of the CWC community in La Fonera canyon are indicative that it withstands high environmental stress of both natural and human origin. PMID:27182776

  17. Characterization of submarine canyon bathymetries in northern Ionian Sea, Italy, using sediment geochemical variation induced by transportation distance and basin depth

    NASA Astrophysics Data System (ADS)

    Francesco, Perri; Tohru, Ohta; Salvatore, Critelli

    2015-07-01

    Geochemical data of marine mud sediments collected from the Esaro, Neto and Corigliano canyons in the northern Ionian Sea (southern Italy) were investigated in order to characterize canyon bathymetry types. Mud sample compositions analyzed by the principal component analysis (PCA) provided useful information for the morphology of the depositional area of the northern Ionian Sea. The use of sediment geochemical data as well as transportation distance and depth as input variables for PCA enabled the extraction of following latent variables: basin depth (PC1), sedimentation rate (PC2) and transportation distance (PC3). Based on these results, we further developed geochemical indices that can estimate basin depth (F1), sedimentation rate (F2) and transportation distance (F3); these functions can be solely calculated from the elemental concentration data of the mud samples. Since these F1, F2 and F3 functions are mathematically independent variables, they facilitate more precise characterization of individual canyon types. That is, the Esaro Canyon is regarded as a sediment-starved deep canyon characterized by a single source area; the Neto Canyon can be seen as a deeply sloped submarine apron system and sediments are mainly supplied by the sediment gravity flows; the Corigliano Canyon is characterized by multiple sources and moderately sloped system, whose sediments disperse mainly by traction currents. These interpretations are concordant with the basin bathymetry of the studied area. Therefore, F1, F2 and F3 functions might be applicable to any oceanic basins.

  18. Slope-confined submarine canyons in the Baiyun deep-water area, northern South China Sea: variation in their modern morphology

    NASA Astrophysics Data System (ADS)

    Li, X. S.; Zhou, Q. J.; Su, T. Y.; Liu, L. J.; Gao, S.; Zhou, S. W.

    2016-05-01

    On the basis of newly collected multibeam bathymetric data, chirp profiles and existing seismic data, we presented a detailed morphological interpretation of a series of slope-confined canyons in water depths of 300-2000 m in the Baiyun deep-water area, northern margin of the South China Sea. Although these canyons are commonly characterized by regular spacing and a straight-line shape, they vary in their lengths, starting and ending water depths, canyon relief, slope gradients, wall slope gradients and depth profiles along the axis. The eastern canyons (C1-C8) have complex surface features, low values in their slope gradient, canyon relief and wall slope gradient and high values in their length and starting and ending depth contrasting to the western ones (C9-C17). From the bathymetric data and chirp profiles, we interpret two main processes that have controlled the morphology and evolution of the canyons: axial incision and landsliding. The western part of the shelf margin where there were at least four stages of submerged reefs differs from the eastern part of the shelf margin where sedimentary undulations occurred at a water depth of ~650 m. We consider that the variation in morphology of submarine canyons in the study area is the result of multiple causes, with the leading cause being the difference in stability of the upper slope which is related to the submerged reefs and sedimentary undulations.

  19. Sedimentary processes at submarine canyons in the Palomares Margin: Approach from swath bathymetry and high resolution side-scan sonar images.

    NASA Astrophysics Data System (ADS)

    Perez-Hernandez, Silvia; Comas, Menchu; Escutia, Carlota

    2010-05-01

    The continental slope of the Palomares Margin (South Iberian Margin, Western Mediterranean) is dissected by submarine canyons. Previous works on the Palomares Margin have been focused mainly on structural studies related to the Gibraltar Arc geodynamics, but the understanding of sedimentary and erosive processes shaping the margin and their control factors have received few attention till now. We present here morphologic features of the two mayor canyons in the Palomares Margin: the Gata and the Alías-Almanzora canyons, and interpret these characteristics in terms of sedimentary processes. Our study is built on swath bathymetry (Simrad EM-120), and deep-towed side-scan sonar (MAK-1M) data. Both canyons incise from the continental shelf of the Palomares Margin conducting sediment transfer by down-canyon gravity flows to the continental rise. The Gata Canyon is 64 km long, and headed by three tributary canyons. The Alías-Almanzora Canyon, which locates about 50 km to the north of the Gata Canyon, is 73 km long and headed by four tributary canyons facing rivers. The side-scan sonar images reveal erosion, transport and sedimentation processes along both canyon-valleys. Erosive bedforms are reliable evidence for the persistence of bottom currents (speed > 1 m s-1) along the thalwegs. The V-shaped of the Gata Canyon, confined by basement seamounts, suggests that turbidity currents have been the most important erosive mechanism and mass-wasting could be the dominant process to favour retrogressive sediment failures. Gullies with a herringbone pattern have been observed at the Alías-Almanzora valley; these forms are interpreted as derived from river-flooding events and/or from water-currents development at the continental shelf. Sediment waves observed at the Alías-Almanzora canyon-mouth can be related to events of contour bottom currents at the base of slope. Relative sea-level variations induced either by tectonic processes (Palomares margin uplift) or Mediterranean eustatic sea-level changes, or both, are considered significant control factors on the evolution of these canyons. Considering the tectonic setting of the studied region, we favour that the Pliocene-to-Present tectonic uplift recognized in the Palomares Margin is the major cause driving the development of these canyons. Acknowledgments: This study was supported by projects CTM2009-07715, TOPOMED-CGL2008-03474-E/BTE and CONSOLIDER-INGENIO2010-CSD2006-00041Projects (MICINN and FEDER funding, Spain) and RNM3713, RNM215 (PAI, Junta de Andalucía funding, Spain.

  20. A Picture on the Wall: Innovative Mapping Reveals Cold-Water Coral Refuge in Submarine Canyon

    PubMed Central

    Huvenne, Veerle A. I.; Tyler, Paul A.; Masson, Doug G.; Fisher, Elizabeth H.; Hauton, Chris; Hühnerbach, Veit; Le Bas, Timothy P.; Wolff, George A.

    2011-01-01

    Cold-water corals are azooxanthellate species found throughout the ocean at water depths down to 5000 m. They occur in patches, reefs or large mound structures up to 380 m high, and as ecosystem engineers create important habitats for a diverse fauna. However, the majority of these habitats are now within reach of deep-sea bottom trawling. Many have been severely damaged or are under threat, despite recent protection initiatives. Here we present a cold-water coral habitat type that so far has been overlooked – quite literally – and that has received minimal impact from human activities. Vertical and overhanging cliffs in deep-sea canyons, revealed using an innovative approach to marine habitat mapping, are shown to provide the perfect substratum for extensive cold-water coral-based communities. Typical canyon-related processes, including locally enhanced internal tides and focussed downslope organic carbon transport, provide favourable environmental conditions (current regime, food input) to sustain the communities, even outside the optimal depth and density envelopes reported elsewhere in the NE Atlantic. Our findings show that deep-sea canyons can form natural refuges for faunal communities sensitive to anthropogenic disturbance, and have the potential to fulfil the crucial role of larval sources for the recolonisation of damaged sites elsewhere on the margin. PMID:22194903

  1. Impact of bottom trawling on deep-sea sediment properties along the flanks of a submarine canyon.

    PubMed

    Martn, Jacobo; Puig, Pere; Masqu, Pere; Palanques, Albert; Snchez-Gmez, Anabel

    2014-01-01

    The offshore displacement of commercial bottom trawling has raised concerns about the impact of this destructive fishing practice on the deep seafloor, which is in general characterized by lower resilience than shallow water regions. This study focuses on the flanks of La Fonera (or Palams) submarine canyon in the Northwestern Mediterranean, where an intensive bottom trawl fishery has been active during several decades in the 400-800 m depth range. To explore the degree of alteration of surface sediments (0-50 cm depth) caused by this industrial activity, fishing grounds and control (untrawled) sites were sampled along the canyon flanks with an interface multicorer. Sediment cores were analyzed to obtain vertical profiles of sediment grain-size, dry bulk density, organic carbon content and concentration of the radionuclide 210Pb. At control sites, surface sediments presented sedimentological characteristics typical of slope depositional systems, including a topmost unit of unconsolidated and bioturbated material overlying sediments progressively compacted with depth, with consistently high 210Pb inventories and exponential decaying profiles of 210Pb concentrations. Sediment accumulation rates at these untrawled sites ranged from 0.3 to 1.0 cm y-1. Sediment properties at most trawled sites departed from control sites and the sampled cores were characterized by denser sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sediments caused by trawling gears. Other alterations of the physical sediment properties, including thorough mixing or grain-size sorting, as well as organic carbon impoverishment, were also visible at trawled sites. This work contributes to the growing realization of the capacity of bottom trawling to alter the physical properties of surface sediments and affect the seafloor integrity over large spatial scales of the deep-sea. PMID:25111298

  2. Impact of Bottom Trawling on Deep-Sea Sediment Properties along the Flanks of a Submarine Canyon

    PubMed Central

    Martín, Jacobo; Puig, Pere; Masqué, Pere; Palanques, Albert; Sánchez-Gómez, Anabel

    2014-01-01

    The offshore displacement of commercial bottom trawling has raised concerns about the impact of this destructive fishing practice on the deep seafloor, which is in general characterized by lower resilience than shallow water regions. This study focuses on the flanks of La Fonera (or Palamós) submarine canyon in the Northwestern Mediterranean, where an intensive bottom trawl fishery has been active during several decades in the 400–800 m depth range. To explore the degree of alteration of surface sediments (0–50 cm depth) caused by this industrial activity, fishing grounds and control (untrawled) sites were sampled along the canyon flanks with an interface multicorer. Sediment cores were analyzed to obtain vertical profiles of sediment grain-size, dry bulk density, organic carbon content and concentration of the radionuclide 210Pb. At control sites, surface sediments presented sedimentological characteristics typical of slope depositional systems, including a topmost unit of unconsolidated and bioturbated material overlying sediments progressively compacted with depth, with consistently high 210Pb inventories and exponential decaying profiles of 210Pb concentrations. Sediment accumulation rates at these untrawled sites ranged from 0.3 to 1.0 cm y−1. Sediment properties at most trawled sites departed from control sites and the sampled cores were characterized by denser sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sediments caused by trawling gears. Other alterations of the physical sediment properties, including thorough mixing or grain-size sorting, as well as organic carbon impoverishment, were also visible at trawled sites. This work contributes to the growing realization of the capacity of bottom trawling to alter the physical properties of surface sediments and affect the seafloor integrity over large spatial scales of the deep-sea. PMID:25111298

  3. Defining biological assemblages (biotopes) of conservation interest in the submarine canyons of the South West Approaches (offshore United Kingdom) for use in marine habitat mapping

    NASA Astrophysics Data System (ADS)

    Davies, Jaime S.; Howell, Kerry L.; Stewart, Heather A.; Guinan, Janine; Golding, Neil

    2014-06-01

    In 2007, the upper part of a submarine canyon system located in water depths between 138 and 1165 m in the South West (SW) Approaches (North East Atlantic Ocean) was surveyed over a 2 week period. High-resolution multibeam echosounder data covering 1106 km2, and 44 ground-truthing video and image transects were acquired to characterise the biological assemblages of the canyons. The SW Approaches is an area of complex terrain, and intensive ground-truthing revealed the canyons to be dominated by soft sediment assemblages. A combination of multivariate analysis of seabed photographs (184-1059 m) and visual assessment of video ground-truthing identified 12 megabenthic assemblages (biotopes) at an appropriate scale to act as mapping units. Of these biotopes, 5 adhered to current definitions of habitats of conservation concern, 4 of which were classed as Vulnerable Marine Ecosystems. Some of the biotopes correspond to descriptions of communities from other megahabitat features (for example the continental shelf and seamounts), although it appears that the canyons host modified versions, possibly due to the inferred high rates of sedimentation in the canyons. Other biotopes described appear to be unique to canyon features, particularly the sea pen biotope consisting of Kophobelemnon stelliferum and cerianthids.

  4. Relationship between environment and the occurrence of the deep-water rose shrimp Aristeus antennatus (Risso, 1816) in the Blanes submarine canyon (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Sardà, F.; Company, J. B.; Bahamón, N.; Rotllant, G.; Flexas, M. M.; Sánchez, J. D.; Zúñiga, D.; Coenjaerts, J.; Orellana, D.; Jordà, G.; Puigdefábregas, J.; Sánchez-Vidal, A.; Calafat, A.; Martín, D.; Espino, M.

    2009-09-01

    We performed a multidisciplinary study characterizing the relationships between hydrodynamic conditions (currents and water masses) and the presence and abundance of the deep-water rose shrimp Aristeus antennatus in a submarine canyon (Blanes canyon in the NW Mediterranean Sea). This species is heavily commercially exploited and is the main target species of a bottom trawl fishery. Seasonal fluctuations in landings are attributed to spatio-temporal movements by this species associated with submarine canyons in the study area. Despite the economic importance of this species and the decreases in catches in the area in recent years, few studies have provided significant insight into the environmental conditions driving shrimp distribution. We therefore measured daily A. antennatus catches over the course of an entire year and analyzed this time series in terms of daily average temperature, salinity, mean kinetic energy (MKE), and eddy kinetic energy (EKE) values using generalized additive models and decision trees. A. antennatus was captured between 600 and 900 m in the Blanes canyon, depths that include Levantine Intermediate Water (LIW) and the underlying Western Mediterranean Deep Water (WMDW). The greatest catches were associated with relatively salty waters (38.5-38.6), low MKE values (6 and 9 cm 2 s -2) and moderate EKE values (10 and 20 cm 2 s -2). Deep-water rose shrimp occurrence appears to be driven in a non-linear manner by environmental conditions including local temperature. A. antennatus appears to prefer relatively salty (LIW) waters and low currents (MKE) with moderate variability (EKE).

  5. From Kings Peak to the Delgado submarine canyon: Tracking littoral inputs to the deep sea at the Mendocino Triple Junction, California

    NASA Astrophysics Data System (ADS)

    Davidson, C. J.; Di Fiori, R. V.; Smith, M. E.; Mueller, E. R.

    2011-12-01

    Gravel coarse enough to overcome viscous damping and impact bedrock underwater is thought prerequisite for incision of submarine canyons, yet with few exceptions, canyons off the California coast have headwalls >2 km offshore at the shelf edge and below storm wave base. This suggests effective disconnection from modern coarse littoral sediment fluxes, and implies they are relict Pleistocene features only actively incised during glacial periods. North of the Transverse Ranges only five submarine canyons approach shore closer than 500 m, and are coincident areas of rapid uplift. Although canyons occur adjacent to major upland-draining streams that transport coarse sediment, submarine canyon headwalls are often laterally offset from stream mouths by ~1-2 km. Coarse stream sediment thus requires littoral transport to enter canyon heads and induce incision. To better understand the evolution of coarse sediment through the littoral system, we measured the texture and composition of coarse sediment in streams and beaches directly onshore of the Delgado submarine canyon, which lies offshore of the fastest uplifting segment of the King Range and onshore the Mendocino Triple Junction. Adjacent to the Delgado Canyon inlet, coarse (d50 > 360 mm) sediment enters the littoral zone from three streams, and is transported alongshore in a predominantly southeast direction. Stream-derived alluvium is comprised of a poorly to moderately sorted mixture of angular to subrounded clasts of well-cemented sandstone (d50 = 256-725 mm) and fissile siliciclastic mudstone (d50 = 90-256 mm). Well sorted and rounded beach gravels adjacent to stream mouths are similarly coarse, and clasts larger than 1 m diameter extend 200-400 meters eastward from stream mouths. In contrast, sediment entering the littoral zone from hillslope erosion between streams is finer (d50 ~16 mm) and is exclusively comprised of pervasively-folded siliciclastic mudstone. Immediately adjacent the Delgado canyon headwall, beach sediments are nearly two orders of magnitude finer than sediment at stream mouths (d50 = 16 mm). However, sandstone clasts are coarser (d50 = 32 mm), comprise ~30% of the total mass, and approximately 10% of these clasts exceed 128 mm in diameter. The mudstone fraction in contrast is much finer (d50 = 4 mm). Particles finer than 0.25 mm represent less than 10% of beach sediment, consistent with effective removal of fines from the littoral environment. Lithologic contrast between sandstone and mudstone rock types is the basis for a multi-lithologic downstream fining model that routes sediment through the littoral system. Inputs of sediment are calculated according to upstream catchment area for 200 m segments of coastline and scaled according to lithologically based erosion rates, with differential diminuation as it is routed through the littoral zone. Initial model results indicate that differential abrasion of mudstone clasts relative to sandstone clasts is important to achieving grain size and lithologic distributions observed at the canyon head, and the presence of clasts >100 mm diameter ~1 km from their input via stream to the littoral zone provides tools needed for incision submarine bedrock.

  6. Trophic relationships at intrannual spatial and temporal scales of macro and megafauna around a submarine canyon off the Catalonian coast (western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Cartes, Joan E.; Fanelli, Emanuela; Papiol, Vanesa; Maynou, Francesc

    2010-04-01

    The spatial and temporal changes of near-bottom macrofauna (suprabenthos and macroplankton) and the trophic relationships of megabenthic decapod crustaceans were analyzed off the Catalonian coasts (western Mediterranean) around Berenguera submarine canyon in four periods (April and December 1991, March and July 1992) and four zones (within Berenguera Canyon at ca. 450 m, and on adjacent slope at ca. 400, 600 m and 1200 m). In March 1992, we found the highest macrofauna abundance and the smallest sizes in the canyon, suggesting a positive effect of river discharges on suprabenthos recruitment. By contrast, macroplankton (decapods, fishes and euphausiids) did not show higher recruitment into canyons. After analyzing the diet of 23 decapod crustaceans, we found a significant segregation between guilds feeding on zooplankton and on benthos. Zooplankton (euphausiids and Pasiphaeidae) and infauna (polychaetes, Calocaris macandreae and ophiuoroids) were consistently the main prey exploited by decapod crustaceans around Berenguera Canyon. We also found some macrophyte ( Posidonia oceanica) consumption, which was higher in periods of water column homogeneity (winter-spring and late autumn). Positive correlations between decapods' gut fullness ( F) and decapod abundance indicate feeding aggregations, while positive correlations were also found between F and Llobregat River (situated ca. 18 km from Berenguera head) flow 1 to 2 months before sampling. Increases in F were delayed only 1 month when zooplankton feeders were analyzed alone, while benthos feeders did not show significant relationships with any environmental variables. That indicates that the response of megabenthic decapods feeding on benthos to environmental shifts is slower than that of zooplankton feeders. The importance of river flows in enhancing food supply of macro- and megabenthos dwelling close to submarine canyons was apparent, with a delay in the fauna response of 0-2 months after river flow peaks.

  7. Megalodicopia hians in the Monterey submarine canyon: Distribution, larval development, and culture

    NASA Astrophysics Data System (ADS)

    Havenhand, Jon. N.; Matsumoto, George I.; Seidel, Ed

    2006-02-01

    The exclusively deep-sea ascidian family Octacnemidae comprises several genera in which the oral siphon has hypertrophied to form two large lips which create an "oral hood" capable of capturing motile prey. Megalodicopia hians is typical of this carnivorous family and has been reported to prey upon small epibenthic crustaceans. Distribution of M. hians in the Monterey Canyon system (36°45'N, 122°00'W) (California) was determined with remotely operated vehicles. M. hians was found sparsely to depths of at least 3800 m throughout the canyon; however, abundance was greatest within the oxygen-minimum zone (400-800 m). Eggs, sperm, and recently fertilized embryos were obtained repeatedly from adults returned to the laboratory in vivo, indicating that this species free-spawns routinely. Overall egg diameter (ovum plus chorion, plus follicle cells) was 175-190 μm—considerably smaller than previously reported for this species. Embryonic development at temperature and oxygen concentrations equivalent to the oxygen-minimum zone was 2-4 d and, embryos gave rise to typical phlebobranch "simple" tadpole larvae. Larval period was extremely variable, and settlement/metamorphosis occurred up to 3 months post-hatching. These results are discussed within the context of settlement-site selection and fertilization ecology of the species.

  8. Observation of internal tide-induced nutrient upwelling in Hungtsai Trough, a submarine canyon in the northern South China Sea

    NASA Astrophysics Data System (ADS)

    Pai, Su-Cheng; Wei, Ching-Ling; Lin, Saulwood; Wen, Liang-Saw; Tseng, Chun-Mao

    2016-06-01

    Temporal variations in hydrographic parameters and nutrients were observed in a 300 m deep submarine canyon (Hungtsai Trough) near the southern tip of Taiwan. A vigorous oscillation below the surface layer has been observed which relates closely to an internal tidal wave generated from the nearby Luzon Strait. The vertical movement can be measured by monitoring an 18 °C isothermal depth which shows an up-and-down oscillation between 90 and 240 m with an average displacement of 110 m within a tidal cycle, a scale significantly larger than has been reported elsewhere. The frequency of this oscillation coincides with the surface tide but in an almost opposite phase. All hydrographic and chemical parameters (oxygen, density, fluorescence, transmittance and nutrients including nitrate, phosphate and silicate) synchronize with the tidal movement, as judged by normalized plots against temperature. When the nutrient-rich deep water upwells and becomes an outcrop over the trough rim at 100 m deep, it is swept horizontally by the strong alongshore tidal current. Consequently, the trough acts as a source point to supply extra nutrients to the coastal ecosystem.

  9. Swept away by a turbidity current in Mendocino submarine canyon, California

    NASA Astrophysics Data System (ADS)

    Sumner, E. J.; Paull, C. K.

    2014-11-01

    We present unique observations and measurements of a dilute turbidity current made with a remotely operated vehicle in 400 m water depth near the head of Mendocino Canyon, California. The flow had a two-layer structure with a thin (0.5 to 30 m), relatively dense (<0.04 vol %) and fast (up to ~1.7 m/s) wedge-shaped lower layer overlain by a thicker (up to 89 m) more dilute and slower current. The fast moving lower layer lagged the slow moving, dilute flow front by 14 min, which we infer resulted from the interaction of two initial pulses. The two layers were strongly coupled, and the sharp interface between the layers was characterized by a wave-like instability. This is the first field-scale data from a turbidity current to show (i) the complex dynamics of the head of a turbidity current and (ii) the presence of multiple layers within the same event.

  10. Delivery of Terrigenous Material to Submarine Fans: Biological Evidence of Local, Staged, and Possibly Full Canyon Sediment Transport Down the Ascension-Monterey Canyon System Off Central California, USA

    NASA Astrophysics Data System (ADS)

    McGann, M.

    2014-12-01

    Submarine canyons are instrumental in transporting sediment from coastal regions to deep-sea fans. Mean grain size, distribution, and sorting have been used to characterize these deposits, but they provide little information on where sediment transport was initiated or the delivery processes involved. Fortunately, the entrained biological constituents have unique environmental signatures that are more precise proxies for source areas than are mineral grains alone. They may identify a single biofacies deposit (SBD) resulting from local sediment transport such as storm waves, peak river discharge, breaking of internal waves, canyon wall sloughing, or hemipelagic deposition, or a displaced, multiple biofacies deposit (MBD) containing several biofacies where sediment is transported from one biofacies to another, is caught behind a slump that acts as a dam, remains there long enough for the local fauna to become established, and then this combined assemblage is transported further downslope when the dam breaks. Multiple episodes of this "staged" storage-and-release process occur sequentially so as to move the sediment progressively down the canyon. Rarely, exceptionally large triggers such as earthquakes, intense storm disturbances, and catastrophic failure of canyon walls result in full canyon flushing events, entraining numerous biofacies during a single rapid descent. These events can be differentiated in recent deposits by the presence of living specimens representing distinct biofacies or in historic records by dating individual biofacies within a turbidite. A 19,000 year record from the Ascension-Monterey Canyon system (core S3-15G, 36°23.53'N, 123°20.52'W; 3491 m) captured hemipelagic mud interspersed with turbiditic sand and silt transported to lower bathyal depths. The relative abundance of displaced benthic foraminifera was found to correlate positively with grain size (75% in cross-bedded turbiditic sands, 39% in laminated turbiditic sands, and 15% in turbiditic muds) and the 65 MBDs recovered originated from the estuarine/inner shelf to the upper middle slope. Sediment bypassing was evident and possibly full canyon flushing as well. Identifying allochthonous biological sediment constituents is a powerful tool in the investigation of sediment transport in submarine canyons.

  11. Spatial and temporal infaunal dynamics of the Blanes submarine canyon-slope system (NW Mediterranean); changes in nematode standing stocks, feeding types and gender-life stage ratios

    NASA Astrophysics Data System (ADS)

    Ingels, Jeroen; Vanreusel, Ann; Romano, Chiara; Coenjaerts, Johan; Mar Flexas, M.; Zúñiga, Diana; Martin, Daniel

    2013-11-01

    Despite recent advances in the knowledge of submarine canyons ecosystems, our understanding of the faunal patterns and processes in these environments is still marginal. In this study, meiobenthic nematode communities (from 300 m to 1600 m depth) obtained in November 2003 and May 2004 at eight stations inside and outside Blanes submarine canyon were analysed for nematode standing stocks (SSs), feeding types and gender-life stage distributions. Environmental data were obtained by sediment traps and current meters, attached to moorings (April 2003-May 2004), and sediments samples analysed for biogeochemistry and grain size (May 2004). In November 2003, nematode SSs decreased with increasing depth (367.2 individuals and 7.31 μg C per 10 cm2 at 388 m water depth to 7.7 individuals and 0.18 μg C per 10 cm2 at 1677 m water depth), showing a significant negative relation (abundance: R2 = 0.620, p = 0.020; biomass: R2 = 0.512, p = 0.046). This was not the case in May 2004 (283.5 individuals and 3.53 μg C per 10 cm2 at 388 m water depth to 490.8 individuals and 4.93 μg C per 10 cm2 at 1677 m water depth; abundance: R2 = 0.003, p = 0.902; biomass: R2 = 0.052, p = 0.587), suggesting a temporal effect that overrides the traditional decrease of SSs with increasing water depth. Both water depth and sampling time played a significant role in explaining nematode SSs, but with differences between stations. No overall differences were observed between canyon and open slope stations. Nematode standing stock (SS) patterns can be explained by taking into account the interplay of phytodetrital input and disturbance events, with station differences such as topography playing an important role. Individual nematode size decreased from November 2003 to May 2004 and was explained by a food-induced genera shift and/or a food-induced transition from a ‘latent’ to a ‘reproductive’ nematode community. Our results suggest that size patterns in nematode communities are not solely governed by trophic conditions over longer periods of time in relatively food-rich environments such as canyons. We hypothesize that food pulses in a dynamic and topographical heterogeneous environment such as canyons regulate nematode size distributions, rather than long-term food availability. Feeding type distributions in the Blanes Canyon did not clearly resemble those from other canyon systems, apart from the spring assemblage at one station in the head of the canyon.

  12. Demography and movement patterns of leopard sharks (Triakis semifasciata) aggregating near the head of a submarine canyon along the open coast of southern California, USA

    USGS Publications Warehouse

    Nosal, D.C.; Cartamil, D.C.; Long, J.W.; Luhrmann, M.; Wegner, N.C.; Graham, J.B.

    2013-01-01

    The demography, spatial distribution, and movement patterns of leopard sharks (Triakis semifasciata) aggregating near the head of a submarine canyon in La Jolla, California, USA, were investigated to resolve the causal explanations for this and similar shark aggregations. All sharks sampled from the aggregation site (n=140) were sexually mature and 97.1 % were female. Aerial photographs taken during tethered balloon surveys revealed high densities of milling sharks of up to 5470 sharks ha-1. Eight sharks were each tagged with a continuous acoustic transmitter and manually tracked without interruption for up to 48 h. Sharks exhibited strong site-fidelity and were generally confined to a divergence (shadow) zone of low wave energy, which results from wave refraction over the steep bathymetric contours of the submarine canyon. Within this divergence zone, the movements of sharks were strongly localized over the seismically active Rose Canyon Fault. Tracked sharks spent most of their time in shallow water (≤2 m for 71.0 % and ≤10 m for 95.9 % of time), with some dispersing to deeper (max: 53.9 m) and cooler (min: 12.7 °C) water after sunset, subsequently returning by sunrise. These findings suggest multiple functions of this aggregation and that the mechanism controlling its formation, maintenance, and dissolution is complex and rooted in the sharks' variable response to numerous confounding environmental factors.

  13. Hazard assessment for a submarine landslide generated local-source tsunami from Kaikoura Canyon

    NASA Astrophysics Data System (ADS)

    DuBois, J.

    2012-04-01

    The Kaikoura Canyon, sediment sink for the Canterbury rivers north of Christchurch, comes to within 500 meters of shore at Goose Bay and accumulates approximately 1.5x106 m3 of sediment each year (Lewis and Barnes, 1999). This sediment, which has accumulated to about seventy meters in thickness (Walters et al., 2006), exhibits tensional fractures, is located in a tectonically active area and could result in catastrophic failure and potentially a local-source tsunami (Lewis and Banes, 1999; Lewis, 1998; Walters et al, 2006). Evidence suggests that this may have happened in the last two hundred years (Lewis, 1998; Lewis and Barnes 1999) and with a return period on the nearby Alpine and Hope faults also in the range of a one to two hundred years (Walters et al, 2006) could happen again relatively soon. A review of the historical record and oral traditions for Kaikoura shows that historically Kaikoura has been affected by 11 events of which 10 are from distant sources and one, though debatable, is possibly from a local source. There are some preserved traditions for the Kaikoura area. These taniwha stories from near Oaro and from the Lyell Creek have been repeated and changed though time though the general essence remains the same. These taniwha legends, though not conclusive, indicate a dangerous shoreline where people have been killed in the past, possibly by flooding or tsunami. Archaeological investigations at Kaikoura found evidence of a Maori occupational layers interrupted by water-worn stones, a "lens of clean gravel between occupation layers" and in other areas of the excavation, the gravels separate discontinuous periods of occupation (Fomison 1963; Foster, 2006). Additionally "pea-gravel" sized greywacke pebbles were found dispersed throughout sections of the South Bay shore platforms, though they were attributesd to slopewash (Duckmanton, 1974) this is less likely since the nearby hills are limestone. A geological investigation along the Kaikoura Coast, at five sites from South Bay to Oara, corroborates this. At four of the sites a similar greywacke pebble bearing layer was found which was not present at test sites to the North and South of the peninsula (Kiwa Rd Campsites and Claverly respectively). These deposits contain diatoms indicating marine provenance. Surveys of Kaikoura peninsula households and businesses showed low levels of preparedness for a local source event. In regards to local-source tsunamis the district council has indicated that they "are unpredictable [and] it is impractical to include rules to mitigate their effects. Instead, the Council is committed to a Civil Defence network which provides an educative role and which sets in place a process for dealing with the results of any tsunami" (Kaikoura District Plan, 2010). Plans and an education strategy need to be formulated and implemented. They need to address considerations such as the fact that about 60% of those surveyed expect some sort of siren warning and the limitations inherent in such a warning system along with signage and public tsunami hazard maps and evacuation zones.

  14. Sedimentology, architecture, and depositional evolution of a coarse-grained submarine canyon fill from the Gelasian (early Pleistocene) of the Peri-Adriatic basin, Offida, central Italy

    NASA Astrophysics Data System (ADS)

    Di Celma, Claudio

    2011-07-01

    The early Pleistocene stratigraphic succession of the Peri-Adriatic basin, eastern central Italy, records the filling of an elongate, N-S oriented piggy-back basin located east of the growing Apennine fold-thrust belt. During the Gelasian (2.588-1.806 Ma), large volumes of gravel, sand and mud derived from the emergent Apennines were redistributed into the basin through a number of slope erosional fairways. These sediment conduits are preserved in the rock record as a series of coarse-grained canyon-fill successions that provide an opportunity for assessing, from an outcrop perspective, how this type of deep-water depositional systems evolves and fills. The present study uses measured stratigraphic sections, photopanels, paleocurrent data, careful lithological mapping, and well-log data from a nearby exploration well to constrain the internal organization of one of these canyon fills, referred to herein as the Offida Canyon. A detailed facies analysis suggests that a variety of gravity-driven subaqueous flows were involved in sediment transport and deposition within the submarine canyon, including slumps, cohesive debris flows, and high- and low-density turbidity currents. Five main lithofacies reflecting both canyon-bounding slope deposits and canyon-filling turbidite and debrite depositional elements have been identified within the exposed succession: (i) clast-supported conglomerates (gravel-rich channel complexes); (ii) medium- to thick-bedded sandstones (overbank lobe); (iii) medium- to very thin-bedded sandstones and mudstones (levee-overbank); (iv) pebbly mudstones and chaotic beds (mudstone-rich mass-transport deposits); and (v) massive mudstones (hemipelagic background deposits). These lithofacies are organized in recurring successions and define fining-upward packages that are regarded as the deep-water expression of high-frequency depositional sequences. Each sequence comprises the sedimentary record of major phases of canyon activity and comprises the following surfaces and systems tracts, in ascending stratigraphic order: (i) a pronounced surface of erosion (sequence boundary) generated by efficient turbidity currents during a period of erosion and complete bypass of sediment to more basinward settings; (ii) a lowstand systems tract composed of a diverse assemblage of genetically related lithofacies (channel-complex conglomerates, levee sandy heterolithics, and overbank lobe sheet-like sandstones) laid down by turbidity currents largely bypassing the area; and (iii) a transgressive to forced regressive systems tract comprising mass-transport deposits produced by instability of shelf-edge staging areas and/or failure of canyon walls when coastal sediment sources were far from the shelf edge. Correlation between sequences and oxygen isotope curve suggests that the recurring fluctuations in sedimentary activity of the submarine canyon are related to the switching on and off of coarse clastic sediments to the slope in response to obliquity-driven (41 ky duration) glacio-eustatic sea-level oscillations, which modulated timing of sediment storage on the shelf and its redistribution beyond the shelf edge.

  15. 78 FR 67086 - Safety Zone, Submarine Cable Replacement Operations, Kent Island Narrows; Queen Anne's County, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    .... SUPPLEMENTARY INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice... public dockets in the January 17, 2008, issue of the Federal Register (73 FR 3316). 4. Public Meeting We... Narrows, within an area bounded by the following points: from position latitude 38 58'14.5'' N,...

  16. Structure-forming corals and sponges and their use as fish habitat in Bering Sea submarine canyons.

    PubMed

    Miller, Robert J; Hocevar, John; Stone, Robert P; Fedorov, Dmitry V

    2012-01-01

    Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide. PMID:22470486

  17. Biophysical Factors Affecting the Distribution of Demersal Fish around the Head of a Submarine Canyon Off the Bonney Coast, South Australia

    PubMed Central

    Currie, David R.; McClatchie, Sam; Middleton, John F.; Nayar, Sasi

    2012-01-01

    We sampled the demersal fish community of the Bonney Canyon, South Australia at depths (100–1,500 m) and locations that are poorly known. Seventy-eight species of demersal fish were obtained from 12 depth-stratified trawls along, and to either side, of the central canyon axis. Distributional patterns in species richness and biomass were highly correlated. Three fish assemblage groupings, characterised by small suites of species with narrow depth distributions, were identified on the shelf, upper slope and mid slope. The assemblage groupings were largely explained by depth (ρw = 0.78). Compared to the depth gradient, canyon-related effects are weak or occur at spatial or temporal scales not sampled in this study. A conceptual physical model displayed features consistent with the depth zonational patterns in fish, and also indicated that canyon upwelling can occur. The depth zonation of the fish assemblage was associated with the depth distribution of water masses in the area. Notably, the mid-slope community (1,000 m) coincided with a layer of Antarctic Intermediate Water, the upper slope community (500 m) resided within the core of the Flinders Current, and the shelf community was located in a well-mixed layer of surface water (<450 m depth). PMID:22253907

  18. Architecture and development of a multi-stage Baiyun submarine slide complex in the Pearl River Canyon, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Wu, Shi-Guo; Li, Qing-Ping; Wang, Da-Wei; Fu, Shao-Ying

    2014-08-01

    The Baiyun submarine slide complex (BSSC) along the Pearl River Canyon of the northern South China Sea has been imaged by multibeam bathymetry and 2D/3D seismic data. By means of maximum likelihood classification with slope aspect and gradient as inputs, the BSSC is subdivided into four domains, denoted as slide area I, II, III and IV. Slide area I is surrounded by cliffs on three sides and has been intensely reshaped by turbidity currents generated by other kinds of mass movement outside the area; slide area II incorporates a shield volcano with a diameter of approximately 10 km and unconfined slides possibly resulting from the toe collapse of inter-canyon ridges; slide area III is dominated by repeated slides that mainly originated from cliffs constituting the eastern boundary of the BSSC; slide area IV is distinguished by a conical seamount with a diameter of 6.5 km and a height of 375 m, and two slides probably having a common source that are separated from each other by a suite of residual strata. The BSSC is interpreted to be composed of numerous slide events, which occurred in the period from 10.5 to 5.5 Ma BP. Six specific factors may have contributed to the development of the BSSC, i.e., gas hydrate dissociation, gas-bearing sediments, submarine volcanic activity, seismicity, sedimentation rate and seafloor geomorphology. A 2D conceptual geological model combining these factors is proposed as a plausible mechanism explaining the formation of the BSSC. However, the BSSC may also have been affected by the Dongsha event (10 Ma BP) as an overriding factor.

  19. Mechanisms of vegetation-induced channel narrowing of an unregulated canyon river: Results from a natural field-scale experiment

    NASA Astrophysics Data System (ADS)

    Manners, Rebecca B.; Schmidt, John C.; Scott, Michael L.

    2014-04-01

    The lower Yampa River in Yampa Canyon, western Colorado serves as a natural, field-scale experiment, initiated when the invasive riparian plant, tamarisk (Tamarix spp.), colonized an unregulated river. In response to tamarisk's rapid invasion, the channel narrowed by 6% in the widest reaches since 1961. Taking advantage of this unique setting, we reconstructed the geomorphic and vegetation history in order to identify the key mechanisms for which, in the absence of other environmental perturbations, vegetation alters fluvial processes that result in a narrower channel. From our reconstruction, we identified a distinct similarity in the timing and magnitude of tamarisk encroachment and channel change, albeit with a lag in the channel response, thus suggesting tamarisk as the driving force. Within a decade of establishment, tamarisk effectively trapped sediment and, as a result, increased floodplain construction rates. Increasing tamarisk coverage over time also reduced the occurrence of floodplain stripping. Tamarisk recruitment was driven by both hydrologic and hydraulic variables, and the majority of tamarisk plants (84%) established below the stage of the 2-year flood. Thus, upon establishment nearly all plants regularly interact with the flow and sediment transport field. Our analyses were predicated on the hypothesis that the flow regime of the Yampa River was stationary, and that only the riparian vegetation community had changed. While not heavily impacted by water development, we determined that some aspects of the flow regime have shifted. However, this shift, which involved the clustering in time of extremely wet and dry years, did not influence fluvial processes directly. Instead these changes directly impacted riparian vegetation and changes in vegetation cover, in turn, altered fluvial processes. Today, the rate of channel change and new tamarisk recruitment is small. We believe that the rapid expansion of tamarisk and related floodplain construction that led to a narrower channel pushed the Yampa River into a new stable state, characterized by a relatively static channel.

  20. Are deep-sea organisms dwelling within a submarine canyon more at risk from anthropogenic contamination than those from the adjacent open slope? A case study of Blanes canyon (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Koenig, Samuel; Fernández, Pilar; Company, Joan B.; Huertas, David; Solé, Montserrat

    2013-11-01

    Due to their geomorphological structure and proximity to the coastline, submarine canyons may act as natural conduit routes for anthropogenic contaminants that are transported from surface waters to the deep-sea. Organisms dwelling in these canyon environments might thus be at risk of experiencing adverse health effects due to higher pollution exposure. To address this question, chemical and biochemical analyses were conducted on two of the most abundant deep-sea fish species in the study area, namely Alepocephalus rostratus and Lepidion lepidion, and the most abundant deep-sea commercial decapod crustacean Aristeus antennatus sampled inside Blanes canyon (BC) and on the adjacent open slope (OS). Persistent organic pollutants (POPs) levels, including polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT) and derivatives, hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were determined in muscle tissue of selected samples from 900 m and 1500 m depth. Potential effects resulting from contaminant exposure were determined using hepatic biomarkers such as ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-deethylase (PROD), catalase (CAT), carboxylesterase (CbE), glutathione-S-transferase (GST), total glutathione peroxidase (GPX), glutathione reductase (GR) and superoxide-dismutase (SOD) enzyme activities and lipid peroxidation levels (LP). L. lepidion and A. antennatus tissues exhibited higher POP levels inside BC compared to the OS at 900 m depth. These findings were consistent with biomarker data (i.e. enzymatic response to presence of contaminant agents). Elevated xenobiotic-metabolizing (EROD and PROD) and antioxidant enzymes (CAT and GPX) indicated higher contaminant exposure in both species caught within BC. No difference in POP accumulation between sites was observed in L. lepidion at 1500 m depth, nor in biomarker data, suggesting that the pollution gradient was less pronounced at greater depths. This trend was further corroborated by the results obtained for A. rostratus at 1500 m depth. Hence, the present findings suggest the, at least temporary, existence of a pollution gradient between Blanes canyon and the open slope at shallower depths and this resulted in alterations of the physiology of deep-sea organisms dwelling within this area.

  1. Marine litter in the upper São Vicente submarine canyon (SW Portugal): Abundance, distribution, composition and fauna interactions.

    PubMed

    Oliveira, Frederico; Monteiro, Pedro; Bentes, Luis; Henriques, Nuno Sales; Aguilar, Ricardo; Gonçalves, Jorge M S

    2015-08-15

    Marine litter has become a worldwide environmental problem, tainting all ocean habitats. The abundance, distribution and composition of litter and its interactions with fauna were evaluated in the upper S. Vicente canyon using video images from 3 remote operated vehicle exploratory dives. Litter was present in all dives and the abundance was as high as 3.31 items100m(-1). Mean abundance of litter over rock bottom was higher than on soft substrate. Mean litter abundance was slightly higher than reported for other canyons on the Portuguese margin, but lower in comparison to more urbanized coastal areas of the world. Lost fishing gear was the prevalent type of litter, indicating that the majority of litter originates from maritime sources, mainly fishing activity. Physical contact with sessile fauna and entanglement of specimens were the major impacts of lost fishing gear. Based on the importance of this region for the local fishermen, litter abundance is expected to increase. PMID:26051154

  2. The community of deep-sea decapod crustaceans between 175 and 2600 m in submarine canyons of a volcanic oceanic island (central-eastern Atlantic)

    NASA Astrophysics Data System (ADS)

    Pajuelo, José G.; Triay-Portella, Raül; Santana, José I.; González, José A.

    2015-11-01

    The community structure and faunal composition of deep-sea decapod crustaceans in submarine canyons on the slope off Gran Canaria Island (Canary Islands, central-eastern Atlantic) were investigated. Samples were collected during five research cruises (115 stations) at depths between 175 and 2554 m. A total of 26387 decapod specimens, belonging to 24 families and 38 species, were collected with traps. A cluster analysis of the stations showed four distinct assemblages: (i) in the transition area between shelf and slope (175-302 m); (ii) on the upper slope (361-789 m); (iii) on the middle slope (803-1973 m); and iv) on the lower slope (2011-2554 m). The deep-sea decapod fauna of the Canary Islands is dominated by shrimp of the family Pandalidae, which make up more than 23% of the species. Within the Pandalidae, species of the genus Plesionika stand out as those of greatest abundance on the island slope. The greatest diversity of species was located on the upper slope. The standardized mean abundance and mean biomass for the transition zone between the shelf and slope and for the upper slope were nearly 5 times greater in abundance and 4 times greater in biomass than those estimated for the middle slope, and nearly 53 and 29 times greater for the lower slope, indicating a lower abundance and biomass at the shallower part of the insular slope. The mean weight per individual showed an increasing pattern with depth and an inverse pattern with the bottom temperature and salinity. The existence of depth boundaries around the Canary Islands is known to be closely linked to oceanographic conditions, determined by the water masses present in this archipelago explaining the discontinuities observed at depths of 800 and 2000 m. The boundary observed inside the bathymetric region of the Eastern North Atlantic Central Water can be related with the transition zone between the shelf and the slope of the island.

  3. Canyon dynamics and related sedimentary impacts off western Portugal

    NASA Astrophysics Data System (ADS)

    Vitorino, J.; Oliveira, A.; Silva, R.; Quaresma, L.; Marreiros, R.

    2003-04-01

    Submarine canyons are areas of increased exchanges between the continental shelf and the deep ocean. We present preliminary results from a multidisciplinary research focussing the dynamics of several canyon systems that occur along the Portuguese continental margin. The research is being conducted in the framework of EU project Eurostrataform and aims to understand the dominant aspects of the interaction between shelf/slope flows and canyons and to relate those aspects with the exportation of sediments from the shelf. The present work is intended to complement results from previous projects that were focussed on the quasi-inertial dynamics of the Portuguese canyon systems. Three contrasting systems are studied: (1) the Nazaré Canyon, a narrow and deep canyon which completely cuts the shelf, with no local riverine sources; (2) the Setubal-Lisbon canyon system, located in an area of complex topography and coastline configuration, with local riverine sources (Tagus and Sado rivers) and (3) the Oporto canyon, which is restricted to the outer shelf and affected by a major riverine source (Douro river). The ongoing program of observations includes multidisciplinary surveys (CTD, ADCP, suspended particle matter measurements, shallow seismic) and both long-term and short-term currentmeter moorings. The observations will cover both the summer upwelling regime as well as the highly energetic winter conditions. Process studies will combine observations and numerical modeling tools through the use of MOCASSIM system, which is presently being developed at Instituto Hidrografico. The system integrates several numerical models and is intended to characterise the wave and current conditions over the study areas.

  4. Topographic analysis of submarine cable failures offshore southwestern taiwan

    NASA Astrophysics Data System (ADS)

    Hsia, Pei Cheng; Shine Liu, Char; Hsu, Ho Han

    2013-04-01

    In 2006, there was large scale of the submarine cable failures offshore southern Taiwan right after the Pingtung Earthquake. Apparently the December 26 Pingtung Earthquake triggered submarine mass movements which generated turbidity currents in the submarine canyons and damaged cables lying across the canyons. In addition, the Typhoon Morakot on August 8-9, 2009 and the Jiashian Earthquake on March 4, 2010 also caused many submarine cable failures offshore southwestern Taiwan. The most of broken cable sites are along the axis of the Gaoping Submarine Canyon (GPSC) and Fangliao Submarine Canyon (FLSC), topography should be an important factor controlling transport processes of submarine mass movement. The cable broken sites indicate that there were submarine mass movement pass through. Therefore, the topographic factor of the cable broken sites can be the threshold to index submarine mass movement. And as, submarine cables are distributed widely offshore southwestern Taiwan, why only a total of 35 sites of submarine cable failures occurred in 2006, 2009 and 2010? We use bathymetry data, CHIRP (compressed high-intensity radar pulse) sonar profile data and the time series of the cable breakage to investigate the characteristics of submarine mass movement and to develop a model for the series of submarine cable failure. Using the Geographic Information System (GIS) software, we analyze the bathymetric data collected before the 35 sites of submarine cable failures offshore southwestern Taiwan. Applying the hydrology in GIS software, the flow movement could be derived from the factors of slope and aspect. We quantify the transport process of submarine mass movement and combine with the time series of the cable breakage to discuss the effect between submarine cable failures. Based on the CHIRP sonar data, we identified the distinct CHIRP echo character patterns after the submarine cable failures and classify the distinct CHIRP echo characters. Using the threshold of topographic factor to expect where will be potential area of submarine mass movement and evidence the result by CHIRP sonar profile data.

  5. Let's Bet on Sediments! Hudson Canyon Cruise--Grades 9-12. Focus: Sediments of Hudson Canyon.

    ERIC Educational Resources Information Center

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

    These activities are designed to teach about the sediments of Hudson Canyon. Students investigate and analyze the patterns of sedimentation in the Hudson Canyon, observe how heavier particles sink faster than finer particles, and learn that submarine landslides are avalanches of sediment in deep ocean canyons. The activity provides learning…

  6. Attack submarines

    SciTech Connect

    Not Available

    1991-01-01

    This issue discusses missions for submarines, technology proliferation; implications for U.S. security; U.S. SSN-21 Seawolf versus other submarines; stability and arms control; nuclear propulsion and nuclear proliferation; air independent propulsion.

  7. Grand Canyon

    Atmospheric Science Data Center

    2014-05-15

    article title:  The Grand Canyon     View Larger Image Northern Arizona and the Grand Canyon are captured in this pair of Multi-angle Imaging SpectroRadiometer ... formats available at JPL December 31, 2000 - Grand Canyon and Lake Powell. project:  MISR ...

  8. Submarine landslide hazard off Northeastern Taiwan

    NASA Astrophysics Data System (ADS)

    Huang, C. L.; Hsu, S. K.; Tsai, C. H.; Doo, W. B.; Lin, S. S.

    2014-12-01

    In the northern margin of the western end of the Okinawa Trough, three major submarine channels running across the continental margin are distinctive. From east to west, they are the North Mein-Hua Submarine Canyon, Mein-Hua Submarine Canyon and the Keelung Valley. To the east of the Mein-Hua Submarine Canyon, the slope of the continental margin is quite gentle, implying that the risk of slope instability is low. However, between the Keelung Valley and the Mei-Hua Submarine Canyon, the slope is rather steep. We have conducted multi-channel reflection seismics, sub-bottom profilers and multi-beam bathymetry in this area. The results show two general trends of fracture or faulting. The NE-SW trending faults generally follow the major orientation of the Taiwan mountain belt. Thus, these faults could be reverse faults from the former collisional thrust faults to currently post-collisional normal faults. Another almost E-W trending faults are consistent with the N-S extending of the Southern Okinawa Trough. Because the most significant faulting in the northwest end of the study is probably associated with the offshore extension of the Kenchiao Fault or the Sanchiao Fault, we consider either of these two faults as the northeast boundary (headwall) of the potential submarine landslide. Taking the stability slope angle of 0.5 degree as the stable landslide slope as shown in the area to the northeast of the study area, we estimate the total volume of the potential submarine landslide could be 300 cubic kilometers. Such a landslide volume may generate a local tsunami and affect especially the northeast coast of Taiwan.

  9. Development of the Astoria Canyon-Fan physiography and comparison with similar systems

    USGS Publications Warehouse

    Nelson, C.H.; Carlson, P.R.; Byrne, J.V.; Alpha, T.R.

    1970-01-01

    A detailed bathymetric study of Astoria Canyon and Astoria Fan provides a model for typical submarine canyon-fan systems. The present canyon head is 9 miles (17 km) west of the Columbia River mouth but buried Pleistocene channels appear to have connected the two features in the past. The canyon, which is distinguished by its relief, V-shaped profiles, and numerous tributaries, winds sinuously and is coincident with apparent structural trends across the continental shelf and slope. At the fan apex, the canyon mouth merges smoothly into Astoria Channel, which is characterized by its U-shaped profiles, lower walls of even height, and levee development. Astoria Channel and the fan valley at the base of the continental slope are the most recently active of a series of main fan valleys that appear to have: (1) progressively "hooked left"; (2) migrated from north to south across the fan during its formation; and (3) been partly responsible for the asymmetrical shape of the fan. The deep, narrow upper fan valleys that characterize the steep (> 1:100, or 0??35???) and rough (10-30 fathoms, or 18-55 m) upper fan surface break into distributaries on the middle fan, where there is the sharpest change in gradient. The main valleys become broader and shallower down the fan, while the generally concave fan surface grades to nearly a flat seafloor (to gradients < 1:1000, or 0??0.5???), (< 10 fathoms, or 18 m relief). Similarity of Astoria Canyon-Fan system with other deep-sea fan and alluvial fan systems, suggests the hypothesis that size of drainage basin, sediment size, and sediment load control the size, gradient, and valley development of any fan system. Data from bathymetry, seismic refraction stations, and sediment load of the Columbia River indicate that the cutting of Astoria Canyon and the deposition of the unconsolidated sediment layer forming Astoria Fan could have been accomplished during the Pleistocene. A similar history can be suggested for other major submarine canyon-fan systems. ?? 1970.

  10. Genotype, soil type, and locale effects on reciprocal transplant vigor, endophyte growth, and microbial functional diversity of a narrow sagebrush hybrid zone in Salt Creek Canyon, Utah

    USGS Publications Warehouse

    Miglia, K.J.; McArthur, E.D.; Redman, R.S.; Rodriguez, R.J.; Zak, J.C.; Freeman, D.C.

    2007-01-01

    When addressing the nature of ecological adaptation and environmental factors limiting population ranges and contributing to speciation, it is important to consider not only the plant's genotype and its response to the environment, but also any close interactions that it has with other organisms, specifically, symbiotic microorganisms. To investigate this, soils and seedlings were reciprocally transplanted into common gardens of the big sagebrush hybrid zone in Salt Creek Canyon, Utah, to determine location and edaphic effects on the fitness of parental and hybrid plants. Endophytic symbionts and functional microbial diversity of indigenous and transplanted soils and sagebrush plants were also examined. Strong selection occurred against the parental genotypes in the middle hybrid zone garden in middle hybrid zone soil; F1 hybrids had the highest fitness under these conditions. Neither of the parental genotypes had superior fitness in their indigenous soils and habitats; rather F1 hybrids with the nonindigenous maternal parent were superiorly fit. Significant garden-by-soil type interactions indicate adaptation of both plant and soil microorganisms to their indigenous soils and habitats, most notably in the middle hybrid zone garden in middle hybrid zone soil. Contrasting performances of F1 hybrids suggest asymmetrical gene flow with mountain, rather than basin, big sagebrush acting as the maternal parent. We showed that the microbial community impacted the performance of parental and hybrid plants in different soils, likely limiting the ranges of the different genotypes.

  11. White submarine

    NASA Astrophysics Data System (ADS)

    While not everyone gets to live in a yellow submarine, the scientific community may get to have a decommissioned U.S. Navy nuclear submarine dedicated to it. The Sturgeon class of submarines, which scientists say are the ideal choice for the project, will be coming up for decommissioning in this next decade. So the time is ripe, scientists say. Two weeks ago, oceanographers, submarine specialists, marine biologists, and geophysicists, among others met at AGU headquarters in Washington to discuss how to get the project in the water. If all goes well, the project would be the "biggest thing that ever happened in ocean and Earth science," according to Lloyd Keigwin of the Woods Hole Oceanographic Institution, who convened the meeting. For example, the submarine could make many types of "compelling" research possible that can not be done now by other means, such as studies in the Arctic that may have significant bearing on global change research, Keigwin says. However, the imposing hurdles that the project must overcome are as big as the opportunities it offers. Foremost, there is a question as to who will pick up the tab for such an endeavor.

  12. Submarine atmospheres.

    PubMed

    Knight, D R; Tappan, D V; Bowman, J S; O'Neill, H J; Gordon, S M

    1989-12-01

    Nuclear submariners live and work in an atmosphere composed of approximately 80% naturally occurring nitrogen, 19% oxygen (manufactured aboard ship), and a complex mixture of inorganic and organic contaminants. The concentrations of contaminants exist as a balance between the rates of production from human and operational activities and the rate of removal by engineering systems. The biological effects of inorganic gases, particularly carbon dioxide, have been extensively studied. Investigators are now attempting to define the composition and concentration of volatile organic compounds that accumulate during 90-day submergences. Medical studies have not conclusively shown that crewmembers incur adverse health effects from continuous exposures to the sealed atmospheres of nuclear submarines. PMID:2574918

  13. Submarine atmospheres

    SciTech Connect

    Knight, D.R.; Tappan, D.V.; Bowman, J.S.; O'Neill, H.J.; Gordon, S.M.

    1990-07-01

    Nuclear submariners live and work in an atmosphere composed of approximately 80% naturally occurring nitrogen, 19% oxygen (manufactured aboard ship), and a complex mixture of inorganic and organic contaminants. The concentrations of contaminants exist as a balance between the rates of production from human and operational activities and the rate of removal by engineering systems. The biological effects of inorganic gases, particularly carbon dioxide, have been extensively studied. Investigators are now attempting to define the composition and concentration of volatile organic compounds that accumulate during 9O-day submergences. Medical studies have not conclusively shown that crewmembers incur adverse health effects from continuous exposures to the sealed atmospheres of nuclear submarines.

  14. Canyon-confined pockmarks on the western Niger Delta slope

    NASA Astrophysics Data System (ADS)

    Benjamin, Uzochukwu; Huuse, Mads; Hodgetts, David

    2015-07-01

    Fluid flow phenomena in the deepwater Niger Delta are important for the safe and efficient exploration, development and production of hydrocarbons in the area. Utilizing 3D seismic data from the western Niger Delta slope, we have identified pockmarks that are confined within a NE-SW oriented submarine canyon system that has been active since the early Quaternary. The pockmarks, subdivided into 'canyon-margin' pockmarks and 'intra-canyon' pockmarks, on the basis of their plan-form distribution patterns, are found to be spatially and stratigraphically related to stratigraphic discontinuities created by erosion cuts associated with the submarine canyon system. We infer that stratigraphic discontinuities provided pathways for fluid migration within the buried canyon system, allowing fluids from deeper parts of the basin to reach the seafloor as indicated by abundant pockmarks above the partly buried canyon. The transportation of fluids from deeper parts of the basin into the buried segment of the canyon system was facilitated by carrier beds expressed as high amplitude reflection packages and by extensional normal faults. The prevalence of the 'canyon margin' pockmarks over the 'intra-canyon' pockmarks is attributed to the direct connection of the buried canyon margins with truncated reservoir facies in hydraulic connection with deeper reservoir facies. The formation of the 'intra-canyon' pockmarks is interpreted to have been limited by fluid flow disconnection often caused by stratigraphic alternation of sand-rich and shale-rich channel deposits that constitute the canyon fill. Muddy canyon fill units act as baffles to fluid flow, while connected sandy infill units constitute pathways for fluid migration. Occurrence of pockmarks throughout the length of the submarine canyon system is an indication of shallow fluid flow within buried reservoir facies. Systematic alignment of seafloor pockmarks are clues to buried reservoirs and provide insights into reservoir architecture which could be crucial in frontier exploration of buried deepwater canyons reservoirs and for risk assessment of development activities on top of submarine canyons. A single mega pockmark linked by a gas chimney to a deeper anticlinal structure was discovered to the north of the canyon system. This structure may be indicative of subsurface geo-pressures close to the fracture gradient, highlighting a significant drilling hazard in this part of the study area.

  15. Morphology, structures and seismic characters of the Chimei Canyon-Fan system offshore eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Hsieh, Y. H.; Liu, C. S.

    2014-12-01

    The Chimei submarine canyon located offshore east Taiwan shows a very distinct morphology, it has a wide (9 km in average) and very smooth bottom, a submarine fan was formed at its foot but the northern part of the submarine fan has been washed away. This canyon starts from the Hsiukuluan River estuary, runs eastward across the eastern flank of the Luzon arc, and merges into the Hualien Canyon near the western end of the Ryukyu Trench off NE Taiwan. The Chimei canyon can be divided into two parts: the upper section is a U-shaped canyon with broad and flat bottom and high walls; the lower section meanders across a deep sea fan in the Huatung basin. In this study, we use multichannel seismic reflection profile data together with high resolution bathymetry data to study the topography, basement structures and seismic sequences along the canyon path and in the distal fan. The U-shaped upper Chimei canyon seems to be carved not only by submarine erosion but also by structural uplift of both side-walls. The canyon walls are up to 950 m above the canyon floor, strata truncations along both sides of the canyon walls and many slumps are observed. The upper Chimei canyon was developed along basement lows of the highly deformed Luzon arc, and runs across a series of N-S trending thrusts. Acoustic basement and lower strata are deformed and folded, and young sediments cover the canyon floor smoothly. We find many thrusts run across the upper Chimei canyon, but now the canyon bottom is smooth. The concave thalweg profile seems to reach the equilibrium between erosion and deposition. An east-vergent thrust fault lies at the foot of the eastern flank of the Luzon arc which separates the upper section from the lower section of the Chimei Canyon. The lower section of the Chimei canyon flows over a submarine fan where eight seismic sequences are recognized. The two lower sequences show continuous, parallel to sub-parallel sheet-drape seismic facies which fill the basement low. They are interpreted to be old deep sea sediment. The six upper sequences show chaotic and mounded seismic facies, and also transparent and continuous parallel seismic strata. We interpret those are characters of submarine fan. Some large slumps occurred at northern half of the submarine fan. The northern half of the submarine fan has been eroded away already by canyon and slumps.

  16. Exploration models for submarine slope sandstones

    SciTech Connect

    Slatt, R.M.

    1986-09-01

    Recent published studies have demonstrated a far greater potential than previously recognized for submarine slope sandstones to contain significant oil and gas reserves in the Gulf Coast and elsewhere. Comparison of modern slopes with outcrop and subsurface analogs from several areas provided the framework for developing the following submarine slope sandstone exploration models: submarine canyon fill, slope gully/channel fill, slope spillover sand sheets, and intraslope basin fill. Submarine canyon fill is mainly shale, but sandstone beds that form stratigraphic traps may be present. Canyon shale fill juxtaposed against older sandstones can also form stratigraphic traps. Gully/channel fills are sandstones deposited on shallow-gradient slopes or ramps. The proximity of these sandstones to slope shales provides opportunities for stratigraphic traps to develop. Spillover sand sheets are resedimented from a shelf to a shallow-gradient slope and are associated with gully/channel fills. Intraslope basin fill is mainly shale, but elongate, sheetlike, or fan-shaped turbidite sandstones can provide stratigraphic traps. In all of these deposits, slope shales may be sufficiently enriched in organic carbon to be potential hydrocarbon source rocks; the potential for organic-rich shales to accumulate is highest in intraslope basin fill.

  17. Characteristics of the potential submarine landslide in the Keelung Shelf, off northern Taiwan

    NASA Astrophysics Data System (ADS)

    Huang, Chi-Lo; Hsu, Shu-Kun; Tsai, Ching-Hui; Doo, Wen-Bin; Lin, Hsiao-Shan

    2015-04-01

    In the northern margin of the westernmost Okinawa Trough, three obviously submarine canyons exist. From east to west, they are the North Mein-Hua Submarine Canyon, Mein-Hua Submarine Canyon and the Keelung Valley. Their orientations are NW-SE across the continental margin. The Okinawa Trough is a backarc basin and is under backarc extension. To better understand the extensional tectonics, we have conducted multi-channel reflection seismics, sub-bottom profilers and multi-beam bathymetry in the westernmost area. In the east, the slope of the continental margin between the Mein-Hua Submarine Canyon and the North Mei-Hua Submarine Canyon is very gentle, implying that the current risk of major slope failure is low. However, between the Keelung Valley and the Mei-Hua Submarine Canyon, the slope is rather steep and the submarine landslide hazard may exist. Our results show two general trends of fracture or faulting. The NE-SW trending faults generally follow the major orientation of the Taiwan mountain belt. Thus, these faults could be reverse faults from the former collisional thrust faults to currently post-collisional normal faults. Secondly, the E-W trending faults are consistent with the N-S extending of the Southern Okinawa Trough. It is probably associated with the offshore extension of the Kenchiao Fault or the Sanchiao Fault. These two faults could be regarded as the headwalls of the potential large submarine landslides. However, our reflection seismic profiles do not show a clear failure surface or a decollement. It could imply that the movement type of the potential submarine landslides could be of spreads.

  18. Hot Canyon

    ScienceCinema

    None

    2013-03-01

    This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."

  19. Hot Canyon

    SciTech Connect

    2012-01-01

    This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."

  20. Potential for SGD induced submarine geohazard off southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Su, C.; Lin, C.; Cheng, Y.; Chiu, H.

    2013-12-01

    The submarine groundwater discharge (SGD) is not only play important roles on material exchange between land and sea, it may also trigger liquefaction process and induce further submarine geohazards in coastal zone. Since 2006, Southern Taiwan was experienced a series of natural hazards including earthquakes and typhoon that induced severe landslides and flooding and caused huge human lives and economics losses. These natural hazards also touched off submarine cable-break incidents off southwestern Taiwan from Gaoping Slope to the northern terminus of the Manila Trench. After the 2006 Pingtung Earthquake, the local fishermen reported disturbed waters at the Fangliao submarine canyon head. Although many researches conjectured the disturbed waters may caused by the eruption of submarine volcanoes which has been widely discovered off the southwestern Taiwan. The subbottom profiles reveal a series of faults and liquefaction strata exist near the head of Fanliao submarine canyon and acoustically transparent sediments with doming structures also observed at the adjacent area. Moreover, we also found pockmarks with acoustic blanking under it on the Gaoping Shelf and a series of gaseous pluming gushed from the seafloor was also observed in the shallow waters. Integrate all these data, we may reasonably infer the disturbed waters which reported by the fishermen may caused by the liquefaction process on the seafloor. In addition to geophysical observations, natural geochemical tracers (radon and radium) in conjunction with side-scan sonar were used to evaluate the distribution of SGD system in the study area. All the evidences indicate that the large earthquake in conjunction with high pore fluid pressures in the surface sediment might have easily triggered liquefaction process and generated large debris flow and swept the submarine cables away from the Fangliao submarine canyon head to the abyss.

  1. The Initiation of Submarine Debris Flow after 2006 Pingtung Earthquake Offshore Southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Su, C. C.; Liu, J. T.; Chiu, H. T.; Li, S. J.

    2014-12-01

    On 26-27 December 2006, a series of submarine cables were damaged offshore southwestern Taiwan from Gaoping Slope to the northern terminus of the Manila Trench. The cable breakages were caused by gravity flows which triggered by the Pingtung earthquake doublet occurred on 26 December 2006 at 20:26 (21.9°N, 120.6°E; ML 7.0) and 20:34 (21.97°N, 120.42°E; ML 7.0) offshore of Fangliao Twonship and meanwhile the local fishermen reported disturbed waters at the head of Fangliao submarine canyon. Although many researchers conjectured the disturbed waters may cause by the eruption of submarine volcanoes which has been widely discovered off the southwestern Taiwan, the actual mechanism is still unclear. In previous studies, a series of faults, liquefaction strata, pockmarks and acoustically transparent sediments with doming structures were observed at the head of Fanliao submarine canyon and may highly related to the submarine groundwater discharge off southwestern Taiwan. Recently, further multi-beam surveys were conducted at the east of Fangliao submarine canyon head and the result shows large area of seafloor subsidence after Pingtung Earthquake. The area of subsidence is over 60 km2 with maximum depth around 5 meters. The north end of the subsidence is connected to the Fangliao submarine canyon where the first cable was failed (CH-US CN-W2-1: 22°13.287'N, 120°33.722'E) after Pingtung Earthquake. All the evidences point out the large earthquake might triggered liquefaction process and generated large debris flow and swept the submarine cables away from the Fangliao submarine canyon head to the abyss.

  2. Preliminar Results On Particulated Matter and Fluxes In The Palamos Canyon

    NASA Astrophysics Data System (ADS)

    Martin, J.; Palanques, A.; Puig, P.; Guillén, J.; García-Ladona, E.; Emelianov, M.; Font, J.; Gili, J. M.; Vert, N.; Segura, M.; Blasco, D.; Montserrat, S.; Gomis, D.; Pascual, A.; Marcos, M.; Tintoré, J.

    Seven moorings equipped with sediment traps, current meters, and turbidimeters were deployed at selected sites in and outside the Palamós Canyon (Northwest Mediter- ranean). The study lasted from March to November 2001, separated in two 4-month deployments. Moorings were deployed from 400-m to 1700-m depth with instru- ments placed near the bottom and at intermediate and surface waters. In addition, four oceanographic cruises were carried out in the area during the study period, and CTD+T+F casts were collected along and across the canyon axis. A major goal of this multidisciplinary study was to characterise the sediment transport processes act- ing in a submarine canyon with a high spatial and temporal resolution. Preliminary results confirm that Palamós Canyon acts as a preferential conduit of matter between the coast and the deep sea, especially during storm events. The temporal series of cur- rents inside the canyon also provide evidence of atmospheric forcing. Total fluxes of particulate matter are higher inside than outside the canyon, and within the canyon, near-bottom fluxes are larger in the canyon axis than in the canyon walls. Transport of particulate matter in nepheloid layers (mainly detached in the upper canyon sec- tion) is linked to the position of a shelf-slope density front intersecting the seabed. Spikes in turbidity measurements and the presence of sporadic and intense bottom nepheloid patches in deeper canyon areas suggest strong resuspension and transport events. This fact is reinforced by the presence of polychaeta and other benthic infauna in the sediment trap samples along the canyon axis. Data from this study shows some similarities with other submarine canyons, but also some particularities never seen before. In Palamós Canyon sediment dynamic processes seem to have a higher activ- ity than in other Northwest Mediterranean canyons, favouring the transfer of matter across the continental margin.

  3. Tectonic control of Cretaceous gravity deposits and submarine Valleys in the subalpine basin, French western Alps

    SciTech Connect

    Philippe, J.; Beaudoin, B.; Fries, G.; Parize, O.

    1988-08-01

    The Late Jurassic-Early Cretaceous series of the French subalpine basin is characterized by alternating limestones and marls with numerous, thick gravity-flow deposits (carbonate debris flows and slumps, siliciclastic grain flows, turbidites). These gravity deposits originate from platforms and slopes and come through the basin via several parallel canyons and submarine valleys. Some carbonate (Berriasian) and siliciclastic (Aptian) deep-sea fans are built at the canyon mouth during intense activity of the canyons and reworking of the sediments. The tectonic control of the gravity deposits is demonstrated by the position and filling of the submarine valleys all along the Cretaceous. The submarine valleys correspond systematically to the lower part of extensional tilted blocks; the gravity deposits come along the main syn-sedimentary normal faults delimiting these tilted blocks. The gravity deposits go from one tilted block to another through some synsedimentary passes which are induced by slight folding, perhaps related to an early diapirism at some nodes of extensional faults. The canyon-like valleys are due to very strong erosion when a submarine valley cuts of the higher part of a tilted block. The gravity deposits are stacked atop each other and progressively fill the valleys. Thus the cutting and filling of the submarine valleys and canyons on occasions during the Early Cretaceous are explained by a permanent synsedimentary activity. These Jurassic and Cretaceous extensional structures are later reactivated by inversion during Tertiary compressional movements.

  4. Assessment of ambulatory activity in the Republic of Korea Navy submarine crew.

    PubMed

    Choi, Seong-Woo; Lee, Jae-Ho; Jang, Young-Keun; Kim, Jung-Ryul

    2010-01-01

    A submarine crew in the Republic of the Korea Navy experienced significant physical inactivity during undersea deployment because of the narrow and confined space. Physical inactivity is known to be associated with a number of adverse health conditions in the long-term perspective. This study aimed to assess the ambulatory activity of submarine crew using pedometers. Study subjects (n=109) were the submarine crew from two diesel submarines and personnel from the Submarine Command. The subjects wore pedometers at their waistline and recorded their walking steps daily for a month. The submarine crew walked more than 7000 steps/day on average during the stationed period. However, the ambulatory activity of the submarine crew greatly declined to a level of around 2000 steps/day during deployment, which corresponded to the sedentary status category. Active exercise is recommended for the submarine crew to prevent potential adverse health outcomes related to the physical inactivity. PMID:21226392

  5. Morphological features and forming mechanism of Central Canyon in the Qiongdongnan basin, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Su, M.; Xie, X.; Jiang, T.; Zhang, C.; Li, J.; Zhang, C.; He, Y.

    2010-12-01

    The Central Canyon in the Qiongdongnan basin, northern South China Sea, with an "S-shaped" geometry, trends NE across the Ledong-Lingshui, Songnan, Baodao and Changchang depressions. According to the morphology, filling and stratigraphic architectures, the Central Canyon can be divided into 4 types in shape: V, U, W, and Complex types, and 3 segments in aera: Eastern, Western and Transfer segments. The Transfer segment aparting the NE to NEE or EW striking of the canyon was coincided with the tectonic transfer zone, located in the Baodao depression. The formation and development of the Central Canyon was response of the tectonic activity and deep-water deposition. Eastern segment was controlled by submarine uplift, as barrier to limit the generation of Central Canyon in Huangliu Formation and supply the restricted channel for the later canyon. The West segemnt was associated with the deep-water deposition. The origin of the filling in the Central Canyon can be ascribed to the gravity sediment. At each stage, the generation of the Central Canyon is simultaneous to or a litter earlier than the one of contemporaneous slope, it can be proposed that the canyon formed initially at the east of Qiongdongnan basin and spread westwards gradually. The planar distribution of the Central Canyon The morphological classification of the Central Canyon

  6. Paint-Stirrer Submarine

    ERIC Educational Resources Information Center

    Young, Jocelyn; Hardy, Kevin

    2007-01-01

    In this article, the authors discuss a unique and challenging laboratory exercise called, the paint-stir-stick submarine, that keeps the students enthralled. The paint-stir-stick submarine fits beautifully with the National Science Education Standards Physical Science Content Standard B, and with the California state science standards for physical…

  7. Submarine cable route survey

    SciTech Connect

    Herrouin, G.; Scuiller, T.

    1995-12-31

    The growth of telecommunication market is very significant. From the beginning of the nineties, more and more the use of optical fiber submarine cables is privileged to that of satellites. These submarine telecommunication highways require accurate surveys in order to select the optimum route and determine the cable characteristics. Advanced technology tools used for these surveys are presented along with their implementation.

  8. Paint-Stirrer Submarine

    ERIC Educational Resources Information Center

    Young, Jocelyn; Hardy, Kevin

    2007-01-01

    In this article, the authors discuss a unique and challenging laboratory exercise called, the paint-stir-stick submarine, that keeps the students enthralled. The paint-stir-stick submarine fits beautifully with the National Science Education Standards Physical Science Content Standard B, and with the California state science standards for physical

  9. Submarine fans in a sequence stratigraphic framework

    SciTech Connect

    Posamentier, H.W.; Erskine, R.D.; Mitchum, R.M.; Vail, P.R.

    1987-05-01

    Submarine fans are fan- or cone-shaped turbiditic deposits formed in upper bathyal or deeper water depths. Within a sequence stratigraphic framework, these basin-floor turbidites can occur during lowstand-fan or lowstand-wedge systems tract time. During lowstand fan time, streams are rejuvenated and depocenters shift from the coastal plain to the upper slope, causing retrogradational slope failure and canyon formation. The sediment delivered here bypasses the canyon and continues down the slope as a succession of gravity flows and is deposited as fan-shaped turbiditic deposits at the base of the slope. Seismic and outcrop evidence suggest that these sand-prone deposits are abruptly introduced into the basin and are generally characterized by subtle external mounding and internal bidirectionally down lapping seismic reflections where seismically resolvable. Deep-water sediment deposited during this interval has no coeval shelf equivalent. During lowstand wedge time, streams cease down cutting and valleys which have been freshly incised begin to fill. Because coarse sediment will preferentially be deposited within these incised valleys, the sand-to-mud ratio delivered to the upper slope will be decreased and, consequently, there is an inherent difference between submarine fans deposited at this time and those deposited during lowstand fan time. Deposition during lowstand wedge time is characterized seismically by slope front fill or wedge-shaped geometries down lapping the earlier submarine fan (i.e., deposited during lowstand fan time). These shale-prone deposits are largely comprised of thinner-bedded turbidites as well as the occasional leveed channel.

  10. Morphology, paleogeographic setting, and origin of the middle Wilcox Yoakum Canyon, Texas coastal plain

    SciTech Connect

    Dingus, W.F. ); Galloway, W.E. )

    1990-07-01

    The Yoakum canyon is the largest of the Gulf Coast Eocene erosional gorges and is interpreted as a buried submarine channel. The canyon can be traced for 67 mi (108 km) from the Wilcox fault zone, which defines the position of the early Eocene shelf edge, nearly to present outcrop. In this paper, the authors expand on previously published descriptions of the canyon and use a more extensive subsurface database. Decompaction of the canyon shale-fill reveals that original depths of the canyon exceeded 3,500 ft (1,067 m). Apparent canyon-wall slump scarps and a peripheral chaotic zone, interpreted as an incipient slump feature, are comparable to similar features of the late Quaternary Mississippi submarine canyon. The Yoakum canyon formed within the Garwood subembayment to the west of and adjacent to the middle Wilcox Rockdale delta system. Quantitative mapping of facies adjacent to the Yoakum shale indicate the following sequence of events. (1) Muddy, distal deltaic and shelf facies of the lower middle Wilcox subgroup were deposited during a retrogradation. (2) A resurgence of progradation deposited upper middle Wilcox deltaic facies atop the unconsolidated, lower middle Wilcox continental margin muds, loading the shelf edge and initiating slump failure of the continental margin. (3) Headward erosion of the canyon across the shelf occurred contemporaneously with a subsidence-induced transgression that coincided with a disruption in sediment supply. The Yoakum canyon was excavated by a combination of slumping and current scour. (4) The canyon was filled by hemipelagic and prodelta muds of the upper Wilcox subgroup. 19 figs.

  11. 4. DARK CANYON SIPHON VIEW ACROSS DARK CANYON AT ...

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

    4. DARK CANYON SIPHON - VIEW ACROSS DARK CANYON AT LOCATION OF SIPHON. VIEW TO NORTHWEST - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

  12. Inter-bed fluid triggered slope failures of the Kaoping Canyon upstream area: Results from memorial R/V Ocean Researcher 5

    NASA Astrophysics Data System (ADS)

    Yeh, Yi-Ching; Shen, Tsung-Fu; Liu, Shao-Yung; Yu, Pai-Sen

    2015-04-01

    As a major pathway of the sediment transportation, the submarine canyons sculpture the seafloor then deposit sediments at the deep ocean. The submarine canyons could be classified to two categories: erosive or deposition based on geological environment or fluid flow down to the canyon. The erosive canyons often 'attack' the levee which may result in submarine landslides or mass transportations due to slope failure. Once slope failure occurs at geological weakness area such as gas hydrate dissociation zone, giant mass slumping will be triggered. These kinds of mass transportations will further develop turbidity current or hyperpycnal flow, which could damage the submarine cables or pipes. The giant mass transportation even triggers devastated tsunami. In this study, a latest swath bathymetric map was compiled by comprising seven cruises between December, 2012 and March 2013. The result shows that regressive erosion may take a place north of 500 meters contour (gas hydrate dissociation region), southwest off Taiwan. Moreover, high resolution seismic image (acquired by Edgetech SB-424 sub-bottom profiler) show that gas rich sediments co-exist with submarine landslide deposits in the edge of the upstream of Kaoping submarine canyon. It implies that slope failures in the study area might be caused by weaken sediment collapse.

  13. The marine soundscape of the Perth Canyon

    NASA Astrophysics Data System (ADS)

    Erbe, Christine; Verma, Arti; McCauley, Robert; Gavrilov, Alexander; Parnum, Iain

    2015-09-01

    The Perth Canyon is a submarine canyon off Rottnest Island in Western Australia. It is rich in biodiversity in general, and important as a feeding and resting ground for great whales on migration. Australia's Integrated Marine Observing System (IMOS) has moorings in the Perth Canyon monitoring its acoustical, physical and biological oceanography. Data from these moorings, as well as weather data from a near-by Bureau of Meteorology weather station on Rottnest Island and ship traffic data from the Australian Maritime Safety Authority were correlated to characterise and quantify the marine soundscape between 5 and 3000 Hz, consisting of its geophony, biophony and anthrophony. Overall, biological sources are a strong contributor to the soundscape at the IMOS site, with whales dominating seasonally at low (15-100 Hz) and mid frequencies (200-400 Hz), and fish or invertebrate choruses dominating at high frequencies (1800-2500 Hz) at night time throughout the year. Ships contribute significantly to the 8-100 Hz band at all times of the day, all year round, albeit for a few hours at a time only. Wind-dependent noise is significant at 200-3000 Hz; winter rains are audible underwater at 2000-3000 Hz. We discuss how passive acoustic data can be used as a proxy for ocean weather. Passive acoustics is an efficient way of monitoring animal visitation times and relative densities, and potential anthropogenic influences.

  14. Bryce Canyon Hoodoos

    Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

  15. Bryce Canyon Vistas

    Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

  16. Bryce Canyon Hoodoo

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  17. Bryce Canyon Benchmark

    A USGS elevation benchmark in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that ...

  18. Bryce Canyon Natural Bridge

    The Bryce Canyon Natural Bridge. Technically, this is not a natural bridge, which forms when running water erodes a tunnel into a rock formation. Instead, this is a natural arch, similar to the ones in nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is...

  19. Bryce Canyon Natural Bridge

    Bryce Canyon's Natural Bridge is technically a natural arch, similar to those in the nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates...

  20. Bryce Canyon Rim

    The rim of Bryce Canyon, viewed from Rainbow Point. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms ...

  1. Bryce Canyon Amphitheater Hoodoos

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  2. Hoodoos of Bryce Canyon

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  3. Bryce Canyon Amphitheater

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  4. Bryce Canyon Hoodoos

    Sandstone hoodoos in Bryce Canyon National Park. In the background, Grand Staircase-Escalante National Monument can be seen. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different er...

  5. Bryce Canyon Amphitheater Panorama

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  6. Bryce Canyon's Cedar Valley

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  7. Bryce Canyon Amphitheater

    Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

  8. Bryce Canyon Sandstone

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  9. Bryce Canyon Cedars

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  10. Bryce Canyon Hoodoo

    Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

  11. Bryce Canyon Hoodoos

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  12. Hoodoos of Bryce Canyon

    Views along the Queen's Garden Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sands...

  13. Glen Canyon Dam

    The USGS Glen Canyon Adaptive Management Working Group took a trip in August from Glen Canyon Dam to Lees Ferry on Friday, August 31, 2012. This spot at Four Mile (four miles downstream from the dam) is where a lot of people fish: There were fishermen that day that claimed to have c...

  14. Le Canyon du Var: Case study of a modern active proximal channel

    SciTech Connect

    Savoye, B.; Voisset, M.; Cochonat, P.; Auffret, G.A.; Bourillet, J.; Droz, L.; Ollier, G.; Coutelle, A.; Le Cann, C.; Auzende, J.; Serge, R. )

    1988-08-01

    The Var Canyon and the continental slope along the French Riviera were investigated using SAR, a new deeply towed high-resolution side-scan sonar and 3.5-kHz subbottom profiler package. Later on, a ground-truth operation using the CYANA submersible and Kuellenberg cores provided in-situ observations and samples. The main characteristics of this area are the narrow shelf, the steep continental slope, and very coarse superficial materials. During the Pliocene, an alluvial cone was built on the floor of a deep ria located at the present Var alluvial plain. This detritic cone overlies the Messinian erosion surface. It is totally submarine and formed by pudding stones, conglomerates, and marls. Since the early Quaternary, this large sedimentary body has been dismantled by gravity processes (mass wasting, debris flows, turbidites). The bed form at the head of the Var Valley (500 m depth) is marked by an anastomosed network eroding the spurs that give the typical herringbone facies of the canyon's flanks. Downslope from this area begins a gravel wave field extending to a water depth of 2,100 m. Wavelength and height appear to be directly controlled by the topography. Downward and according to a break in the slope, the sea floor is characterized by a rhythmic alternance of gravel fields and mud fields (to 2,400 m). The muddy areas are always located on relatively high points of the sea bottom. The significance of these bed forms will be discussed and related to the sedimentary processes which may have operated in this area.

  15. Regional Jurassic Submarine Arc-Apron Complex in the Northern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Templeton, J. H.; Hanson, R. E.; Hargrove, U. S.; Ruff, K. L.

    2005-05-01

    The Tuttle Lake Formation (TLF), a distinctive unit forming part of the wall rocks to the Mesozoic Sierra Nevada batholith in northern California, is interpreted to have developed within a major island arc fringing the western margin of North America during the Jurassic. It extends for 75 km along strike, from mountainous terrain NW of Truckee to the Mt. Tallac pendant SW of Lake Tahoe. Superb glaciated exposures at various locations along strike provide a window into the proximal parts of a submarine Jurassic arc-apron complex. The TLF is >4 km thick and consists mainly of massively bedded, matrix-supported, polymict volcanic breccias containing poorly vesicular, subangular to angular basaltic to andesitic clasts up to 2 m in length. Characteristics of the polymict breccias indicate deposition from submarine debris flows derived from slumping of near-vent accumulations of lithic debris or sector collapse of parts of the volcanic edifice. Interbeds of finer grained andesitic and silicic turbidites and ash-fall tuffs occur sparsely within the debris-flow sequence, as do volumetrically minor pillow-hyaloclastite breccias, recording local extrusion of lavas on the seafloor. Coarse-grained TLF debris-flow deposits abruptly overlie the Early to Middle Jurassic Sailor Canyon Formation, which consists dominantly of andesitic volcanic sandstones and mudstones deposited from distal turbidity currents in a long-lived, deep marine basin. This marked lithologic change records rapid influx of coarse-grained volcanogenic detritus into the Sailor Canyon basin, related to a major shift in position of volcanic centers. Available data show that the TLF accumulated in a narrow time frame in the Middle Jurassic, just prior to regional tilting and batholith emplacement at ~165 Ma. Coeval basaltic to andesitic hypabyssal intrusions typically compose >15% of the exposed area of the TLF. They have identical major- and trace-element compositions and REE patterns to clasts within the host debris-flow sequence, and all analyses plot as a tight group in calc-alkaline, volcanic-arc fields on standard discrimination diagrams. The intrusions range from 3 km in length down to smaller pods and intrusive pillows a few meters across, many of which appear to be tubular feeder conduits in 3D. Marginal peperites indicate that intrusion occurred while the host sediments were still wet and unconsolidated. Abundant, isolated pockets of globular and blocky peperite are inferred to have been supplied by conduits extending from larger intrusions. Magma/sediment interaction was generally non-explosive, but steam explosions locally played a role in generating dispersed peperite. The overall characteristics of the TLF support a model in which coarse-grained volcaniclastic deposits accumulated rapidly in a proximal submarine setting around a major vent complex within the Middle Jurassic arc. Magma/wet-sediment interaction occurred over large areas within proximal parts of the arc apron, where uprising batches of magma were unable to penetrate the thick volcaniclastic sequence to undergo extrusion. Instead, an extensive network of hypabyssal intrusions and peperite formed at shallow levels beneath the sea floor. Complex hypabyssal networks of this type are probably common in submarine arc sequences, but detailed mapping is required to document their full extent and significance.

  16. Constraining the timing of turbidity current driven sediment transport down Monterey Canyon, offshore California

    NASA Astrophysics Data System (ADS)

    McGann, M.; Stevens, T.; Paull, C. K.; Ussler, W.; Buylaert, J.

    2013-12-01

    Turbidity currents are responsible for transport of sand down the Monterey Submarine Canyon, offshore California, from the shoreline to Monterey Fan. However the timing of sediment transport events and their frequencies are not fully understood despite recent monitoring of canyon events and AMS 14C dating of foraminifera from hemipelagic sediments bracketing sand deposited during turbidity flows. Quartz optically stimulated luminescence (OSL) dating in sand sequences provides a complementary means of dating sand transport. OSL dates reflect the time interval since the sand grains were last exposed to sunlight. However, the technique has never been applied extensively to canyon sediments before. Here we report both quartz OSL ages of sand deposits and benthic foraminifera ages sampled from the axial channel within Monterey Submarine Canyon and Fan via ROV-collected vibracores. This allows a rare opportunity to directly test the frequency and timing of turbidity current events at different points in the canyon. We use both single-grain and small (~2 mm area) single aliquot regeneration OSL approaches on vibracore samples from various water depths to determine sand transport frequency. Within the upper canyon (<2,000 m water depths) the OSL data require sub-decadal to decadal transit times. Sand bearing fining upward sequences yielding middle Holocene to last few hundred year ages indicate turbidity currents occur at 150 to 250 year event frequencies within the fan channel out to 3,600 m water depth. We suggest that turbidity currents have been active during the current sea-level high stand and that the submarine fan has recorded turbidity currents over the entire Holocene. The increased age spread in single grain OSL dates with water depth provides evidence of sediment mixing and reworking during turbidity flows. Apparently, sand is stored within the canyon for various amounts of time while it is in route to its current location on the fan.

  17. Fourmile Canyon Fire

    The beginning of the Fourmile Canyon fire, which burned about 6,000 acres in Boulder County, Colorado, in September 2010. Storms after wildfire led to downstream water-quality impairment. Photo taken from Bear Peak, near Boulder, CO....

  18. Making a Submarine.

    ERIC Educational Resources Information Center

    Cornacchia, Deborah J.

    2002-01-01

    Describes Archimedes principle and why a ship sinks when it gets a hole in it. Suggests an activity for teaching the concept of density and water displacement through the construction of a simple submarine. Includes materials and procedures for this activity. (KHR)

  19. Giant submarine landslides off NW-Africa

    NASA Astrophysics Data System (ADS)

    Meyer, Mathias; Geersen, Jacob; Schwenk, Tillmann; Krastel, Sebastian

    2010-05-01

    The passive continental margin off Northwest Africa is dominated by high terrigenous sediment input (fluvial and aeolian) and high primary production in upwelling areas. The redeposition of these sediments is controlled by both gravitational and bottom current induced along slope sediment transport. Some sections of the margin show repeated instabilities, while other regions are stable for a long time. Two prominent examples for large scale landslides are the Dakar Slide offshore Senegal and Sahara Slide offshore West-Sahara. High resolution seismic and hydro-acoustic data acquired during Cruise MSM11/2 in spring 2009 in addition to data from cruise M65/2 in 2005 reveal an giant submarine slide offshore Senegal named Dakar Slide. The slide shows a headwall with a length of at least 90km along slope in between water depths of 3.100 to 3.400m. The slide is confined by the Dakar Canyon in the north and the Diola Canyon in the south. The northern sidewall runs for 90 km into the deep-sea where it crosses the distal part of the Dakar Canyon. Seismic data show that the distal part of the Canyon was repeatedly destroyed and filled by slide deposits. Erosion structures in former canyon fill shows reactivation of the Canyon in the past. The area above the slide does not show major mass-wasting events even though the slope gradient there with 3° is steeper than the slope angle of 0.5-1° in the headwall region of the slide. Beneath the northern headwall and sidewall of the Dakar Slide the seismic data show a large scale wavy sediment structure, which covers at least 400 km² and is up to 1km thick. The crests of the waves strike in an along slope direction, and we interpret this feature as listric faults, which might have originated from creeping prior to the main catastrophic failure event. Furthermore upslope of this area between 1.300 and 2.000 meters bathymetric and high resolution seismic data show additional signs for (active/recent) creeping in the form of down slope orientated bulges. Until now, however, it is unclear if there is a relation between the creeping and the slope failure. The Dakar and the Diola Canyon seem to limit the slide to this area and therefore restrict the expansion of the slide further along the slope. As indicated by the repeated slide deposits filling the Dakar Canyon and the abundance of deeper lying chaotic to transparent sediment structures in the seismic data, mass-wasting events prior to Dakar Slide were common. Seismic data from cruise M58/1 in 2003 and new bathymetric data of the headwall area of the Sahara-Slide also collected during Cruise MSM11/2 show a mega slide with a length of ~700km and an estimated volume of ~600km. The age of the main slide event is 50-60ka. The distal part of this slide complex is well studied, while data in the source-area are sparse. Available data of the source area indicate vertically stacked slide deposits and a relatively recent reactivation of the headwall. To investigate this observation in more detail additional data will be acquired during the upcoming Poseidon P395 Cruise in February 2010.

  20. Superelevation and overspill control secondary flow dynamics in submarine channels

    NASA Astrophysics Data System (ADS)

    Dorrell, R. M.; Darby, S. E.; Peakall, J.; Sumner, E. J.; Parsons, D. R.; Wynn, R. B.

    2013-08-01

    In subaerial and submarine meander bends, fluid flow travels downstream in a helical spiral, the structure of which is determined by centrifugal, hydrostatic, baroclinic, and Coriolis forces that together balance frictional stresses generated by the flow. The sense of rotation of this helical flow, and in particular, whether the near bed flow is directed toward the inner bank, e.g., "river-normal," or outer bank, e.g., "river-reversed," is crucial to the morphodynamic evolution of the channel. However, in recent years, there has been a debate over the river-normal or river-reversed nature of submarine flows. Herein, we develop a novel three-dimensional closure of secondary flow dynamics, incorporating downstream convective material transport, to cast new light on this debate. Specifically, we show that the presence of net radial material transport, arising from flow superelevation and overspill, exerts a key control on the near bed orientation of secondary flow in submarine meanders. Our analysis implies that river-reversed flows are likely to be much more prevalent throughout submarine-canyon fan systems than prior studies have indicated.

  1. Flow in bedrock canyons.

    PubMed

    Venditti, Jeremy G; Rennie, Colin D; Bomhof, James; Bradley, Ryan W; Little, Malcolm; Church, Michael

    2014-09-25

    Bedrock erosion in rivers sets the pace of landscape evolution, influences the evolution of orogens and determines the size, shape and relief of mountains. A variety of models link fluid flow and sediment transport processes to bedrock incision in canyons. The model components that represent sediment transport processes are increasingly well developed. In contrast, the model components being used to represent fluid flow are largely untested because there are no observations of the flow structure in bedrock canyons. Here we present a 524-kilometre, continuous centreline, acoustic Doppler current profiler survey of the Fraser Canyon in western Canada, which includes 42 individual bedrock canyons. Our observations of three-dimensional flow structure reveal that, as water enters the canyons, a high-velocity core follows the bed surface, causing a velocity inversion (high velocities near the bed and low velocities at the surface). The plunging water then upwells along the canyon walls, resulting in counter-rotating, along-stream coherent flow structures that diverge near the bed. The resulting flow structure promotes deep scour in the bedrock channel floor and undercutting of the canyon walls. This provides a mechanism for channel widening and ensures that the base of the walls is swept clear of the debris that is often deposited there, keeping the walls nearly vertical. These observations reveal that the flow structure in bedrock canyons is more complex than assumed in the models presently used. Fluid flow models that capture the essence of the three-dimensional flow field, using simple phenomenological rules that are computationally tractable, are required to capture the dynamic coupling between flow, bedrock erosion and solid-Earth dynamics. PMID:25254474

  2. Coastal and submarine instabilities distribution in the tectonically active SW margin of the Corinth Rift (Psathopyrgos, Achaia, Greece)

    NASA Astrophysics Data System (ADS)

    Simou, Eirini; Papanikolaou, Dimitrios; Lykousis, Vasilios; Nomikou, Paraskevi; Vassilakis, Emmanuel

    2014-05-01

    The Corinth Rift, one of the most active rifts in the world as local extension trending NE-SW reaches the amount of 14±2 mm/yr, corresponds to one of the largest zones of seismically active normal faulting. The formation, growth and migration southwards of the prevailing fault systems, which evolve simultaneously with the intense morphogenetic processes, are overprinted in the age, facies and thickness of the Plio-Pleistocene sequences constructing the south margin of the western Gulf of Corinth. The dominant fault blocks, defined by east-west trending, north dipping normal faults, are accompanied by several morphological features and anomalies, noticed in both the terrestrial and the marine environment. Our main aim has been to examine how the tectonic evolution, in combination with the attendant fierce erosional and sedimentary processes, has affected the morphology through geodynamic processes expressed as failures in the wider coastal area. High resolution multibeam bathymetry in combination with the available land surface data have contributed to submarine and subaerial morphological mapping. These have been used as a basis for the detection of all those geomorphic features that indicate instabilities probably triggered, directly or indirectly, by the ongoing active tectonic deformation. The interpretation of the combined datasets shows that the southwestern margin of the Corinth Rift towards Psathopyrgos fault zone is characterized by intense coastal relief and a narrow, almost absent, continental shelf, which passes abruptly to steep submarine slopes. These steep slope values denote the effects of the most recent brittle deformation and are related to coastal and submarine instabilities and failures. High uplift rates and rapid sedimentation, indicative of the regional high-energy terrestrial and submarine environment, are subsequently balanced by the transportation of the seafloor currents, especially where slope gradients decrease, disintegrating the probable slide deposits. Conversely, the nearby active -but older- tectonic structure of the Heliki fault, is related to less steep slopes. Canyons are extensive and sediment mass failures appear as retrogressive landslide scars identified near the headwalls. The mass movements evolving near the coastal and shallow marine areas may have a high tsunamigenic potential, which depends on the volumes of the mobilized materials. As a special interest has been arisen nowadays concerning risk assessment and management, the results of our study can be further evaluated from a geohazard perspective.

  3. Distribution and transport of suspended particulate matter in Monterey Canyon, California

    USGS Publications Warehouse

    Xu, J. P.; Noble, M.; Eittreim, S.L.; Rosenfeld, L.K.; Schwing, F.B.; Pilskaln, C.H.

    2002-01-01

    From August 1993 to August 1994, six moorings that measure current, temperature, salinity, and water clarity were deployed along the axis of Monterey Canyon to study the circulation and transport of water and suspended particulate matter through the canyon system. The moorings occupied three sites that are morphologically different: a narrow transverse section (axis width 900 m) at 1450 m water depth, a wide transverse section at 2837 m, and a third site in the fan valley axis farther offshore at 3223 m that recorded for 3 yr. In addition, CTD/transmissometer casts were conducted within and near the Monterey Canyon during four cruises. Our data show a mainly biogenic, surface turbid layer, a limited intermediate nepheloid layer, and a bottom nepheloid layer. There is a consistent presence of a turbid layer within the canyon at a water depth of about 1500 m. Tidal flow dominates at all sites, but currents above the canyon rim and within the canyon appear to belong to two distinct dynamic systems. Bottom intensification of currents plays an important role in raising the near-bottom shear stress high enough that bottom sediments are often, if not always, resuspended. Mean flow pattern suggests a convergence zone between the narrow and wide site: the near-bed (100 m above bottom where the lowest current meter was located) mean transport is down-canyon at the 1450-m site, while the near-bottom transport at the 2837-m site is up-canyon, at a smaller magnitude. Transport at the 3223-m site is dominantly NNW, cross-canyon, with periods of up-canyon flow over 3 yr. A very high-turbidity event was recorded 100 m above the canyon bottom at the narrow site. The event started very abruptly and lasted more than a week. This event was not detected at either of the deeper sites. A canyon head flushing event is likely the cause. ?? 2002 Elsevier Science B.V. All rights reserved.

  4. Newly recognized submarine slide complexes in the southern California Bight

    NASA Astrophysics Data System (ADS)

    Conrad, J. E.; Lee, H. J.; Edwards, B. D.; McGann, M.; Sliter, R. W.

    2012-12-01

    New high-resolution bathymetric and seismic-reflection surveys have imaged large (<0.5 km3) submarine landslides offshore southern California that have not been previously recognized in the Borderland. The new data show several large slides or slide complexes that include: 1) a slide complex consisting of numerous (>7) individual overlapping slides along the western margin of Santa Cruz Basin (SCB slide); 2) a series of slumps and slide scars on the slope south of San Pedro shelf (SPS slide); and 3) a slope failure along the shelf edge in northern San Diego County, termed the Del Mar slide. The SCB slide complex extends for 30 km along the western slope of Santa Cruz Basin, with debris lobes extending 5-8 km into the basin. Head scarps of some of these slides are 50-75 m high. The SPS slide complex also appears to consist of multiple slides, which roughly parallel the Palos Verdes Fault and the San Gabriel Canyon submarine channel on the shelf edge and slope south of San Pedro shelf. Slide deposits associated with this complex are only partially mapped due to limited high-resolution bathymetric coverage, but extend to the south in the area SW of Lasuen Knoll. Seismic-reflection profiles show that some of these deposits are up to 20 m thick. The Del Mar slide is located about 10 km north of La Jolla Canyon and extends about 6 km along the shelf edge. The head scarp lies along the trend of a branch of the Rose Canyon Fault Zone. Radiocarbon ages of sediment overlying this slide indicate the Del Mar slide is approximately 12-16 ka. These large slide complexes have several characteristics in common. Nearly all occur in areas of tectonic uplift. All of the complexes show evidence of recurrent slide activity, exhibiting multiple headwall scarps and debris lobes, and where available, high-resolution seismic-reflection profiles of these slide areas provide evidence of older, buried mass transport deposits. Assuming typical sedimentation rates, the recurrence interval of major slide events appears to be on the order of tens of thousands of years. Most of the slide complexes do not appear to be located in areas of high sediment input. The SCB and Del Mar slides are in areas receiving relatively small terrestrial sediment input from fluvial sources, as are most other previously recognized submarine slides in the Borderland. Only the SPS slide, which lies adjacent to the San Gabriel Canyon submarine channel, is associated with a significant fluvial sediment source.

  5. Is Perceptual Narrowing Too Narrow?

    ERIC Educational Resources Information Center

    Cashon, Cara H.; Denicola, Christopher A.

    2011-01-01

    There is a growing list of examples illustrating that infants are transitioning from having earlier abilities that appear more "universal," "broadly tuned," or "unconstrained" to having later abilities that appear more "specialized," "narrowly tuned," or "constrained." Perceptual narrowing, a well-known phenomenon related to face, speech, and…

  6. Arctic Submarine Slope Stability

    NASA Astrophysics Data System (ADS)

    Winkelmann, D.; Geissler, W.

    2010-12-01

    Submarine landsliding represents aside submarine earthquakes major natural hazard to coastal and sea-floor infrastructure as well as to coastal communities due to their ability to generate large-scale tsunamis with their socio-economic consequences. The investigation of submarine landslides, their conditions and trigger mechanisms, recurrence rates and potential impact remains an important task for the evaluation of risks in coastal management and offshore industrial activities. In the light of a changing globe with warming oceans and rising sea-level accompanied by increasing human population along coasts and enhanced near- and offshore activities, slope stability issues gain more importance than ever before. The Arctic exhibits the most rapid and drastic changes and is predicted to change even faster. Aside rising air temperatures, enhanced inflow of less cooled Atlantic water into the Arctic Ocean reduces sea-ice cover and warms the surroundings. Slope stability is challenged considering large areas of permafrost and hydrates. The Hinlopen/Yermak Megaslide (HYM) north of Svalbard is the first and so far only reported large-scale submarine landslide in the Arctic Ocean. The HYM exhibits the highest headwalls that have been found on siliciclastic margins. With more than 10.000 square kilometer areal extent and app. 2.400 cubic kilometer of involved sedimentary material, it is one of the largest exposed submarine slides worldwide. Geometry and age put this slide in a special position in discussing submarine slope stability on glaciated continental margins. The HYM occurred 30 ka ago, when the global sea-level dropped by app. 50 m within less than one millennium due to rapid onset of global glaciation. It probably caused a tsunami with circum-Arctic impact and wave heights exceeding 130 meters. The HYM affected the slope stability field in its neighbourhood by removal of support. Post-megaslide slope instability as expressed in creeping and smaller-scaled slides are the consequence. Its geometrical configuration and timing is different from submarine slides on other glaciated continental margins. Thus, it raises the question whether slope stability within the Arctic Ocean is governed by processes specific to this environment. The extraordinary thick slabs (up to 1600 m) that were moved translationally during sliding rise the question on the nature of the weak layers associated with this process. Especially theories involving higher pore pressure are being challenged by this observation, because either extreme pore pressures or alternative explanations (e.g. mineralogical and/or textural) can be considered. To assess the actual submarine slope stability and failure potential in the Arctic Ocean, we propose to drill and recover weak layer material of the HYM from the adjacent intact strata by deep drilling under the framework of Integrated Ocean Drilling Program. This is the only method to recover weak layer material from the HYM, because the strata are too thick. We further propose to drill into the adjacent deforming slope to identify material properties of the layers acting as detachment and monitor the deformation.

  7. Active submarine volcano sampled

    USGS Publications Warehouse

    Taylor, B.

    1983-01-01

    On June 4, 1982, two full dredge hauls of fresh lava were recovered from the upper flanks of Kavachi submarine volcano, Solomon Islands, in the western Pacific Ocean, from the water depths of 1,200 and 2,700 feet. the shallower dredge site was within 0.5 mile of the active submarine vent shown at the surface by an area of slick water, probably caused by gas emissions. Kavachi is a composite stratovolcano that has been observed to erupt every year or two for at least the last 30 years (see photographs). An island formed in 1952, 1961, 1965, and 1978; but, in each case, it rapidly eroded below sea level. The latest eruption was observed by Solair pilots during the several weeks up to and including May 18, 1982. 

  8. The turbidity currents records of Kaoping Canyon during past 32000 yrs

    NASA Astrophysics Data System (ADS)

    Yu, S.; Lin, A. T.; Tsai, L.

    2013-12-01

    Taiwan is both located in East Asia Monsoon area and plate collision boundary; as the result, frequently episodic rainfall and fractal geologic setting will cause Taiwan become a high potential area that gravity flows happen. When the high density terristrial flows were exported to the sea, it will become the hyperpycnal flow and perhaps can cause submarine geo-hazard happen (i.e. In 2010 Typhoon Morakot, there are numerous terrestrial sediments be delivered to the southwestern offshore Taiwan along the Kaoping Canyon and causing submarine cable be broken). Additionally, turbidite will also be triggered by earthquakes and it will also have the chance to cause submarine geo-hazard. For an example, Pintung earthquake happened in Hengchun, Taiwan in 1996; this earthquake triggered very huge magnitude submarine landslide happened and damaged several hundred kilometers submarine cable along the Kaoping Canyon. Taiwan is a island surrounded by ocean, and there are lots of submarine cables across these seas, especially along the Kaoping Canyon in southwestern offshore Taiwan. In order to avoid too much economic and safety waste, the risk estimation of geo-hazard is very important, and the frequency of turbidity currents happened is a very visible index. Hence, we collected a core located at the downstream of Kaoping Canyon in 2800 meters water depth. Its length is about 39 meters and we can divide this core into two different lithofacies roughly by core description. The upper part is dominated by mud and silt inter-bedded, and the lower part is dominated by massive mud. By the 14C dating, the age of lithofacies change is about 11000 yrs BP. According to the previous studies, We supposed due to Kaoping Canyon is connected with Kaoping river directly and the terrestrial materials of Pintong plain can be delivered from the land to deep ocean directly via the high energy flooding events. In other words, the lithoface change is related to the high energy events happened in land; hence, we propose that from 32000 yrs BP to 11000 yrs BP, the weather in southwestern Taiwan was dryer, and after 11000 yrs BP, it became wetter and frequently turbidity currents happened in Kaoping canyon system.

  9. 18. VIEW OF A CANYON IN THE CLEANUP PHASE. CANYONS ...

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

    18. VIEW OF A CANYON IN THE CLEANUP PHASE. CANYONS WERE PROCESSING ROOMS USED TO HOUSE PLUTONIUM HANDLING OPERATIONS THAT WERE NOT CONTAINED WITHIN GLOVE BOXES. CANYONS WERE DESIGNED TO BECOME CONTAMINATED. (5/10/88) - Rocky Flats Plant, Plutonium Recovery Facility, Northwest portion of Rocky Flats Plant, Golden, Jefferson County, CO

  10. Paleogene canyons of Tethyan margin and their hydrocarbon potential, Czechoslovakia

    SciTech Connect

    Picha, F.J. )

    1991-03-01

    Two Paleogene canyons buried below the Neogene foredeep and the Carpathian thrust belt in Southern Moravia have been outlined by drilling and seismic profiling. The features, as much as 12 km wide and over 1000 m deep, have been traced for 40 km. They are cut into Mesozoic and Paleozoic carbonate and clastic deposits and underlying Precambrian crystalline rocks. The sedimentary fill is made of late Eocene and early oligocene marine deposits, predominantly silty mudstones and siltstones. Sandstones and conglomerates are distributed mainly in the lower axial part of the valleys. Proximal and distal turbidites, grain-flow and debris-flow deposits have been identified in the fill. The common occurrence of slump folds, pebbly mudstones, and chaotic slump deposits indicate that mass movement played a significant role in sediment transport inside the canyons. The canyons are interpreted as being cut by rivers, then submerged and further developed by submarine processes. The organic rich mudstones of the canyon fill are significant source rocks (1-10% TOC). They reached the generative stage only after being tectonically buried below the Carpathian thrust belt in middle Miocene time. Channelized sandstones and proximal turbidities provide reservoirs of limited extent, although more substantial accumulations of sands are possible further downslope at the mouth of these canyons. Several oil fields have been discovered both within the canyon fill and the surrounding rocks. Similar Paleogene valleys may be present elsewhere along the ancient Tethyan margins buried below the Neogene foredeeps and frontal zones of the Alps and Carpathians. Their recognition could prove fruitful in the search for hydrocarbons.

  11. Climate control on submarine landslides: How certain can we be?

    NASA Astrophysics Data System (ADS)

    Urlaub, M.; Talling, P. J.; Masson, D. G.

    2012-04-01

    Submarine landslides are the main contributor to the oceans' sediment budgets, can cause damaging tsunamis and pose a major threat to any kind of offshore construction. They can occur on very shallow slope angles (< 2°), which are almost always stable on land. We are yet to monitor one of these low gradient slope failures, and mechanisms that can initiate submarine landslides remain highly speculative. Changes in environmental conditions such as transitions between ice- and greenhouse worlds as well as corresponding sea level changes are believed to affect slope stability. Based on geotechnical models and field data we discuss how climate and sea level changes may and may not affect submarine slope stability. Understanding any correlation of the timing of submarine landslides and climate changes would help to narrow down the large number of hypotheses that are suggested to explain submarine slope failure, as well as aiding in the evaluation of future hazard. In order to relate the temporal distribution of submarine slides to global climate robust dating is essential. Climate archives document past temperatures with almost annual resolution and jumps of up to 3°C within 100 years are recorded. But how precise are the ages that are obtained for submarine landslides? Taking the Storegga slide as an example, the number of age measurements necessary to obtain a reliable age is assessed. We then critically review the quality and reliability of the available ages for a number of other open continental slope slides. Our results indicate that caution must be taken in correlating landslide occurrence with global temperatures.

  12. Anomalous topography on the continental shelf around Hudson Canyon

    USGS Publications Warehouse

    Knebel, H. J.

    1979-01-01

    Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.

  13. Braiding of submarine channels controlled by aspect ratio similar to rivers

    NASA Astrophysics Data System (ADS)

    Foreman, Brady Z.; Lai, Steven Y. J.; Komatsu, Yuhei; Paola, Chris

    2015-09-01

    The great majority of submarine channels formed by turbidity and density currents are meandering in planform; they consist of a single, sinuous channel that transports a turbid, dense flow of sediment from submarine canyons to ocean floor environments. Braided turbidite systems consisting of multiple, interconnected channel threads are conspicuously rare. Furthermore, such systems may not represent the spontaneous planform instability of true braiding, but instead result from erosive processes or bathymetric variability. In marked contrast to submarine environments, both meandering and braided planforms are common in fluvial systems. Here we present experiments of subaqueous channel formation conducted at two laboratory facilities. We find that density currents readily produce a braided planform for flow aspect ratios of depth to width that are similar to those that produce river braiding. Moreover, we find that stability model theory for river planform morphology successfully describes submarine channels in both experiments and the field. On the basis of these observations, we propose that the rarity of braided submarine channels is explained by the generally greater flow depths in submarine systems, which necessitate commensurately greater widths to achieve the required aspect ratio, along with feedbacks among flow thickness, suspended sediment concentration and channel relief that induce greater levee deposition rates and limit channel widening.

  14. The narrow, shallow, low-accommodation shelf of central Brazil: Sedimentology, evolution, and human uses

    NASA Astrophysics Data System (ADS)

    Dominguez, José Maria Landim; da Silva, Rian Pereira; Nunes, Alina Sá; Freire, Antonio Fernando Menezes

    2013-12-01

    The continental shelf off the coast of central Brazil, extending from 10 to 16°S, is unusually narrow (~ 20 km) and rests on the São Francisco craton. The shelf break is located between the 45 and 50 m isobaths and coincides with major hinge-lines of the marginal basins. The shelf was exposed for most of the Quaternary period, particularly during the last 1 my, when the average sea level was - 62 m. Submarine geomorphology is strongly influenced by this extended sub-aerial exposure and reduced subsidence, resulting in widespread incisions on the shelf. During the limited episodes of shelf inundation, as is the case today, a few meters of non-framework grain assemblages dominated by coralline algae accumulated on the outer shelf, while quartz sands were restricted to water depths of less than 10-15 m. Mud accumulation on this unusually shallow shelf is aided by additional accommodation space provided by incisions and canyon heads indenting the shelf. Artisanal fisheries, targeting high-value commercial species associated with hard bottoms located on the outer shelf and shelf break, are the most important human use of this shelf. Data used in this study have been compiled from theses and previously conducted surveys and consist of four piston cores, 509 km of chirp subbottom profiles and side scan recordings, and 711 bottom grab samples that have been analyzed for various textural and compositional aspects.

  15. Glen Canyon Dam

    The Glen Canyon Dam on the Colorado River in Arizona. At noon Monday, Nov. 19, U.S. Interior Secretary Ken Salazar will open the dam’s river outlet tubes, releasing controlled flows larger than the usual 8,000-25,000 cubic feet per second that flows through the turbines of the Glen...

  16. Sandbar in Grand Canyon

    Picture showing the size of the sandbar before the November 2012 controlled flood from the Glen Canyon Dam. This location is 65 miles downstream from Lees Ferry and the view is looking downstream. These and additional photographs depicting the results of the recent controlled floods can be viewed on...

  17. Submarine Landslides: A Multidisciplinary Crossroad

    NASA Astrophysics Data System (ADS)

    Moscardelli, L. G.

    2014-12-01

    The study of submarine landslides has advanced considerably in the last decade. A multitude of geoscience disciplines, including marine, petroleum and planetary geology, as well as geohazard assessments, are concerned with the study of these units. Oftentimes, researchers working in these fields disseminate their findings within their own communities and a multidisciplinary approach seems to lack. This presentation showcases several case studies in which a broader approach has increased our understanding of submarine landslides in a variety of geologic settings. Three-dimensional seismic data from several continental margins (Trinidad, Brazil, Morocco, Canada, GOM), as well as data from outcrop localities are shown to explore geomorphological complexities associated with submarine landslides. Discussion associated with the characterization and classification of submarine landslides is also part of this work. Topics that will be cover include: 1) how data from conventional oil and gas exploration activities can be used to increase our understanding of the dynamic behavior of submarine landslides, 2) analogies between terrestrial submarine landslides and potential Martian counterparts, 3) impact of submarine landslides in margin construction, as well as their economic significance and 4) the importance of quantifying the morphology of submarine landslides in a systematic fashion.

  18. Current submarine atmosphere control technology.

    PubMed

    Mazurek, W

    1998-01-01

    Air purification in submarines was introduced towards the end of World War II and was limited to the use of soda lime for the removal of carbon dioxide and oxygen candles for the regeneration of oxygen. The next major advances came with the advent of nuclear-powered submarines. These included the development of regenerative and, sometimes, energy-intensive processes for comprehensive atmosphere revitalization. With the present development of conventional submarines using air-independent propulsion there is a requirement for air purification similar to that of the nuclear-powered submarines but it is constrained by limited power and space. Some progress has been made in the development of new technology and the adoption of air purification equipment used in the nuclear-powered submarines for this application. PMID:11876194

  19. High-Resolution Acoustic Imaging in the Agadir-Canyon Region, NW-Africa: Morphology, Processes and Geohazards

    NASA Astrophysics Data System (ADS)

    Krastel, S.; Wynn, R. B.; Feldens, P.; Unverricht, D.; Huehnerbach, V.; Stevenson, C.; Glogowski, S.; Schuerer, A.

    2014-12-01

    Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during Cruise MSM32. We collected ~ 1500 km of high-resolution seismic 2D-lines in combination with a dense net of hydroacoustic data. About 1000 km2 of sea floor were imaged during three deployments of TOBI (deep-towed sidescan sonar operated by the National Oceanography Centre Southampton). A total of 186 m of gravity cores and several giant box cores were recovered at more than 50 stations. The new data show that Agadir canyon is the source area of the world's largest submarine sediment flow, which occurred about 60,000 years ago. Up to 160 km3 of sediment was transported to the deep ocean in a single catastrophic event. For the first time, sediment flows of this scale have been tracked along their entire flow pathway. A major landslide area was identified south of Agadir Canyon. Landslide material enters Agadir canyon in about 2500 m water depth; the material is transported as debrite for at least another 200 km down the canyon. Initial data suggest that the last major slide from this source entered Agadir canyon at least 130,000 years ago. A large field of living deep-water corals was imaged north of Agadir canyon. To our knowledge, these are the first living cold water corals recovered off the coast of Morocco (except for the Gulf of Cadiz). They represent an important link between the known cold-water coral provinces off Mauritania and in the Gulf of Cádiz.

  20. Variability in turbidity current frequency within a central Portuguese margin canyon

    NASA Astrophysics Data System (ADS)

    Allin, Joshua R.; Talling, Peter J.; Hunt, James E.; Clare, Michael E.; Pope, Ed

    2015-04-01

    Submarine canyons constitute one of the most important pathways for sediment transport into ocean basins. For this reason, understanding canyon architecture and sedimentary processes has significance for oil and gas reservoir characterisation, carbon budgets and geohazard assessment. Canyon sedimentation in the form of turbidity-currents is known to operate on a variety of scales and result from a number of different processes, including landslides, river-derived hyperpycnal flows and tidal or storm resuspension. Despite the expanding knowledge of turbidity current triggers, the spatial variability in turbidity current frequency within most canyon systems is not well defined. Here, new chronologies from cores in the lower reaches of Nazaré Canyon illustrate changes in turbidity current frequency and their relationship to sea level. These flows were relatively frequent during the last glacial maximum and the last deglaciation, with an average recurrence interval of ~70 years. Mid to early Holocene slowdown in activity (avg. recurrence of 1625 years) appears to occur later than other systems along the Iberian margin. Cores from the Iberian Abyssal Plain also provide the first recurrence interval estimates for large run-out turbidity currents from the central Portuguese margin. These large turbidity currents have an average recurrence interval of 2750 years, broadly comparable to modern turbidity flow events in the lower Nazaré Canyon. This indicates that Nazaré Canyon acted as a depocentre, capturing large volumes of sediment during glacial periods prior to large scale canyon flushing events. However, this sediment capture has largely been restricted to the middle and upper canyon since stabilisation of Holocene sea level. Recurrence intervals suggest that large turbidity flows which flush the canyon operate on a timescale independent of the sea level forcing evident in the lower canyon. While instability-triggered landsliding and tidal/storm resuspension are likely responsible for canyon restricted turbidity flows, a different trigger may exist for long run-out turbidity flows capable of travelling several hundred kilometres. Canyon flushing events in other systems have been suggested as resulting from landslides triggered by regional earthquakes. However, turbidites from the Iberian Abyssal Plain do not correlate well with previously suggested earthquake-triggered landslides in the Tagus Abyssal Plain to the south. The inconclusiveness of a test for synchronous deposition in distinct basins makes identifying a seismic trigger problematic. The Nazaré fault, which intersects the canyon head, may have a distinct return time for large earthquakes that is different from seismically active areas to the south. This further suggests the need for caution in the use of turbidites as a palaeo-seismological indicator along the Iberian margin.

  1. Morphology, evolution and fill: Implications for sand and mud distribution in filling deep-water canyons and slope channel complexes

    NASA Astrophysics Data System (ADS)

    Cronin, Bryan T.; Akhmetzhanov, Andrey M.; Mazzini, Adriano; Akhmanov, Grigorii; Ivanov, Michael; Kenyon, Neil H.; TTR-10 Shipboard Scientists

    2005-08-01

    A survey of the northeastern margin of the Rockall Trough on the Irish margin examined the transition from shelf edge to basin floor, in morphology and sedimentary activity, of a deeply incised submarine canyon system, the Donegal Bay submarine canyon. The survey produced superb 3D profiling of the canyon along its entire length, marking a transition from 'cauliflower' shaped head region with numerous tributary gullies feeding into one main canyon, to a single trunk canyon. This canyon, with an initial combined width and depth of > 17 km and > 800 m in the 'cauliflower' head area, decreases rapidly to > 4.5 km wide and > 450 m deep after the zone of tributary confluence. Eighteen kilometers further down dip, the canyon loses topographic expression as it approaches the lower rise and floor of the Rockall Trough. Degrees of recent sedimentary activity are evaluated by comparing side scan sonar systems of different frequency, and thus of different penetration sub sea, and by ground-truthing using drop (gravity) cores. The canyon was a very active system, dominated by sand transportation towards the floor of the Rockall Trough, along the slope as coarse-grained contourite, or as sand spillover from the shelf. Sand was also deposited as overbank deposits outside the main head region of the canyon, presumably by large volume turbidity currents and more active lateral gullies. The head area of the canyon system has been progressively cut off from sand source by progressive sea level rise since the last glaciation. Sand was locally deposited on terraces but not in the overbank area. Less frequent, lower volume and finer grained turbidity currents have become more common in the system. The initial sand and bypass-dominated system with small sediment waves, which may be gravels, has become dominated by muddy debrites in the lower reaches and by slumps in the upper reaches. Slumping in those upper reaches leads to ponding of sand in the head and upper reach areas, with only very occasional turbidity currents transporting sand further down the system in small channels. A model is produced to explain the mechanism and expression of backfilling in a large deep-water canyon system whose hinterland has been flooded back since glacial drawdown of sea level in the eastern Rockall Trough area. This model explains how sand may be trapped in large volumes in the upper reaches of a canyon system, due to slumping from the canyon margins and nearby upper slope regions. The focusing of sand deposition in areas where this is not usually expected will have important implications for hydrocarbon explorationists who wish to map the distribution of potential reservoir sand bodies within large, confined deep-water canyon systems.

  2. Sedimentary processes in the middle Nazar Canyon

    NASA Astrophysics Data System (ADS)

    Masson, D. G.; Huvenne, V. A. I.; de Stigter, H. C.; Arzola, R. G.; LeBas, T. P.

    2011-12-01

    Nazar Canyon extends from a water depth of 50 m near the Portuguese coast to 5000 m at the edge of the Iberian Abyssal Plain. The system is not connected to a modern river and instead obtains its present day sediment input by capture of along-shelf sediment transport. Much of this sediment is deposited in the middle canyon between about 2700 and 3800 m. However, the middle canyon is a highly heterogeneous environment, with areas of both high and low sedimentation rates, exposed rock outcrop, erosion and stable and unstable slopes in close juxtaposition. This paper explores how the various sedimentary processes interact to create the observed heterogeneous canyon environment, which will influence benthic biodiversity in the canyon. Seafloor heterogeneity is investigated using a nested approach to data interpretation, using local high-resolution data to calibrate regional lower resolution data. Six different data types, ship and ROV-mounted swath bathymetry, 30 kHz sidescan sonar images, sediment cores, seafloor video/photographs and current metre/acoustic backscatter data, were incorporated into the analysis. The main morphological characteristic of the middle canyon is a narrow, steep-sided, axial channel flanked by gently sloping terraces. Small-scale landsliding, active at the present day, is the main process that exposes a variety of substrates, ranging from semi-consolidated Holocene sediments to rock of probable Mesozoic age, on the steep axial channel walls. The axial channel floor is characterised in part by large-scale sediment bedforms and in part by landslide debris, suggesting some reworking of landslide debris by currents within the channel. The terraces are interpreted as inner levees with high sedimentation rates. Cores show a dominantly muddy sequence interrupted by thin turbidite sands emplaced on decadal to centennial timescales. The fine-grained sedimentation is the product of continuous settling from fine-grained flows that range from gravity currents to lateral advection of nepheloid layers. The close proximity of areas of high sedimentation and erosion creates a highly heterogeneous seafloor, with the highest heterogeneity on the steepest slopes.

  3. Mapping the True 3D Morphology of Deep-Sea Canyons

    NASA Astrophysics Data System (ADS)

    Huvenne, V. A.; Masson, D.; Tyler, P. A.; Huehnerbach, V.

    2010-12-01

    The importance of submarine canyons as ecosystem hotspots and sediment transport pathways has been recognised for decades (e.g. Heezen et al., 1955; Vetter & Dayton, 1998). However, studying canyon systems in detail is a challenge, because of the complexity and steepness of the terrain. Acoustic surveys are hampered by side-echoes, while the high slope angles cause most types of sampling equipment, deployed from surface vessels, to fail. Ship-borne bathymetric surveys tend to represent the canyon topography in an overly smoothed way as a result of their limited resolution in deep water compared to the scale of the terrain variability. Moreover, it is clear that overhanging cliffs cannot be mapped correctly with traditional, downward looking multibeam echosounders. The increasing availability of underwater vehicles, however, opens new opportunities. During summer 2009, we mapped several submarine canyon habitats in detail, using the UK deep-water Remotely Operated Vehicle (ROV) ISIS. In particular, we developed a new methodology to map vertical cliffs and overhangs by placing the high-resolution Simrad SM2000 multibeam system of the ROV in a forward-looking position rather than in the traditional downward-looking configuration. The cliff morphology was then mapped by moving the ROV laterally in parallel passes at different depths. Repeating this approach at different distances from the cliff face, we obtained maps of varying resolution and extent. The low resolution maps provide an overview of the general geological framework, while individual strata and faunal colonies can be recognised on the highest resolution maps. Using point-cloud models, we combined the ship-borne bathymetry with the ROV-based data, in order to obtain a true 3D seabed morphology of the canyon study site, which can be used for fly-throughs, geomorphological analysis or habitat mapping. With this approach, we could visualise the spatial structure and density distribution of a unique and previously unknown cold-water coral reef, formed as a hanging garden under a 1600 m long and 120 m high overhanging wall, at 1350 m water depth in the Whittard Canyon, NE Atlantic margin. Heezen, B.C., Ewing, M. and Menzies, R. (1955). The influence of submarine turbidity currents on abyssal productivity. Oikos, 6, 170-182. Vetter, E.W. & Dayton, P.K. (1998). Macrofaunal communities within and adjacent to a detritus-rich submarine canyon system. Deep-Sea Research II, 45, 25-54.

  4. Seismic depth conversion problems associated with the Mississippi Canyon in the vicinity of Ewing Bank Block 305 field, offshore Louisiana

    SciTech Connect

    Leveille, G.P. ); Sahai, K.S.; McDaniel, P.G.

    1990-05-01

    Ewing Bank Block 305 field is located on the outermost edge of the continental shelf, approximately 145 km south of New Orleans, Louisiana. The geology of the field is fairly typical of other fields found offshore of Louisiana, except there is a huge, partly filled, Pleistocene submarine canyon that overlies the field. This canyon, which is commonly referred to as the Mississippi Canyon, causes a large seismic depth conversion problem that makes it virtually impossible to correctly map the structure of the field using normally processed marine seismic data The Mississippi Canyon is a large erosional feature that was formed at the mouth of the ancestral Mississippi River during the last glacial sea level lowstand. In the vicinity of the field, the canyon is about 10 km wide and 1 km deep, which is approximately two-thirds the size of the Grand Canyon of the Colorado River, and is filled mostly with Holocene sediments. Because the sediments that fill the canyon are very young, their interval velocities are much lower than the interval velocities of the sediments that form the canyon walls. This creates abrupt near surface lateral velocity variations that distort the geometry of seismic reflectors such that the time geometries seen on seismic lines are not at all indicative of the structure of the subsurface. Using a model-based processing technique and available well control, the authors have been able to solve this difficult depth conversion problem and have gained a better understanding of the geology of this field.

  5. Flow structure in submarine meandering channels, a continuous discussion on secondary flow

    NASA Astrophysics Data System (ADS)

    Abad, J. D.; Parker, G.; Sequeiros, O.; Spinewine, B.; Garcia, M. H.; Pirmez, C.

    2011-12-01

    The understanding of the flow structure in deep-sea turbidity currents is important for the formation of submarine meandering channels. Similarly to the case of subaerial channels, several types of secondary flows include turbulence-, curvature- and bed morphodynamic-driven flow structures that modulate sediment transport and channel bed morphodynamics. This study focuses on [1] a review of long-time research effort (Abad et al., 2011) that tackles the description of the secondary flow associated with a subaqueous bottom current (saline) in a high-curvature meandering channel and [2] ongoing numerical simulations of similar settings as the experiments to describe the entire flow structure. In the case of subaerial channels, the classical Rozovskiian paradigm is often invoked which indicates that the near-bottom secondary flow in a bend is directed inward. It has recently been suggested based on experimental and theoretical considerations, however, that this pattern is reversed (near-bottom secondary flow is directed outward) in the case of submarine meandering channels. Experimental results presented here, on the other hand, indicate near-bottom secondary flows that have the same direction as observed in a river (normal secondary flow). The implication is an apparent contradiction between experimental results. This study combines theory, experiments, reconstructions of field flows and ongoing simulations to resolve this apparent contradiction based on the flow densimetric Froude number. Three ranges of densimetric Froude number are found, such that a) in an upper regime, secondary flow is reversed, b) in a middle regime, it is normal and c) in a lower regime, it is reversed. These results are applied to field scale channel-forming turbidity currents in the Amazon submarine canyon-fan system (Amazon Channel) and the Monterey canyon and a saline underflow in the Black Sea flowing from the Bosphorus. Our analysis indicates that secondary flow should be normal throughout most of the Amazon submarine fan reach, lower-regime reversed in the case of the Black Sea underflow, and upper-regime reversed in the case of the Monterey canyon. The analysis predicts both normal and reversed regimes in the Amazon submarine canyon reach. This research presents insights on the importance of flow structure not only to describe subaqueous bed morphodynamics, but also to understand evolution of submarine meandering channels, therefore its importance for developing accurate morphodynamic models. Reference: Abad, J. D., Sequeiros, O. E., Spinewine, B., Pirmez, C., Garcia, M. H., Parker, G. (2011). SECONDARY CURRENT OF SALINE UNDERFLOW IN A HIGHLY MEANDERING CHANNEL: EXPERIMENTS AND THEORY. In press, Journal of Sedimentary Research

  6. Geomorphologic Features and Age Estimation of Submarine Landslides in the Southwestern Colombian Caribbean

    NASA Astrophysics Data System (ADS)

    Idarraga Garcia, J.; Vargas-Jimenez, C. A.

    2013-05-01

    We analyzed ~17000 km2 of high-resolution-bathymetric data in the southwestern Caribbean Sea of Colombia between the La Aguja Submarine Canyon (LASC) and the Gulf of Urabá. The data allowed us to identify and describe submarine landslides and to calculate their ages based on scarp dating by using numerical solutions of the diffusion equation. The ages are presented in terms of the constant k of diffusivity due to the absence of well constrained values for submarine environments. In the northeastern sector of the study area we differentiated 31 submarine failures associated with the LASC flanks, between 1200 and 3285 m depth, with escarpments slopes ranging between 6.1° and 36.8°; estimated ages suggest ranges between ~407 and ~103.5 k (m2). Triggering mechanisms of these landslides are close related to the occurrence of earthquakes originated in the convergence zone of the Santa Marta and Oca fault systems, and to the flanks instabilities product of the mud diapirism phenomena that is present in the area. In the central sector of the study zone, the continental margin is dominated by the presence of the Magdalena Submarine Fan (MSF). Here, most of the submarine failures are disintegrative (i.e. with no obvious deposit near or at the base of the scar) and all are related to a system of canyons belonging to the Magdalena turbidite system and to an abrupt slope break at the border of the continental shelf. Scarp dating suggests a wide range of ages fluctuating between ~207.1 and ~146427.8 k (m2). Landslides at southernmost sector of the study zone are mainly associated to anticline-related ridges of the Sinú Accretionary Prism. These ridges are structural highs cut by channels and canyons, and are associated with slopes of 10°-25°. In many cases, the failures are disintegrative and it is probable that the associated landslide deposits are buried by subsequent sediments related to broad fans forming in the mouth of channels and canyons. Additionally, some cohesive landslides identified exhibit blocky deposits with rubbles up to 50 m high and runout distances between 3.6 and 11 km. Ages of these failures range between ~182.9 and ~15476.3 k (m2)

  7. Submarine ramp facies model for delta-fed, sand-rich turbidite systems

    SciTech Connect

    Heller, P.L.; Dickinson, W.R.

    1985-06-01

    Some sandy turbidite successions contain facies that differ in significant ways from those predicted by the canyonfed submarine fan depositional model. The key differences are the absence of a master slope channel or canyon through which sediment is transported to the basin, and the lack of facies segregation into distinct channel and overbank or interchannel facies associations within the turbidite sequence. These types of sequences can be better described using a delta-fed submarine ramp depositional model. The primary components of this model are: a sandy deltaic system that has prograded to the shelf-slope break; an abbreviated section of mud-rich slope deposits traversed by multiple shallow channels that transport sand from the delta front to the deeper basin; very sandy proximal ramp deposits composed dominantly of laterally continuous sheets of Facies B turbidites; and less sandy distal ramp deposits characterized by an increase in the abundance of Facies C and D turbidites. Ramp turbidites characteristically display statistically random patterns of bed thickness. Submarine ramp development requires rapid sediment accumulation (>800 ft or 250 m/m.y.) in turbidite basins of shallow to moderate depth where deltaic progradation is rapid enough to mask the structural relief along basin margins. The delta-fed submarine ramp facies model may be useful in describing short-lived sandy depositonal episodes in some rapidly aggrading and prograding basinal sequences. As such, they represent one member in a spectrum of submarine fan depositional styles.

  8. Timing of occurrence of large submarine landslides on the Atlantic Ocean margin

    USGS Publications Warehouse

    Lee, H.J.

    2009-01-01

    Submarine landslides are distributed unevenly both in space and time. Spatially, they occur most commonly in fjords, active river deltas, submarine canyon-fan systems, the open continental slope and on the flanks of oceanic volcanic islands. Temporally, they are influenced by the size, location, and sedimentology of migrating depocenters, changes in seafloor pressures and temperatures, variations in seismicity and volcanic activity, and changes in groundwater flow conditions. The dominant factor influencing the timing of submarine landslide occurrence is glaciation. A review of known ages of submarine landslides along the margins of the Atlantic Ocean, augmented by a few ages from other submarine locations shows a relatively even distribution of large landslides with time from the last glacial maximum until about five thousand years after the end of glaciation. During the past 5000??yr, the frequency of occurrence is less by a factor of 1.7 to 3.5 than during or shortly after the last glacial/deglaciation period. Such an association likely exists because of the formation of thick deposits of sediment on the upper continental slope during glacial periods and increased seismicity caused by isostatic readjustment during and following deglaciation. Hydrate dissociation may play a role, as suggested previously in the literature, but the connection is unclear.

  9. Photomosaics and logs of trenches on the San Andreas Fault at Mill Canyon near Watsonville, California

    USGS Publications Warehouse

    Fumal, Thomas E.; Dawson, Timothy E.; Flowers, Rebecca; Hamilton, John C.; Heingartner, Gordon F.; Kessler, James; Samrad, Laura

    2004-01-01

    We present photomosaics and logs of the walls of trenches excavated for a paleoseismic study at Mill Canyon, one of two sites along the San Andreas fault in the Santa Cruz Mtns. on the Kelley-Thompson Ranch. This site was a part of Rancho Salsipuedes begining in 1834. It was purchased by the present owner’s family in 1851. Remnants of a cabin/mill operations still exist up the canyon dating from 1908 when the area was logged. At this location, faulting has moved a shutter ridge across the mouth of Mill Canyon ponding Holocene sediment. Recent faulting is confined to a narrow zone near the break in slope.

  10. Canyon in DCS Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released July 26, 2004 This image shows two representations of the same infra-red image covering a portion of Ganges Chasma. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.

    The northern canyon at the top of this image is dominated by a bright red/magenta area consisting primarly basaltic materials on the floor of the canyon and atmospheric dust. Within that area, there are patches of purple, on the walls and in the landslides, that may be due to an olivine rich mineral layer. In the middle of the image, the green on the mesa between the two canyons is from a layer of dust. The patchy blue areas in the southern canyon are likely due to water ice clouds.

    Image information: IR instrument. Latitude -6.6, Longitude 316 East (44 West). 100 meter/pixel resolution.

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

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

  11. Rainbow Point of Bryce Canyon

    View of Bryce Canyon National Park from Rainbow Point. In the foreground are sandstone hoodoos and in the background is the Grand Staircase-Escalante National Monument, which is managed by the Bureau of Land Management. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a ...

  12. Bryce Canyon's Wall of Windows

    Bryce Canyon's Wall of Windows, a series of sandstone arches and hoodoos in the Bryce Amphitheater. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolom...

  13. Cedar Valley in Bryce Canyon

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  14. Cedar Forest in Bryce Canyon

    A cedar forest in Bryce Canyon National Park, viewed from Rainbow Point. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the ...

  15. Bryce Canyon Wall of Windows

    Bryce Canyon's Wall of Windows, a series of sandstone arches and hoodoos in the Bryce Amphitheater. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolom...

  16. Cedar Forests of Bryce Canyon

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  17. Bryce Canyon's Navajo Loop Trail

    Views along the Navajo Loop Trail in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandston...

  18. Rainbow Point of Bryce Canyon

    View of Bryce Canyon National Park from Rainbow Point. In the foreground are sandstone hoodoos. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite ...

  19. Cedar Tree in Bryce Canyon

    A cedar tree in Bryce Canyon National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their ba...

  20. Snow-covered Bryce Canyon

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  1. Yuccas in Pine Creek Canyon

    The Mojave Desert, home to drought-tolerant plants like yuccas, gradually mixes with loblolly pine ecosystems in Pine Creek Canyon. Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Cany...

  2. Chollas in Pine Creek Canyon

    The Mojave Desert, home to drought-tolerant plants like Cholla cacti, gradually mixes with loblolly pine ecosystems in Pine Creek Canyon. Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Roc...

  3. Sunset in Pine Creek Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  4. Sunset over Pine Creek Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  5. Sunset over Red Rock Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  6. Manzanita in Pine Creek Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  7. Yucca in Pine Creek Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  8. An investigation of the physical factors controlling the sense of secondary flow circulation within submarine meanders

    NASA Astrophysics Data System (ADS)

    Darby, S. E.; Dorrell, R. M.; Peakall, J.; Sumner, E.; Parsons, D. R.; Wynn, R.

    2012-12-01

    Motivated by the symposium held at the 2011 AGU on "Submarine Channel Systems: Flow Dynamics and Sedimentary Deposits", we have undertaken a holistic investigation into the factors affecting secondary flow circulation within submarine meander bends. In both subaerial and submarine meander bends, fluid flow travels in a helical spiral, as centrifugal and hydrostatic forces balance the turbulent shear stress within the flow. Understanding the sense of the secondary flow circulation is important because the near bed orientation of the fluid flow vector strongly affects sediment transport and meander bend morphodynamic evolution, the patterns of surface grain size sorting and, ultimately it controls the character of the sedimentary deposits produced. The study we present here uses a simplified analytical model, considering the fundamental interconnectedness of the principle physical forces driving the rotational flow within submarine meanders. This holistic radial flow model, which incorporates centrifugal and Coriolis forces, the radial pressure gradient and the baroclinicity of the flow, is formulated using existing empirical models. The analytical model is validated using experimental data and used to highlight the influence of the principal physical forces acting on the flow. Previous analytical studies have considered a temporally constant, two-dimensional, rotationally invariant, framework that leads to vanishing material flux conditions when applied to flows within bounded channels. However, with reference to experimental studies, we show that a three-dimensional flow framework, with non-zero material fluxes, is required to capture the rotational structure of flow within submarine meanders. Given this three-dimensional model, we present phase-space diagrams indicating the variation of the generic vertical structure of rotational flow within submarine meanders are presented. These phase-space analyses allow a system wide discussion of secondary flow structure within submarine canyon-fan networks. Our findings highlight the importance of (i) Coriolis, (ii) flow baroclinicity, and (iii) the dimensionality of the space-time continuum in controlling the sense of helical flow in submarine meanders. Specifically, the new model presented here suggests that the propensity for the occurrence of meander 'reversed' flow circulations in canyon-fan networks may be considerably greater than recently advocated.

  9. The bathypelagic community of Monterey Canyon

    NASA Astrophysics Data System (ADS)

    Robison, Bruce H.; Sherlock, Rob E.; Reisenbichler, Kim R.

    2010-08-01

    We used a quiet, deep-diving remotely operated vehicle (ROV) to conduct oblique, quantitative video transects of the bathypelagic fauna at depths between 1000 and 3500 m at a site over the Monterey Submarine Canyon, in the eastern North Pacific off central California. Fifteen such dives were made over a two-year period. Analyses of the video data revealed a rich and diverse fauna dominated by gelatinous animals. In particular, the holopelagic polychaete Poeobius meseres was an important detritivore in the upper half of this depth range. As Poeobius abundance eventually declined with increasing depth, larvacean abundance increased. In contrast, the relative numbers of crustacean grazers, principally copepods and mysids, remained relatively constant with depth. Medusae were most abundant and most diverse among the gelatinous predators, which also included ctenophores, and siphonophores. Chaetognaths occurred chiefly in the upper half of the depth range. While there is considerable overlap, the bathypelagic fauna can be separated into upper (1000 to 2300 m) and lower (2400 to 3300 m) zones, as well as a distinct and populous benthic boundary layer. Within the overall bathypelagic community is a complex web of trophic links involving gelatinous predators that feed on both gelatinous and hard-bodied particle feeders, as well as on each other. The amount of organic carbon contained in this jelly web is substantial but its ecological fate is uncertain. The assessment of bathypelagic communities will be important for establishing baselines to conserve deep pelagic biodiversity within high-seas protected areas.

  10. An ongoing large submarine landslide at the Japan trench

    NASA Astrophysics Data System (ADS)

    Nitta, S.; Kasaya, T.; Miura, S.; Kawamura, K.

    2013-12-01

    This paper deals with an active submarine landslide on a landward trench slope in the Japan trench. Studied area is located on the upper terrace ranging from 400 to 1200 m in water depth, off Sendai, northeast Japan. We have surveyed in detail the seabed topography using a multi narrow beam (hereafter MBES) and a subbottom profiler (hereafter SBP) during the cruise MR12-E02 of R/V Mirai. The survey lines were 12 lines in N-S, and 3 lines in E-W, and situated in the region from 141°45'E, 37°40'N to 142°33'E, 38°32'N. Moreover, we used multi-channel seismic profile by the cruise KR04-10 of R/V Kairei in the interpretation of the SBP results. In general, horseshoe-shaped depressions of about 100 km wide along the trench slope are arrayed along the Japan trench. It has thought that they were formed by large submarine landslides, but we could not understand critically the relationship between the depressions and the submarine landslides. Based on the survey results, we found signals of an active submarine landslide in the depression as follows. 1) We observed arcuate-shaped lineaments, which are sub-parallel to a horseshoe-shaped depression. The lineaments concentrate in the south region from 38°N at about 20 km wide. These lineaments are formed by deformation structures as anticlines, synclines and normal fault sense displacements. 2) Most of the synclines and anticlines are not buried to form the lineaments. 3) Normal faults cutting about 1 km deep are observed in a multi-channel seismic profile. The normal faults are located just below the arcuate-shaped lineaments, and are tilted eastward being the downslope direction. It indicates a large submarine landslide. We concluded that the arcuate-shaped lineaments were generated by surface sediment movement with the submarine landsliding. We think that the submarine landslide of about 20 km wide and about 1 km thick move continuously down the landward trench slope. This would be the formation process of the horseshoe-shaped depression along the Japan trench.

  11. Geomorphological evidence for upslope canyon-forming processes on the northern KwaZulu-Natal shelf, SW Indian Ocean, South Africa

    NASA Astrophysics Data System (ADS)

    Green, Andrew N.; Goff, John A.; Uken, Ron

    2007-12-01

    A geomorphological and statistical analysis of slope canyons from the northern KwaZulu-Natal continental margin is documented and compared with submarine canyons from the Atlantic margin of the USA. The northern KwaZulu-Natal margin is characterized by increasing upslope relief, concave slope-gradient profiles and features related to upslope growth of the canyon forms. Discounting slope-gradient profile, this morphology is strikingly similar to canyon systems of the New Jersey slope. Several phases of canyon incision indicate that downslope erosion is also an important factor in the evolution of the northern KwaZulu-Natal canyon systems. Despite the strong similarities between the northern KwaZulu-Natal and New Jersey slope-canyon systems, key differences are evident: (1) the concavity of the northern KwaZulu-Natal slope, contrasting with the ˜linear New Jersey slope; (2) the relative isolation of the northern KwaZulu-Natal canyons, rather than the dense clustering of the New Jersey canyons; and (3) the absence of strongly shelf-breaching canyons along the northern KwaZulu-Natal margin. In comparison with the New Jersey margin, we surmise a more youthful stage of canyon evolution, a result of either the canyons themselves being younger or the formative processes being less active. Less complicated patterns of erosion resulting from reduced sediment availability have developed in northern KwaZulu-Natal. The reduction in slope concavity on the New Jersey margin may be the result of grading of the upper slope by intensive headward erosion, a process more subdued—or less evident—on the KwaZulu-Natal margin.

  12. New York Canyon Stimulation

    SciTech Connect

    Raemy, Bernard

    2012-06-21

    The New York Canyon Stimulation Project was to demonstrate the commercial application of Enhanced Geothermal System techniques in Buena Vista Valley area of Pershing County, Nevada. From October 2009 to early 2012, TGP Development Company aggressively implemented Phase I of Pre-Stimulation and Site/Wellbore readiness. This included: geological studies; water studies and analyses and procurement of initial permits for drilling. Oversubscription of water rights and lack of water needed for implementation of EGS were identified and remained primary obstacles. Despite extended efforts to find alternative solutions, the water supply circumstances could not be overcome and led TGP to determine a "œNo Go" decision and initiate project termination in April 2012.

  13. Canyon waste dump case study

    SciTech Connect

    Land, M.D.; Brothers, R.R. ); McGinn, C.W. )

    1991-01-01

    This data packet contains the Canyonville Canyon Waste Dump results of the various physical environmental sampling. Core samples were taken from the on site waste material. Vertical grab samples were made from these borings. The waste samples were screened fro volatile organic compounds (VOC) and logged for lithology. Soil samples were also tested for VOC. Composite sediment samples were taken using a coring device known as a clam gun. No surface water was available for testing from the intermittent Canyon Wash. The hydrogeology of the Canyon Waste Dump was inferred from lithologic logs and hydraulic data from the five monitoring wells located along the canyon floor. Groundwater was monitored through five wells. The soil vapor and air screening techniques used were adaptations of the EPA ERT and NIOSH methodologies. 4 figs., 9 tabs.

  14. Propagation and dissipation of the internal tide in upper Monterey Canyon

    NASA Astrophysics Data System (ADS)

    Wain, D. J.; Gregg, M. C.; Alford, M. H.; Lien, R.-C.; Hall, R. A.; Carter, G. S.

    2013-10-01

    Submarine canyons are sites of intense turbulence and mixing. Monterey Canyon cuts into the continental shelf off California, and is defined by its sinuous nature. Temperature, salinity, and current velocity measurements were made over 21 days in April 2009 with a depth-cycling towed body to understand internal tide propagation and dissipation through the canyon bends. Cross-canyon transects reveal complex flow patterns that follow large-scale bathymetry on scales greater than 5 km. Changes in thalweg direction deflect baroclinic energy flux, but the bends in the measurement region are too sharp for the flux to follow the thalweg. Ridges that form the bends in the canyon act as obstacles to the flow, and turbulent dissipation rates greater than 1 × 10-5 m2 s-3 were observed on their flanks, especially at the largest meander (the Gooseneck). The canyon-integrated baroclinic energy flux increased from 2.7 MW at the most western section to 3.7 MW at the Gooseneck Ridge, which has a nearly critical bottom slope with respect to the semidiurnal baroclinic tide on the western side; baroclinic energy flux was 50% less on the eastern side of the ridge. While measured dissipation near the Gooseneck Meander was sufficient to explain the flux divergence, turbulence near the Gooseneck may have been undersampled. Between the Gooseneck Ridge and the most eastern cross-canyon transect, dissipation may account for the decrease in the energy flux; though a local energy balance does not hold, the energy budget is balanced over the larger scale of the measurement region east of the Gooseneck Ridge.

  15. Hawaiian submarine manganese-iron oxide crusts - A dating tool?

    USGS Publications Warehouse

    Moore, J.G.; Clague, D.A.

    2004-01-01

    Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae landslide southwest of Oahu has yielded samples with the greatest manganese-iron oxide crusts (9.5 mm thick) and therefore apparently represents the oldest submarine material yet found in the study area. The submarine volcanic field 100 km southwest of Oahu is apparently younger than the Waianae landslide. ?? 2004 Geological Society of America.

  16. Habitat characterization of deep-water coral reefs in La Gaviera Canyon (Avilés Canyon System, Cantabrian Sea)

    NASA Astrophysics Data System (ADS)

    Sánchez, Francisco; González-Pola, Cesar; Druet, María; García-Alegre, Ana; Acosta, Juan; Cristobo, Javier; Parra, Santiago; Ríos, Pilar; Altuna, Álvaro; Gómez-Ballesteros, María; Muñoz-Recio, Araceli; Rivera, Jesus; del Río, Guillermo Díaz

    2014-08-01

    Surveys conducted at the complex Avilés Canyon System (southern Bay of Biscay) in order to identify vulnerable habitats and biological communities revealed the presence of noteworthy deep-water coral reefs in one of the tributaries of the system (La Gaviera Canyon). The aim of the present study is to determine why this deep-sea canyon provides suitable environmental conditions for corals to grow. This hanging canyon is characterized by an irregular U-shaped floor with two narrow differentiated flanks. Sand ripples and rocky outcrops structured in diverse W-E directed steps are observed on the canyon floor, suggesting intense hydrodynamic activity. Accordingly, high-frequency near-bottom current and thermal structure profiles showed that there occur strong shifts in currents/hydrography behaving as front-like features at each tidal cycle. These involve the sudden increase of along-axis velocities to over 50 cm/s and vertical velocities of over 5 cm/s in each tidal cycle associated with the passage of sharp thermal fronts and thermal inversions suggesting overturning. A year-long near-bottom current record showed events with near-bottom velocities well over 1 m/s lasting for several days. Three cold-water coral settings were distinguished: a dense coral reef located on stepped rocky bottoms of the eastern and western flanks, carbonate mounds (20-30 m high) located on the canyon floor, and a cluster of shallower water dead coral framework at the head sector of the canyon. Video and still images from a towed sled and ROV verified the presence of dropstones and rippled sand sheets surrounding the mounds and revealed changes in the coral population (alive or dead; total or patchy coverage) in coral reef and carbonate mound areas. The dominant species of the reef are Lophelia pertusa and Madrepora oculata, which considerably increase the habitat‧s complexity and biodiversity in relation to other facies described in the canyon. The presence of living cold-water reefs is directly related to a high-energy environment at depths between 700 and 1200 m in the levels between the lower bound of Eastern North Atlantic Central Water (ENACW) and the core of Mediterranean Water (MW). Such level matches the water density range σθ=27.35-27.65 kg m-3 which has been identified as limits for cold-water coral distribution in the North Atlantic.

  17. Mineral resources of the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas, Carbon Emery, and Grand counties, Utah

    SciTech Connect

    Cashion, W.B.; Kilburn, J.E.; Barton, H.N.; Kelley, K.D.; Kulik, D.M. ); McDonnell, J.R. )

    1990-09-01

    This paper reports on the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas which include 242,000 acres, 33,690 acres, and 23,140 acres. Coal deposits underlie all three study areas. Coal zones in the Blackhawk and Nelsen formations have identified bituminous coal resources of 22 million short tons in the Desolation Canyon Study Area, 6.3 million short tons in the Turtle Canyon Study Area, and 45 million short tons in the Floy Canyon Study Area. In-place inferred oil shale resources are estimated to contain 60 million barrels in the northern part of the Desolation Canyon area. Minor occurrences of uranium have been found in the southeastern part of the Desolation Canyon area and in the western part of the Floy Canyon area. Mineral resource potential for the study areas is estimated to be for coal, high for all areas, for oil and gas, high for the northern tract of the Desolation Canyon area and moderate for all other tracts, for bituminous sandstone, high for the northern part of the Desolation Canyon area, and low for all other tracts, for oil shale, low in all areas, for uranium, moderate for the Floy Canyon area and the southeastern part of the Desolation Canyon area and low for the remainder of the areas, for metals other than uranium, bentonite, zeolites, and geothermal energy, low in all areas, and for coal-bed methane unknown in all three areas.

  18. 30. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONNECTICUT. ...

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

    30. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONNECTICUT. 2 JUNE 1930. SUBMARINE TRAINING TANK - STEELWORK 98% COMPLETE; BRICKWORK 95% COMPLETE, PIPING 10% IN PLACE. LOOKING NORTH. CONTRACT NO. Y-1539-ELEVATOR, SUBMARINE ESCAPE TANK.' - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  19. Implications for the Removal of Invasive Species in Canyon de Chelly National Monument

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As part of a study to investigate the causes of channel narrowing and incision in Canyon de Chelly National Monument, the effects of Tamarisk and Russian-olive on streambank stability were evaluated. Root tensile strengths and distributions in streambanks were measured and used in combination in a r...

  20. Submarine Silicic Explosive Eruptions: what can submarine pyroclasts tell us?

    NASA Astrophysics Data System (ADS)

    Carey, R.; Allen, S.; McPhie, J.; Fiske, R. S.; Tani, K.

    2014-12-01

    Our understanding of submarine volcanism is in its infancy with respect to subaerial eruption processes. Two fundamental differences between eruptions in seawater compared to those on land are that (1) eruptions occur at higher confining pressures, and (2) in a seawater medium, which has a higher heat capacity, density and viscosity than air. Together with JAMSTEC collaborators we have a sample suite of submarine pumice deposits from modern volcanoes of known eruption depths. This sample suite spans a spectrum of eruption intensities, from 1) powerful explosive caldera-forming (Myojin Knoll caldera); to 2) weakly explosive cone building (pre-caldera Myojin Knoll pumice and Kurose-Nishi pumice); to 3) volatile-driven effusive dome spalling (Sumisu knoll A); to 4) passive dome effusion (Sumisu knoll B and C). This sample suite has exceptional potential, not simply because the samples have been taken from well-constrained, sources but because they have similar high silica contents, are unaltered and their phenocrysts contain melt inclusions. Microtextural quantitative analysis has revealed that (i) clast vesicularities remain high (69-90 vol.%) regardless of confining pressure, mass eruption rate or eruption style , (ii) vesicle number densities scale with inferred eruption rate, and (iii) darcian and inertial permeabilities of submarine effusive and explosive pyroclasts overlap with explosively-erupted subaerial pyroclasts.

  1. Possible Connections Between the Coronado Bank Fault Zone and the Newport-Inglewood, Rose Canyon, and Palos Verdes Fault Zones Offshore San Diego County, California.

    NASA Astrophysics Data System (ADS)

    Sliter, R. W.; Ryan, H. F.

    2003-12-01

    High-resolution multichannel seismic-reflection and deep-tow Huntec data collected by the USGS were interpreted to map the Coronado Bank fault zone (CBFZ) offshore San Diego County, California. The CBFZ is comprised of several major strands (eastern, central, western) that change in both orientation and degree of deformation along strike. Between Coronado Bank and San Diego, the CBFZ trends N25W and occupies a narrow 7 km zone. Immediately north of La Jolla submarine canyon (LJSC), the easternmost strand changes orientation to almost due north and appears to be offset in a right-lateral sense across the canyon axis. The strand merges with a prominent fault that follows the base of the continental slope in about 600 m water depth. The central portion of the CBFZ is mapped as a negative flower structure and deforms seafloor sediment as far north as 15 km north of LJSC. Farther north, this structure is buried by more than 400 m of basin sediment. Along the eastern edge of the Coronado Bank, the western portion of the CBFZ is characterized by high angle normal faults that dip to the east. North of the Coronado Bank, the western segment follows the western edge of a basement high; it cuts through horizontal basin reflectors and in places deforms the seafloor. We mapped an additional splay of the CBFZ that trends N40W; it is only observed north and west of LJSC. Although the predominant trend of the CBFZ is about N40W, along strike deviations from this orientation of some of the strands indicate that these strands connect with other offshore fault zones in the area. Based on the limited data available, the trend of the CBFZ south of Coronado Bank suggests that it might connect with the Rose Canyon fault zone (RCFZ) that has been mapped in San Diego Bay. North of Coronado Bank, the CBFZ is a much broader fault zone (about 25 km wide) composed of diverging fault strands. The westernmost strand may merge with the western strand of the Palos Verdes fault zone (PVFZ) south of Lasuen Knoll. The eastern strand trends toward the Newport-Inglewood fault zone (NIFZ) as imaged offshore near Dana Point. These connections suggest that the CBFZ is linked at depth with other prominent fault zones to the north (PVFZ and NIFZ) as well as to the south (RCFZ).

  2. Saga is largest commercial submarine ever

    SciTech Connect

    Not Available

    1985-05-01

    The long-range autonomous submarine, Saga, went nuclear last year with an agreement between the French and two Canadian companies. The agreement to convert the prototype from Swedish Stirling closed-cycle combustion engines to a nuclear power supply will make Saga the first non-defense nuclear submarine. With an external hull displacement of 500 tons, Saga will be the largest commercial submarine ever built.

  3. Russian nuclear-powered submarine decommissioning

    SciTech Connect

    Bukharin, O.; Handler, J.

    1995-11-01

    Russia is facing technical, economic and organizational difficulties in dismantling its oversized and unsafe fleet of nuclear powered submarines. The inability of Russia to deal effectively with the submarine decommissioning crisis increases the risk of environmental disaster and may hamper the implementation of the START I and START II treaties. This paper discusses the nuclear fleet support infrastructure, the problems of submarine decommissioning, and recommends international cooperation in addressing these problems.

  4. 34. VIEW OF SUBMARINE ESCAPE TRAINING TANK PRIOR TO ADDITION ...

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

    34. VIEW OF SUBMARINE ESCAPE TRAINING TANK PRIOR TO ADDITION OF BLISTERS IN 1959, LOOKING SOUTHEAST - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  5. Influence of the Nazaré Canyon, central Portuguese margin, on late winter coccolithophore assemblages

    NASA Astrophysics Data System (ADS)

    Guerreiro, Catarina; Sá, Carolina; de Stigter, Henko; Oliveira, Anabela; Cachão, Mário; Cros, Lluϊsa; Borges, Carlos; Quaresma, Luis; Santos, Ana I.; Fortuño, José-Manuel; Rodrigues, Aurora

    2014-06-01

    This paper presents a first attempt to characterize coccolithophore assemblages occurring in the context of an active submarine canyon. Coccolithophores from the upper-middle sections of the Nazaré Canyon (central Portuguese margin) - one of the largest canyons of the European continental margin - were investigated during a late winter period (9-12 March 2010). Species distributions were analyzed in a multiparameter environmental context (temperature, salinity, turbidity, Chl-a and nutrient concentrations). Monthly averaged surface water Chl-a concentrations between 2006 and 2011 assessed from satellite data are also presented, as a framework for interpreting spatial and temporal distribution of phytoplankton in the Nazaré Canyon. The Nazaré Canyon was observed to act as a conduit for advection of relatively nutrient-poor oceanic waters of ENACWst origin into nearshore areas of the continental shelf (less than 10 km off the coast), whilst at the surface a nutrient-rich buoyant plume resulting from intensive coastal runoff prior and during the beginning of the cruise was spreading in oceanward direction. Two distinct coccolithophore assemblages appear representative for the coast to open-ocean gradient: (1) Emiliania huxleyi together with Gephyrocapsa ericsonii and Coronosphaera mediterranea dominated the more productive assemblage present within coastal-neritic surface waters; and (2) Syracosphaera spp. and Ophiaster spp. displayed a higher affinity with open-ocean conditions, and also generally a broader vertical distribution. Local “hotspots” of coccolithophore and phytoplankton biomass potentially associated with perturbations of surface water circulation by the canyon are discussed.

  6. Sediment transport processes at the head of Halibut Canyon, Eastern Canada margin: An interplay between internal tides and dense shelf water cascading.

    NASA Astrophysics Data System (ADS)

    Puig, Pere; Greenan, Blair J. W.; Li, Michael Z.; Prescott, Robert H.; Piper, David J. W.

    2013-04-01

    To investigate the processes by which sediment is transported through a submarine canyon incised in a glaciated margin, the bottom boundary layer quadrapod RALPH was deployed at 276-m depth in the West Halibut Canyon (off Newfoundland) during winter 2008-2009. Two main sediment transport processes were identified throughout the deployment. Firstly, periodic increases of near-bottom suspended-sediment concentrations (SSC) were recorded associated with the up-canyon propagation of the semidiurnal internal tidal bore along the canyon axis, carrying fine sediment particles resuspended from deeper canyon regions. The recorded SSC peaks, lasting less than one hour, were observed sporadically and were linked to bottom intensified up-canyon flows concomitant with sharp drops in temperature. Secondly, sediment transport was also observed during events of intensified down-canyon current velocities that occurred during periods of sustained heat loss from surface waters, but were not associated with large storms. High-resolution velocity profiles throughout the water column during these events revealed that the highest current speeds (~1 m s-1) were centered several meters above the sea floor and corresponded to the region of maximum velocities of a gravity flow. Such flows had associated low SSC and cold water temperatures and have been interpreted as dense shelf water cascading events channelized along the canyon axis. Sediment transport during these events was largely restricted to bedload and saltation, producing winnowing of sands and fine sediments around larger gravel particles. Analysis of historical hydrographic data suggests that the origin of such gravity flows is not related to the formation of coastal dense waters advected towards the canyon head. Rather, the dense shelf waters appear to be generated around the outer shelf, where convection during winter is able to reach the sea floor and generate a pool of near-bottom dense water that cascades into the canyon during one or two tidal cycles. A similar transport mechanism can occur in other submarine canyons along the eastern Canadian margin, as well in other canyoned regions elsewhere, where winter convection generally reaches the shelf-edge.

  7. Attributes and origins of ancient submarine slides and filled embayments: Examples from the Gulf Coast basin

    SciTech Connect

    Morton, R.A. )

    1993-06-01

    Large submarine slides and associated shelf margin embayments represent an intermediate member in the continuum of unstable shelf margin features. On seismic profiles, they may resemble submarine canyons, but are different in their size, morphology, origin, and hydrocarbon exploration potential. Two large Neogene submarine slides, located in the northwestern Gulf Coast Basin, formed on the upper slope and flanks of prominent shelf-margin deltas. The basal detachment surface of each slide is a structural discontinuity that may be misinterpreted as an erosional unconformity and misidentified as a stratigraphic boundary separating depositional sequences. Regional stratigraphic correlations indicate that both slides were initiated after the continental platform was flooded. The condensed sections deposited during the rise in relative sea level contain the basal detachment surfaces. The relationships between the slides and sea level fluctuations are uncertain. The shelf-margin embayments created by the slides apparently were partly excavated during periods of lowered relative sea level and were filled during sea level rise and highstand. Eventually the preslide morphology of the shelf margin was restored by coalsced prograding deltas. Submarine slides exhibit landward dipping, wavy, mounded, and chaotic seismic reflection that are manifestations of slump blocks and other mass transport material. Composition of these internally derived slide deposits depends on th composition of the pre-existing shelf margin. Embayment fill above the slide consists mostly of externally derived mudstones and sandstones deposited by various disorganized slope processes, as well as more organized submarine channel-level systems. Thickest slope sandstones, which are potential hydrocarbon reservoirs, commonly occur above the basal slide mudstones where seismic reflections change from chaotic patterns to overlying wavy or subhorizontal reflections. 46 refs., 10 figs., 1 tab.

  8. Seven years of geomorphic change in the head of Monterey Canyon, CA: Steady state equilibrium or monotonic change?

    NASA Astrophysics Data System (ADS)

    Smith, D. P.; Kvitek, R. G.; Ross, E.; Iampietro, P.; Paull, C. K.; Sandersfeld, M.

    2010-12-01

    The head of Monterey submarine canyon has been surveyed with high-precision multibeam sonar at least once each year since September 2002. This poster provides a summary of changes between September 2002 and September 2008. Data were collected with a variety of Reson mulitbeam sonar heads, and logged with an ISIS data acquisition system. Vessel attitude was corrected using an Applanix POS MV equipped with an auxillary C-Nav 2050 GPS receiver. Data were processed and filtered and cleaned in Caris HIPS. Depth changes for various time spans were determined through raster subtraction of pairs of 3-m resolution bathymetric grids in ArcMap. The depth change analyses focused on the canyon floor, except where a landslide occurred on a wall, and where obvious gullying near the headwall had occurred during the time of our study. Canyon walls were generally excluded from analysis. The analysis area was 1,414,240 sq meters. The gross changes between 2002 and 2008 include net erosion of 2,300,000 m^3 +/- 800,000 m^3 of material from the canyon. The annualized rate of net sediment loss from this time frame agrees within an order of magnitude with our previously published estimates from earlier (shorter) time frames, so the erosion events seem to be moderate magnitude and frequent, rather than infrequent and catastrophic. The greatest sediment loss appears to be from lateral erosion of channel-bounding terraces rather than deepening or scouring of the existing channel axis. A single landslide event that occurred in summer 2003 had an initial slide scar (void) volume of 71,000 m^3. The scar was observed to increase annually, and had grown to approximately 96,000 m^3 by 2008. The initial slide was too small to be tsunamigenic. In contrast to the monotonic canyon axis widening, the shoreward terminus of the canyon (canyon lip) appears to be in steady state equilibrium with sediment supply entering the canyon from the littoral zone. The lip position, indicated by the clearly defined shelf/slope break, typically oscillates offshore and onshore about 20 m to 30 m annually, but a 50 m change was measured. This oscillation likely represents cycles of sediment wedge progradation followed by slope failure and shoreward lip retreat. At this time, it appears that buildings along Moss Landing strand are not at risk from net shoreward canyon growth. The canyon appears to be excavating material that was previously stored in the canyon during an era when sediment supply outcompeted submarine transport processes. Published ages and pollen analyses from the canyon walls indicate that an enormous volume of sediment entered the canyon in post-European settlement time, with up to 1.6 m of sediment drape occurring after 1945 (presence of trace DDT). Likewise, 1930’s-era bathymetric charts indicate that major depositional features now located in the canyon were not present in the 1930’s, again suggesting a very young age for the deposits now being excavated from the canyon. One possible source of the young deposits is the construction of nearby Moss Landing Harbor in 1946, which has led to very high erosion rates in adjacent Elkhorn Slough.

  9. A Laboratory model for the flow in urban street canyons induced by bottom heating

    NASA Astrophysics Data System (ADS)

    Liu, Huizhi; Liang, Bin; Zhu, Fengrong; Zhang, Boyin; Sang, Jianguo

    2003-07-01

    Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Image Visualization) technique. Fluid experiments show that with calm ambient wind, the flows in the street canyon are completely driven by thermal force, and the convection can reach the upper atmosphere of the street canyon. Horizontal and vertical motions also appear above the roofs of the buildings. These are the conditions which favor the exchange of momentum and air mass between the street canyon and its environment. More than two vortices are induced by the convection, and the complex circulation pattern will vary with time in a wider street canyon. However, in a narrow street canyon, just one vortex appears. With a light ambient wind, the bottom heating and the associated convection result in just one main vortex. As the ambient wind speed increases, the vortex becomes more organized and its center shifts closer to the leeward building.

  10. Submarines, spacecraft and exhaled breath.

    PubMed

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another important concern is a suite of products from chemical reactions among oxidizing compounds with biological chemicals such as amines, thiols and carbonyls. SAMAP Meeting We (Armin and Joachim) attended the 2011 SAMAP conference in Taranto, Italy (10-14 October), which occurred just a few weeks after the IABR meeting in Parma, Italy (11-15 September 2011). It was held at the Officers' Club of the Taranto Naval Base under the patronage of the Italian navy; the local host was Lucio Ricciardi of the University of Insubria, Varese, Italy. At the 2011 SAMAP meeting, the theme was air-independent propulsion (AIP), meaning the capability of recharging the main batteries of the submarine without the need to surface. Only a few navies (e.g. US, UK, France, Russia, China) have historically had this capability using nuclear-powered submarines that can function underwater for extended periods of time (months). Most navies operate submarines with conventional diesel-electric propulsion, wherein diesel-powered generators charge battery banks which then drive an electric motor connected to the propeller. The batteries are charged while the boat is on the surface or during snorkelling, when the boat is submerged a few meters below the surface and a snorkel tube is extended to the surface. The period between battery charges can vary from several hours to one or two days depending on the power requirements and the nature of the mission. The process is necessary for breathing air revitalization (flushing out accumulated contaminants) and for the operation of the diesel engines. However, during this period the submarine is vulnerable to detection. Since the 1940s there have been various attempts to develop a power generation system that is independent of external air (AIP). To this end hydrogen peroxide was initially used and later liquid oxygen (LOX). Currently, most AIP submarines use fuel cell technology (LOX and hydrogen) to supplement the conventional diesel-electric system in order to extend the underwater endurance to 2-3 weeks. These propulsion engineering changes also reduce periodic ventilation of the submarine's interior and thus put a greater burden on the various maintenance systems. We note that the spaceflight community has similar issues; their energy production mechanisms are essentially air independent in that they rely almost entirely on photovoltaic arrays for electricity generation, with only emergency back-up power from alcohol fuel cells. In response to prolonged underwater submarine AIP operations, months-long spaceflight operations onboard the ISS and planning for future years-long missions to Mars, there has been an increasing awareness that bio-monitoring is an important factor for assessing the health and awareness states of the crewmembers. SAMAP researchers have been proposing various air and bio-monitoring instruments and methods in response to these needs. One of the most promising new methodologies is the non-invasive monitoring of exhaled breath. So, what do the IABR and SAMAP communities have in common? Inhalation toxicology. We are both concerned with contamination from the environment, either as a direct health threat or as a confounder for diagnostic assessments. For example, the exhaled breath from subjects in a contaminated and enclosed artificial environment (submarine or spacecraft) can serve as a model system and a source of contamination for their peers in a cleaner environment. In a similar way, exhaled anaesthetics can serve as a source of contamination in hospital/clinical settings, or exhalation of occupational exposures to tetrachloroethylene can impact family members at home. Instrumentation development. Both communities have similar needs for better, more specific and more sensitive instruments. Certainly, the analytical instruments to be used onboard submarines and spacecraft have severe restrictions on energy use, physical size and ease of operation. The medical and clinical communities have similar long-term plans for their analytical tools, in this case to take breath analysis away from the large complex instruments in the laboratory to the outpatient clinic and eventually to the home care market. Similarly, for environmental and public health research, it is always desirable to have easily operated and deployable instruments that can be taken to the field, rather than bringing numerous subjects to a central laboratory. Bio-monitoring. Although the SAMAP community is much more focused on air rather than breath measurement, this is changing because of the realization that longer deployment times (on submarines and spacecraft) will affect more than just acute health. To monitor longer-term health outcomes, there is a great deal of commonality between our respective research communities. Any instrument that monitors for contaminants in environmental air could certainly be adapted to breath analysis for assessing exposures and health state. Instruments that simultaneously provide rapid response and high specificity to a broad range of analytes, such as those based on optical spectroscopy and mass spectrometry, are particularly valued. The path forward We found the SAMAP meeting to be a worthwhile experience, largely from the discovery that another high-tech community exists with similar needs as the IABR community. Some collaboration could be fruitful for us; we suggest that the IABR community stay in contact with SAMAP in the future and attempt to attend each other's meetings if possible. SAMAP meetings tend to run on a two year cycle and so the next one has not yet been announced. We will let the IABR community know when the next meeting is scheduled, and will certainly make the SAMAP people aware of IABR meetings and the Journal of Breath Research. This article has been subjected to EPA Agency review and approved for publication. Statements do not necessarily reflect official Agency policy. PMID:22366644

  11. Why SRS Matters - H Canyon

    SciTech Connect

    Hunt, Paul; Lewczyk, Mike; Swain, Mike

    2015-02-17

    A video series presenting an overview of the Savannah River Site's (SRS) mission and operations. Each episode features a specific area/operation and how it contributes to help make the world safer. This episode features H Canyon's mission and operations.

  12. Tubes at Glen Canyon Dam

    The river outlet tubes at Glen Canyon Dam on the Colorado River in Arizona. At noon Monday, Nov. 19, U.S. Interior Secretary Ken Salazar will open the dam's river outlet tubes, releasing controlled flows larger than the usual 8,000-25,000 cubic feet per second that flows through the turbines of...

  13. Thomas Moran: "The Grand Canyon."

    ERIC Educational Resources Information Center

    Brubaker, Ann

    1986-01-01

    Presents a lesson plan for introducing students in grades four through six to Thomas Moran's painting, "The Grand Canyon." The goal of the lesson is to illustrate the importance of the American West as a subject for artists in the nineteenth century. (JDH)

  14. Amplification of bedrock canyon incision by wind

    NASA Astrophysics Data System (ADS)

    Perkins, Jonathan P.; Finnegan, Noah J.; de Silva, Shanaka L.

    2015-04-01

    Bedrock canyons are ubiquitous on Earth and Mars, and river canyon morphology is commonly used to interpret the climatic and tectonic histories of landscapes. On both planets, however, many bedrock canyons exist in dry, wind-dominated environments. Although wind abrasion can significantly influence the evolution of arid landscapes, the role of wind in shaping arid bedrock canyon systems is poorly understood and thus typically neglected. Here we exploit a natural experiment on the western slope of the central Andes that allows direct comparison of wind-affected and wind-protected canyons. Through a combined analysis of the morphology of 36 canyons and topographic wind simulations, we show that wind abrasion can amplify bedrock canyon incision rates by an order of magnitude above fluvial rates. Our results imply that wind can extend bedrock canyons--landforms traditionally thought to evolve only from flowing water. Furthermore, our analyses reveal a direct relationship between aerodynamics and landscape evolution on varying scales. Topographic shielding of high winds by mountains modulates the pace of canyon retreat, while individual canyon profiles become aerodynamically streamlined. We conclude that wind abrasion can significantly modify the morphology of bedrock canyons and suggest that wind may have similarly reshaped fluvial landscapes on the martian surface.

  15. Reference PMHS Sled Tests to Assess Submarining.

    PubMed

    Uriot, Jérôme; Potier, Pascal; Baudrit, Pascal; Trosseille, Xavier; Petit, Philippe; Richard, Olivier; Compigne, Sabine; Masuda, Mitsutoshi; Douard, Richard

    2015-11-01

    Sled tests focused on pelvis behavior and submarining can be found in the literature. However, they were performed either with rigid seats or with commercial seats. The objective of this study was to get reference tests to assess the submarining ability of dummies in more realistic conditions than on rigid seat, but still in a repeatable and reproducible setup. For this purpose, a semi-rigid seat was developed, which mimics the behavior of real seats, although it is made of rigid plates and springs that are easy to reproduce and simulate with an FE model. In total, eight PMHS sled tests were performed on this semirigid seat to get data in two different configurations: first in a front seat configuration that was designed to prevent submarining, then in a rear seat configuration with adjusted spring stiffness to generate submarining. All subjects sustained extensive rib fractures from the shoulder belt loading. No pelvis fractures and no submarining were observed in the front seat configuration, but two subjects sustained lumbar vertebrae fractures. In the rear seat configuration, all subjects sustained pelvic fractures and demonstrated submarining. Corridors were constructed for the external forces and the PMHS kinematics. They are provided in this paper as new reference tests to assess the biofidelity of human surrogates in different configurations that either result in submarining or do not. In future, it is intended to analyze further seat and restraint system configurations to be able to define a submarining predictor. PMID:26660745

  16. Submarine mass failures as tsunami sources: their climate control.

    PubMed

    Tappin, D R

    2010-05-28

    Recent research on submarine mass failures (SMFs) shows that they are a source of hazardous tsunamis, with the tsunami magnitude mainly dependent on water depth of failure, SMF volume and failure mechanism, cohesive slump or fragmental landslide. A major control on the mechanism of SMFs is the sediment type, together with its post-depositional alteration. The type of sediment, fine- or coarse-grained, its rate of deposition together with post-depositional processes may all be influenced by climate. Post-depositional processes, termed sediment 'preconditioning', are known to promote instability and failure. Climate may also control the triggering of SMFs, for example through earthquake loading or cyclic loading from storm waves or tides. Instantaneous triggering by other mechanisms such as fluid overpressuring and hydrate instability is controversial, but is here considered unlikely. However, these mechanisms are known to promote sediment instability. SMFs occur in numerous environments, including the open continental shelf, submarine canyon/fan systems, fjords, active river deltas and convergent margins. In all these environments there is a latitudinal variation in the scale of SMFs. The database is limited, but the greatest climate influence appears to be in high latitudes where glacial/interglacial cyclicity has considerable control on sedimentation, preconditioning and triggering. Consideration of the different types of SMFs in the context of their climate controls provides additional insight into their potential hazard in sourcing tsunamis. For example, in the Atlantic, where SMFs are common, the tsunami hazard under the present-day climate may not be as great as their common occurrence suggests. PMID:20403835

  17. Amplification of bedrock canyon incision by wind

    NASA Astrophysics Data System (ADS)

    Perkins, J. P.; Finnegan, N. J.; de Silva, S. L.

    2013-12-01

    Bedrock canyons etch much of the surface of Earth and Mars, and commonly inform interpretations of long-term hydrologic or tectonic changes within these landscapes. However, many bedrock canyons (particularly on Mars) exist in arid environments where wind abrasion can dramatically alter surface morphology. Although it is hypothesized that wind carves or modifies bedrock canyons on Mars, the interplay of wind and fluvial processes in shaping canyon landscapes is, to our knowledge, unexplored. Consequently, here we exploit a natural experiment along the 4.09 Ma Puripicar ignimbrite, situated on the western slope of the Andes in the Atacama Desert and subject to significant erosion from both wind and rivers. The Puripicar exhibits a series of bedrock gorges nested behind a broad north-south escarpment whose southern half is protected from wind by a large topographic barrier. This shielding provides a natural control to examine the effects of wind abrasion on canyon morphology and in particular knickpoint retreat. Our results show that for a given drainage area, knickpoints in wind-affected canyons have incised an order of magnitude farther upstream than wind-protected canyons. In addition, wind-affected canyons are wider and have more streamlined aspect ratios for a given drainage area than wind-protected canyons. Aeolian abrasion appears to result in knickpoints with average slopes half those of shielded canyons (0.2 and 0.4, respectively). Lastly, although the magnitude of knickpoint retreat is larger in wind-affected canyons, the scaling exponent between knickpoint retreat and drainage area is virtually identical for wind-affected canyons (0.56, R = 0.71) and wind-protected canyons (0.60, R = 0.80). Taken together, our results suggest that fluvial incision and wind abrasion are coupled processes in this landscape: convergent canyons funnel wind towards knickpoints, thereby leading to enhanced aeolian abrasion rates at knickpoints. We speculate that the apparent drainage area dependence of knickpoint retreat in wind-affected canyons reflects the fact that larger rivers create wider canyon mouths. Larger canyons mouths, in turn, increase wind convergence and drive higher aeolian abrasion rates at the heads of larger canyons. This study is the first to demonstrate knickpoint retreat via wind abrasion, and highlights that even in landscapes where large river gorges are present, wind may still exert a dominant control on canyon morphology.

  18. Narrow Bandwidth Telecommunications.

    ERIC Educational Resources Information Center

    Kessler, William J.; Wilhelm, Michael J.

    The basic principles of narrow bandwidth telecommunications are treated in a manner understandable to the non-engineer. The comparative characteristics of the various narrow bandwidth communications circuits are examined. Currently available graphics transmission and reception equipment are described and their capabilities and limitations…

  19. The role of upper-regime flow bedforms in the morphodynamics of submarine channels

    NASA Astrophysics Data System (ADS)

    Covault, Jacob A.; Kostic, Svetlana; Fildani, Andrea

    2014-05-01

    Advances in acoustic imaging of submarine canyons and channels have provided accurate renderings of seafloor geomorphology. Still, a fundamental understanding of channel inception, evolution, sediment transport, and the nature of the currents traversing these channels remains elusive. Here, we review a mosaic of geomorphology, shallow stratigraphy, and morphodynamics of channelized deep-water depositional systems of tectonically active slopes offshore of California, USA. These systems are imaged in high-resolution multi-beam sonar bathymetry (dominant frequency ~200 kHz) and seismic-reflection (2-16 kHz) data. From north to south, the Monterey East, Lucia Chica, and San Mateo channelized deep-water depositional systems show a breadth of geomorphology and stratigraphic architecture, including channel reaches of varying sinuosity, levees, terraces within channels, and crescent-shaped bedforms, especially in the thalwegs of incipient channel elements. Morphodynamic numerical modeling is combined with interpretations of seafloor and shallow subsurface stratigraphic imagery to demonstrate that the crescent-shaped bedforms common to channel thalwegs are likely to be cyclic steps. We propose that net-erosional and net-depositional cyclic steps play a fundamental role in the formation, filling, and maintenance phases of submarine channels in continental margins with high gradient, locally rugose bathymetry. These margins include passive-margin slopes subjected to gravity-driven tectonic deformation. In such settings, high gradients support the development of densimetric Froude-supercritical turbidity currents, and abrupt slope breaks can promote hydraulic jumps and the spontaneous evolution of an erodible seabed into cyclic steps. This morphodynamic investigation of turbidity currents and the seafloor has the potential to enhance prediction of the locations, stratigraphic evolution, and architecture of submarine canyon-channel systems.

  20. Carbonate apron models: Alternatives to the submarine fan model for paleoenvironmental analysis and hydrocarbon exploration

    USGS Publications Warehouse

    Mullins, H.T.; Cook, H.E.

    1986-01-01

    Sediment gravity flow deposition along the deep-water flanks of carbonate platforms typically does not produce submarine fans. Rather, wedge-shaped carbonate aprons develop parallel to the adjacent shelf/slope break. The major difference between submarine fans and carbonate aprons is a point source with channelized sedimentation on fans, versus a line source with sheet-flow sedimentation on aprons. Two types of carbonate aprons may develop. Along relatively gentle (< 4??) platform-margin slopes, aprons form immediately adjacent to the shallow-water platform and are referred to as carbonate slope aprons. Along relatively steep (4-15??) platform margin slopes, redeposited limestones accumulate in a base-of-slope setting, by-passing an upper slope via a multitude of small submarine canyons, and are referred to as carbonate base-of-slope aprons. Both apron types are further subdivided into inner and outer facies belts. Inner apron sediments consist of thick, mud-supported conglomerates and megabreccias (Facies F) as well as thick, coarse-grained turbidites (Facies A) interbedded with subordinate amounts of fine-grained, peri-platform ooze (Facies G). Outer apron sediments consist of thinner, grain-supported conglomerates and turbidites (Facies A) as well as classical turbidites (Facies C) with recognizable Bouma divisions, interbedded with approximately equal proportions of peri-platform ooze (Facies G). Seaward, aprons grade laterally into basinal facies of thin, base-cut-out carbonate turbidites (Facies D) that are subordinate to peri-platform oozes (Facies G). Carbonate base-of-slope aprons grade shelfward into an upper slope facies of fine-grained peri-platform ooze (Facies G) cut by numerous small canyons that are filled with coarse debris, as well as intraformational truncation surfaces which result from submarine sliding. In contrast, slope aprons grade shelfward immediately into shoal-water, platform-margin facies without an intervening by-pass slope. The two carbonate apron models presented here offer alternatives to the submarine-fan model for paleoenvironmental analysis and hydrocarbon exploration for mass-transported carbonate facies. ?? 1986.

  1. Morphology of late Quaternary submarine landslides along the U.S. Atlantic continental margin

    USGS Publications Warehouse

    Twichell, D.C.; Chaytor, J.D.; ten Brink, U.S.; Buczkowski, B.

    2009-01-01

    The nearly complete coverage of the U.S. Atlantic continental slope and rise by multibeam bathymetry and backscatter imagery provides an opportunity to reevaluate the distribution of submarine landslides along the margin and reassess the controls on their formation. Landslides can be divided into two categories based on their source areas: those sourced in submarine canyons and those sourced on the open continental slope and rise. Landslide distribution is in part controlled by the Quaternary history of the margin. They cover 33% of the continental slope and rise of the glacially influenced New England margin, 16% of the sea floor offshore of the fluvially dominated Middle Atlantic margin, and 13% of the sea floor south of Cape Hatteras. The headwall scarps of open-slope sourced landslides occur mostly on the lower slope and upper rise while they occur mostly on the upper slope in the canyon-sourced ones. The deposits from both landslide categories are generally thin (mostly 20-40??m thick) and comprised primarily of Quaternary material, but the volumes of the open-slope sourced landslide deposits can be larger (1-392??km3) than the canyon-sourced ones (1-10??km3). The largest failures are located seaward of shelf-edge deltas along the southern New England margin and near salt domes that breach the sea floor south of Cape Hatteras. The spatial distribution of landslides indicates that earthquakes associated with rebound of the glaciated part of the margin or earthquakes associated with salt domes were probably the primary triggering mechanism although other processes may have pre-conditioned sediments for failure. The largest failures and those that have the potential to generate the largest tsunamis are the open-slope sourced landslides.

  2. Mineral resources of the Coal Canyon, Spruce Canyon, and Flume Canyon Wilderness Study Areas, Grand county, Utah

    SciTech Connect

    Dickerson, R.P.; Gaccetta, J.D.; Kulik, D.M.; Kreidler, T.J.

    1990-01-01

    This paper reports on the Coal Canyon, Spruce Canyon, and Flume Canyon Wilderness Study Areas in the Book and Roan Cliffs in Grand Country, Utah, approximately 12 miles west of the Colorado state line. The wilderness study areas consist of a series of deep, stair-step-sided canyons and high ridges eroded into the flatlying sedimentary rocks of the Book Cliffs. Demonstrated coal reserves totaling 22,060,800 short tons and demonstrated subeconomic coal resources totaling 39,180,000 short tons are in the Coal Canyon Wilderness Study Area. Also, inferred subeconomic coal resources totaling 143,954,000 short tons are within the Coal Canyon Wilderness Study Area. No known deposits of industrial minerals are in any of the study area. All three of the wilderness study areas have a high resource potential for undiscovered deposits of coal and for undiscovered oil and gas.

  3. 47 CFR 32.2424 - Submarine & deep sea cable.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Submarine & deep sea cable. 32.2424 Section 32... Submarine & deep sea cable. (a) This account shall include the original cost of submarine cable and deep sea... defined below, are to be maintained for nonmetallic submarine and deep sea cable and metallic...

  4. 32 CFR 700.1058 - Command of a submarine.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Command of a submarine. 700.1058 Section 700... Command Detail to Duty § 700.1058 Command of a submarine. The officer detailed to command a submarine... submarines....

  5. 47 CFR 32.2424 - Submarine & deep sea cable.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Submarine & deep sea cable. 32.2424 Section 32... Submarine & deep sea cable. (a) This account shall include the original cost of submarine cable and deep sea... defined below, are to be maintained for nonmetallic submarine and deep sea cable and metallic...

  6. 47 CFR 32.2424 - Submarine & deep sea cable.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Submarine & deep sea cable. 32.2424 Section 32... Submarine & deep sea cable. (a) This account shall include the original cost of submarine cable and deep sea... defined below, are to be maintained for nonmetallic submarine and deep sea cable and metallic...

  7. 47 CFR 32.2424 - Submarine & deep sea cable.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Submarine & deep sea cable. 32.2424 Section 32... Submarine & deep sea cable. (a) This account shall include the original cost of submarine cable and deep sea... defined below, are to be maintained for nonmetallic submarine and deep sea cable and metallic...

  8. 32 CFR 700.1058 - Command of a submarine.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Command of a submarine. 700.1058 Section 700... Command Detail to Duty § 700.1058 Command of a submarine. The officer detailed to command a submarine... submarines....

  9. 32 CFR 700.1058 - Command of a submarine.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 5 2012-07-01 2012-07-01 false Command of a submarine. 700.1058 Section 700... Command Detail to Duty § 700.1058 Command of a submarine. The officer detailed to command a submarine... submarines....

  10. 29. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION AT ...

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

    29. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION AT POINT JUST ABOVE THE SUBMARINE SECTION AT THE 110-FOOT LEVEL 1929-1930 - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  11. 32 CFR 700.1058 - Command of a submarine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 5 2013-07-01 2013-07-01 false Command of a submarine. 700.1058 Section 700... Command Detail to Duty § 700.1058 Command of a submarine. The officer detailed to command a submarine... submarines....

  12. 32 CFR 700.1058 - Command of a submarine.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 5 2014-07-01 2014-07-01 false Command of a submarine. 700.1058 Section 700... Command Detail to Duty § 700.1058 Command of a submarine. The officer detailed to command a submarine... submarines....

  13. 32. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONN. ...

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

    32. VIEW OF PHOTO CAPTIONED 'SUBMARINE BASE, NEW LONDON, CONN. OCTOBER 3, 1932. COMPLETION OF ERECTION OF STEELWORK FOR ELEVATOR. LOOKING NORTH. CONTRACT NO. Y-1539-ELEVATOR, SUBMARINE ESCAPE TANK.' - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  14. Bell Canyon test and results

    SciTech Connect

    Christensen, C.L.; Hunter, T.O.

    1980-01-01

    The purposes of the Borehold Plugging Program are: to identify issues associated with sealing boreholes and shafts; to establish a data base from which to assess the importance of these issues; and to develop sealing criteria, materials, and demonstrative test for the Waste Isolation Pilot Plant (WIPP). The Bell Canyon Test described in this report is one part of that program. Its purpose was to evaluate, in situ, the state of the art in borehole plugs and to identify and resolve problems encountered in evaluating a typical plug installation in anhydrite. The test results are summarized from the work of Peterson and Christensen and divided into two portions: system integrity and wellbore characterization tests prior to plug installation, and a series of tests to evaluate isolation characteristics of the 1.8-m-long plug. Conclusions of the Bell Canyon Test are: brine and fresh-water grouts, with acceptable physical properties in the fluid and hardened states, have been developed; the field data, taken together with laboratory data, suggest that the predominant flow into the test region occurs through the cement plug/borehold interface region, with lesser contributions occurring through the wellbore damage zone, the plug core, and the surrounding undisturbed anhydrite bed; and the 1.8-m-long by 20-cm-diameter grout plug, installed in anhydrite at a depth of 1370 m in the AEC-7 borehole, limits flow from the high pressure Bell Canyon aquifer to 0.6 liters/day.

  15. A submarine shipboard smoking cessation program.

    PubMed

    Scali, W K

    1989-11-01

    The discouragement of tobacco abuse in the military requires effective smoking cessation assistance for all active duty and dependent personnel. Specifically tailoring this assistance to the unique features of the various military communities will help to make it more effective. The program presented herein was designed for use in the submarine fleet. It combines basic proven workplace smoking cessation techniques with lessons learned from experience in submarines. It is believed that other military populations can benefit from similar efforts. This paper is an abridged version of the author's Submarine Medical Officer qualification thesis. PMID:2511509

  16. A study of sound absorption by street canyon boundaries and asphalt rubber concrete pavement

    NASA Astrophysics Data System (ADS)

    Drysdale, Graeme Robert

    A sound field model, based on a classical diffusion equation, is extended to account for sound absorption in a diffusion parameter used to model sound energy in a narrow street canyon. The model accounts for a single sound absorption coefficient, separate accommodation coefficients and a combination of separate absorption and accommodation coefficients from parallel canyon walls. The new expressions are compared to the original formula through numerical simulations to reveal the effect of absorption on sound diffusion. The newly established analytical formulae demonstrate satisfactory agreement with their predecessor under perfect reflection. As well, the influence of the extended diffusion parameter on normalized sound pressure levels in a narrow street canyon is in agreement with experimental data. The diffusion parameters are used to model sound energy density in a street canyon as a function of the sound absorption coefficient of the street canyon walls. The acoustic and material properties of conventional and asphalt rubber concrete (ARC) pavement are also studied to assess how the crumb rubber content influences sound absorption in street canyons. The porosity and absolute permeability of compacted specimens of asphalt rubber concrete are measured and compared to their normal and random incidence sound absorption coefficients as a function of crumb rubber content in the modified binder. Nonlinear trends are found between the sound absorption coefficients, porosity and absolute permeability of the compacted specimens and the percentage of crumb rubber in the modified binders. The cross-sectional areas of the air voids on the surfaces of the compacted specimens are measured using digital image processing techniques and a linear relationship is obtained between the average void area and crumb rubber content. The measured material properties are used to construct an empirical formula relating the average porosity, normal incidence noise reduction coefficients and percentage of crumb rubber in the modified binder of the compacted specimens.

  17. Turkish Straits System and Southern Black Sea: Exchange. Mixing and Shelf / Canyon Interactions

    NASA Astrophysics Data System (ADS)

    Özsoy, Emin; Gürses, Özgür; Tutsak, Ersin

    2015-04-01

    Based largely on an experiment employing high-resolution measurements carried out in June-July 2013 and re-interpretation of past experiments, the oceanographic variability of the exchange through the Turkish Straits System (TSS) and the interactions with the southern Black Sea are revealed through CTD, ADCP, oxygen and light transmission measurements. The exchange flow is primarily governed by the complex topography spanning two narrow straits, wide continental shelf regions, steep slopes and numerous canyons connecting deep basins. Water properties and currents in the high energy environment depends on the mosaic of fine-scale processes and pathways. The TSS, often approximated as a two-layer system has a hydraulically controlled, upper ocean and straits intensified regime, leading to surface jets and bottom plumes participating in mixing and renewal processes. The exit of the 'Mediterranean effluent' onto the Black Sea past a sill overflow from the Bosphorus passes through two subsequent hydraulic jumps and proceeds along a narrow canyon that veers to the west clear of the greater Bosphorus Canyon finally cascading down the few small canyons. A diffusive spread from the bottom vein of salty water reforms to the east and spills down the Bosphorus Canyon. The suspended particulate signature of the cascade, as well as its influence in hydrography is traced over the shelf and slope waters and through the numerous canyons into deep water where the reformed flow is found to sustain signatures of the past evolution of intrusive waters. An evaluation of the processes is given with reference to model development carried out in parallel to the analyses of the measurements.

  18. Nicolas and Eel submarine fans, California continental borderland

    SciTech Connect

    Reynolds, S.; Gorsline, D.S.

    1987-04-01

    Nicolas and Eel Submarine Fans occur in the San Nicolas basin - an outer basin of the California continental borderland that has a low sedimentation rate. Nicolas Fan lies southeast of San Nicolas Island and the broad San Nicolas Bank. The upper fan is characterized by numerous channels. The midfan region may be divided into three distinct areas: a central midfan and two subfans. The central midfan deposition system is typical of Normark's suprafan. The subfans are essentially flat, sandy lobes. Eel Fan lies west of San Clemente Island and is fed by an erosional valley. Its midfan region may also be characterized as a flat, sandy lobe. Box-core data show that holocene turbidity currents have occurred on the central Nicolas Fan, whereas the subfans and Eel Fan are nearly inactive. The local tectonic regime influences these fans by determining slope trends, creating bathymetric obstacles, controlling canyon location, and triggering mass movements. Sea level changes affect sedimentation patterns of the fans by increasing the mean grain size and the amount of sediment delivered to the fan during lowstands. These changes may, in turn, affect the morphology of the fan. The characteristics of these fans represent variations of the generalized fan models described in the literature. 12 figures, 1 table.

  19. Modes of development of slope canyons and their relation to channel and levee features on the Ebro sediment apron, off-shore northeastern Spain

    USGS Publications Warehouse

    O'Connell, S.; Ryan, William B. F.; Normark, W.R.

    1987-01-01

    Six submarine slope canyons in an area of the northwestern Mediterranean, offshore from the Ebro River and Delta, were surveyed with bathymetric swathmapping (SeaBeam) and mid-range side-looking sonar (SeaMARC I). All of the canyons have slightly winding paths with concave-upwards gradients that are relatively steep shallower than 1,200 m. Two major types of canyons are identified on the basis of their morphologic character at the base of the slope; Type-I canyons lead to an unchannelled base-of-slope deposit and Type-II canyons are continuous with channel-levee systems that cross the rise. Four Type-I canyons were surveyed in the area. Two of these are broad, U-shaped, steep (average gradients of 1:14), do not indent the shelf, and terminate downslope at debris-flow deposits. These two canyons, the most northern in the area, have rounded heads with extensive gullies separated by knife-edge ridges. Relief of the canyon walls is about equal on both sides of the canyons, although the right-hand walls (looking downslope) are generally steeper. The other two Type-I canyons in the area are similar in that they do not indent the shelf, but they are much smaller and shallower and coalesce before terminating in the base-of-slope region. The two Type-II canyons that feed leveed-channels are U-shaped with flatter floors, longer profiles and gentler gradients than Type-I canyons. They are closer to the Valencia Valley and have relatively small cross-sectional areas. We propose a four-stage evolutionary sequence to explain the development of the canyons observed in this section on the prograding Ebro margin. During the initial stage, slumping and erosion on the slope creates a network of small gullies. During the next stage, headward growth of one (or more) gully leads to a major indentation of the shelf. This is the critical factor for developing a channel that will incise the slope and provide a major conduit for moving sediment to the basin. Stage 3 is characterized by the development of a continuous channel accompanied by levee growth across the lobe. In the final stage, the channel-levee system becomes inactive either through destruction by mass wasting, infilling of the channel, or loss of the major sediment source. ?? 1987.

  20. 2. VIEW OF HIGH FLUME, LOOKING DOWN WARM SPRINGS CANYON ...

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

    2. VIEW OF HIGH FLUME, LOOKING DOWN WARM SPRINGS CANYON TO SANTA ANA RIVER CANYON. VIEW TO WEST-NORTHWEST. - Santa Ana River Hydroelectric System, Warm Springs Canyon-SAR-3 Flumes, Redlands, San Bernardino County, CA

  1. California State Waters Map Series--Hueneme Canyon and vicinity, California

    USGS Publications Warehouse

    Johnson, Samuel Y.; Dartnell, Peter; Cochrane, Guy R.; Golden, Nadine E.; Phillips, Eleyne L.; Ritchie, Andrew C.; Kvitek, Rikk G.; Greene, H. Gary; Krigsman, Lisa M.; Endris, Charles A.; Clahan, Kevin B.; Sliter, Ray W.; Wong, Florence L.; Yoklavich, Mary M.; Normark, William R.

    2012-01-01

    In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California's State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Hueneme Canyon and vicinity map area lies within the eastern Santa Barbara Channel region of the Southern California Bight. The area is part of the Western Transverse Ranges geologic province, which is north of the California Continental Borderland. Significant clockwise rotation - at least 90° - since the early Miocene has been proposed for the Western Transverse Ranges, and the region is presently undergoing north-south shortening. This geologically complex region forms a major biogeographic transition zone, separating the cold-temperate Oregonian province north of Point Conception from the warm-temperate California province to the south. The map area, which is offshore of the Oxnard plain and west of and along the trend of the south flank of the Santa Monica Mountains, lies at the east end of the Santa Barbara littoral cell, characterized by west-to-east littoral transport of sediment derived mainly from coastal watersheds. The Hueneme Canyon and vicinity map area in California's State Waters is characterized by two major physiographic features: (1) the nearshore continental shelf, and (2) the Hueneme and Mugu Submarine Canyon system, which, in the map area, includes Hueneme Canyon and parts of three smaller, unnamed headless canyons incised into the shelf southeast of Hueneme Canyon. The shelf is underlain by tens of meters of interbedded upper Quaternary shelf, estuarine, and fluvial deposits that formed as sea level fluctuated in the last several hundred thousand years. Hueneme Canyon extends about 15 km offshore from its canyon head near the dredged navigation channel of the Port of Hueneme. The canyon is relatively deep (about 150 m at the California's State Waters limit) and steep (canyon flanks as steep as 25° to 30°). Historically, Hueneme Canyon functioned as the eastern termination of the Santa Barbara littoral cell by trapping all eastward littoral drift, not only feeding the large Hueneme submarine fan but acting as the major conduit of sediment to the deep Santa Monica Basin; however, recent dredging programs needed to maintain Channel Islands Harbor and the Port of Hueneme have moved the nearshore sediment trapped by jetties and breakwaters to an area southeast of the Hueneme Canyon head. Seafloor habitats in the broad Santa Barbara Channel region consist of significant amounts of soft sediment and isolated areas of rocky habitat that support kelp-forest communities nearshore and rocky-reef communities in deep water. The potential marine benthic habitat types mapped in the Hueneme Canyon and vicinity map area are related directly to the geomorphology and sedimentary processes that are the result of its Quaternary geologic history. The two basic megahabitats in the map area are Shelf (continental shelf) and Flank (continental slope). The flat seafloor of the continental shelf in the Hueneme Canyon and vicinity map area is dynamic, as indicated by mobile sand sheets and coarser grained scour depressions. The active Hueneme Canyon provides considerable relief to the continental shelf in the map area, and its irregular morphology of eroded walls, landslide scarps, and deposits and gullies provide promising habitat for groundfish, crabs, shrimp, and other marine benthic organisms. Most invertebrates observed in the map area during camera ground-truth field operations are found on the edge of Hueneme Canyon, which may be an important area of recruitment and retention to other invertebrates and fishes. The smaller, more subtle, nonactive headless canyons located primarily on the continental slope also offer relief that provides habitat for groundfish and other organisms.

  2. De-Stabilization of Streambanks by Removal of Invasive Species in Canyon de Chelly National Monument, Arizona

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As part of a study to investigate the causes of channel narrowing and incision in Canyon de Chelly National Monument, the effects of Tamarisk and Russian-olive on streambank stability were evaluated. The National Park Service (NPS) is currently engaged in an experimental program to remove the invasi...

  3. CHALLENGES POSED BY RETIRED RUSSIAN NUCLEAR SUBMARINES

    SciTech Connect

    Rudolph, Dieter; Kroken, Ingjerd; Latyshev, Eduard; Griffith, Andrew

    2003-02-27

    The purpose of this paper is to provide an overview of the challenges posed by retired Russian nuclear submarines, review current U.S. and International efforts and provide an assessment of the success of these efforts.

  4. Sediment concentrations, flow conditions, and downstream evolution of two turbidity currents, Monterey Canyon, USA

    USGS Publications Warehouse

    Xu, Jingping; Octavio E. Sequeiros; Noble, Marlene A.

    2014-01-01

    The capacity of turbidity currents to carry sand and coarser sediment from shallow to deep regions in the submarine environment has attracted the attention of researchers from different disciplines. Yet not only are field measurements of oceanic turbidity currents a rare achievement, but also the data that have been collected consist mostly of velocity records with very limited or no suspended sediment concentration or grain size distribution data. This work focuses on two turbidity currents measured in Monterey Canyon in 2002 with emphasis on suspended sediment from unique samples collected within the body of these currents. It is shown that concentration and grain size of the suspended material, primarily controlled by the source of the gravity flows and their interaction with bed material, play a significant role in shaping the characteristics of the turbidity currents as they travel down the canyon. Before the flows reach their normal or quasi-steady state, which is defined by bed slope, bed roughness, and suspended grain size, they might pass through a preliminary adjustment stage where they are subject to capacity-driven deposition, and release heavy material in excess. Flows composed of fine (silt/clay) sediments tend to be thicker than those with sands. The measured velocity and concentration data confirm that flow patterns differ between the front and body of turbidity currents and that, even after reaching normal state, the flow regime can be radically disrupted by abrupt changes in canyon morphology.

  5. Sediment concentrations, flow conditions, and downstream evolution of two turbidity currents, Monterey Canyon, USA

    NASA Astrophysics Data System (ADS)

    Xu, J. P.; Sequeiros, Octavio E.; Noble, Marlene A.

    2014-07-01

    The capacity of turbidity currents to carry sand and coarser sediment from shallow to deep regions in the submarine environment has attracted the attention of researchers from different disciplines. Yet not only are field measurements of oceanic turbidity currents a rare achievement, but also the data that have been collected consist mostly of velocity records with very limited or no suspended sediment concentration or grain size distribution data. This work focuses on two turbidity currents measured in Monterey Canyon in 2002 with emphasis on suspended sediment from unique samples collected within the body of these currents. It is shown that concentration and grain size of the suspended material, primarily controlled by the source of the gravity flows and their interaction with bed material, play a significant role in shaping the characteristics of the turbidity currents as they travel down the canyon. Before the flows reach their normal or quasi-steady state, which is defined by bed slope, bed roughness, and suspended grain size, they might pass through a preliminary adjustment stage where they are subject to capacity-driven deposition, and release heavy material in excess. Flows composed of fine (silt/clay) sediments tend to be thicker than those with sands. The measured velocity and concentration data confirm that flow patterns differ between the front and body of turbidity currents and that, even after reaching normal state, the flow regime can be radically disrupted by abrupt changes in canyon morphology.

  6. Chirp seismic-reflection data from the Baltimore, Washington, and Norfolk Canyons, U.S. mid-Atlantic margin

    USGS Publications Warehouse

    Obelcz, Jeffrey B.; Brothers, Daniel S.; ten Brink, Uri S.; Chaytor, Jason D.; Worley, Charles R.; Moore, Eric M.

    2014-01-01

    A large number of high-resolution geophysical surveys between Cape Hatteras and Georges Bank have been conducted by federal, state, and academic institutions since the turn of the century. A major goal of these surveys is providing a continuous view of bathymetry and shallow stratigraphy at the shelf edge in order to assess levels of geological activity during the current sea level highstand. In 2012, chirp seismic-reflection data was collected by the U.S. Geologial Survey aboard the motor vessel Tiki XIV near three United States mid-Atlantic margin submarine canyons. These data can be used to further our understanding of passive continental margin processes during the Holocene, as well as providing valuable information regarding potential submarine geohazards.

  7. Research Furthers Conservation of Grand Canyon Sandbars

    USGS Publications Warehouse

    Melis, Theodore S.; Topping, David J.; Rubin, David M.; Wright, Scott A.

    2007-01-01

    Grand Canyon National Park lies approximately 25 km (15 mi) down-river from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border in Glen Canyon National Recreation Area. Before the dam began to regulate the Colorado River in 1963, the river carried such large quantities of red sediment, for which the Southwest is famous, that the Spanish named the river the Rio Colorado, or 'red river'. Today, the Colorado River usually runs clear below Glen Canyon Dam because the dam nearly eliminates the main-channel sand supply. The daily and seasonal flows of the river were also altered by the dam. These changes have disrupted the sedimentary processes that create and maintain Grand Canyon sandbars. Throughout Grand Canyon, sandbars create habitat for native plants and animals, supply camping beaches for river runners and hikers, and provide sediment needed to protect archaeological resources from weathering and erosion. Maintenance of sandbars in the Colorado River ecosystem, the river corridor that stretches from the dam to the western boundary of Grand Canyon National Park, is a goal of the Glen Canyon Dam Adaptive Management Program. The program is a federally authorized initiative to ensure that the mandates of the Grand Canyon Protection Act of 1992 are met through advances in information and resource management. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center has responsibility for scientific monitoring and research efforts for the program. Extensive research and monitoring during the past decade have resulted in the identification of possible alternatives for operating Glen Canyon Dam that hold new potential for the conservation of sand resources.

  8. Personality characteristics of successful Navy submarine personnel.

    PubMed

    Moes, G S; Lall, R; Johnson, W B

    1996-04-01

    This study evaluated the personality characteristics of senior enlisted and occupationally successful Navy submarine personnel. One hundred subjects completed the Schedule for Nonadaptive and Adaptive Personality (SNAP). Results indicated that the traits of detachment, propriety, and workaholism were most descriptive of the sample. Thirty-seven percent met SNAP criteria for a personality disorder, typically antisocial, obsessive-compulsive, or avoidant. The results are discussed in terms of adaptation to environmental demands aboard submarines. Suggestions for further research are offered. PMID:8935516

  9. Hudson Canyon benthic habitats characterization and mapping by integrated analysis of multidisciplinary data

    NASA Astrophysics Data System (ADS)

    Pierdomenico, Martina; Guida, Vincent G.; Rona, Peter A.; Macelloni, Leonardo; Scranton, Mary I.; Asper, Vernon; Diercks, Arne

    2013-04-01

    Hudson Canyon, about 180 km SE of New York City, is the largest eastern U.S. submarine canyon and is under consideration for HAPC (Habitat Area of Particular Concern) status, representing a fisheries and biodiversity hot spot. Interest in the area, within the perspective of ecosystem based management, marine spatial planning, habitat and species conservation, led to a joint project between NOAA Northeast Fisheries, U.S. Geological Survey (USGS), Mississippi Mineral Research Institute (MMRI), National Institute for Undersea Science and Technology (NIUST), Stony Brook and Rutgers Universities for the study of benthic habitats, that includes the assembly of existing data with newly collected ones: acoustic mapping, visual ground-truthing, hydrographic, sedimentological, and trawl data collections. Acoustic mapping, performed using AUV-mounted multibeam sonar, provided ultra-high resolution bathymetric and backscatter imagery (3m and 1m respectively) at all water depths for identification of geomorphological features and for the characterization of surficial sediments along the two thirds of the shelf portion of the canyon. Identification of benthic and demersal communities was accomplished by visual ground thruthing with underwater vehicle video and still cameras, and from trawl catch data. A CTD-rosette sampler provided water column salinity-temperature profiles and water samples for dissolved methane analysis in the vicinity of suspected bottom sources. Analysis of data revealed a complex of topographic structures and hydrological patterns that provide a wide range of physical habitats in a relatively small area. A mosaic of sandy and muddy substrates, gravel beds, rock outcrops, and semilithified clay outcrops host rich and varied faunal assemblages, including deepwater corals and sponge communities. Pockmark fields, occurring below 300 m depth, suggest that methane-based chemosynthetic carbonate deposition contributes to creation of specific hard bottom habitats. Previously described hummocky terrain associated with extensive, long-term burrowing activity by golden tilefish (Lopholatilus chamaeleonticeps) was clearly delineated along the canyon rims. Bedform fields and potential current deposits observed along the upper portion of canyon walls suggest the presence of intense bottom currents flowing parallel to canyon axis. A benthic habitat map of Hudson Canyon head was produced by integration of the different datasets. The distribution of habitats was primarily inferred from geophysical data characteristics. Furthermore habitat characteristics can be related to sedimentary and oceanographic processes acting on the seafloor. Comparison and refinement of bathymetric and backscatter imagery with ground truth data enabled validation of acoustic classification of the seafloor, allowing the definition of morpho-acoustic classes corresponding to as many habitats, and to extend the predictive results over larger areas.

  10. [Tuberculosis in the crew of a submarine].

    PubMed

    Suzuki, S; Nakabayashi, K; Ohkouchi, H; Hatada, J; Kawaguchi, S; Sakai, M; Sasaki, N; Ito, A

    1997-01-01

    We report the apparent spread of mycobacterial tuberculosis among a submarine crew from a crew member with a low grade of infectivity. The air-conditioning system of submarines requires completely closed recirculation of ambient air. If a person with pulmonary tuberculosis were in a submarine, one would expect to find a high incidence of tuberculosis among others on the ship. The index patient was a 35-year-old member of a submarine crew. An abnormal shadow was found on a chest roentgenogram during an annual medical checkup, and he was hospitalized for examination. Acid-fast bacilli were found in his gastric secretions, but he did not complain of coughing and no tuberculosis bacilli were found in his sputum. All members of the submarine crew were examined, and some who were on board with the index patient reacted strongly. Because those who were also suspected to be infected were usually not close to the index patient's living quarters and had little contact with the patient in the submarine, we strongly suspect that the closed ventilation system contributed to the spread of the infection. Control of tuberculosis in a sealed environment requires detailed investigation of the environment and completion of chemoprophylaxis. Adequate ventilation and ultraviolet radiation are more effective than decontamination with disinfectants for the control of infectious droplet nuclei. Ships should be equipped with those systems. PMID:9071158

  11. Submarine landslides: processes, triggers and hazard prediction.

    PubMed

    Masson, D G; Harbitz, C B; Wynn, R B; Pedersen, G; Løvholt, F

    2006-08-15

    Huge landslides, mobilizing hundreds to thousands of km(3) of sediment and rock are ubiquitous in submarine settings ranging from the steepest volcanic island slopes to the gentlest muddy slopes of submarine deltas. Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential. The major hazards related to submarine landslides include destruction of seabed infrastructure, collapse of coastal areas into the sea and landslide-generated tsunamis. Most submarine slopes are inherently stable. Elevated pore pressures (leading to decreased frictional resistance to sliding) and specific weak layers within stratified sequences appear to be the key factors influencing landslide occurrence. Elevated pore pressures can result from normal depositional processes or from transient processes such as earthquake shaking; historical evidence suggests that the majority of large submarine landslides are triggered by earthquakes. Because of their tsunamigenic potential, ocean-island flank collapses and rockslides in fjords have been identified as the most dangerous of all landslide related hazards. Published models of ocean-island landslides mainly examine 'worst-case scenarios' that have a low probability of occurrence. Areas prone to submarine landsliding are relatively easy to identify, but we are still some way from being able to forecast individual events with precision. Monitoring of critical areas where landslides might be imminent and modelling landslide consequences so that appropriate mitigation strategies can be developed would appear to be areas where advances on current practice are possible. PMID:16844646

  12. Stratigraphic evolution of a long-lived submarine channel system in the Late Cretaceous Nanaimo Group, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Bain, Heather A.; Hubbard, Stephen M.

    2016-05-01

    Submarine canyons and slope channel systems are important conveyers of sediment from uplifted catchments to oceanic sedimentary sinks. Long-lived conduits can be established through deep incision of submarine canyons, with bathymetric relief of hundreds of meters to greater than a kilometer in many instances. Alternatively, a combination of erosion of the continental slope and aggradation of levees can yield a broadly comparable stratigraphic product through evolution of channels with more subdued bathymetric relief. Despite differences in formative geomorphic elements on the paleo-seafloor, differentiating the stratigraphic architecture amongst these systems is challenging, particularly in outcrop datasets. Accurate stratigraphic interpretation has significant implications for understanding the frequency and magnitude of controlling processes such as mountain building and denudation or eustatic sea-level fluctuations. In this study, deep-water channel strata of the Late Cretaceous Nanaimo Group are examined at Hornby and Denman islands, British Columbia, Canada. Evidence for a long-lived submarine conduit records the history of sediment transfer at multiple temporal and spatial scales. The composite submarine channel system deposit is 19.5 km wide and 1500 m thick, which formed and filled over ~ 15 Ma. Facies scale analyses highlight conglomeratic channel fill juxtaposed against thin-bedded out-of-channel deposits. Erosional surfaces are commonly mantled by mass-transport deposits, which provide evidence for conduit wall reworking and maintenance. At a larger scale, a series of composite, conglomerate-prone channelform bodies are observed to stratigraphically stack in two distinct phases: (1) early persistence of laterally offset (migrated) channels; and (2) later vertically aligned and aggraded channels. This stratigraphic trend is comparable to composite, multi-phase degradational-aggradational submarine channel complexes observed globally. As such, we consider the stratigraphic evolution of the large submarine conduit deposit (1500 m thick) to have formed through the protracted processes of geomorphic channels with subdued paleo-bathymetric relief (20-200 m). Detailed observations at the scale of facies and stratigraphic architecture provide criteria for recognition and interpretation of long-lived slope channel systems, emphasizing a disparate relationship between stratigraphic and geomorphic surfaces.

  13. The role of erosion by fish in shaping topography around Hudson submarine canyon.

    USGS Publications Warehouse

    Twichell, D.C.; Grimes, Craig B.; Jones, R. S.; Able, K.W.

    1985-01-01

    The close match of areas of rough topography and high tilefish populations, the active burrowing of the sea floor, and the clustered distribution of the burrows suggest that the hummocky topography in this area may be the result of continuous erosion by tilefish and associated crustaceans during the Holocene. -from Authors

  14. H-Canyon Recovery Crawler

    SciTech Connect

    Kriikku, E. M.; Hera, K. R.; Marzolf, A. D.; Phillips, M. H.

    2015-08-01

    The Nuclear Material Disposition Project group asked the Savannah River National Lab (SRNL) Research and Development Engineering (R&DE) department to help procure, test, and deploy a remote crawler to recover the 2014 Inspection Crawler (IC) that tipped over in the H-Canyon Air Exhaust Tunnel. R&DE wrote a Procurement Specification for a Recovery Crawler (RC) and SRNS Procurement Department awarded the contract to Power Equipment Manufacturing Inc. (PEM). The PEM RC was based on their standard sewer inspection crawler with custom arms and forks added to the front. The arms and forks would be used to upright the 2014 Inspection Crawler. PEM delivered the RC and associated cable reel, 2014 Inspection Crawler mockup, and manuals in late April 2015. R&DE and the team tested the crawler in May of 2015 and made modifications based on test results and Savannah River Site (SRS) requirements. R&DE delivered the RC to H-Area at the end of May. The team deployed the RC on June 9, 10, and 11, 2015 in the H-Canyon Air Exhaust Tunnel. The RC struggled with some obstacles in the tunnel, but eventually made it to the IC. The team spent approximately five hours working to upright the IC and eventually got it on its wheels. The IC travelled approximately 20 feet and struggled to drive over debris on the air tunnel floor. Unfortunately the IC tripped over trying to pass this obstacle. The team decided to leave the IC in this location and inspect the tunnel with the RC. The RC passed the IC and inspected the tunnel as it travelled toward H-Canyon. The team turned the RC around when it was about 20 feet from the H-Canyon crossover tunnel. From that point, the team drove the RC past the manway towards the new sand filter and stopped approximately 20 feet from the new sand filter. The team removed the RC from the tunnel, decontaminated the RC, and stored it the manway building, 294-2H. The RC deployment confirmed the IC was not in a condition to perform useful tunnel inspections and would require significant maintenance to become inspection ready. The RC traveled approximately 660 feet in the tunnel and viewed the tunnel and ceiling wall surfaces that were not blocked by existing ducts. This deployment also documented the tunnel obstacles for future inspections. Overall, the RC deployment was a success.

  15. Snow-covered Sandstone at Bryce Canyon

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  16. Bryce Canyon and Grand Staircase-Escalante

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  17. Panorama of Bryce Canyon National Park

    Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates for the dolomite that caps them and the sandstone that forms their base. Bryce Canyon is also home to large numbe...

  18. Bryce Canyon and Grand Staircase-Escalante

    Views along the Queen's Garden Trail in Bryce Canyon National Park; Grand Staircase-Escalante National Monument can be seen in the background. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed d...

  19. Environmental assessment: Davis Canyon site, Utah

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considering for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization.

  20. Environmental assessment: Davis Canyon site, Utah

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high- level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of the five sites suitable for characterization.

  1. Loblolly Pines in Pine Creek Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  2. Barrel Cactus in Pine Creek Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  3. Sunset Panorama in Pine Creek Canyon

    Pine Creek Canyon is a remnant ecosystem of loblolly pines. A remnant ecosystem is the last vestige of an ecosystem type that used to be more widespred. Red Rock Canyon is a National Conservation Area managed by the Bureau of Land Management, located just outside of Las Vegas, Nevada. It is part of...

  4. ACCELERATED PILOT PROJECT FOR U CANYON DEMOLITION

    SciTech Connect

    KEHLER KL

    2011-01-13

    At the U.S. Department of Energy's Hanford Site in southeast Washington State, CH2M HILL Plateau Remediation Company (CH2M HILL) is underway on a first-of-a-kind project with the decommissioning and demolition of the U Canyon. Following the U.S. Environmental Protection Agency's Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) Record of Decision for the final remediation of the canyon, CH2M HILL is combining old and new technology and techniques to prepare U Canyon for demolition. The selected remedial action called first for consolidating and grouting equipment currently in the canyon into lower levels of the plant (openings called cells), after which the cell galleries, hot pipe trench, ventilation tunnel, drains and other voids below the operating deck and crane-way deck levels will be filled with approximately 20,000 cubic yards of grout and the canyon roof and walls demolished down to the approximate level of the canyon deck. The remaining canyon structure will then be buried beneath an engineered barrier designed to control potential contaminant migration for a 500-year life. Methods and lessons learned from this project will set the stage for the future demolition of Hanford's four other canyon-type processing facilities.

  5. Grand Canyon Monitoring and Research Center

    USGS Publications Warehouse

    Hamill, John F.

    2009-01-01

    The Grand Canyon of the Colorado River, one of the world's most spectacular gorges, is a premier U.S. National Park and a World Heritage Site. The canyon supports a diverse array of distinctive plants and animals and contains cultural resources significant to the region's Native Americans. About 15 miles upstream of Grand Canyon National Park sits Glen Canyon Dam, completed in 1963, which created Lake Powell. The dam provides hydroelectric power for 200 wholesale customers in six western States, but it has also altered the Colorado River's flow, temperature, and sediment-carrying capacity. Over time this has resulted in beach erosion, invasion and expansion of nonnative species, and losses of native fish. Public concern about the effects of Glen Canyon Dam operations prompted the passage of the Grand Canyon Protection Act of 1992, which directs the Secretary of the Interior to operate the dam 'to protect, mitigate adverse impacts to, and improve values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established...' This legislation also required the creation of a long-term monitoring and research program to provide information that could inform decisions related to dam operations and protection of downstream resources.

  6. 76 FR 8359 - Boulder Canyon Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-14

    ... kilowattmonth (kWmonth), and the proposed composite rate is 22.16 mills/kWh. \\1\\ 75 FR 57912. \\2\\ 133 FERC ] 62... Area Power Administration Boulder Canyon Project AGENCY: Western Area Power Administration, DOE...) is proposing an adjustment to the Boulder Canyon Project (BCP) electric service base charge and...

  7. Hydraulic Jumps, Cyclic Steps and Scour Formation in an Active Submarine Channel

    NASA Astrophysics Data System (ADS)

    Sumner, E. J.; Peakall, J.; Parsons, D. R.; Darby, S. E.; Dorrell, R. M.; Wynn, R.

    2011-12-01

    Field scale submarine channel gravity currents are notoriously difficult to measure and thus directly investigate due to their inaccessible location and infrequent nature, which is compounded by present sea-level high-stand. An exception to this is the almost continuous density-driven current that results from the inflow of saline Mediterranean water, via the Bosporus strait, into the Black Sea. This flow has carved a sinuous channel system in water depths of 70 to 120 m containing a series of prominent scours at the upstream end. Despite being driven by the salinity contrast, the flow is sufficiently energetic to transport and rework coarse sand within the channel network. The relatively shallow depths of the channel and the continuous nature of this current provide a unique opportunity to study three-dimensional flow dynamics and the interaction of the flow with a seafloor channel network. Thus, it provides a rare analogue for channelized dilute sediment-laden turbidity currents. There has been speculation for nearly half a century that hydraulic jumps are an important process in submarine density currents. Hydraulic jumps have been implicated in causing the development of submarine fans, large scale (km-scale) scouring, the formation of cyclic steps and channel genesis. However, until now this has been inferred from a combination of small scale laboratory experiments and making inferences about flow processes from the geological record and modern bathymetry. Here we provide the first direct field evidence of hydraulic jumps and cyclic step formation in a density-driven current. The decrease in density due to entrainment of fluid across the jump is negligible compared to entrainment into the supercritical flow prior to the jump. The largest hydraulic jump imaged corresponds to a 100 m scour in the seafloor, with which it is in-phase. The decrease in velocity and thus bed shear stress across the jump is not as extreme as present models predict, and this suggests that hydraulic jumps need not lead to instantaneous deposition of submarine fans as density currents exit canyons as presently envisaged. Instead there is likely to be an area of erosion at the base of the canyon followed by fan deposition more distally.

  8. Urban street canyons: Coupling dynamics, chemistry and within-canyon chemical processing of emissions

    NASA Astrophysics Data System (ADS)

    Bright, Vivien Bianca; Bloss, William James; Cai, Xiaoming

    2013-04-01

    Street canyons, formed by rows of buildings in urban environments, are associated with high levels of atmospheric pollutants emitted primarily from vehicles, and substantial human exposure. The street canyon forms a semi-enclosed environment, within which emissions may be entrained in a re-circulatory system; chemical processing of emitted compounds alters the composition of the air vented to the overlying boundary layer, compared with the primary emissions. As the prevailing atmospheric chemistry is highly non-linear, and the canyon mixing and predominant chemical reaction timescales are comparable, the combined impacts of dynamics and chemistry must be considered to quantify these effects. Here we report a model study of the coupled impacts of dynamical and chemical processing upon the atmospheric composition in a street canyon environment, to assess the impacts upon air pollutant levels within the canyon, and to quantify the extent to which within-canyon chemical processing alters the composition of canyon outflow, in comparison to the primary emissions within the canyon. A new model for the simulation of street canyon atmospheric chemical processing has been developed, by integrating an existing Large-Eddy Simulation (LES) dynamical model of canyon atmospheric motion with a detailed chemical reaction mechanism, a Reduced Chemical Scheme (RCS) comprising 51 chemical species and 136 reactions, based upon a subset of the Master Chemical Mechanism (MCM). The combined LES-RCS model is used to investigate the combined effects of mixing and chemical processing upon air quality within an idealised street canyon. The effect of the combination of dynamical (segregation) and chemical effects is determined by comparing the outputs of the full LES-RCS canyon model with those obtained when representing the canyon as a zero-dimensional box model (i.e. assuming mixing is complete and instantaneous). The LES-RCS approach predicts lower (canyon-averaged) levels of NOx, OH and HO2, but higher levels of O3, compared with the box model run under identical chemical and emissions conditions. When considering the level of chemical detail implemented, segregation effects were found to reduce the error introduced by simplifying the reaction mechanism. Chemical processing of emissions within the canyon leads to a significant increase in the Ox flux from the canyon into the overlying boundary layer, relative to primary emissions, for the idealised case considered here. These results demonstrate that within-canyon atmospheric chemical processing can substantially alter the concentrations of pollutants injected into the urban canopy layer, compared with the raw emission rates within the street canyon. The extent to which these effects occur is likely to be dependent upon the nature of the domain (canyon aspect ratio), prevailing meteorology and emission/pollution scenario considered.

  9. Human-Powered Submarine Competition: World Submarine International 1996 [and] Design Technology Exhibit: A School Model.

    ERIC Educational Resources Information Center

    Hibberd, John C.; Edwards, Don

    1996-01-01

    Hibbard describes the process used by students at Millersville University to build a human-powered submarine for entry in an international submarine competition. Edwards discusses the Design Technology Exhibit held at Lu Sutton Elementary School, the purpose of which was to challenge students to design a useful structure and provide them with the

  10. Human-Powered Submarine Competition: World Submarine International 1996 [and] Design Technology Exhibit: A School Model.

    ERIC Educational Resources Information Center

    Hibberd, John C.; Edwards, Don

    1996-01-01

    Hibbard describes the process used by students at Millersville University to build a human-powered submarine for entry in an international submarine competition. Edwards discusses the Design Technology Exhibit held at Lu Sutton Elementary School, the purpose of which was to challenge students to design a useful structure and provide them with the…

  11. Following the Cantabrian (Ventaniella) fault into the Bay of Biscay: a deeply incised canyon, a change of trend, and 20002 km of unstable continental slope

    NASA Astrophysics Data System (ADS)

    Fernandez Viejo, G.; Lopez-Fernandez, C.; Dominguez-Cuesta, M.

    2012-12-01

    The Cantabrian fault, known traditionally with the local name of Ventaniella fault is a long-lived rectilinear feature that runs in a NW-SE direction for more than 200 km across northwest Spain. Its origins are linked to the end of the Variscan orogeny, but its important role took place during the extensional processes of the Mesozoic that led Iberia to become a microplate separated from Europe and Africa. With the initiation of the alpine orogeny Iberia converges with Europe pushed from the south by Africa, and the Ventaniella fault acted as a dextral strike slip fault with an important reverse component. It has a relatively low topographic expression, although its NE block is slightly uplifted with respect to the SW one. Traditionally it has been mapped offshore following the trace of the Aviles canyon, a deeply incised canyon 7 miles from the coast, oblique to the E-W coast trend and which descents from 160 m in the continental shelf , down to 4750 m in the abyssal plain of the Bay of Biscay . All this incision occurs along just 50 km length of the narrow continental shelf in this area, making the Aviles canyon one of the steepest in the Atlantic. Through seismic reflection lines across the continental shelf and slope, a bathymetric model up to date and a 3D geological model the fault has been mapped into the sea integrating the seismicity associated to its SW block and the newest geological mapping on land. At the same time, what is observed in the northwest prolongation and termination of the fault against the oceanic crust of the abyssal plain is a continental slope that is full of mass-wasting processes along more than 80 km length, showing gravitational and submarine slide processes in an area that roughly occupies 2000 km 2 and involves a volume of unstable mass estimated in more than 1000 km3 . One of the biggest displaced masses made the Aviles canyon change its trend to N-S in an almost 90° bend close to the middle slope. Although the displaced masses are big, it does not seem to pose an immediate hazard, as they all show a short run-out distance and, being the actual seismicity of low grade, it is not enough to trigger the fall of the unstable slope. The Ventaniella fault runs in the continental shelf and slope in NW-SE direction, but it also has been deduced with the new data a secondary fault trace slightly more W-E, interpreted as a termination in horsetail of the main strike-slip feature. Both structures seem to be responsible for the seismicity and the mass wasting processes observed along this strip of the Cantabrian margin.

  12. Environmental assessment overview, Davis Canyon site, Utah

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 3 figs.

  13. Marine neotectonic investigation of the San Gregorio Fault Zone on the northern flank of Monterey Canyon, offshore central California

    NASA Astrophysics Data System (ADS)

    Maier, K. L.; Paull, C. K.; Brothers, D. S.; McGann, M.; Caress, D. W.; Lundsten, E. M.; Anderson, K.; Gwiazda, R.

    2014-12-01

    The San Gregorio Fault Zone (SGFZ) is part of the North American-Pacific plate boundary and is thought to accommodate right-lateral offset up to 10 mm/yr. Because much of the SGFZ in Monterey Bay, central California, lies offshore in steep submarine canyon bathymetry, little is known of its recent activity. We provide initial direct evidence for faulting where the SGFZ has been interpreted based on canyon morphology to cross the northern flank of Monterey Canyon. High-resolution multibeam bathymetry and chirp subbottom profiles were acquired during 13 dives with the Monterey Bay Aquarium Research Institute's (MBARI) Autonomous Underwater Vehicle (AUV) from 2009-2014 on the northern flank of Monterey Canyon, extending from the shelf edge ~15 km offshore Santa Cruz to ~1850 m water depth. Chirp profiles resolve layered sediments up to ~40 m subsurface in this region, and no fault scarps or seafloor lineaments are visible in the 1-m resolution multibeam bathymetry. At least one subsurface fault is identified within the SGFZ by offset reflections across a discrete, nearly vertical fault. However, this fault is only imaged where mass wasting has exhumed older strata to within ~25 m of the seafloor. Numerous slumps scars on the seafloor and packages of chaotic internal reflectivity in chirp profiles suggest that submarine landslide processes dominate the study area. To constrain the age of reflections offset by the fault, MBARI's Remotely Operated Vehicle (ROV) Doc Ricketts, sampled faces of slump scars where the offset reflections crop out using vibracores and horizontal push cores. Radiocarbon dating of foraminifera within these core samples is being used to constrain the last recorded movement on the fault. Application of AUV and ROV methods allows detailed neotectonic investigation of significant offshore structures, like the SGFZ, that contribute to hazard assessment.

  14. Narrowness and Liberality

    ERIC Educational Resources Information Center

    Agresto, John

    2003-01-01

    John Agresto, whose task has been to rebuild the war-ravaged infrastructure of a Middle-Eastern university system, is discouraged to see that narrow expertise is the only goal of education there, to the utter exclusion of intellectual breadth. He comments that, although it is not that bad in the U.S., he feels that doctoral programs as currently…

  15. Prehistoric deforestation at Chaco Canyon?

    PubMed Central

    Wills, W. H.; Drake, Brandon L.; Dorshow, Wetherbee B.

    2014-01-01

    Ancient societies are often used to illustrate the potential problems stemming from unsustainable land-use practices because the past seems rife with examples of sociopolitical “collapse” associated with the exhaustion of finite resources. Just as frequently, and typically in response to such presentations, archaeologists and other specialists caution against seeking simple cause-and effect-relationships in the complex data that comprise the archaeological record. In this study we examine the famous case of Chaco Canyon, New Mexico, during the Bonito Phase (ca. AD 860–1140), which has become a prominent popular illustration of ecological and social catastrophe attributed to deforestation. We conclude that there is no substantive evidence for deforestation at Chaco and no obvious indications that the depopulation of the canyon in the 13th century was caused by any specific cultural practices or natural events. Clearly there was a reason why these farming people eventually moved elsewhere, but the archaeological record has not yet produced compelling empirical evidence for what that reason might have been. Until such evidence appears, the legacy of Ancestral Pueblo society in Chaco should not be used as a cautionary story about socioeconomic failures in the modern world. PMID:25071220

  16. Prehistoric deforestation at Chaco Canyon?

    PubMed

    Wills, W H; Drake, Brandon L; Dorshow, Wetherbee B

    2014-08-12

    Ancient societies are often used to illustrate the potential problems stemming from unsustainable land-use practices because the past seems rife with examples of sociopolitical "collapse" associated with the exhaustion of finite resources. Just as frequently, and typically in response to such presentations, archaeologists and other specialists caution against seeking simple cause-and effect-relationships in the complex data that comprise the archaeological record. In this study we examine the famous case of Chaco Canyon, New Mexico, during the Bonito Phase (ca. AD 860-1140), which has become a prominent popular illustration of ecological and social catastrophe attributed to deforestation. We conclude that there is no substantive evidence for deforestation at Chaco and no obvious indications that the depopulation of the canyon in the 13th century was caused by any specific cultural practices or natural events. Clearly there was a reason why these farming people eventually moved elsewhere, but the archaeological record has not yet produced compelling empirical evidence for what that reason might have been. Until such evidence appears, the legacy of Ancestral Pueblo society in Chaco should not be used as a cautionary story about socioeconomic failures in the modern world. PMID:25071220

  17. A 250-Year Sediment Record of Anthropogenic Contaminants in the Lisbon Canyon, Portuguese Margin

    NASA Astrophysics Data System (ADS)

    de Stigter, H. C.; Richter, T. O.; Booij, K.; Boer, W.; Jesus, C. C.; van Weering, T. C.

    2008-12-01

    The Lisbon Canyon on the continental margin of Portugal is located in the immediate vicinity of a densely populated and industrialized metropolitan area, and receives terrigenous sediments from the Tagus River draining a large part of the Iberian Peninsula. Radionuclide records (210Pb, 137Cs) for piston cores retrieved from the canyon indicate rapid and almost continuous accumulation over the last 250 years, with sedimentation rates of up to 1 cm per year. The devastating 1755AD Lisbon Earthquake is represented in some cores by a sandy turbidite layer with erosive base, but subsequently disturbance of the sedimentary record by mass sedimentation events has been very limited. In one core at 1710 m water depth, Pb concentrations increased gradually over the last 250 years, and more abruptly after ~1960AD. Subsequently, anthropogenic lead contributed more than half of total lead deposition. Stable Pb isotope ratios indicate concurrent shifts in sources of Pb and increasing influence of anthropogenic pollutants. A slight reversal in both long-term trends after ~1990AD presumably reflects the phase-out of leaded gasoline. Organic contaminant analyses of a core collected from 1112 m water depth demonstrate enrichment of the canyon sediments with a variety of polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs) over the last century. PCBs increased abruptly during the second half of the 20th century but show a slight decrease over the most recent decade. PAHs appear to have had their maximum in the late 19th century, possibly reflecting fallout of coal dust from one of the busiest shipping routes of the eastern Atlantic. The present study illustrates the potential of submarine canyon sediments as high-resolution archives of human impacts on the continental margin.

  18. Deep-Sea, Deep-Sequencing: Metabarcoding Extracellular DNA from Sediments of Marine Canyons.

    PubMed

    Guardiola, Magdalena; Uriz, María Jesús; Taberlet, Pierre; Coissac, Eric; Wangensteen, Owen Simon; Turon, Xavier

    2015-01-01

    Marine sediments are home to one of the richest species pools on Earth, but logistics and a dearth of taxonomic work-force hinders the knowledge of their biodiversity. We characterized α- and β-diversity of deep-sea assemblages from submarine canyons in the western Mediterranean using an environmental DNA metabarcoding. We used a new primer set targeting a short eukaryotic 18S sequence (ca. 110 bp). We applied a protocol designed to obtain extractions enriched in extracellular DNA from replicated sediment corers. With this strategy we captured information from DNA (local or deposited from the water column) that persists adsorbed to inorganic particles and buffered short-term spatial and temporal heterogeneity. We analysed replicated samples from 20 localities including 2 deep-sea canyons, 1 shallower canal, and two open slopes (depth range 100-2,250 m). We identified 1,629 MOTUs, among which the dominant groups were Metazoa (with representatives of 19 phyla), Alveolata, Stramenopiles, and Rhizaria. There was a marked small-scale heterogeneity as shown by differences in replicates within corers and within localities. The spatial variability between canyons was significant, as was the depth component in one of the canyons where it was tested. Likewise, the composition of the first layer (1 cm) of sediment was significantly different from deeper layers. We found that qualitative (presence-absence) and quantitative (relative number of reads) data showed consistent trends of differentiation between samples and geographic areas. The subset of exclusively benthic MOTUs showed similar patterns of β-diversity and community structure as the whole dataset. Separate analyses of the main metazoan phyla (in number of MOTUs) showed some differences in distribution attributable to different lifestyles. Our results highlight the differentiation that can be found even between geographically close assemblages, and sets the ground for future monitoring and conservation efforts on these bottoms of ecological and economic importance. PMID:26436773

  19. Deep-Sea, Deep-Sequencing: Metabarcoding Extracellular DNA from Sediments of Marine Canyons

    PubMed Central

    Guardiola, Magdalena; Uriz, María Jesús; Taberlet, Pierre; Coissac, Eric; Wangensteen, Owen Simon; Turon, Xavier

    2015-01-01

    Marine sediments are home to one of the richest species pools on Earth, but logistics and a dearth of taxonomic work-force hinders the knowledge of their biodiversity. We characterized α- and β-diversity of deep-sea assemblages from submarine canyons in the western Mediterranean using an environmental DNA metabarcoding. We used a new primer set targeting a short eukaryotic 18S sequence (ca. 110 bp). We applied a protocol designed to obtain extractions enriched in extracellular DNA from replicated sediment corers. With this strategy we captured information from DNA (local or deposited from the water column) that persists adsorbed to inorganic particles and buffered short-term spatial and temporal heterogeneity. We analysed replicated samples from 20 localities including 2 deep-sea canyons, 1 shallower canal, and two open slopes (depth range 100–2,250 m). We identified 1,629 MOTUs, among which the dominant groups were Metazoa (with representatives of 19 phyla), Alveolata, Stramenopiles, and Rhizaria. There was a marked small-scale heterogeneity as shown by differences in replicates within corers and within localities. The spatial variability between canyons was significant, as was the depth component in one of the canyons where it was tested. Likewise, the composition of the first layer (1 cm) of sediment was significantly different from deeper layers. We found that qualitative (presence-absence) and quantitative (relative number of reads) data showed consistent trends of differentiation between samples and geographic areas. The subset of exclusively benthic MOTUs showed similar patterns of β-diversity and community structure as the whole dataset. Separate analyses of the main metazoan phyla (in number of MOTUs) showed some differences in distribution attributable to different lifestyles. Our results highlight the differentiation that can be found even between geographically close assemblages, and sets the ground for future monitoring and conservation efforts on these bottoms of ecological and economic importance. PMID:26436773

  20. 78 FR 21415 - Glen Canyon Dam Adaptive Management Work Group

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-10

    ...The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning Glen Canyon Dam operations and other management actions to protect resources downstream of Glen Canyon Dam, consistent with the Grand Canyon Protection Act. The AMWG meets two to three times a...

  1. Baltimore Canyon Trough, a clastic-carbonate system

    SciTech Connect

    Edson, G.M. )

    1990-05-01

    Baltimore Canyon Trough is similar in age, architecture, and sedimentary framework to neighboring marginal basins offshore from eastern North America. The other basins are the Scotian and Georges Bank basins and the Carolina Trough. All contain a Jurassic-earliest Cretaceous clastic-carbonate sedimentary section composed of terrigenous basin fill and a shallow-water limestone platform. In Baltimore Canyon Trough, the platform is believed to be over 10 km thick. Upward through the Jurassic System, the platform progrades seaward and narrows. The platform top is earliest Cretaceous (Berriasian) and only about 5-15 km wide. Width of the base is indeterminate but apparently much wider. At the seaward edge of the platform is a limestone buildup and reef complex that consists of bioclastic wackestones, packstones, grainstones, and sponge-stromatoporoid-algal bindstones. Foreslope deposits are thrombolitic stromatactis-pelletal carbonate mudstones. Landward of the buildup, the platform contains numerous siliciclastic interbeds, consisting of mostly calcareous shale and siltstone with inertinite. The calciclastic lime mudstone beds of the platform contain terrigenous siliciclasts and kerogens. All units are oxidized and show considerable sedimentary reworking. Through the Jurassic System and into the Cretaceous, terrigenous clastic sediments became increasingly dominant in the basin and erosional-depositional cycles continually reworked carbonate, as well as siliciclastic, units.

  2. Subsurface architecture of the Currituck submarine landslide complex: New insights from high-resolution MCS data

    NASA Astrophysics Data System (ADS)

    Hill, J. C.; Brothers, D. S.; Ten Brink, U. S.; Craig, B.; Chaytor, J. D.; Flores, C. H.

    2014-12-01

    The Currituck submarine landslide complex located offshore North Carolina is one of the most pronounced geomorphic features of the US Mid-Atlantic Margin, evacuating and redepositing sediment over an area greater than 6500 km2 along continental slope and upper rise. Despite its geomorphic significance, the factors that preconditioned the Currituck slope for failure remain poorly understood. We present an integrated analysis of new high-resolution multichannel seismic (MCS) reflection profiles acquired by the USGS, multibeam bathymetry data, and 1980s vintage industry MCS profiles. The Currituck slope appears to be made up of multiple failure events. Bathymetry data show evidence for multiple surface scarps, while the MCS data suggest there are additional buried scarps within the Pleistocene section. A ~500-m-thick section of relatively intact strata is observed across a 10 x 18 km swath of the lower slope and adjacent to the primary slide evacuation zone. Within this section, chaotic mass transport deposits are sandwiched between parallel reflectors, suggesting older landslides occurred along the upper slope prior to the most recent episode of slope failure. Plio-Pleistocene strata imaged below the main Currituck slide surface display seaward divergence and little to no evidence for buried submarine canyons, suggesting that the Currituck slope was progradational prior to failure. In contrast, the slope to the north and south of Currituck is heavily canyonized and Plio-Pleistocene depocenters are concentrated on the upper rise, suggesting these regions were dominated by sediment bypass and erosion. 3-D mapping of allostratigraphic surfaces imaged in industry MCS profiles reveal significant spatial variation in the antecedent margin morphology that may have set the stage for the accumulation of unstable Plio-Pleistocene depocenters. Upper Miocene strata to the north and south of Currituck show an angular shelf-edge and steep upper slope, whereas the Currituck region displays a rounded and gentle shelf-edge/upper slope. The gentler slope profile may have allowed for preferential sediment accumulation.

  3. Dense-water cascading and the resulting sedimentation patterns in Lacaze-Duthiers and Cap Creus Canyons, Gulf of Lions

    NASA Astrophysics Data System (ADS)

    Drexler, T. M.; Nittrouer, C. A.; Ogston, A. S.; Mullenbach, B. L.; Degeest, A. L.; Puig, P.

    2008-12-01

    Modern sediment dispersal in the Gulf of Lions is controlled by the interaction of strong marine storms and dense-water formation on the shelf. Regional cyclonic circulation and the narrowing of the southwest shelf lead to off-shelf sediment export via Lacaze-Duthiers and Cap Creus Canyons. Canyon heads are areas of sediment bypassing due to intense current interaction and the frequent occurrence of dense-water cascading. In winter 2004-2005, off-shelf export was dominated by dense-water cascading with additional contributions from internal-wave resuspension, hemipelagic settling and sediment gravity flows. Sedimentation in the canyon heads is asymmetrical with erosion (and coarse sediment) dominating the western flank and main entrant, and pockets of fine-grained sediment on the eastern flank where the Northern Current drapes over the canyon edge. Sedimentation in the lower canyon depths (>400 m) shows evidence of both hemipelagic settling and intermittent sediment gravity flows. Modern fine-grained sediment accumulation in the southwest canyons accounts for <10% of the annual sediment discharge from the Rhne River. This is likely a conservative estimate as the area used to calculate the budget was based on channel-floor areas only. Areas of increased sediment focus may occur within deeper portions of canyons, which were not resolved in this study. Lacaze-Duthiers and Cap Creus Canyon are modern conduits for sediment transport from the shelf to the deep sea with increased deposition likely occurring in years when dense-water cascading occurs in conjunction with winter-storm resuspension events.

  4. Benthic foraminifera from Capbreton Canyon revisited; faunal evolution after repetitive sediment disturbance

    NASA Astrophysics Data System (ADS)

    Bolliet, T.; Jorissen, F. J.; Schmidt, S.; Howa, H.

    2014-06-01

    At a 650 m deep site in the axis of Capbreton Canyon an 18-cm-thick turbidite was deposited in December 1999. During subsequent campaigns, an almost monospecific fauna of the benthic foraminifer Technitella melo, considered as a pioneer species, was found in May 2000. In 2001 this fauna had disappeared and was replaced by an exceptionally rich fauna strongly dominated by the opportunistic species Bolivina subaenariensis. We present sedimentological, radionuclide and foraminiferal data of new cores, sampled in 2005 and 2011, taken with the aim to study the further evolution of the benthic ecosystem. Cores sampled in 2005 show that in the canyon axis a new, ca. 5 cm thick, turbidite has been deposited. The live benthic foraminiferal faunas were much poorer than in 2001, but still had a high dominance and low diversity, although less extreme than in 2001. We conclude that in the canyon axis, benthic foraminiferal faunas remain in an early stage of ecosystem colonization. It appears that the very thick 1999 turbidite marks an exceptional event. The uncommonly rich faunas observed in 2001 could be a response to the concentration of organic-rich material in the fine-grained top of this deposit. In 2011, cores were sampled at a slightly different site, on the lower canyon flank. The sedimentary sequence here is marked by the absence of coarse turbidite layers, although some levels show slightly increased grain size, and lower 210Pbxs activities, indicative of an admixture with advected older sediments. Live foraminiferal faunas are much more equilibrated, as shown by their higher diversity, lower dominance, and deeper penetration into the sediment. All these characteristics are indicative of a much more stable ecosystem. Dead faunas are present throughout the core, indicating that the levels with slightly elevated grain size are not typical turbidites resulting from hyperpycnal currents (which are characterized by levels barren of foraminifera) but denote other, more long-term sedimentary processes leading to the advection of older material, such as bottom nepheloid layers, or repetitive fine-grained turbidite deposits due to small-scale slumping. The comparison of live and dead fauna shows that at both sites, the foraminiferal turnover rates are fairly low. At the lower canyon flank site sampled in 2011, the foraminiferal faunas are renewed every 1.5-2 years. Such a fairly long foraminiferal lifespan corresponds to earlier estimates, but is surprisingly high for the opportunistic taxa that dominate the faunal assemblages in these unstable and food-enriched submarine canyon settings.

  5. Mars Science Laboratory at Canyon

    NASA Technical Reports Server (NTRS)

    2003-01-01

    December 2, 2003

    NASA's Mars Science Laboratory travels near a canyon on Mars in this artist's concept. The mission is under development for launch in 2009 and a precision landing on Mars in 2010.

    Once on the ground, the Mars Science Laboratory would analyze dozens of samples scooped up from the soil and cored from rocks as it explores with greater range than any previous Mars rover. It would investigate the past or present ability of Mars to support life. NASA is considering nuclear energy for powering the rover to give it a long operating lifespan.

    NASA's Jet Propulsion Laboratory, Pasadena, Calif., is managing development of the Mars Smart Laboratory for the NASA Office of Space Science, Washington, D.C.

  6. Reducing Unsteady Loads on a Piggyback Miniature Submarine

    NASA Technical Reports Server (NTRS)

    Lin, John

    2009-01-01

    A small, simple fixture has been found to be highly effective in reducing destructive unsteady hydrodynamic loads on a miniature submarine that is attached in piggyback fashion to the top of a larger, nuclear-powered, host submarine. The fixture, denoted compact ramp, can be installed with minimal structural modification, and the use of it does not entail any change in submarine operations.

  7. 32 CFR 707.7 - Submarine identification light.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Submarine identification light. 707.7 Section... RULES WITH RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive means of identification, an intermittent flashing amber beacon...

  8. 47 CFR 32.2424 - Submarine & deep sea cable.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Submarine & deep sea cable. 32.2424 Section 32... Submarine & deep sea cable. (a) This account shall include the original cost of submarine cable and deep sea cable and other material used in the construction of such plant. Subsidiary record categories,...

  9. 31. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION OF ...

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

    31. VIEW OF SUBMARINE ESCAPE TRAINING TANK DURING CONSTRUCTION OF THE ELEVATOR AND PASSAGEWAYS TO THE 18- AND 50-FOOT LOCKS AND CUPOLA 1932 - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  10. 32 CFR 707.7 - Submarine identification light.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 5 2013-07-01 2013-07-01 false Submarine identification light. 707.7 Section... RULES WITH RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive means of identification, an intermittent flashing amber beacon...

  11. 35. INTERIOR VIEW OF EQUIPMENT HOUSE, SUBMARINE ESCAPE TRAINING TANK, ...

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

    35. INTERIOR VIEW OF EQUIPMENT HOUSE, SUBMARINE ESCAPE TRAINING TANK, PRIOR TO ENLARGEMENT OF ROOM AND INSTALLATION OF TRIPLE-LOCK RECOMPRESSION CHAMBER IN 1957 - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  12. 32 CFR 707.7 - Submarine identification light.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 5 2012-07-01 2012-07-01 false Submarine identification light. 707.7 Section... RULES WITH RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive means of identification, an intermittent flashing amber beacon...

  13. 32 CFR 707.7 - Submarine identification light.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Submarine identification light. 707.7 Section... RULES WITH RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive means of identification, an intermittent flashing amber beacon...

  14. 32 CFR 707.7 - Submarine identification light.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 5 2014-07-01 2014-07-01 false Submarine identification light. 707.7 Section... RULES WITH RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.7 Submarine identification light. Submarines may display, as a distinctive means of identification, an intermittent flashing amber beacon...

  15. 36. VIEW OF CUPOLA, SUBMARINE ESCAPE TRAINING TANK, SHOWING ROVING ...

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

    36. VIEW OF CUPOLA, SUBMARINE ESCAPE TRAINING TANK, SHOWING ROVING RESCUE BELL SUSPENDED ABOVE TANK, WITH TWO-LOCK RECOMPRESSION CHAMBER AT REAR, LOOKING WEST. Photo taken after installation of recompression chamber in 1956. - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  16. Multidisciplinary Investigations of Submarine Flow to Biscayne Bay, Florida

    NASA Astrophysics Data System (ADS)

    Halley, R. B.; Reich, C. D.; Swarzenski, P. W.; Langevin, C. D.

    2005-05-01

    Biscayne Bay and Biscayne National Park (BNP) are located next to the Miami-Dade urban complex and are adjacent to the Dade County South Dade Landfill Facility and the Miami-Dade Water and Sewer South District Plant. The base of the landfill is lined to separate it from the underlying Miami Limestone, the host rock for the surficial Biscayne Aquifer. The sewage-treatment facility injects treated sewage into the lower Florida Aquifer (750 m) that is overlain by an aquitard termed the Middle Confining Unit (450 m). The Biscayne Aquifer (up to 50 m thick) borders the western margin of BNP, and the Floridan Aquifer underlies the entire park. There is concern about leakage of contaminated aquifer water into BNP and its potential effects on water quality. Groundwater flux to Biscayne Bay is being studied using pressure measurements and geochemical analyses from submarine wells, electromagnetic seepage meters, streaming resistivity profiling, and local and regional model simulations. Both seepage meters and water analyses provide point information that can be placed into the regional context provided by flow models and geochemical and geophysical profiling, which, in turn, constrain the groundwater contribution. Water samples were collected approximately quarterly from August 2002 until March 2004 from submarine wells along a transect through Biscayne Bay and across the reef to the shelf edge. Samples were analyzed for conductivity (salinity), dissolved oxygen, temperature, redox potential, nutrients, metals, strontium isotopes, radon, sulfate, and wastewater compounds. Low-salinity water was identified from nearshore wells and indicates seepage from the Biscayne Aquifer and/or surface-water intrusion into the rocks along western Biscayne Bay. Analyses of water samples (n = 109) collected from wells across the Florida shelf show no consistent evidence of wastewater contaminants occurring in groundwater beneath BNP. No significant leakage from the Floridan Aquifer (characterized by low strontium-isotope ratios) was detected in the wells. The groundwater beneath the shelf can be characterized as reduced seawater, modified by microbial respiration to remove oxygen, and interacting with sediments and minerals in the host limestone. The data from submarine well samples are consistent with groundwater model results that indicate a narrow zone of discharge along the western margin of Biscayne Bay. This zone varies in width from 100 to 1000 m along the coast. A seepage meter placed in this zone during March 2004 recorded an average flow of 23 cm/day. Submarine discharge is estimated to be about 6% of the surface-water flow to Biscayne Bay, and almost all of this is in the northern half of the bay, where shoreline and water-table elevations are greatest. Saltwater intrusion extends farther inland in the southern portion of the bay, where water-table and coastal elevations are low. Shoreline-parallel radon-222 profiles also indicate more seepage in the north than south, but suggest low-salinity water extends between 1 and 2 km offshore. Resistivity profiling provided a fourth technique (along with wells, models, and radon) that documents low-salinity water along the coast, particularly toward the northern bay. Resistivity is the only methodology that indicates presence of brackish water 5 km offshore, an observation that requires verification. Interdisciplinary approaches that estimate submarine flow to this tropical estuary are helping reinforce observations made by complimentary methods, while clearly identifying other observations as worthy of further investigation and verification.

  17. A model for the submarine depthkeeping team

    NASA Technical Reports Server (NTRS)

    Ware, J. R.; Best, J. F.; Bozzi, P. J.; Kleinman, D. W.

    1981-01-01

    The most difficult task the depthkeeping team must face occurs during periscope-depth operations during which they may be required to maintain a submarine several hundred feet long within a foot of ordered depth and within one-half degree of ordered pitch. The difficulty is compounded by the facts that wave generated forces are extremely high, depth and pitch signals are very noisy and submarine speed is such that overall dynamics are slow. A mathematical simulation of the depthkeeping team based on the optimal control models is described. A solution of the optimal team control problem with an output control restriction (limited display to each controller) is presented.

  18. Transporting submarine engines to power the PRT

    NASA Technical Reports Server (NTRS)

    1926-01-01

    The city of Hampton was unable to supply adequate electric power to operate the PRT. Navy Captain Walter S. Diehl, Bureau of Aeronautics, acquired two 1000 hp submarine engines which were to be disposed of. BuAer 'loaned' the engines to the NACA, one of which is shown here. Next to the engine is Donald H. Wood, a mechanical engineer from Rensselaer Polytechnic Institute and Fred Weick's assistant. Propeller Research Tunnel (PRT) engineer Donald H. Wood ponders the unlikely transfer of a submarine engine from rail car to NACA truck, May 1926. Two such diesel engines powered the PRT.

  19. Utilization of reactor bays of decommissioned submarines

    SciTech Connect

    Lugavtsov, O.V.; Malakhov, A.G.; Popkov, K.K.

    1994-11-01

    Radiation concerns regarding dismantling and storage of decommissioned reactors and reactor bays from nuclear submarines are briefly summarized. Calculation results are presented for gamma dose rates, contamination density, and the expected location of maximum exposure dose rate on the submarine hull. However, it is noted that radiation measurements must be obtained for each ship due to differences in operating conditions. Long-term storage options for containerized reactors and reactor bays are very briefly outlined; these include placing them in concrete-lined trenches shielded from the atmosphere or in underground tunnels shielded from water. 5 refs., 1 fig., 1 tab.

  20. Physical volcanology of the submarine Mariana and Volcano Arcs

    NASA Astrophysics Data System (ADS)

    Bloomer, Sherman H.; Stern, Robert J.; Smoot, N. Christian

    1989-05-01

    Narrow-beam maps, selected dredge samplings, and surveys of the Mariana and Volcano Arcs identify 42 submarine volcanos. Observed activity and sample characteristics indicate 22 of these to be active or dormant. Edifices in the Volcano Arc are larger than most of the Mariana Arc edifices, more irregularly shaped with numerous subsidiary cones, and regularly spaced at 50 70 km. Volcanos in the Mariana Arc tend to be simple cones. Sets of individual cones and volcanic ridges are elongate parallel to the trend of the arc or at 110° counterclockwise from that trend, suggesting a strong fault control on the distribution of arc magmas. Volcanos in the Mariana Arc are generally developed west of the frontal arc ridge, on rifted frontal arc crust or new back-arc basin crust. Volcanos in the central Mariana Arc are usually subaerial, large (> 500 km3), and spaced about 50 70 km apart. Those in the northern and southern Marianas are largely submarine, closer together, and generally less than 500 km3 in volume. There is a shoaling of the arc basement around Iwo Jima, accompanied by the appearance of incompatible-element enriched lavas with alkalic affinities. The larger volcanic edifices must reflect either a higher magma supply rate or a greater age for the larger volcanos. If the magma supply (estimated at 10 20 km3/km of arc per million years at 18° N) has been relatively constant along the Mariana Arc, we can infer a possible evolutionary sequence for arc volcanos from small, irregularly spaced edifices to large (over 1000 km3) edifices spaced at 50 70 km. The volcano distribution and basal depths are consistent with the hypothesis of back-arc propagation into the Volcano Arc.

  1. Wintertime meteorology of the Grand Canyon region

    SciTech Connect

    Whiteman, C.D.

    1992-09-01

    The Grand Canyon region of the American Southwest is an interesting region meteorologically, but because of its isolated location, the lack of major population centers in the region, and the high cost of meteorological field experiments, it has historically received little observational attention. In recent years, however, attention has been directed to episodes of visibility degradation in many of the US National parks, and two recent field studies focused on this visibility problem have greatly increased the meteorological data available for the Grand Canyon region. The most recent and comprehensive of these studies is the Navajo Generating Station Winter Visibility Study of 1989--90. This study investigated the sources of visibility degradation in Grand Canyon National Park and the meteorological mechanisms leading to low visibility episodes. In this paper we present analyses of this rich data set to gain a better understanding of the key wintertime meteorological features of the Grand Canyon region.

  2. Environmental assessment: Davis Canyon site, Utah

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has fond that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 181 figs., 175 tabs.

  3. Different Views of the Grand Canyon

    NASA Astrophysics Data System (ADS)

    Elders, Wilfred A.

    Each year the spectacular scenery of the Grand Canyon of Arizona awes its more than 4,000,000 visitors. Just as its enormous scale dwarfs our human sense of space, its geology also dwarfs our human sense of time. Perhaps here, more than anywhere else on the planet, we can experience a sense of ``Deep Time.'' The colorful rocks exposed in the vertical walls of the canyon display a span of 1.8 billion years of Earth's history [Beus and Morales, 2003]. But wait! There is a different view! According to Vail [2003], this time span is only 6,000 years and the Grand Canyon and its rocks are a record of the Biblical 6 days of creation and Noah's flood. During a visit to Grand Canyon, in August 2003, I learned that Vail's book, Grand Canyon: A Different View, is being sold within the National Park. The author and compiler of Grand Canyon: A Different View is a Colorado River guide who is well acquainted with the Grand Canyon at river level. He has produced a book with an attractive layout and beautiful photographs. The book is remarkable because it has 23 co-authors, all male, who comprise a veritable ``Who's Who'' in creationism. For example, Henry Morris and John Whitcomb, the authors of the seminal young Earth creationist text, The Genesis Flood [Whitcomb and Morris, 1961], each contribute a brief introduction. Each chapter of Grand Canyon: A Different View begins with an overview by Vail, followed by brief comments by several contributors that ``have been peer reviewed to ensure a consistent and Biblical perspective.'' This perspective is strict Biblical literalism.

  4. Psychiatric aspects of adaptation to long submarine missions.

    PubMed

    Weybrew, B B; Noddin, E M

    1979-06-01

    The case histories of 261 submarines disqualified psychiatrically for further submarine duty revealed that the major symptomatology was emotional in nature, with character pathology second in frequency. The latter pathology resulted in disqualification much earlier than the former, a fact indicative of effective neurotic defenses. The submariners who show these slow-developing neurotic symptoms appear to be reacting maladaptively to the stresses of the 60-d submarine patrols. Some etiological factors appear to be related to the role of man occupies within the crew, to the nature of the mission itself and, perhaps, to the length of the submarine patrols. PMID:475704

  5. Dynamics of deep submarine silicic explosive eruptions in the Kermadec arc, as reflected in pumice vesicularity textures

    NASA Astrophysics Data System (ADS)

    Rotella, Melissa D.; Wilson, Colin J. N.; Barker, Simon J.; Ian Schipper, C.; Wright, Ian C.; Wysoczanski, Richard J.

    2015-08-01

    Despite increasing recognition of silicic pumice-bearing deposits in the deep marine environment, the processes involved in explosive silicic submarine eruptions remain in question. Here we present data on bubble sizes and number densities (number of bubbles per unit of melt matrix) for deep submarine-erupted pumices from three volcanoes (Healy, Raoul SW and Havre) along the Kermadec arc (SW Pacific) to investigate the effects of a significant (>~1 km) overlying water column and the associated increased hydrostatic pressure on magma vesiculation and fragmentation. We compare these textural data with those from chemically similar, subaerially-erupted pyroclasts from nearby Raoul volcano as well as submarine-erupted 'Tangaroan' fragments derived by non-explosive, buoyant detachment of foaming magma from Macauley volcano, also along the Kermadec arc. Deep submarine-erupted pumices are macroscopically similar (colour, density, texture) to subaerial or shallow submarine-erupted pumices, but show contrasting microscopic bubble textures. Deep submarine-erupted pyroclasts have fewer small (< 10 μm diameter) bubbles and narrower bubble size distributions (BSDs) when compared to subaerially erupted pyroclasts from Raoul (35-55 μm vs. 20-70 μm range in volume based median bubble size, respectively). Bubble number density (BND) values are consistently lower than subaerial-erupted pyroclasts and do not display the same trends of decreasing BND with increasing vesicularity. We interpret these textural differences to result from deep submarine eruptions entering the water column at higher pressures than subaerial eruptions entering the atmosphere (~ 10 MPa vs. 0.1 MPa for a vent at 1000 mbsl). The presence of an overlying water column acts to suppress rapid acceleration of magma, as occurs in the upper conduit of subaerial eruptions, therefore suppressing coalescence, permeability development and gas loss, amounting to closed-system degassing conditions. The higher confining pressure environment of deep submarine settings hinders extensive post-fragmentation clast expansion, coalescence of bubbles, and thinning of bubble walls, causing clasts to have similar BND values regardless of their vesicularity. Although deep submarine-erupted pyroclasts are closely similar to their subaerial counterparts on the basis of bulk vesicularities and macroscopic appearance, they differ markedly in their microscopic textures, allowing them to be fingerprinted in modern and ancient pumiceous marine sediments.

  6. Geology of an Ordovician stratiform base-metal deposit in the Long Canyon Area, Blaine County, Idaho

    USGS Publications Warehouse

    Otto, B.R.; Zieg, G.A.

    2003-01-01

    In the Long Canyon area, Blaine County, Idaho, a strati-form base-metal-bearing gossan is exposed within a complexly folded and faulted sequence of Ordovician strata. The gossan horizon in graptolitic mudrock suggests preservation of bedded sulfides that were deposited by an Ordovician subaqueous hydrothermal system. Abrupt thickness changes and geochemi-cal zoning in the metal-bearing strata suggest that the gossan is near the source of the hydrothermal system. Ordovician sedimentary rocks at Long Canyon represent a coarsening-upward section that was deposited below wave base in a submarine depositional environment. The lowest exposed rocks represent deposition in a starved, euxinic basin and over-lying strata represent a prograding clastic wedge of terrigenous and calcareous detritus. The metalliferous strata are between these two types of strata. Strata at Long Canyon have been deformed by two periods of thrust faulting, at least three periods of normal faulting, and two periods of folding. Tertiary extensional faulting formed five subhorizontal structural plates. These low-angle fault-bounded plates truncate Sevier-age and possibly Antler-age thrust faults. The presence of gossan-bearing strata in the four upper plates suggests that there was only minor, although locally complex, stratigraphic displacement and rotation. The lack of correlative strata in the lowest plate suggests the displacement was greater than 2000 ft. The metalliferous strata were exposed to surface weathering, oxidation, and erosion prior to and during deposition of the Eocene Challis Volcanic Group. The orientations of erosional canyons formed during this early period of exposure were related to the orientations of Sevier-age thrust faults, and stream-channel gravel was deposited in the canyons. During this and subsequent intervals of exposure, sulfidic strata were oxi-dized to a minimum depth of 700 ft.

  7. Seatbelt submarining injury and its prevention countermeasures: How a cantilever seat pan structure exacerbate submarining.

    PubMed

    Thorbole, Chandrashekhar K

    2015-01-01

    The purpose of this study and a case report was to demonstrate seat belt webbing induced injury due to seatbelt submarining during the frontal motor vehicle crash. Submarining is an undesired phenomenon during a frontal crash scenario and is dependent on design features of the seat pan and seatbelt system. The lack of adequate anti-submarining features at any seating position with three-point restraint can cause abdominal solid and hollow organ injuries. This paper reports a case of submarining and factors that exacerbated this phenomenon leading to critical occupant abdominal injury. This case report and the following injury causation analysis demonstrate the shortcomings of a cantilever seat pan design in context to the occupant safety. The inadequate seat pan anti-submarining feature in association with lack of seatbelt load-limiter and Pretensioner reduces the level of occupant protection offered by the seat belt system in the rear seat. This case report shows the dangers of cantilever seat pan design and its association with increased risk of submarining causing severe abdominal injuries. PMID:26985421

  8. Seatbelt submarining injury and its prevention countermeasures: How a cantilever seat pan structure exacerbate submarining

    PubMed Central

    Thorbole, Chandrashekhar K.

    2015-01-01

    The purpose of this study and a case report was to demonstrate seat belt webbing induced injury due to seatbelt submarining during the frontal motor vehicle crash. Submarining is an undesired phenomenon during a frontal crash scenario and is dependent on design features of the seat pan and seatbelt system. The lack of adequate anti-submarining features at any seating position with three-point restraint can cause abdominal solid and hollow organ injuries. This paper reports a case of submarining and factors that exacerbated this phenomenon leading to critical occupant abdominal injury. This case report and the following injury causation analysis demonstrate the shortcomings of a cantilever seat pan design in context to the occupant safety. The inadequate seat pan anti-submarining feature in association with lack of seatbelt load-limiter and Pretensioner reduces the level of occupant protection offered by the seat belt system in the rear seat. This case report shows the dangers of cantilever seat pan design and its association with increased risk of submarining causing severe abdominal injuries. PMID:26985421

  9. Addressing submarine geohazards through scientific drilling

    NASA Astrophysics Data System (ADS)

    Camerlenghi, A.

    2009-04-01

    Natural submarine geohazards (earthquakes, volcanic eruptions, landslides, volcanic island flank collapses) are geological phenomena originating at or below the seafloor leading to a situation of risk for off-shore and on-shore structures and the coastal population. Addressing submarine geohazards means understanding their spatial and temporal variability, the pre-conditioning factors, their triggers, and the physical processes that control their evolution. Such scientific endeavour is nowadays considered by a large sector of the international scientific community as an obligation in order to contribute to the mitigation of the potentially destructive societal effects of submarine geohazards. The study of submarine geohazards requires a multi-disciplinary scientific approach: geohazards must be studied through their geological record; active processes must be monitored; geohazard evolution must be modelled. Ultimately, the information must be used for the assessment of vulnerability, risk analysis, and development of mitigation strategies. In contrast with the terrestrial environment, the oceanic environment is rather hostile to widespread and fast application of high-resolution remote sensing techniques, accessibility for visual inspection, sampling and installation of monitoring stations. Scientific Drilling through the IODP (including the related pre site-survey investigations, sampling, logging and in situ measurements capability, and as a platform for deployment of long term observatories at the surface and down-hole) can be viewed as the centre of gravity of an international, coordinated, multi-disciplinary scientific approach to address submarine geohazards. The IODP Initial Science Plan expiring in 2013 does not address openly geohazards among the program scientific objectives. Hazards are referred to mainly in relation to earthquakes and initiatives towards the understanding of seismogenesis. Notably, the only drilling initiative presently under way is the multi-platform drilling of the Nankai seismogenic zone. Scientific initiatives are flourishing to drive IODP towards the study of submarine geohazards. In the last three years international workshops, were held to address the topic: ESF-ECORD sponsored a Magellan Workshop focussed on submarine landslides (Barcelona, Spain, 2006); IODP sponsored a world-wide Geohazard Workshop (Portland, Oregon, 2007); ESF-ECORD sponsored another Magellan Workshop focussed on Mediterranean submarine geohazards (Luleå, Sweden, 2008). In addition, following the ECORD-Net Conference on the Deep Sea Frontier (Naples, Italy, 2006), the history, monitoring and prediction of geohazards was identified as one of the 6 major areas for a European science plan to integrate Ocean Drilling, Ocean Margin, and Seabed research. More than 200 scientists and private companies representatives have been mobilized world-wide to attend these meetings, from where it emerged that Ocean Drilling will play a key role in the future to answer the following basic open questions on submarine geohazards: - What is the frequency, magnitude, and distribution of geohazard events? - Do precursory phenomena exist and can they be recognized? - What are the physical and mechanical properties of materials prone to failure? - What are the roles of preconditioning vs. triggering in rapid seafloor deformation? - Can the tsunamigenic potential of past and future events be assessed? Within the global-ocean geohazards, worth of note is the attention given in this preparatory phase to submarine geohazards in the Mediterranean basin, a miniature ocean often called a "natural laboratory" because of the diversity of geological environments it contains. The coastline is very densely-populated, totalling 160 million inhabitants sharing 46,000 km of coastline. The Mediterranean is the World's leading holiday destination, receiving an average of 135 million visitors annually. Submarine landslides, volcanic flank collapses, volcanic island eruptions, earthquakes and the associated tsunamis can lead to destruction of seafloor structures potentially capable of releasing hydrocarbon pollutants into Mediterranean waters, and damage to a dense telecommunication cables net that would cause severe economic loss. However, the most devastating effect would be that of earthquake or landslide-induced tsunamis. When compared to other basins, the Mediterranean has larger vulnerability due to its small dimensions, resulting in close proximity to tsunami sources and impact areas. Recent examples include the 1979 Nice airport submarine landslide and tsunami and the 2002 Stromboli volcano landslide and tsunami. Future international scientific drilling must include submarine geohazards among priority scientific objectives. The science advisory structure must be prepared to receive and evaluate proposal specifically addressing submarine geohazards. The implementing organizations need to be prepared for the technological needs of drilling proposals addressing geohazards. Among the most relevant: geotechnical sampling, down-hole logging at shallow depths below the seafloor, in situ geotechnical and physical measurements, capability of deployment of long-term in situ observatories. Pre-site surveys will often aim at the highest possible resolution, three dimensional imaging of the seafloor ant its sub-surface. Drilling for submarine geohazards is seen as an opportunity of multiplatform drilling, and for Mission Specific drilling in particular. Rather than turning the scientific investigation in a purely engineering exercise, proposals addressing submarine geohazards should offer an opportunity to scientists and engineers to work together to unravel the details of basic geological processes that may turn into catastrophic events.

  10. Chemical environments of submarine hydrothermal systems

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such determinations rely on studies of pieces of deep oceanic crust uplifted by tectonic forces such as along the Southwest Indian Ridge, or more complete sections of oceanic crust called ophiolite sequences which are presently exposed on continents owing to tectonic emplacement. Much of what is thought to happen in submarine hydrothermal systems is inferred from studies of ophiolite sequences, and especially from the better-exposed ophiolites in Oman, Cyprus and North America. The focus of much that follows is on a few general features: pressure, temperature, oxidation states, fluid composition and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

  11. Phase 1 Final Report: Titan Submarine

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

    2015-01-01

    The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of liquid methane into the currently predicted predominantly ethane Kraken Mare. During an extended ninety-day mission, it would transit the throat of Kraken (now Seldon Fretum) and perform similar explorations in other areas of Kraken Mare. Once this half year of exploration is completed the submarine could be tasked to revisit points of interest and perhaps do a complete sonar mapping of the seas. All in all, the submarine could explore over 3,000 km (1,864 mi) in its primary mission at an average speed of 0.3 meters per second.

  12. Narrow Angle movie

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This brief three-frame movie of the Moon was made from three Cassini narrow-angle images as the spacecraft passed by the Moon on the way to its closest approach with Earth on August 17, 1999. The purpose of this particular set of images was to calibrate the spectral response of the narrow-angle camera and to test its 'on-chip summing mode' data compression technique in flight. From left to right, they show the Moon in the green, blue and ultraviolet regions of the spectrum in 40, 60 and 80 millisecond exposures, respectively. All three images have been scaled so that the brightness of Crisium basin, the dark circular region in the upper right, is the same in each image. The spatial scale in the blue and ultraviolet images is 1.4 miles per pixel (2.3 kilometers). The original scale in the green image (which was captured in the usual manner and then reduced in size by 2x2 pixel summing within the camera system) was 2.8 miles per pixel (4.6 kilometers). It has been enlarged for display to the same scale as the other two. The imaging data were processed and released by the Cassini Imaging Central Laboratory for Operations (CICLOPS) at the University of Arizona's Lunar and Planetary Laboratory, Tucson, AZ.

    Photo Credit: NASA/JPL/Cassini Imaging Team/University of Arizona

    Cassini, launched in 1997, is a joint mission of NASA, the European Space Agency and Italian Space Agency. The mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

  13. Water/Magma Interaction: Physical considerations for the deep submarine environment

    NASA Astrophysics Data System (ADS)

    Wohletz, Kenneth H.

    One might conclude that in deep submarine environments, where hydrostatic pressure is in excess of water's critical pressure, water/magma interaction does not produce expanding vapor and explosive behavior cannot occur. This conclusion is supported by the apparent paucity of hydroclastic material in samples recovered from deep submarine environments. Analog molten fuel-coolant interaction (MFCI) experiments, however, demonstrate explosive dynamics for conditions where water is pressurized above its critical pressure before interaction; MFCI theory further indicates this explosive potential. Thermodynamic predictions show that the conversion of thermal to mechanical energy is only high enough to support explosive behavior for a narrow range of water/magma mass ratios. In submarine environments, apparent mass ratios are too high for explosive behavior, but effective mass ratios (those determined from the water and magma directly involved during interaction) depend upon characteristic times, determined by the sound speed of the water and interface geometry. At high pressure, a supercritical fluid film grows at the water/magma contact surface and can become unstable. With instability the film oscillates, rapidly expanding and collapsing, with a periodicity of milliseconds or less. Each film collapse imparts kinetic energy into the magma, causing magma fragmentation, especially where quench contraction has weakened the magma. With fragmentation more magma surface area is exposed to water, and the film growth/collapse process escalates. When perturbed by some external pressure wave, the unstable film is prone to a detonation-like phenomenon that causes rapid, localized vapor expansion even at high ambient pressure.

  14. Effects of Wall Heating on Flow Characteristics in a Street Canyon

    NASA Astrophysics Data System (ADS)

    Cai, Xiao-Ming

    2012-03-01

    We develop a large-eddy simulation (LES) model based on a meteorological numerical model for a real scale street-canyon flow with rough building facets heated by a given temperature. The model is applied to a canyon with the aspect ratio of unity for two idealized heating scenarios: (1) the roof and the entire upstream wall are heated, named as `assisting cases', and (2) the roof and the entire downstream wall are heated, named as `opposing cases'. These facets were heated up to 15 K above the air temperature. A wall function for temperature is proposed for a rough facet with an assumption that the thermal roughness length, z 0T, is much smaller than the aerodynamic roughness length, z 0. It is demonstrated that the sensible heat flux and canyon-air temperature are significantly influenced by the near-facet process that is parametrized by z 0T as the primary factor; other processes such as in-canyon mixing and roof-level exchange are secondary. This new finding strongly suggests that it is vital to choose an appropriate value of z 0T in a numerical simulation of street-canyon flows with the facet-air exchange processes of heat or any scalar. The finding also raises an awareness of the demand for carefully designed laboratory or field experiments of quantifying z 0T values for various urban surfaces. For the opposing cases, an unsteady penetrating narrow updraft zone appears occasionally along the heated wall and this feature is consistent field observations. The unique result indicates the superior capability of LES. The results of this study can be used to guide the parametrization of turbulent processes inside the urban canopy layer.

  15. Pollutant Removal, Dispersion and Entrainment over Two-Dimensional Idealized Street Canyons: an LES Approach

    NASA Astrophysics Data System (ADS)

    Wong, C.; Liu, C.

    2010-12-01

    Unlike pollutant transport over flat terrain, the mechanism and plume dispersion over urban areas is not well known. This study is therefore conceived to examine how urban morphology modifies the pollutant transport over urban areas. The computational domain and boundary condition used in this study is shown in Figure 1. The LES shows that inside the street canyon, the ground-level pollutants are carried to roof-level by the re-circulating flow, which are then removed from the street canyon to the UBL. Right above the roof level, narrow high-speed air masses in the streamwise flows and intensive downdrafts have been found in the shear layer. Different from the flows over a smooth surface, the maximum turbulence intensities descend that are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses rapidly over the buildings exhibiting a Gaussian-plume form in the UBL. The mean component of vertical pollutant flux shows that the mean wind contributes to pollutant removal and entrainment simultaneously. Whereas, the fluctuating component demystifies that pollutant removal is mainly governed by atmospheric turbulence. Over the roof level, atmospheric flows slow down rapidly in the wake behind leeward building, suggesting the momentum entrainment into the street canyons. The decelerating streamwise flows in turn lead to upward flows carrying pollutants away from the street canyons, illustrating the basic pollutant removal mechanism in the skimming flow regime. Figure 1: Computational domain and boundary conditions Figure 2: Ensemble average vertical pollutant flux along the roof level. (a). Mean component; (b). turbulent component.

  16. Modelling Aerosol Dispersion in Urban Street Canyons

    NASA Astrophysics Data System (ADS)

    Tay, B. K.; Jones, D. P.; Gallagher, M. W.; McFiggans, G. B.; Watkins, A. P.

    2009-04-01

    Flow patterns within an urban street canyon are influenced by various micrometeorological factors. It also represents an environment where pollutants such as aerosols accumulate to high levels due to high volumes of traffic. As adverse health effects are being attributed to exposure to aerosols, an investigation of the dispersion of aerosols within such environments is of growing importance. In particular, one is concerned with the vertical structure of the aerosol concentration, the ventilation characteristics of the street canyon and the influence of aerosol microphysical processes. Due to the inherent heterogeneity of the aerosol concentrations within the street canyon and the lack of spatial resolution of measurement campaigns, these issues are an on-going debate. Therefore, a modelling tool is required to represent aerosol dispersion patterns to provide insights to results of past measurement campaigns. Computational Fluid Dynamics (CFD) models are able to predict detailed airflow patterns within urban geometries. This capability may be further extended to include aerosol dispersion, by an Euler-Euler multiphase approach. To facilitate the investigation, a two-dimensional, multiphase CFD tool coupled with the k-epsilon turbulence model and with the capability of modelling mixed convection flow regimes arising from both wind driven flows and buoyancy effects from heated walls was developed. Assuming wind blowing perpendicularly to the canyon axis and treating aerosols as a passive scalar, an attempt will be made to assess the sensitivities of aerosol vertical structure and ventilation characteristics to the various flow conditions. Numerical studies were performed using an idealized 10m by 10m canyon to represent a regular canyon and 10m by 5m to represent a deep one. An aerosol emission source was assigned on the centerline of the canyon to represent exhaust emissions. The vertical structure of the aerosols would inform future directives regarding the recommended height for pollutant measurements to represent pedestrian exposure. The vertical structure of aerosols within a street canyon is a topic of constant debate, due to the inability of measurement campaigns to have sufficient spatial resolution to adequately represent the entire vertical structure. Several vertical profiles have been proposed: one where the concentration is the highest at the bottom, decreasing exponentially with increasing height; a homogenous profile across the canyon depth or one with a maximum observed near the road surface. Consistent with previous measurement results, modelling studies found that at the leeward side of the canyon, there was an increase in aerosol concentration up to approximately 2 m in height, followed by a decrease along the height of the canyon. It was also found that the vertical structure of the aerosols would be influenced by the relative contributions of convection and turbulent diffusivities and therefore vary at different locations of the canyon. Using a first-order eddy viscosity turbulence closure, knowledge of the vertical structure of the aerosol concentration would provide insights into the emission velocity structure within the canyon and account for its observed heterogeneity. Investigation of the different factors which influence the ventilation characteristics of the canyon are presented and we show how these facilitate parameterizations into other modelling platforms. Both vertical turbulent flux and flux due to mean flow contribute to the overall ventilation characteristics of a street canyon and these are described. The influence of micro-meteorological factors on the vertical flux of aerosols at the roof level of the street canyon and the relative contributions of flux due to mean flow and turbulent flux at different flow conditions are also investigated. Turbulent flux was found to be of an order of magnitude higher than mean flow flux in isothermal conditions. Therefore, whilst the net effect of turbulent flux is the loss of aerosols to the urban canopy and the net effect of mean flow flux is to re-entrain aerosols into the canyon, the net effect of both factors is a net loss of aerosols. Consistent with previous measurement campaigns, a strong correlation was found between turbulent flux and inflow conditions (wind speed and turbulent intensities). Also, the poorer ventilation characteristic of deep canyons is demonstrated. However, when the contribution of buoyancy to the vertical velocity component of the flow field is considered, it was found that the contribution of mean flow flux to the net flux could surpass that of turbulent flux when buoyancy is important. This implies that both mean flow flux and turbulent flux have to be considered together when buoyancy effects are important to the flow regime considered. The multiphase model was further extended to investigate condensational growth of aerosols within the street canyon due to the presence of organic vapour. Condensational growth is incorporated as a function of the partial pressure of the condensing species and its saturation vapour pressure. The size distribution evolution pattern within the canyon and the sensitivity of aerosol growth to the characteristics of the organic vapour and flow conditions will be discussed.

  17. Grand Canyon Humpback Chub Population Improving

    USGS Publications Warehouse

    Andersen, Matthew E.

    2007-01-01

    The humpback chub (Gila cypha) is a long-lived, freshwater fish found only in the Colorado River Basin. Physical adaptations-large adult body size, large predorsal hump, and small eyes-appear to have helped humpback chub evolve in the historically turbulent Colorado River. A variety of factors, including habitat alterations and the introduction of nonnative fishes, likely prompted the decline of native Colorado River fishes. Declining numbers propelled the humpback chub onto the Federal list of endangered species in 1967, and the species is today protected under the Endangered Species Act of 1973. Only six populations of humpback chub are currently known to exist, five in the Colorado River Basin above Lees Ferry, Ariz., and one in Grand Canyon, Ariz. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center oversees monitoring and research activities for the Grand Canyon population under the auspices of the Glen Canyon Dam Adaptive Management Program (GCDAMP). Analysis of data collected through 2006 suggests that the number of adult (age 4+ years) humpback chub in Grand Canyon increased to approximately 6,000 fish in 2006, following an approximate 40-50 percent decline between 1989 and 2001. Increasing numbers of adult fish appear to be the result of steadily increasing numbers of juvenile fish reaching adulthood beginning in the mid- to late-1990s and continuing through at least 2002.

  18. Storm-triggered mass failure and sediment liquefaction in the Swatch of No Ground canyon, offshore Bangladesh

    NASA Astrophysics Data System (ADS)

    Goodbred, S. L.; Rogers, K. G.; Khan, S. R.; Ullah, M. S.; Mondal, D. R.

    2008-12-01

    In November 2007 the eye of a major tropical storm, Cyclone Sidr, tracked over the offshore canyon associated with the Ganges-Brahmaputra river delta. Known as the Swatch of No Ground (SoNG), this large canyon incises within 30 km of the deltaic coast and is accreting rapidly (10 to >50 cm/yr) with fluvially derived sediments. Historically numerous tropical storms have affected the northern Bay of Bengal each year, but more recently cyclogenesis has been weak and Sidr is the first major cyclone to impact the Bengal shelf since 1991. As part of an ongoing study, our research team had just completed a high-resolution sub- bottom sonar (chirp) survey of the SoNG canyon head six months prior to Cyclone Sidr. Following the storm, we organized a second sub-bottom survey to assess the storm's impact on canyon morphology and sedimentation patterns. A comparison of our pre- and post-storm surveys reveal dramatic mass failures around the canyon wall, but also vast areas that were largely unaffected. Among the failures, many had dimensions 10s of meters thick and >1 km wide. These large-scale failures appear to have been preferentially located where there is pre-storm evidence for fluid escape, perhaps via submarine groundwater discharge through onshore sandy delta complex. Fluid chimneys, apparently gas charged, are also associated with many of the large failures. However, many locations with prominent shallow gas show no disruption after the storm, suggesting that zones prone to major failure are associated fluid flow. Other areas of the canyon show storm-induced liquefaction of surface sediments (<5 m below seabed) and resulting mudflows. Runout distances are only a few hundred meters, though, suggesting rapid consolidation of the flows even on sloping surfaces (1-3). As interesting as these storm-related failures are the actively accreting, steep-walled (>5) gullies that show no apparent effect of the storm. Overall it appears that areas of the canyon most susceptible to failure are not necessarily the steepest or most rapidly accreting, but rather those associated with subsurface fluid flow and planes of weakness along escape structures.

  19. 43. and Design, Grand Canyon National Park, dated August 23, ...

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

    43. and Design, Grand Canyon National Park, dated August 23, 1934, and September 17, 1934 (original located at Federal Records Center, Denver, Colorado, #113/3084-set of 2) SEWAGE PLANT ADDITION. - Water Reclamation Plant, Grand Canyon, Coconino County, AZ

  20. Overview of the Colorado River Canyon from the helicopter pad. ...

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

    Overview of the Colorado River Canyon from the helicopter pad. View of the Nevada side where new bridge will cross canyon, view northwest - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

  1. NFC - Narrow Field Camera

    NASA Astrophysics Data System (ADS)

    Koukal, J.; Srba, J.; Gorková, S.

    2015-01-01

    We have been introducing a low-cost CCTV video system for faint meteor monitoring and here we describe the first results from 5 months of two-station operations. Our system called NFC (Narrow Field Camera) with a meteor limiting magnitude around +6.5mag allows research on trajectories of less massive meteoroids within individual parent meteor showers and the sporadic background. At present 4 stations (2 pairs with coordinated fields of view) of NFC system are operated in the frame of CEMeNt (Central European Meteor Network). The heart of each NFC station is a sensitive CCTV camera Watec 902 H2 and a fast cinematographic lens Meopta Meostigmat 1/50 - 52.5 mm (50 mm focal length and fixed aperture f/1.0). In this paper we present the first results based on 1595 individual meteors, 368 of which were recorded from two stations simultaneously. This data set allows the first empirical verification of theoretical assumptions for NFC system capabilities (stellar and meteor magnitude limit, meteor apparent brightness distribution and accuracy of single station measurements) and the first low mass meteoroid trajectory calculations. Our experimental data clearly showed the capabilities of the proposed system for low mass meteor registration and for calculations based on NFC data to lead to a significant refinement in the orbital elements for low mass meteoroids.

  2. [Functional status of submariners after short-time submarine raid in the sea].

    PubMed

    Kalmanov, A S; Pisarev, A A; Khankevich, Yu R; Bloshchinskii, I A; Valskii, A V

    2015-10-01

    Short-time sea submarine raids (from a few days to a few weeks), performed during one working cycle, negatively influence on the functional state of the submariners organism. Upon returning to the point of basing the crew involved in the maintenance of the material and performs preparations for further access to the sea. Due to the high workload and lack of time personnel are not held in any correctional and rehabilitation activities, and therefore the time for the next release in the sea functional condition and functional reserves of the body does not have time to fully recover. The transfer of the submarine crew and referral to medical and psychological rehabilitation assumed only after the end of the operating cycle after the crew the task of further voyage. Based on the assessment of the functional systems of the submarine after a short voyage concluded on the need to develop a set of remedial measures for the recovery of submarine crews during inter-cruise period. PMID:26827506

  3. Voluminous submarine lava flows from Hawaiian volcanoes

    SciTech Connect

    Holcomb, R.T.; Moore, J.G.; Lipman, P.W.; Belderson, R.H.

    1988-05-01

    The GLORIA long-range sonar imaging system has revealed fields of large lava flows in the Hawaiian Trough east and south of Hawaii in water as deep as 5.5 km. Flows in the most extensive field (110 km long) have erupted from the deep submarine segment of Kilauea's east rift zone. Other flows have been erupted from Loihi and Mauna Loa. This discovery confirms a suspicion, long held from subaerial studies, that voluminous submarine flows are erupted from Hawaiian volcanoes, and it supports an inference that summit calderas repeatedly collapse and fill at intervals of centuries to millenia owing to voluminous eruptions. These extensive flows differ greatly in form from pillow lavas found previously along shallower segments of the rift zones; therefore, revision of concepts of volcano stratigraphy and structure may be required.

  4. Submarine paleoseismology based on turbidite records.

    PubMed

    Goldfinger, Chris

    2011-01-01

    Many of the largest earthquakes are generated at subduction zones or other plate boundary fault systems near enough to the coast that marine environments may record evidence of them. During and shortly after large earthquakes in the coastal and marine environments, a spectrum of evidence may be left behind, mirroring onshore paleoseismic evidence. Shaking or displacement of the seafloor can trigger processes such as turbidity currents, submarine landslides, tsunami (which may be recorded both onshore and offshore), and soft-sediment deformation. Marine sites may also share evidence of fault scarps, colluvial wedges, offset features, and liquefaction or fluid expulsion with their onshore counterparts. This article reviews the use of submarine turbidite deposits for paleoseismology, focuses on the dating and correlation techniques used to establish stratigraphic continuity of marine deposits, and outlines criteria for distinguishing earthquake deposits and the strategies used to acquire suitable samples and data for marine paleoseismology. PMID:21329198

  5. Influence of Anchoring on Burial Depth of Submarine Pipelines.

    PubMed

    Zhuang, Yuan; Li, Yang; Su, Wei

    2016-01-01

    Since the beginning of the twenty-first century, there has been widespread construction of submarine oil-gas transmission pipelines due to an increase in offshore oil exploration. Vessel anchoring operations are causing more damage to submarine pipelines due to shipping transportation also increasing. Therefore, it is essential that the influence of anchoring on the required burial depth of submarine pipelines is determined. In this paper, mathematical models for ordinary anchoring and emergency anchoring have been established to derive an anchor impact energy equation for each condition. The required effective burial depth for submarine pipelines has then been calculated via an energy absorption equation for the protection layer covering the submarine pipelines. Finally, the results of the model calculation have been verified by accident case analysis, and the impact of the anchoring height, anchoring water depth and the anchor weight on the required burial depth of submarine pipelines has been further analyzed. PMID:27166952

  6. Prevalence of Helicobacter pylori in United States Navy submarine crews.

    PubMed

    Jackman, R P; Schlichting, C; Carr, W; Dubois, A

    2006-06-01

    Helicobacter pylori prevalence is elevated in German submarine crews and in United States Navy (USN) surface fleet personnel, but H. pylori prevalence in USN submariners was unknown. The goal of the study was to determine the prevalence of H. pylori in the crews of USN nuclear submarines compared to other military personnel and to the general US population. The presence of H. pylori IgG antibodies was determined in serum samples using a commercial ELISA. Only 47 out of 451 submariners (9.4%) were H. pylori positive, which is similar to that of the US general population with a similar level of education. In contrast, H. pylori prevalence is significantly higher in US Army recruits (26%), USN surface fleet personnel (25%), and German diesel submariners (38%). These data demonstrate that submarine service (and by inference activity requiring isolation and close contact, per se) is not a risk factor for H. pylori infection. PMID:16194289

  7. Influence of Anchoring on Burial Depth of Submarine Pipelines

    PubMed Central

    Zhuang, Yuan; Li, Yang; Su, Wei

    2016-01-01

    Since the beginning of the twenty-first century, there has been widespread construction of submarine oil-gas transmission pipelines due to an increase in offshore oil exploration. Vessel anchoring operations are causing more damage to submarine pipelines due to shipping transportation also increasing. Therefore, it is essential that the influence of anchoring on the required burial depth of submarine pipelines is determined. In this paper, mathematical models for ordinary anchoring and emergency anchoring have been established to derive an anchor impact energy equation for each condition. The required effective burial depth for submarine pipelines has then been calculated via an energy absorption equation for the protection layer covering the submarine pipelines. Finally, the results of the model calculation have been verified by accident case analysis, and the impact of the anchoring height, anchoring water depth and the anchor weight on the required burial depth of submarine pipelines has been further analyzed. PMID:27166952

  8. 7. DARK CANYON SIPHON Photographic copy of construction drawing ...

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

    7. DARK CANYON SIPHON - Photographic copy of construction drawing c1907 (from Record Group 115, Box 17, Denver Branch of the National Archives, Denver) DARK CANYON SIPHON PLAN, ELEVATION, AND SECTIONS - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

  9. 5. DARK CANYON SIPHON Photographic copy of historic photo, ...

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

    5. DARK CANYON SIPHON - Photographic copy of historic photo, November 11, 1906 (original print located at the Carlsbad Irrigation District offices, Carlsbad, New Mexico) photographer unknown 'LOWER END OF DARK CANYON SIPHON CONSTRUCTION' - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

  10. 6. DARK CANYON SIPHON Photographic copy of historic photo, ...

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

    6. DARK CANYON SIPHON - Photographic copy of historic photo, January 29, 1907 (original print filed in Record Group 115, National Archives, Washington, D.C.) W.J.Lubken, photographer 'RIPRAP AT THE ENTRANCE END OF DARK CANYON PRESSURE PIPE' - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

  11. 27 CFR 9.152 - Malibu-Newton Canyon.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Malibu-Newton Canyon. 9... Malibu-Newton Canyon. (a) Name. The name of the viticultural area described in this petition is “Malibu-Newton Canyon.” (b) Approved maps. The appropriate map for determining the boundary of the...

  12. 27 CFR 9.152 - Malibu-Newton Canyon.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Malibu-Newton Canyon. 9... Malibu-Newton Canyon. (a) Name. The name of the viticultural area described in this petition is “Malibu-Newton Canyon.” (b) Approved maps. The appropriate map for determining the boundary of the...

  13. 27 CFR 9.152 - Malibu-Newton Canyon.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Malibu-Newton Canyon. 9... Malibu-Newton Canyon. (a) Name. The name of the viticultural area described in this petition is “Malibu-Newton Canyon.” (b) Approved maps. The appropriate map for determining the boundary of the...

  14. 77 FR 43117 - Glen Canyon Dam Adaptive Management Work Group

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-23

    ... Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation, Interior. ACTION: Notice of public meeting. SUMMARY: The Glen Canyon Dam Adaptive Management Work Group... other management actions to protect resources downstream of Glen Canyon Dam, consistent with the...

  15. 77 FR 22801 - Glen Canyon Dam Adaptive Management Work Group

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-17

    ... Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation... Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning Glen Canyon Dam operations and other management actions to protect resources downstream of Glen Canyon...

  16. 27 CFR 9.152 - Malibu-Newton Canyon.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Malibu-Newton Canyon. 9... Malibu-Newton Canyon. (a) Name. The name of the viticultural area described in this petition is “Malibu-Newton Canyon.” (b) Approved maps. The appropriate map for determining the boundary of the...

  17. 27 CFR 9.152 - Malibu-Newton Canyon.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Malibu-Newton Canyon. 9... Malibu-Newton Canyon. (a) Name. The name of the viticultural area described in this petition is “Malibu-Newton Canyon.” (b) Approved maps. The appropriate map for determining the boundary of the...

  18. 78 FR 7810 - Glen Canyon Dam Adaptive Management Work Group

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    ... Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation, Interior. ACTION: Notice of public meeting. SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning Glen Canyon Dam operations...

  19. 76 FR 24516 - Glen Canyon Dam Adaptive Management Work Group

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-02

    ... Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation, Interior. ACTION: Notice of public meeting. SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning Glen Canyon Dam operations...

  20. 77 FR 9265 - Glen Canyon Dam Adaptive Management Work Group

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-16

    ... Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation, Interior. ACTION: Notice of public meeting. SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG) makes recommendations to the Secretary of the Interior concerning Glen Canyon Dam operations...

  1. 36 CFR 7.4 - Grand Canyon National Park.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Grand Canyon National Park. 7... SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial... motor vehicles to Grand Canyon National Park contained in § 5.4 of this chapter shall be subject to...

  2. 27 CFR 9.217 - Happy Canyon of Santa Barbara.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Happy Canyon of Santa... Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of the viticultural area described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of this chapter, “Happy...

  3. 27 CFR 9.217 - Happy Canyon of Santa Barbara.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Happy Canyon of Santa... Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of the viticultural area described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of this chapter, “Happy...

  4. 27 CFR 9.217 - Happy Canyon of Santa Barbara.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Happy Canyon of Santa... Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name. The name of the viticultural area described in this section is “Happy Canyon of Santa Barbara”. For purposes of part 4 of this chapter, “Happy...

  5. Metazoan meiofauna in deep-sea canyons and adjacent open slopes: A large-scale comparison with focus on the rare taxa

    NASA Astrophysics Data System (ADS)

    Bianchelli, S.; Gambi, C.; Zeppilli, D.; Danovaro, R.

    2010-03-01

    Metazoan meiofaunal abundance, total biomass, nematode size and the richness of taxa were investigated along bathymetric gradients (from the shelf break down to ca. 5000-m depth) in six submarine canyons and on five adjacent open slopes of three deep-sea regions. The investigated areas were distributed along >2500 km, on the Portuguese to the Catalan and South Adriatic margins. The Portuguese and Catalan margins displayed the highest abundances, biomass and richness of taxa, while the lowest values were observed in the Central Mediterranean Sea. The comparison between canyons and the nearby open slopes showed the lack of significant differences in terms of meiofaunal abundance and biomass at any sampling depth. In most canyons and on most slopes, meiofaunal variables did not display consistent bathymetric patterns. Conversely, we found that the different topographic features were apparently responsible for significant differences in the abundance and distribution of the rare meiofaunal taxa (i.e. taxa accounting for <1% of total meiofaunal abundance). Several taxa belonging to the temporary meiofauna, such as larvae/juveniles of Priapulida, Holothuroidea, Ascidiacea and Cnidaria, were encountered exclusively on open slopes, while others (including the Tanaidacea and Echinodea larvae) were found exclusively in canyons sediments. Results reported here indicate that, at large spatial scales, differences in deep-sea meiofaunal abundance and biomass are not only controlled by the available food sources, but also by the region or habitat specific topographic features, which apparently play a key role in the distribution of rare benthic taxa.

  6. Surface Composition Differences in Martian Canyon

    NASA Technical Reports Server (NTRS)

    2003-01-01

    (Released 29 May 2002) Color differences in this daytime infrared image taken by the camera on NASA's Mars Odyssey spacecraft represent differences in the mineral composition of the rocks, sediments and dust on the surface. The image shows a portion of a canyon named Candor Chasma within the great Valles Marineris system of canyons, at approximately 5 degrees south latitude, 285 degrees east (75 degrees west) longitude. The area shown is approximately 30 by 175 kilometers (19 by 110 miles). The image combines exposures taken by Odyssey's thermal emission imaging system at three different wavelengths of infrared light: 6.3 microns, 7.4 microns and 8.7 microns.

  7. HELLS CANYON STUDY AREA, OREGON AND IDAHO.

    USGS Publications Warehouse

    Simmons, George C.; Close, Terry J.

    1984-01-01

    The Hells Canyon study area occupies nearly 950 sq mi along and near Hells Canyon of the Snake River in northeast Oregon and west-central Idaho. Geologic, geochemical, aeromagnetic, and mine and prospect investigations to determine the mineral-resource potential of the area were carried out. As a result, 42 sq mi or about 4 percent of the lands, in 21 separate areas, were classified as having probable or substantiated resource potential for base and precious metals, molybdenum, and tungsten. No energy resource potential was identified in this study.

  8. Hydrothermal mineralization along submarine rift zones, Hawaii

    USGS Publications Warehouse

    Hein, J.R.; Gibbs, A.E.; Clague, D.A.; Torresan, M.

    1996-01-01

    Describes mineralization of midplate submarine rift zones and hydrothermal manganese oxide mineralization of midplate volcanic edifices. Hydrothermal Mn oxides were recovered from submarine extensions of two Hawaiian rift zones, along Haleakala and Puna Ridges. These Mn oxides form two types of deposits, metallic stratiform layers in volcaniclastic rocks and cement for clastic rocks; both deposit types are composed of todorokite and birnessite. Unlike most other hydrothermal Mn oxide deposits, those from Hawaiian rift zones are enriched in the trace metals Zn, Co, Ba, Mo, Sr, V, and especially Ni. Metals are derived from three sources: mafic and ultramafic rocks leached by circulating hydrothermal fluids, clastic material (in Mn-cemented sandstone), and seawater that mixed with the hydrothermal fluids. Precipitation of Mn oxide below the seafloor is indicated by its occurrence as cement, growth textures that show mineralizing fluids were introduced from below, and pervasive replacement of original matrix of clastic rocks.Hydrothermal Mn oxides were recovered from submarine extensions of two Hawaiian rift zones, along Haleakala and Puna Ridges. These Mn oxides form two types of deposits, metallic stratiform layers in volcaniclastic rocks and cement for clastic rocks. Both deposit types are composed of todorokite and birnessite. This article describes in detail the specific characteristics of these Mn oxides.

  9. The submarine service of the future?

    PubMed

    Bland, S A

    2000-01-01

    Space missions, although now routine, are unique in terms of their environment and logistical requirements. The number of missions (man-hours) remains relatively small and planning still relies on comparisons with analogous missions, including submarine operations. Antarctic missions, which tend not to be classified, have provided more information about isolated communities because of the number of personnel per base. Space medicine has traditionally been an extension of aviation medicine with high g-forces involved in the transition from Earth to orbit and astronauts such as Neil Armstrong recruited from the test pilot fraternity. As the length of a mission increases and the space habitation relies more on regenerative systems, the environment becomes more analogous with today's nuclear submarines. As well as the air purification implications, radiation still is a significant hazard with even greater impact on future Mars missions requiring the provision of health physics monitoring, advice and countermeasures well established in the submarine flotilla. Nevertheless, the specialty space medicine will progress as a specialty in its own right, pooling expertise from other specialties such as aviation, radiation, emergency and occupational medicine taking human exploration beyond the confines of land and sea. PMID:11346925

  10. Depositional environments of late glacial to Holocene sediments on the deep water levees of Setúbal and Nazaré Canyons, offshore Portugal: preliminary results

    NASA Astrophysics Data System (ADS)

    Pascoletti, F. C.; Masson, D.; Innocenti, C.

    2010-12-01

    The west Iberian margin is indented by a network of submarine canyons that create rugged seafloor morphology and act as major pathways for the transport of sediment from land to the abyssal plains. The Setúbal and Nazaré Canyons are part of this complex environment and strongly influence sediment distribution, capturing sediments from the Tagus River and the littoral cell transport respectively. Deep submarine sedimentary sequences thus reflect changes in sediment input and depositional environments. The high-resolution sedimentological study here presented was applied in four cores of the deep water levees of Nazaré and Setúbal Canyons in order to explore how sediment input to the canyons changed during the last glacial - interglacial transition, and how this reflects changing environmental conditions on land. By means of non-destructive corelogger measurements and analyses of spectral signatures, geochemical compositions and colour variations, it was possible to identify ice-rafted debris (IRD) deposits, to characterize hemipelagic and turbidite layers and to investigate terrestrial-derived sediments input variation during the last 26 ka. Preliminary results from the sedimentological and turbidite frequency analyses show that highest turbidite occurrence is recorded during the glacial stage, confirming that the generation of turbidity flows in submarine canyons is tightly related to low sea-level stands. We found that major peaks in frequency and thickness of turbidite deposits in the deep Portuguese margin are mainly coeval with abrupt climatic (H2 and 1) and sea-level changes (~ 19 and ~ 23 ka BP), as a consequence of which a major amount of continentally-derived material was transported into the deep sea. During the Holocene, the inception of sea-level rises, independent of their magnitude, has been found to be sufficient to generate turbidity currents, particularly in the Nazaré system. Moreover, a multiple regression analysis was attempted in order to estimate the sediment carbonate content from VIS reflectance spectrophotometry data acquired with a Konica Minolta spectrophotometer (39 bands, wavelength range from 360 nm to 740 nm). The equation obtained for recent mostly hemipelagic sediments, has an adjusted coefficient of determination of 0.97 and a root main squared error (RMSE) of ± 4.02 %, indicating a very good correspondence between analytically determined percent calcium carbonate and reflectance-based calcium carbonate estimates. However the spectral technique failed on deeper and older core sections, characterized by a general higher variability in sediment components, including a major terrestrial input and carbonate from a variety of biogenic and nonbiogenic sources.

  11. 50. PIPING FOR SUBMARINE SECTION, Y&D No. 107728 Scale 3/8' ...

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

    50. PIPING FOR SUBMARINE SECTION, Y&D No. 107728 Scale 3/8' = 1'; August 26, 1929 - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  12. 16. INTERIOR VIEW OF SUBMARINE SECTION AT 110FOOT LEVEL, ESCAPE ...

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

    16. INTERIOR VIEW OF SUBMARINE SECTION AT 110-FOOT LEVEL, ESCAPE TRAINING TANK, SHOWING LADDER TO ESCAPE TANK, LOOKING SOUTH - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  13. Morphology of Neptune Node Sites, Barkley Canyon, Cascadia Margin

    NASA Astrophysics Data System (ADS)

    Lundsten, E. M.; Anderson, K.; Paull, C. K.; Caress, D. W.; Thomas, H. J.; Riedel, M.

    2014-12-01

    High-resolution multibeam bathymetry and chirp seismic reflection profiles collected with MBARI's mapping autonomous underwater vehicle reveal the fine-scale morphology and shallow seafloor structure of the flanks and floor of Barkley Canyon on the Cascadia continental margin off British Columbia. The surveys characterize the environment surrounding three nodes on the Neptune Canada cabled observatory located within the canyon. The canyon floor between 960 and 1020 m water depth lacks channeling and contains ≥ 24 m of acoustically uniform sediment fill, which is ponded between the canyon's steep sidewalls. The fill overlies a strong reflector that outlines an earlier, now buried, canyon floor channel system. Debris flow tongues contain meter scale blocks sticking-up through the fill. Apparently the present geomorphology surrounding the Canyon Axis node in 985 m is attributable to local debris flows, rather than organized down canyon processes. In the survey area the canyon sidewalls extend ~300 m up and in places the slope of the canyons sides exceed 40°. Both the Hydrate node in 870 m water depths and the Mid-Canyon node at 890 m are located on a headland that forms intermediate depth terraces on the canyon's western flank. While the seafloor immediately surrounding the Mid-canyon node is smooth, the Hydrate node is marked by 10 circular mounds up to 2 m high and 10 m in diameter, presumable associated with hydrate formation. Although wedges of sediment drape occur in places on the canyon sides, the chirp profiles show no detectible sediment drape at either node site and suggest these nodes are situated on older, presumably pre-Quaternary strata. The lack of reflectors in the chirp profiles indicates most of the canyon's sidewalls are largely sediment-bare. Lineations in the bathymetry mark the exposed edges of truncated beds. Rough, apparently fresh textures, within slide scarps show the importance of erosion on the development of the canyon flanks.

  14. Geohydrology of White Rock Canyon of the Rio Grande from Otowi to Frijoles Canyon

    SciTech Connect

    Purtymun, W.D.; Peters, R.J.; Owens, J.W.

    1980-12-01

    Twenty-seven springs discharge from the Totavi Lentil and Tesuque Formation in White Rock Canyon. Water generally acquires its chemical characteristics from rock units that comprise the spring aquifer. Twenty-two of the springs are separated into three groups of similar aquifer-related chemical quality. The five remaining springs make up a fourth group with a chemical quality that differs due to localized conditions in the aquifer. Localized conditions may be related to recharge or discharge in or near basalt intrusion or through faults. Streams from Pajarito, Ancho, and Frijoles Canyons discharge into the Rio Grande in White Rock Canyon. The base flow in the streams is from springs. Sanitary effluent in Mortandad Canyon from the treatment plant at White Rock also reaches the Rio Grande.

  15. A Submarine Perspective on Hawaiian Volcanoes

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Moore, J. G.

    2011-12-01

    Postwar improvements in navigation, sonar-based mapping, and submarine photography enabled the development of bathymetric maps, which revealed submarine morphologic features that could be dredged or explored and sampled with a new generation of manned and unmanned submersibles. The maps revealed debris fields from giant landslides, the great extent of rift zones radiating from volcanic centers, and two previously unknown submarine volcanoes named Mahukona and Loihi, the youngest Hawaiian volcano. About 70 major landslides cover half the flanks of the Hawaiian Ridge out to Midway Island. Some of the landslides attain lengths of 200 km and have volumes exceeding 5,000 km3. More recent higher resolution bathymetry and sidescan data reveal that many submarine eruptions construct circular, flat-topped, monogenetic cones; that large fields of young strongly alkalic lava flows, such as the North Arch and South Arch lava fields, erupt on the seafloor within several hundred km of the islands; and that alkalic lavas erupt during the shield stage on Kilauea and Mauna Loa. The North Arch flow field covers about 24,000 km2, has an estimated volume between about 1000 and 1250 km3, has flows as long as 108 km, and erupted from over 100 vents. The source and melting mechanisms for their production is still debated. The maps also displayed stair-step terraces, mostly constructed of drowned coral reefs, which form during early rapid subsidence of the volcanoes during periods of oscillating sea level. The combination of scuba and underwater photography facilitated the first motion pictures of the mechanism of formation of pillow lava in shallow water offshore Kilauea. The age progression known from the main islands was extended westward along the Hawaiian Ridge past Midway Island, around a bend in the chain and northward along the Emperor Seamounts. Radiometric dating of dredged samples from these submarine volcanoes show that the magma source that built the chain has been active for over 80 Ma and established the remarkable linearity of the age-progression along the chain. Glass rinds on submarine lava quenched at depth contain initial magmatic volatiles and yield data on the juvenile water, sulfur, CO2, and rare gas contents of basaltic magmas, and continue to reveal nuances of the volatile contents of lava. Rock sampling at Loihi Seamount led to the discovery of the pre-shield alkalic phase of Hawaiian volcanism, which mirrors the well-known post-shield alkalic phase. Lava compositions from the Hawaiian Ridge and Emperor Seamounts have clear affinities to present-day Hawaiian lavas, but subtle source differences as well. The progression from small to large and back to small degrees of melting at individual volcanoes and the compositional changes along the chain constrain the melting processes and source compositions of Hawaiian volcanism. Coupling the age of lavas with that of submerged coral reefs has provided data on the growth and subsidence of volcanic centers. This information has meshed nicely with the age, composition, and morphology of lavas from the 3.2-km-deep Hawaiian Scientific Drill Hole. Submarine studies have taught us much about the workings of Hawaiian Volcanoes, and in the process have stimulated new work and concepts on marine volcanism worldwide.

  16. The origin of Messinian canyons in the Mediterranean: the role of brine-related dense shelf water cascading currents

    NASA Astrophysics Data System (ADS)

    Roveri, Marco; Bergamasco, Andrea; Marcello Falcieri, Francesco; Gennari, Rocco; Lugli, Stefano; Manzi, Vinicio; Schreiber, B. Charlotte

    2013-04-01

    Recent studies on modern deep-sea environments have documented the role of submarine processes, such as turbidity currents, fluvial flood-related hyperpycnal flows and dense shelf water cascading (DSWC), in the genesis and evolution of canyons and gullies. These processes are largely independent from sea-level fluctuations and significant erosion has been shown to occur even at present-day sea-level highstand conditions. The study of ancient deep-marine environments and processes may take great advantage from the knowledge produced during the last decade in this field of research. The study of some exceptional events of the past is an exciting issue for a common effort of specialists from different disciplines (geomorphology, geology, physical oceanography) in the understanding of modern and ancient deep seascape. An example is provided by the genesis of the widespread Messinian erosional surface (MES) and the associated gullies and canyons, which have been recognized through seismic data along the Mediterranean shelves and slopes. These features are commonly related to subaerial fluvial processes that imply a 1500 m drawdown and the desiccation of the Mediterranean Sea during what has been called the "Messinian salinity crisis" (MSC). Such an interpretation is one of the main arguments for the shallow-water deep-basin model (Hsü et al., 1973), which is the current paradigm for the MSC. However, no unquestionable evidence for subaerial deposits associated with the MES has been ever documented. We suggest that fully submarine erosional processes played a significant role in shaping the Mediterranean slopes also during the MSC; thus, no desiccation is needed to explain canyon formation and/or rejuvenation. We want to stress here the importance of the processes, driven by evaporative fluxes in shallow areas, that lead to the formation of seasonal high-density contrasts and cause the development of cascading along the continental slopes (Shapiro et al., 2003). These processes are active today in the Mediterranean margins where they produce large-scale erosional features within canyons (Canals et al., 2006; Palanques et al., 2012). On the basis of modelling of cascading events that recently occurred in the Gulf of Lions, we performed numerical simulations of Messinian brine-related cascading currents at different water density contrasts. Our results show that the activation of downslope flow of hypersaline dense waters may well account for both significant slope erosion and progressive salinity rise leading to the accumulation of deep-seated supersaturated brines. These findings support a "deep-water deep-basin" model thus implying that the evaporite deposition occurred in a non-desiccated basin with strongly reduced connections with the global ocean. References Canals M. et al., 2006. Flushing submarine canyons, Nature, 444, 354-357. Hsü K.J., Ryan W.B.F. and Cita M.B., 1973 Late Miocene desiccation of the Mediterranean. Nature, 242, 240-244. Palanques A. et al., 2012. Sediment transport to the deep canyons and open-slope of the western Gulf of Lyon during 2006 intense cascading and open-sea convection period, Progress in Oceanography, 106, 1-15. Shapiro G.I., Huthnance J.M. and Ivanov V.V., 2003 Dense water cascading off the continental shelf, J. Geophys. Res., 108, 3390.

  17. Secondary Circulation in Sinuous Submarine Channels: First Results from the Black Sea

    NASA Astrophysics Data System (ADS)

    Peakall, J.; Parsons, D. R.; Hiscott, R. N.; Aksu, A. E.; Flood, R. D.; Mouland, D.

    2009-05-01

    Sinuous submarine channels are important features on ocean floors, and are key conduits for sediment, carbon and other nutrients into the deep-sea. Their gross planform similarity to river channels has long led to comparison with their subaerial meandering river counterparts. However, they are formed by the action of gravity flows and therefore might be expected to exhibit different processes from the open-channel, single phase flows of river channels. Changes in their morphology and deposits have been observed, however, little is known about the flow processes that occur in these channels. The best available data from modern systems have been limited to single at a point downstream velocity profiles; the best of these being from submarine canyons rather than channels. In order to understand flow dynamics and how they relate to channel processes, sedimentary dynamics and channel evolution, more detailed 2D and 3D flow data is required. Here we report the first such data from a sinuous channel on the Black Sea shelf, and examine the nature of secondary circulation in submarine channels. River channels have long been known to exhibit a three-dimensional helical flow comprising both a dominant downstream component, and a secondary (cross-stream) flow. Such secondary flows are the result of centrifugal acceleration induced by bend curvature, and an inwardly directed radial pressure gradient, which results from a super-elevation of the water surface at the outside of the bend. In river bend apices these secondary flows are directed towards the inner bend at the base of the flow, and towards the outer bank at the top of the flow. Until very recently, it was assumed that submarine channels showed a similar distribution. However, theoretical analysis of the governing equations for river channels, with the incorporation of an appropriate downstream velocity distribution for gravity currents, indicated that submarine channels could display reversed secondary circulation orientation with respect to meandering rivers (Corney et al. 2006, 2008). This theory was backed up by an extensive physical modeling program that also showed reversed secondary circulation in all cases (Keevil et al., 2006, 2007). Other experiments though have shown examples of secondary circulation similar to river channels, and there has been intense debate on the validity of different approaches and datasets. Immediately north of the exit of the Bosphorus Strait, north of Istanbul there is a spectacular sinuous channel network on the Black Sea shelf. This channel network is created by the higher density of seawater of Mediterranean origin as it flows into the much lower salinity Black Sea. The near-constant gravity currents that run through these channels provide the perfect laboratory for studying the detailed fluid dynamics of submarine channel flows. Here we report results from the apex of a major sinuous channel bend that is 20-30 m deep. An acoustic Doppler current profiler (ADCP) towed across the bend recorded a maximum velocity of ~1 m/s. There, the saline underflow is density-stratified, exhibits marked outer-bank super-elevation, and the sense of secondary flow is opposite to that in rivers. Future 3D flow monitoring will use the British autonomous vehicle AutoSub3.

  18. Bryce Canyon and Grand Staircase-Escalante

    In the foreground are sandstone hoodoos and in the background is the Grand Staircase-Escalante National Monument, which is managed by the Bureau of Land Management. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars...

  19. Grand Canyon, Lake Powell, and Lake Mead

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A snowfall in the American West provides contrast to the landscape's muted earth tones and indicates changes in topography and elevation across (clockwise from top left) Nevada, Utah, Colorado, New Mexico, Arizona, and California. In Utah, the southern ranges of the Wasatch Mountains are covered in snow, and the Colorado River etches a dark ribbon across the red rock of the Colorado Plateau. In the center of the image is the reservoir created by the Glen Canyon Dam. To the east are the gray-colored slopes of Navaho Mountain, and to the southeast, dusted with snow is the region called Black Mesa. Southwest of Glen Canyon, the Colorado enters the Grand Canyon, which cuts westward through Arizona. At a deep bend in the river, the higher elevations of the Keibab Plateau have held onto snow. At the end of the Grand Canyon lies another large reservoir, Lake Mead, which is formed by the Hoover Dam. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  20. Sandbar growth Grand Canyon following controlled flood

    Picture showing the increased size of the sandbar after the November 2012 controlled flood from the Glen Canyon Dam. This location is 65 miles downstream from Lees Ferry and the view is looking downstream. These and additional photographs depicting the results of the recent controlled floods can be ...

  1. The Colorado River in the Grand Canyon.

    ERIC Educational Resources Information Center

    Speece, Susan

    1991-01-01

    An assessment of the water quality of the Colorado River in the Grand Canyon was made, using the following parameters: dissolved oxygen, water temperature, hydrogen ion concentration, total dissolved solids, turbidity, and ammonium/nitrogen levels. These parameters were used to provide some clue as to the "wellness" and stability of the aquatic…

  2. Navajo generating plant and Grand Canyon haze

    SciTech Connect

    Norris, J.E.

    1991-01-15

    This article examines the question of whether the Navajo generating plant pollution is contributing to pollution of the air in the Grand Canyon region. The topics include the regulatory context of the plant, the experiment known as the Winter Haze Intensive Tracer Experiment (WHITEX), the National Research Council evaluation of the WHITEX, and The Navajo Generating Station Visibility Study.

  3. Map Your Way to the Grand Canyon

    ERIC Educational Resources Information Center

    Yoder, Holly

    2005-01-01

    In the introductory assignment, each randomly assigned group spends about 10 to 15 minutes at each station. The author incorporates as much sensory stimulation in the activity as possible. At the first station, students view a PowerPoint show from a geology class the author participated in at the Grand Canyon. At station two, students look at a…

  4. 78 FR 7775 - Boulder Canyon Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    .... \\1\\ 75 FR 57912 (September 23, 2010). \\2\\ 133 FERC ] 62,229. The proposed BCP electric service base... in power rate adjustments (10 CFR part 903) were published on September 18, 1985 (50 FR 87835... Area Power Administration Boulder Canyon Project AGENCY: Western Area Power Administration, DOE....

  5. 77 FR 2533 - Boulder Canyon Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-18

    ... composite rate is 20.45 mills/kWh. \\1\\ 75 FR 57912 (Sept. 23, 2010). \\2\\ 133 FERC ] 62,229. The proposed BCP... 18, 1985 (50 FR 87835). Availability of Information All brochures, studies, comments, letters... Area Power Administration Boulder Canyon Project AGENCY: Western Area Power Administration, DOE....

  6. The Colorado River in the Grand Canyon.

    ERIC Educational Resources Information Center

    Speece, Susan

    1991-01-01

    An assessment of the water quality of the Colorado River in the Grand Canyon was made, using the following parameters: dissolved oxygen, water temperature, hydrogen ion concentration, total dissolved solids, turbidity, and ammonium/nitrogen levels. These parameters were used to provide some clue as to the "wellness" and stability of the aquatic

  7. Creationism in the Grand Canyon, Texas Textbooks

    NASA Astrophysics Data System (ADS)

    Folger, Peter

    2004-01-01

    AGU President Bob Dickinson, together with presidents of six other scientific societies, have written to Joseph Alston, Superintendent of Grand Canyon National Park, pointing out that a creationist book, The Grand Canyon: A Different View, is being sold in bookstores within the borders of the park as a scientific explanation about Grand Canyon geologic history. President Dickinson's 16 December letter urges that Alston clearly separate The Grand Canyon: A Different View from books and materials that discuss the legitimate scientific understanding of the origin of the Grand Canyon. The letter warns the Park Service against giving the impression that it approves of the anti-science movement known as young-Earth creationism, or that it endorses the advancement of religious tenets disguised as science. The text of the letter is on AGU's Web site http://www.agu.org/sci_soc/policy/sci_pol.html. Also, this fall, AGU sent an alert to Texas members about efforts by intelligent design creationists aimed at weakening the teaching of biological evolution in textbooks used in Texas schools. The alert pointed scientists to a letter, drafted by AGU, together with the American Institute of Physics, the American Physical Society, the Optical Society of America, and the American Astronomical Society, that urged the Texas State Board of Education to adopt textbooks that presented only accepted, peer-reviewed science and pedagogical expertise. Over 550 scientists in Texas added their names to the letter (http://www.agu.org/sci_soc/policy/texas_textbooks.pdf ), sent to the Board of Education on 1 November prior to their vote to adopt a slate of new science textbooks. The Board voted 11-5 in favor of keeping the textbooks free of changes advocated by groups supporting intelligent design creationism.

  8. Bioavailable compounds in sinking particulate organic matter, Blanes Canyon, NW Mediterranean Sea: Effects of a large storm and sea surface biological processes

    NASA Astrophysics Data System (ADS)

    Lopez-Fernandez, Pilar; Bianchelli, Silvia; Pusceddu, Antonio; Calafat, Antoni; Danovaro, Roberto; Canals, Miquel

    2013-11-01

    To ascertain whether the Blanes submarine canyon functions as a conduit of labile organic compounds to the deep margin, we analyzed phytopigment, protein, carbohydrate and lipid contents of sinking particles during a 6-months period comprised between a large storm event and the spring phytoplankton bloom. Four sediment traps were deployed, at 300, 900, 1200, and 1500 m depth along the axis of the canyon from November 2008 to April 2009. Fluxes of all study variables (organic carbon, proteins, carbohydrates and lipids) peaked from mid to late December. Afterwards, organic matter fluxes in the upper canyon decreased to values comparable (BC1200) or much lower (BC900) than those observed at the beginning of the monitoring period. The algal fraction of biopolymeric C (i.e. the percentage contribution of phytopigments to biopolymeric C utilized here as an indicator of particles’ freshness), ranging from 14 to about 100%, was generally low (median value about 32%), and showed the highest values from November to early December 2008 at all stations, except for the station at 1200 m which peaks in April 2009. A severe storm that occurred the 26th of December 2008 determined a strong increase in the downward transport of organic matter along the Blanes Canyon, though associated with a decrease in its nutritional quality. Values of the protein to carbohydrate ratio (utilized here as an indicator of particles’ nutritional quality) ranged from 0.4 to >2.0, increasing from late winter to early spring at 900 and 1200 m depth in association with the spring phytoplankton bloom in superficial waters. The material collected by sediment traps in spring had a higher nutritional value than in autumn-winter at both stations. According to the optimal foraging theory, the results of this study suggest that, following winter episodic events, deep-sea detritus feeders would need to ingest more detritus to fulfill their requirements for labile food than in spring, when fresher material is derived from sinking particles associated with phytoplankton blooms. We conclude that whilst submarine canyons like the Blanes Canyon act as major conduits for material exported from the continental shelf after high-energy episodic events, the supply of labile food to the deep-sea benthic ecosystem is connected to biological processes occurring at the sea surface.

  9. Evidence of clastic evaporites in the canyons of the Levant basin (Israel): implications for the Messinian salinity crisis

    NASA Astrophysics Data System (ADS)

    Lugli, Stefano; Schreiber, B. Charlotte; Gvirtzman, Zohar; Manzi, Vinicio; Roveri, Marco

    2013-04-01

    The recognition of widespread and thick evaporite deposits below the floor of the Mediterranean Sea has boosted a long standing controversy concerning their depositional setting (shallow versus deep) and their correlation with the onshore sequences. Until a new scientific campaign might be launched to cross those deposits, the discussion is still open to speculation. Many Messinian evaporitic deposits have been interpreted as primary precipitates in very shallow-water or coastal environments, thus favouring the idea of a desiccated Mediterranean basin (Hsu et al., 1973). Recent studies have questioned this interpretation (Hardie and Lowenstein, 2004) and widespread, thick, clastic evaporite facies have been identified in the Mediterranean (Manzi et al., 2005). These clastic deposits are not compatible with a desiccation model as they were clearly emplaced by fully subaqueous, deep-water processes, ranging from submarine slides, to high- and low-density gravity flows. One of the most relevant areas for the understanding of the salinity crisis is the Levant basin where the Messinian evaporites partially fill some of the erosional features (canyons) considered to have formed as a consequence of significant drawdown related to the desiccation of the Mediterranean Sea (up to - 850 m, Druckman et al., 1995). Our complete revisitation of the available cores from onshore Israel cutting through the sedimentary filling of the Messinian canyons (Afiq 1, Ashdod 2, Be'eri Sh1, Be'eri Sh4, Jaffa 1 and Talme-Yaffe 3) revealed exclusively clastic sulfate facies. This is the first direct evidence that the Lower Evaporite Unit offshore Israel may actually consist of deep-water resedimented evaporites that were originally deposited on the margin of the Levant Basin. References Druckman Y., Buchbinder B., Martinotti G.M., Tov R.S., Aharon P., 1995. The buried Afiq Canyon (eastern Mediterranean, Israel): a case study of a Tertiary submarine canyon exposed in Late Messinian times. Marine Geology, 123, 167-185. Hardie L.A. & Lowenstein T.K., 2004. Did the Mediterranean Sea dry out during the Miocene? A reassessment of the evaporite evidence from DSDP Legs 13 and 42A cores. JSR, 74, 453-461. Hsu, K.J., Cita, M.B., and Ryan, W.B.F, 1973. The origin of the Mediterranean evaporites, in Ryan, W.B.F., et al. eds., Initial Reports of the Deep Sea Drilling Project, v. 13, Washington, 1203-1231. Manzi V., Lugli S., Ricci Lucchi F., Roveri M., 2005. Deep-water clastic evaporites deposition in the Messinian Adriatic foredeep (northern Apennines, Italy): did the Mediterranean ever dry out? Sedimentology, 52, 875-902.

  10. Identification of a ship or submarine from its magnetic signature

    NASA Technical Reports Server (NTRS)

    Ioannidis, G.

    1977-01-01

    The relationship between the measured time fluctuations of the ambient magnetic field due to the passage of a ship or submarine and the characteristic magnetization properties of this vessel are derived. This relationship would be useful in identifying or classifying ships and submarines according to their magnetization properties.

  11. Submarine escape trials 1999-2001--provision of medical support.

    PubMed

    Benton, Peter

    2002-01-01

    Since the early 1960s all Royal Navy submarines have been fitted with an escape system comprising a single escape tower (SET) and submarine escape immersion suit (SEIS). This system enables escape from a submarine at a depth of 180 metres (1.9 MPa) provided that the submarine compartment is at a pressure of no greater than 1 bar (0.1 MPa). Due to a variety of causes which may include flooding and leakage of high pressure air systems it is the highly probable that the submarine compartment will be at a pressure in excess of 1 bar (0.1 MPa) at the time of the escape. To investigate and determine what constitutes a 'safe' maximum escape depth from any given compartment pressure (the safe to escape curve), a purpose built chamber complex, the Submarine Escape Simulator (SES) has been constructed at the QinetiQ, formerly the Defence Evaluation and Research Agency (DERA), Alverstoke site. Unlike escapes from a submarine where once released from the submarine the escapee's ascent can not be halted, within the SES it is possible to halt the ascent phase. This article describes the systems and procedures developed to enable medical support to be provided rapidly to a subject at any stage of the compression decompression profile. The article also provides details of the results to date that have been obtained from this work. PMID:12838773

  12. Sensitivity of Greenland outlet glacier dynamics to submarine melting

    NASA Astrophysics Data System (ADS)

    Beckmann, Johanna; Siegrfied, Merten; Perrette, Mahé; Carlov, Reinhard; Ganopolski, Andrey

    2015-04-01

    Over the last few decades Greenland ice mass loss has strongly increased due to surface melt and dynamic changes in marine-terminating outlet glaciers. A major reason for the retreat of these glaciers is believed to be related to increased submarine melting, which in turn is caused by surrounding ocean warming and the enhanced subglacial water discharge. These complex physical processes are not yet fully understood. Inspecting the sensitivities of submarine melting to model formulation and model parameters is crucial for investigations of outlet glacier response to future climate change. Different approaches have been used to compute submarine melt rates of outlet glaciers using experimental data, numerical modelling and simplified analytical solutions. To model the process of submarine melting for a selection of Greenland outlet glaciers, a simple submarine melt parameterization is incorporated into a one-dimensional dynamic ice-flow model. The behaviour of this submarine melt parameterization is demonstrated by running a suite of simulations to investigate the sensitivity of submarine melt to changes in ocean properties and the amount and distribution of subglacial water discharge. A comparison of the simple parameterization with three-dimensional models and experimental data is conducted to assess the quality of parameterization and improve the parameterization of submarine melting.

  13. Detail of conning tower atop the submarine. Note the wire ...

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

    Detail of conning tower atop the submarine. Note the wire rope wrapped around the base of the tower, which may have been used in an attempt to pull the submarine offshore. - Sub Marine Explorer, Located along the beach of Isla San Telmo, Pearl Islands, Isla San Telmo, Former Panama Canal Zone, CZ

  14. Hydrogen isotope systematics of submarine basalts

    USGS Publications Warehouse

    Kyser, T.K.; O'Neil, J.R.

    1984-01-01

    The D/H ratios and water contents in fresh submarine basalts from the Mid-Atlantic Ridge, the East Pacific Rise, and Hawaii indicate that the primary D/H ratios of many submarine lavas have been altered by processes including (1) outgassing, (2) addition of seawater at magmatic temperature, and (3) low-temperature hydration of glass. Decreases in ??D and H2O+ from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between ??D and H2O+ in basalts from the Galapagos Rise and the FAMOUS Area are attributed to outgassing of CH4 and H2. A good correlation between ??D values and H2O is observed in a suite of submarine tholeiites dredged from the Kilauea East Rift Zone where seawater (added directly to the magma), affected only the isotopic compositions of hydrogen and argon. Analyses of some glassy rims indicate that the outer millimeter of the glass can undergo lowtemperature hydration by hydroxyl groups having ??D values as low as -100. ??D values vary with H2O contents of subaerial transitional basalts from Molokai, Hawaii, and subaerial alkali basalts from the Society Islands, indicating that the primary ??D values were similar to those of submarine lavas. Extrapolations to possible unaltered ??D values and H2O contents indicate that the primary ??D values of most thoteiite and alkali basalts are near -80 ?? 5: the weight percentages of water are variable, 0.15-0.35 for MOR tholeiites, about 0.25 for Hawaiian tholeiites, and up to 1.1 for alkali basalts. The primary ??D values of -80 for most basalts are comparable to those measured for deep-seated phlogopites. These results indicate that hydrogen, in marked contrast to other elements such as Sr, Nd, Pb, and O, has a uniform isotopic composition in the mantle. This uniformity is best explained by the presence of a homogeneous reservoir of hydrogen that has existed in the mantle since the very early history of the Earth. ?? 1984.

  15. Miniature Robotic Submarine for Exploring Harsh Environments

    NASA Technical Reports Server (NTRS)

    Behar, Alberto; Bruhn, Fredrik; Carsey, Frank

    2004-01-01

    The miniature autonomous submersible explorer (MASE) has been proposed as a means of scientific exploration -- especially, looking for signs of life -- in harsh, relatively inaccessible underwater environments. Basically, the MASE would be a small instrumented robotic submarine (see figure) that could launch itself or could be launched from another vehicle. Examples of environments that might be explored by use of the MASE include subglacial lakes, deep-ocean hydrothermal vents, acidic or alkaline lakes, brine lenses in permafrost, and ocean regions under Antarctic ice shelves.

  16. Optical Guidance for a Robotic Submarine

    NASA Astrophysics Data System (ADS)

    Schulze, Karl R.; LaFlash, Chris

    2002-11-01

    There is a need for autonomous submarines that can quickly and safely complete jobs, such as the recovery of a downed aircraft's black box recorder. In order to complete this feat, it is necessary to use an optical processing algorithm that distinguishes a desired target and uses the feedback from the algorithm to retrieve the target. The algorithm itself uses many bit mask filters for particle information, and then uses a unique rectation method in order to resolve complete objects. The algorithm has been extensively tested on an AUV platform, and proven to succeed repeatedly in approximately five or more feet of water clarity.

  17. The provenance of extreme flood induced submarine gravity flow deposits off Southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Su, C.

    2012-12-01

    Gaoping Submarine Canyon (GPSC) is the major pathway for sediments disperse from Gaoping River (GPR) into deep sea. In previous studies (Su et al., 2012), the cores collected from GPSC show the catastrophic events induced by typhoon may lead to extreme export of terrestrial sediment into GPSC and temporally quick buried in the upper reach or further caused gravity flows in the canyon. For understanding the provenance of the terrestrial sediments deposited in the GPSC during the extreme flooding period, core samples collected in cruise OR1-785, OR1-851 and OR1-923 were used for clay mineral analysis. Clay minerals are one of the most useful indicators to decipher the provenance and transport of sediments in marine environments. The composition and distribution of clay minerals in sediments are related to the climate and the nature of their parent rocks. Our result shows illite is the most abundant clay mineral in the GPSC (over 70%), chlorite and kaolinite are minor (around 20%), and nearly no smectite in core samples. According to the 550°C treatment X-ray diffraction patterns, the diffraction peaks at 7Å and 3.5Å partly preserved in OR1-785-GC5A, OR1-851-GCC and OR1-923-K11A core samples and implies the existence of Mg-chlorite which is widespread in green rocks in the Central Mountain Range. We suggested the extreme flooding event may fast transport the sediment from the Central Mountain Range through GPSC into deep sea environment.

  18. Lava Flows in the Grand Canyon

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Over vast expanses of time, natural processes like floods and volcanoes deposit layers of rock on the Earth's surface. To delve down through layers of rock is to explore our planet's history. Sometimes rock layers are exposed through human activity, such as drilling or excavation. Other times, rivers carve through the rock. One of the best, and most well-known, examples of a river exposing ancient rocks is Colorado River in Arizona's Grand Canyon. What fewer people know is that the Grand Canyon also has a history of relatively recent (on geologic time scales) volcanism. The evidence--hardened lava--spills down the canyon walls all the way to the river. On June 22, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the Grand Canyon, near 36.2 degrees north latitude and 113.2 degrees west longitude. ASTER detects light visible to human eyes as well as 'invisible' infrared light. Because different minerals reflect different portions of the light spectrum, ASTER can see varying mineral compositions of the rocks it observes, as well as detecting vegetation. In this three-dimensional visualization, lava fields appear brownish gray, darker than the layers of limestone, sandstone and other rock in the canyon. Vegetation appears green, and sparsely vegetated areas appear mustard. Water in the Colorado River is blue-purple. Geologists estimate that between 1.8 million and 400,000 years ago, lava flows actually dammed the Colorado River more than a dozen times. Some of the lava dams were as high as 600 meters (about 1,969 feet), forming immense reservoirs. Over time, enough water and sediment built up to push the river flow over the tops of these dams and eventually erode them away. Today, remnants of these lava dams remain throughout the area, along with the much older rock layers they cover. Among the most well known examples of these 'frozen' lava cascades is Lava Falls, which spills down to the river next to a cinder cone known as Volcan's Throne. Numerous flows spread down into Whitmore Canyon, a Colorado River tributary, as well.

  19. 3D View of Grand Canyon, Arizona

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Grand Canyon is one of North America's most spectacular geologic features. Carved primarily by the Colorado River over the past six million years, the canyon sports vertical drops of 5,000 feet and spans a 445-kilometer-long stretch of Arizona desert. The strata along the steep walls of the canyon form a record of geologic time from the Paleozoic Era (250 million years ago) to the Precambrian (1.7 billion years ago).

    The above view was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument aboard the Terra spacecraft. Visible and near infrared data were combined to form an image that simulates the natural colors of water and vegetation. Rock colors, however, are not accurate. The image data were combined with elevation data to produce this perspective view, with no vertical exaggeration, looking from above the South Rim up Bright Angel Canyon towards the North Rim. The light lines on the plateau at lower right are the roads around the Canyon View Information Plaza. The Bright Angel Trail, which reaches the Colorado in 11.3 kilometers, can be seen dropping into the canyon over Plateau Point at bottom center. The blue and black areas on the North Rim indicate a forest fire that was smoldering as the data were acquired on May 12, 2000.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats, monitoring potentially active volcanoes, identifying crop stress, determining cloud morphology and physical properties, wetlands Evaluation, thermal pollution monitoring, coral reef degradation, surface temperature mapping of soils and geology, and measuring surface heat balance.

  20. Hydraulics of floods upstream of horseshoe canyons and waterfalls

    NASA Astrophysics Data System (ADS)

    Lapotre, Mathieu G. A.; Lamb, Michael P.

    2015-07-01

    Horseshoe waterfalls are ubiquitous in natural streams, bedrock canyons, and engineering structures. Nevertheless, water flow patterns upstream of horseshoe waterfalls are poorly known and likely differ from the better studied case of a one-dimensional linear step because of flow focusing into the horseshoe. This is a significant knowledge gap because the hydraulics at waterfalls controls sediment transport and bedrock incision, which can compromise the integrity of engineered structures and influence the evolution of river canyons on Earth and Mars. Here we develop new semiempirical theory for the spatial acceleration of water upstream of, and the cumulative discharge into, horseshoe canyons and waterfalls. To this end, we performed 110 numerical experiments by solving the 2-D depth-averaged shallow-water equations for a wide range of flood depths, widths and discharges, and canyon lengths, widths and bed gradients. We show that the upstream, normal flow Froude number is the dominant control on lateral flow focusing and acceleration into the canyon head and that focusing is limited when the flood width is small compared to a cross-stream backwater length scale. In addition, for sheet floods much wider than the canyon, flow focusing into the canyon head leads to reduced discharge (and drying in cases) across the canyon sidewalls, which is especially pronounced for canyons that are much longer than they are wide. Our results provide new expectations for morphodynamic feedbacks between floods and topography, and thus canyon formation.

  1. Seismically induced rock slope failures resulting from topographic amplification of strong ground motions: The case of Pacoima Canyon, California

    USGS Publications Warehouse

    Sepulveda, S.A.; Murphy, W.; Jibson, R.W.; Petley, D.N.

    2005-01-01

    The 1994 Northridge earthquake (Mw = 6.7) triggered extensive rock slope failures in Pacoima Canyon, immediately north of Los Angeles, California. Pacoima Canyon is a narrow and steep canyon incised in gneissic and granitic rocks. Peak accelerations of nearly 1.6 g were recorded at a ridge that forms the left abutment of Pacoima Dam; peak accelerations at the bottom of the canyon were less than 0.5 g, suggesting the occurrence of topographic amplification. Topographic effects have been previously suggested to explain similarly high ground motions at the site during the 1971 (Mw = 6.7) San Fernando earthquake. Furthermore, high landslide concentrations observed in the area have been attributed to unusually strong ground motions rather than higher susceptibility to sliding compared with nearby zones. We conducted field investigations and slope stability back-analyses to confirm the impact of topographic amplification on the triggering of landslides during the 1994 earthquake. Our results suggest that the observed extensive rock sliding and falling would have not been possible under unamplified seismic conditions, which would have generated a significantly lower number of areas affected by landslides. In contrast, modelling slope stability using amplified ground shaking predicts slope failure distributions matching what occurred in 1994. This observation confirms a significant role for topographic amplification on the triggering of landslides at the site, and emphasises the need to select carefully the inputs for seismic slope stability analyses. ?? 2005 Elsevier B.V. All rights reserved.

  2. Basin configuration and depositional trends in the Mission Canyon and Ratcliffe beds, U.S. portion of the Williston basin

    SciTech Connect

    Hendricks, M.L.

    1996-06-01

    Construction of Mission Canyon and Ratcliffe depositional trends utilizing shoreline models and anhydrite edge maps shows a significant change in basin configuration associated with regional sea level changes. Sea level highstand, which began during deposition of the Scallion member of the Lodgepole Formation, was punctuated by two lowstand events. The first occurred during deposition of the MC-2 anhydrite (Tilston). During this lowstand event, the width of the carbonate basin decreased significantly. With sea level rise, a broad basin formed with carbonate and evaporate ramp deposition (Lands, Wayne, Glenburn and Mohall members). The top of the Mohall contains evidence of the second lowstand event. This event introduced quartz sand detritus into the basin (Kisbey Sandstone). Because of sea level lowstand, Sherwood and younger Mission Canyon beds were deposited during highstand in a narrower carbonate basin. Funneling of marine currents and tides in this basin created higher energy shoreline and shoal deposits than those commonly found in older Mission Canyon sediments. The top of the Mission Canyon (Rival) was capped by a deepening event or transgression which enlarged the basin and created broad Ratcliffe ramp systems similar to those that existed during Glenburn and Mohall deposition. By utilizing sequence stratigraphy and mapping shoreline trends and basin configuration, reservoir and trap geometries are identified, and exploration success is improved.

  3. A reevaluation of the Munson-Nygren-Retriever submarine landslide complex, Georges bank lower slope, western north Atlantic

    USGS Publications Warehouse

    Chaytor, Jason D.; Twichell, David C.; ten Brink, Uri S.

    2012-01-01

    The Munson-Nygren-Retriever (MNR) landslide complex is a series of distinct submarine landslides located between Nygren and Powell canyons on the Georges Bank lower slope. These landslides were first imaged in 1978 using widely-spaced seismic reflection profiles and were further investigated using continuous coverage GLORIA sidescan imagery collected over the landslide complex in 1987. Recent acquisition of highresolution multibeam bathymetry across these landslides has provided an unprecedented view of their complex morphology and allows for a more detailed investigation of their evacuation and deposit morphologies and sizes, modes of failure, and relationship to the adjacent sections of the margin, including the identification of an additional landslide within the MNR complex, referred to here as the Pickett slide. The evacuation zone of these landslides covers an area of approximately 1,780 km2 . The headwalls of these landslides are at a depth of approximately 1,800 m, with evacuation extending for approximately 60 km downslope to the top of the continental rise. High-relief debris deposits, in the form of blocks and ridges, are present down the length of the majority of the evacuation zones and within the deposition area at the base of the slope. On the continental rise, the deposits from each of the most recent failures of the MNR complex landslides merge with debris from earlier continental slope failures, canyon and alongslope derived deposits, and prominent upper-rise failures.

  4. Sliding of outrunner blocks from submarine landslides

    NASA Astrophysics Data System (ADS)

    De Blasio, Fabio Vittorio; Engvik, Lars Enok; Elverhøi, Anders

    2006-03-01

    Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine landslide and flow ahead of the front. Data gathered from different sliding areas highlight some properties of outrunner blocks and in particular their inordinate mobility reflected in runouts of up to 25 kilometres, even on very gentle slopes. Blocks may produce an erosion glide track on the sea floor few centimetres to several metres deep, which in some cases exhibits regularly spaced grooves along the flow direction. Understanding the dynamics of outrunner blocks may shed light on the flow and lubrication of submarine landslides. We develop a simple hydrodynamic model of a rigid block interacting with ambient water and subject to lubrication with the sea floor, and calculate numerically the equation of motion for the block. We find that as a consequence of lift forces and water lubrication, the block may reach long runouts, in agreement with data. When the block is moving at high speed, we find an oscillating solution to the equations of motion which could explain the creation of dashed grooves.

  5. Argon geochronology of Kilauea's early submarine history

    USGS Publications Warehouse

    Calvert, A.T.; Lanphere, M.A.

    2006-01-01

    Submarine alkalic and transitional basalts collected by submersible along Kilauea volcano's south flank represent early eruptive products from Earth's most active volcano. Strongly alkalic basalt fragments sampled from volcaniclastic deposits below the mid-slope Hilina Bench yield 40Ar/39Ar ages from 212 ?? 38 to 280 ?? 20 ka. These ages are similar to high-precision 234 ?? 9 and 239 ?? 10 ka phlogopite ages from nephelinite clasts in the same deposits. Above the mid-slope bench, two intact alkalic to transitional pillow lava sequences protrude through the younger sediment apron. Samples collected from a weakly alkalic basalt section yield 138 ?? 30 to 166 ?? 26 ka ages and others from a transitional basalt section yield 138 ?? 115 and 228 ?? 114 ka ages. The ages are incompatible with previous unspiked K-Ar studies from samples in deep drill holes along the east rift of Kilauea. The submarine birth of Kilauea volcano is estimated at <300 ka. If the weakly alkalic sequence we dated is representative of the volcano as a whole, the transition from alkalic to tholeiitic basalt compositions is dated at ??? 150 ka. ?? 2005 Elsevier B.V. All rights reserved.

  6. Submarine 'safe to escape' studies in man.

    PubMed

    Jurd, K M; Seddon, F M; Thacker, J C; Blogg, S L; Stansfield, M R D; White, M G; Loveman, G A M

    2014-01-01

    The Royal Navy requires reliable advice on the safe limits of escape from a distressed submarine (DISSUB). Flooding in a DISSUB may cause a rise in ambient pressure, increasing the risk of decompression sickness (DCS) and decreasing the maximum depth from which it is safe to escape. The aim of this study was to investigate the pressure/depth limits to escape following saturation at raised ambient pressure. Exposure to saturation pressures up to 1.6 bar (a) (160 kPa) (n = 38); escapes from depths down to 120 meters of sea water (msw) (n = 254) and a combination of saturation followed by escape (n = 90) was carried out in the QinetiQ Submarine Escape Simulator, Alverstoke, United Kingdom. Doppler ultrasound monitoring was used to judge the severity of decompression stress. The trials confirmed the previously untested advice, in the Guardbook, that if a DISSUB was lying at a depth of 90 msw, then it was safe to escape when the pressure in the DISSUB was 1.5 bar (a), but also indicated that this advice may be overly conservative. This study demonstrated that the upper DISSUB saturation pressure limit to safe escape from 90 msw was 1.6 bar (a), resulting in two cases of DCS. PMID:25109084

  7. Deep-Sea Submarine 'Ben Franklin'

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The deep-sea submarine 'Ben Franklin' is being docked in the harbor. Named for American patriot and inventor Ben Franklin, who discovered the Gulf Steam, the 50-foot Ben Franklin was built between 1966 and 1968 in Switzerland for deep-ocean explorer Jacques Piccard and the Grumman Aircraft Engineering Corporation. The submersible made a famous 30-day drift dive off the East Coast of the United States and Canada in 1969 mapping the Gulf Stream's currents and sea life. It also made space exploration history by studying the behavior of aquanauts in a sealed, self-contained, self-sufficient capsule for NASA. On July 14, 1969, the Ben Franklin was towed to the high-velocity center of the Stream off the coast of Palm Beach, Florida. With a NASA observer on board, the sub descended to 1,000 feet off of Riviera Beach, Florida and drifted 1,400 miles north with the current for more than four weeks, reemerging near Maine. During the course of the dive, NASA conducted exhaustive analyses of virtually every aspect of onboard life. They measured sleep quality and patterns, sense of humor and behavioral shifts, physical reflexes, and the effect of a long-term routine on the crew. The submarine's record-shattering dive influenced the design of Apollo and Skylab missions and continued to guide NASA scientists as they devised future marned space-flight missions.

  8. Deep-Sea Research Submarine 'Ben Franklin'

    NASA Technical Reports Server (NTRS)

    1969-01-01

    This is an aerial view of the deep-sea research submarine 'Ben Franklin' at dock. Named for American patriot and inventor Ben Franklin, who discovered the Gulf Steam, the 50-foot Ben Franklin was built between 1966 and 1968 in Switzerland for deep-ocean explorer Jacques Piccard and the Grumman Aircraft Engineering Corporation. The submersible made a famous 30-day drift dive off the East Coast of the United States and Canada in 1969 mapping the Gulf Stream's currents and sea life, and also made space exploration history by studying the behavior of aquanauts in a sealed, self-contained, self-sufficient capsule for NASA. On July 14, 1969, the Ben Franklin was towed to the high-velocity center of the Stream off the coast of Palm Beach, Florida. With a NASA observer on board, the sub descended to 1,000 feet off of Riviera Beach, Florida and drifted 1,400 miles north with the current for more than four weeks, reemerging near Maine. During the course of the dive, NASA conducted exhaustive analyses of virtually every aspect of onboard life. They measured sleep quality and patterns, sense of humor and behavioral shifts, physical reflexes, and the effects of a long-term routine on the crew. The submarine's record-shattering dive influenced the design of Apollo and Skylab missions and continued to guide NASA scientists as they devised future marned space-flight missions.

  9. Mineralized microbes from Giggenbach submarine volcano

    NASA Astrophysics Data System (ADS)

    Jones, Brian; de Ronde, C. E. J.; Renaut, Robin W.

    2008-08-01

    The Giggenbach submarine volcano, which forms part of the Kermadec active arc front, is located ˜780 km NNE of the North Island of New Zealand. Samples collected from chimneys associated with seafloor hydrothermal vents on this volcano, at a depth of 160-180 m, contain silicified microbes and microbes entombed in reticular Fe-rich precipitates. The mineralized biota includes filamentous, rod-shaped, and rare coccoid microbes. In the absence of organic carbon for rDNA analysis or preserved cells, the taxonomic affinity of these microbes, in terms of extant taxa, remains questionable because of their architectural simplicity and the paucity of taxonomically significant features. The three-dimensional preservation of the microbes indicates rapid mineralization with a steady supply of supersaturated fluids to the nucleation sites present on the surfaces of the microbes. The mineralization styles evident in the microbes from the Giggenbach submarine volcano are similar to those associated with mineralized microbes found in terrestrial hot spring deposits in New Zealand, Iceland, Yellowstone, and Kenya. These similarities exist even though the microbes are probably different and the fluids become supersaturated with respect to opal-A by different mechanisms. For ancient rocks it means that interpretations of the depositional settings cannot be based solely on the silicified microbes or their style of silicification.

  10. Attack submarines: The case for negotiated reductions

    SciTech Connect

    Lacy, J.L.

    1990-12-01

    In East-West naval arms control, the realistic and genuinely useful options are fairly limited. The United States is likely to resist constraints on the numbers and operations of naval assets that serve national interests beyond East-West security. It is not altogether clear, in a post-Cold War environment, that such constraints on U.S. forces would be in the Soviet interest either. The attack submarine, however, is different - an artifact of the Cold War, with very limited utility in non-Cold War contingencies. Controlling its operations and movements has always been difficult, and is bound to remain so. But operations can be controlled indirectly, and costs can be reduced, by cutting inventories. To bring a substantial benefit, such cuts would need to be large, mutual, and to a more-or-less common ceiling. If something along the lines suggested above were agreed upon and implemented, the United States and the Soviet Union would eliminate from the world's oceans between 200 and 300 attack submarines. That would seem to be quite a respectable start toward building confidence, security, and stability at sea, and toward a more sensible force structure for both navies. 1 tab.

  11. Seismic response of buried submarine pipelines

    SciTech Connect

    Datta, T.K.; Mashaly, E.A.

    1988-12-01

    Submarine pipelines are many a time buried into a jet-blasted channel in the seabed. Seismic response of such buried pipelines are investigated in this paper. The earthquake is considered as a partially correlated stationary random proceeds characterized by a power spectral density function (PSDF). The cross-spectral density function between two random inputs along the length of the pipe is defined with the help of the local earthquake PSDF, which is the same for all points, and a frequency-dependent, exponentially decaying function (with distance). A lumped-mass model with 2-D beam elements is used to write the equation of motion. Soil resistance to dynamic excitation along the pipe length is obtained in an approximate manner with the help of frequency-independent impedance functions derived from half-space analysis and Mindlin's static stresses within the soil due to point loads. The responses are obtained by a spectral analysis for horizontal ground motions in two principal directions, which are assumed to coincide with pipe axis and the perpendicular to it. Using the proposed method of analysis, a parametric study is conducted. The results of the study help in understanding the behavior of buried submarine pipelines under seismic forces and its differences from that of the buried pipelines on land.

  12. Surprise and opportunity for learning in Grand Canyon: the Glen Canyon Dam Adaptive Management Program

    USGS Publications Warehouse

    Melis, Theodore S.; Walters, Carl; Korman, Josh

    2015-01-01

    With a focus on resources of the Colorado River ecosystem below Glen Canyon Dam, the Glen Canyon Dam Adaptive Management Program has included a variety of experimental policy tests, ranging from manipulation of water releases from the dam to removal of non-native fish within Grand Canyon National Park. None of these field-scale experiments has yet produced unambiguous results in terms of management prescriptions. But there has been adaptive learning, mostly from unanticipated or surprising resource responses relative to predictions from ecosystem modeling. Surprise learning opportunities may often be viewed with dismay by some stakeholders who might not be clear about the purpose of science and modeling in adaptive management. However, the experimental results from the Glen Canyon Dam program actually represent scientific successes in terms of revealing new opportunities for developing better river management policies. A new long-term experimental management planning process for Glen Canyon Dam operations, started in 2011 by the U.S. Department of the Interior, provides an opportunity to refocus management objectives, identify and evaluate key uncertainties about the influence of dam releases, and refine monitoring for learning over the next several decades. Adaptive learning since 1995 is critical input to this long-term planning effort. Embracing uncertainty and surprise outcomes revealed by monitoring and ecosystem modeling will likely continue the advancement of resource objectives below the dam, and may also promote efficient learning in other complex programs.

  13. Submarine mass wasting on the Ionian Calabrian margin

    NASA Astrophysics Data System (ADS)

    Ceramicola, S.; Forlin, E.; Coste, M.; Cova, A.; Praeg, D.; Fanucci, F.; Critelli, S.

    2010-12-01

    Mass wasting processes on continental margins have strong relevance both for geohazards of coastal areas and for the emplacement and monitoring of offshore infrastructures. The seabed dynamics of the Ionian Calabrian Margin (ICM) are currently being examined in the context of the project MAGIC (Marine Geohazard along the Italian Coasts). The objective of this project is the definition of elements that may constitute geological risk for coastal areas. The ICM is a tectonically-active margin, the structures of which reflect two main processes: frontal compression and fore-arc extension during the SE advance of the Calabrian accretionary prism since the late Miocene; and a rapid uplift (up to 1mm/yr) of onshore and shallow shelf areas since the mid-Pleistocene. These processes are reflected in different tectonic settings at seabed, which is characterized by a narrow continental shelf above a slope of irregular morphology in water depths of 150-2000 m. In the north, a broad slope is dominated by ridges and intervening basins that are the morphological expression of the southern Apennine fold-and-thrust belt; in the south, the continental slope descends steeply towards the deep-water Crotone and Spartivento fore-arc basins. The overall objective of this study is to map major features of mass wasting on the slopes of the ICM, investigate possible triggering mechanisms and consider the geohazards these features may represent for coastal areas. The study is based on an integrated analysis of multibeam morpho-bathymetric data and subbottom profiles, which together allow the recognition of four main types of mass wasting phenomena along the slopes of the ICM: 1) mass transport complexes (MTCs) within intra-slope basins - these are identified in the northern area, within the piggy-back basins: seabed imagery show the slopes of all the seabed ridges to be marked by headwall scarps recording widespread failure, while Chirp profiles show the adjacent basins to contain unstratified bodies indicative of debris flows buried beneath stratified sediments; multiple debris flows in several basins indicate one or more past episodes of failure that may be linked to activity on the faults bounding the structural highs. 2) slope slide scars - these are identified in two locations along the relatively steep southern Calabrian slope; the slide scars record several episodes of failure, linked to deposits within the deep-water basins that are yet to be identified. 3) possible gravity sliding - in one area of the southern Calabrian slope, elongate seabed features oriented subparallel to contours are observed, associated with diapiric structures that have been linked to Messinian salt observed on seismic profiles (Rossi & Sartori 1981); we suggest that the elongate seabed features may record a form of downslope sediment sliding above salt, resulting in features analogous to the cobblestone topography of the outer Calabrian Arc; 4) canyon headwalls - in the upper parts of all canyons, numerous headwall scarps are consistent with retrogressive activity of the canyons.

  14. New supply for canyon fire foam system

    SciTech Connect

    Gainey, T.

    1995-01-01

    The raw water supply for the B-Plant Canyon fire foam system is being replaced. The 4 inche water supply line to the foam system is being rerouted from the 6 inches raw water line in the Pipe Gallery to the 10 inches raw water main in the Operating Gallery. This document states the acceptance criteria for the flushing and testing to be performed by the contractor.

  15. Focusing of baroclinic tidal energy in a canyon

    NASA Astrophysics Data System (ADS)

    Vlasenko, Vasiliy; Stashchuk, Nataliya; Inall, Mark E.; Porter, Marie; Aleynik, Dmitry

    2016-04-01

    Strong three-dimensional focusing of internal tidal energy in the Petite Sole Canyon in the Celtic Sea is analyzed using observational data and numerical modeling. In a deep layer (500-800 m) in the center of the canyon, shear variance was elevated by an order of magnitude. Corresponding large vertical oscillations of deep isotherms and a local maximum of horizontal velocity were replicated numerically using the MITgcm. The elevated internal tidal activity in the deep part of the canyon is explained in terms of the downward propagation and focusing of multiple internal tidal beams generated at the shelf break. The near-circular shape of the canyon head and steep bottom topography throughout the canyon (steeper than the tidal beam) create favorable conditions for the lens-like focusing of tidal energy in the canyon's center. Observations and modeling show that the energy focusing greatly intensifies local diapycnal mixing that leads to local formation of a baroclinic eddy.

  16. Greening of the Grand Canyon -- developing a sustainable design for the Grand Canyon National Park

    SciTech Connect

    Gordon, H.T.

    1995-11-01

    The Grand Canyon National Park (GCNP) is faced with increasing visitor demand that is threatening the natural and cultural resources of one of the most popular recreation sites in the United States. The National Park Service (NPS) developed a draft General Management Plan (GMP), which provides management objectives and visions for the entire park, with alternative plans for the park`s developed areas. With the GMP as a starting point, a Grand Canyon Sustainable Design Workshop was conducted to make the Grand Canyon National Park more environmentally and economically sustainable. The workshop, which used the Environmental Design Charrette process, addressed integrated environmental solutions and their implementation in three primary areas: Integrated Information, Visitor Experience, and Resource Efficiency. This paper describes the Environmental Design Charrette process and the efforts of the Resource Efficiency group.

  17. 4. View to northwest from within Castro Creek Canyon, looking ...

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

    4. View to northwest from within Castro Creek Canyon, looking up at 'Antique' Building (HABS-CA-2611-C) at left and center, 'Champagne' Building (HABS-CA-2611-D) at right behind redwood trees. View gives indication of steepness of canyon, siting of these two buildings at canyon's edge. - Deetjen's Big Sur Inn, East Side of State Highway 1, Big Sur, Monterey County, CA

  18. The mortality of Royal Naval submariners 1960-89.

    PubMed Central

    Inskip, H; Snee, M; Styles, L

    1997-01-01

    OBJECTIVES: To examine the mortality pattern of submariners in the Royal Navy to assess the long term effects on health of serving in submarines. Any specific cause of death which was increased was considered in advance to be of interest, but attention focused particularly on cancer mortality. METHOD: A mortality follow up study: 15 138 submariners who had conducted their first submarine training between 1960 and 1979 were followed up through their time in the Navy and into civilian life, up to the end of 1989. The main outcome measures were the numbers of deaths and standardised mortality ratios (SMRs) which indicate whether the mortality from all causes and specific causes, particularly cancers, exceeds that in men in England and Wales. RESULTS: Mortality in submariners was lower than that for men in England and Wales with an all cause SMR of 86; this was comparable with that found in other studies of armed forces personnel. Cancer mortality was particularly low with an SMR of 69 and there was no particular cancer site which showed an excess. Increased mortality from digestive diseases was found, the excess being attributable to cirrhosis of the liver, which had an SMR of 221 based on 12 deaths, alcohol being a contributory factor in eight. Deaths from accidents and violence were also higher than expected with an SMR of 115, but this was due to high levels of accidents occurring after discharge from the Navy. There was no apparent trend in mortality with time since starting submarine work. Likewise there was no pattern by calendar period, although the excess of cirrhosis of the liver was confined to the period 1970-9. CONCLUSION: The submariners seemed to be a healthy group with low mortality overall. Working in submarines was not associated with any increased cancer mortality. Excess deaths from cirrhosis of the liver, and from accidents and violence after leaving the Navy, were of some concern but they cannot be attributed directly to the submarine environment. PMID:9155783

  19. 77 FR 8895 - Jimbilnan, Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-15

    ... Mountain, and Bridge Canyon Wilderness Areas Wilderness Management Plan/Environmental Impact Statement... Prepare an Environmental Impact Statement for the Wilderness Management Plan for the Jimbilnan, Pinto Valley, Black Canyon, Eldorado, Ireteba Peaks, Nellis Wash, Spirit Mountain, and Bridge Canyon...

  20. Ventilation Processes in a Three-Dimensional Street Canyon

    NASA Astrophysics Data System (ADS)

    Nosek, Štěpán; Kukačka, Libor; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2016-05-01

    The ventilation processes in three different street canyons of variable roof geometry were investigated in a wind tunnel using a ground-level line source. All three street canyons were part of an urban-type array formed by courtyard-type buildings with pitched roofs. A constant roof height was used in the first case, while a variable roof height along the leeward or windward walls was simulated in the two other cases. All street-canyon models were exposed to a neutrally stratified flow with two approaching wind directions, perpendicular and oblique. The complexity of the flow and dispersion within the canyons of variable roof height was demonstrated for both wind directions. The relative pollutant removals and spatially-averaged concentrations within the canyons revealed that the model with constant roof height has higher re-emissions than models with variable roof heights. The nomenclature for the ventilation processes according to quadrant analysis of the pollutant flux was introduced. The venting of polluted air (positive fluctuations of both concentration and velocity) from the canyon increased when the wind direction changed from perpendicular to oblique, irrespective of the studied canyon model. Strong correlations (>0.5) between coherent structures and ventilation processes were found at roof level, irrespective of the canyon model and wind direction. This supports the idea that sweep and ejection events of momentum bring clean air in and detrain the polluted air from the street canyon, respectively.

  1. Ventilation Processes in a Three-Dimensional Street Canyon

    NASA Astrophysics Data System (ADS)

    Nosek, Štěpán; Kukačka, Libor; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2016-02-01

    The ventilation processes in three different street canyons of variable roof geometry were investigated in a wind tunnel using a ground-level line source. All three street canyons were part of an urban-type array formed by courtyard-type buildings with pitched roofs. A constant roof height was used in the first case, while a variable roof height along the leeward or windward walls was simulated in the two other cases. All street-canyon models were exposed to a neutrally stratified flow with two approaching wind directions, perpendicular and oblique. The complexity of the flow and dispersion within the canyons of variable roof height was demonstrated for both wind directions. The relative pollutant removals and spatially-averaged concentrations within the canyons revealed that the model with constant roof height has higher re-emissions than models with variable roof heights. The nomenclature for the ventilation processes according to quadrant analysis of the pollutant flux was introduced. The venting of polluted air (positive fluctuations of both concentration and velocity) from the canyon increased when the wind direction changed from perpendicular to oblique, irrespective of the studied canyon model. Strong correlations (> 0.5) between coherent structures and ventilation processes were found at roof level, irrespective of the canyon model and wind direction. This supports the idea that sweep and ejection events of momentum bring clean air in and detrain the polluted air from the street canyon, respectively.

  2. Submarine pipelines routing planning based on GIS and dynamic programming

    NASA Astrophysics Data System (ADS)

    Gao, Yanming; Wang, Haihong; Wang, Bo; Yang, Lifen; Shi, Zhen

    2009-09-01

    A novel submarine pipelines routing (SPR) planning method to find an optimal pipeline route automatically is proposed based on spatial analysis of geographical information system (GIS) and dynamic programming theory. By analyzing the effects of engineering geology conditions, ocean environmental conditions and ocean exploitation conditions around the submarine pipeline system, an analytical model is provided to plan the pipelines to improve the pipeline stabilities and reduce the costs. Dynamic programming is used to found the optimal routing with a performance index. The spatial database is designed and the GIS-aided submarine pipeline system is developed. An example is carried out to verify the method proposed.

  3. Submarine pipelines routing planning based on GIS and dynamic programming

    NASA Astrophysics Data System (ADS)

    Gao, YanMing; Wang, HaiHong; Wang, Bo; Yang, Lifen; Shi, Zhen

    2010-11-01

    A novel submarine pipelines routing (SPR) planning method to find an optimal pipeline route automatically is proposed based on spatial analysis of geographical information system (GIS) and dynamic programming theory. By analyzing the effects of engineering geology conditions, ocean environmental conditions and ocean exploitation conditions around the submarine pipeline system, an analytical model is provided to plan the pipelines to improve the pipeline stabilities and reduce the costs. Dynamic programming is used to found the optimal routing with a performance index. The spatial database is designed and the GIS-aided submarine pipeline system is developed. An example is carried out to verify the method proposed.

  4. Submarine landslides and tsunami potential Off SE Australian Margin: results from the voyage SS2008/12

    NASA Astrophysics Data System (ADS)

    Rahman Talukder, Asrarur; Boyd, Ron; Keene, Jock; Hubble, Tom; Clarke, Samantha; Kinsela, Michael; Exon, Neville; Gardner, Jim; Felzenberg, Janice

    2010-05-01

    Although the continental margins around Australia are themselves passive, they are surrounded by the Pacific Ring of Fire characterized by a great many earthquakes, tsunamis and submarine landslides. The Earthquake Catalogue of Geo-science Australia shows that in Australia earthquakes with a magnitude 5.5+ occur on average every two years with the potential of a disastrous earthquake of magnitude 6 or more every six years. Historical records also show that there were 47 tsunami hits in Australian Coasts during the last 150 years. The main objective of Voyage SS2008/12 onboard RV Southern Surveyor in 2008, was to map out the submarine landslides in the region off northern New South Wales and southern Queensland in order to investigate its tsunami-genic potential that could impact their densely populated coastal cities. During the survey ca. 13,000 square km of multi-beam swath bathymetry data (MBES) along with TOPAS high resolution seismic and different types of ground truth samples were collected in the continental slope. This study presents the preliminary morpho-tectonic analysis of the collected acoustic images of the seabeds and near surfaces. In the survey area, the continental slopes extend from the shelf break to the abyssal plain between ~150m to ~4500m water depth. The survey area can be divided into northern and southern areas separated by relatively stable seabed of the Nerang Plateau. The average slopes range from a minimum of 2.8° on plateau to a maximum of 8.5° in steeper segments. Submarine slides of all sizes from 0.5 to 20 cubic km were encountered, there having different morphologies. They can be characterized as slab slides, debris flows and carbonate platform slides. The gravity cores takes from selected slide planes suggest that they have different ages (between ca. 6 to 25 ka) and the northern slides are older than the southern ones. Other bathymetric features are box canyons, linear canyons, volcanic cones, carbonate mounds and pockmarks. The most important discovery seems to be the observation of a "hanging block" in the mid continental slope off Merton Island, Queensland. The block has a volume of over 100 cubic km with prominent crown cracks. It seems that the block is a remnant left by canyon excavations in the mid to lower continental slopes. The crown cracks indicate its instability and the inception of the sliding processes. The toe of the block is already wasted and characterized by plunge pools. The tsunami-genic potential of this giant block depends on how it would fail: either altogether or piecewise, and how rapid the process would be. Many big landslides observed in the survey area show the evidence for multiple and recurrent sliding events. Our future research activity would focus to determine the tsunami-genic potential of these potential, massive, submarine landslides.

  5. Early Experience & Multisensory Perceptual Narrowing

    PubMed Central

    Lewkowicz, David J.

    2014-01-01

    Perceptual narrowing is a reflection of early experience and contributes in key ways to perceptual and cognitive development. In general, findings have shown that unisensory perceptual sensitivity in early infancy is broadly tuned such that young infants respond to, and discriminate, native as well as non-native sensory inputs, whereas older infants only respond to native inputs. Recently, my colleagues and I discovered that perceptual narrowing occurs at the multisensory processing level as well. The present article reviews this new evidence and puts it in the larger context of multisensory perceptual development and the role that perceptual experience plays in it. Together, the evidence on unisensory and multisensory narrowing shows that early experience shapes the emergence of perceptual specialization and expertise. PMID:24435505

  6. Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona; executive summary

    USGS Publications Warehouse

    Schmidt, J.C.; Graf, J.B.

    1988-01-01

    High discharges that occurred in 1983-85 resulted in redistribution of sand stored in zones of recirculating current in the Colorado River in Grand Canyon National Park. Redistribution resulted in net loss in the number of reattachment deposits in narrow reaches and aggradation of some separation deposits. Separation deposits were more stable than other types of deposits. Alluvial sand deposits that are large enough and of sufficient areal extent for use as campsites were more stable than smaller lower-elevation deposits. Fluctuating flows between October 1985 and January 1986 caused erosion throughout the Grand Canyon and caused erosion of some deposits created by the high flows of 1983-85. (Author 's abstract)

  7. Mixing at the head of a canyon: A laboratory investigation of fluid exchanges in a rotating, stratified basin

    NASA Astrophysics Data System (ADS)

    Wells, Judith R.; Helfrich, Karl R.

    2006-12-01

    Observations indicate that oceanic mixing is intensified near the head of submarine canyons. How the presence of canyon walls affects the local production and distribution of mixed fluid is an open question. These dynamics are addressed through rotating tank experiments which impose mixing at middepth at the closed end of a channel open to a larger body of water. Turbulence is generated in a linearly stratified fluid with initial buoyancy frequency N by means of a single bar oscillated with frequency ω. The mixed fluid quickly reaches a steady state height h ˜ (ω/N)1/2 independent of the Coriolis frequency f and collapses into the channel interior. A small percentage of the fluid exported from the turbulent zone enters a boundary current. The bulk forms a cyclonic circulation in front of the bar. As the recirculation cell expands to fill the channel, it restricts horizontal entrainment into the turbulent zone. Mixed fluid flux decays with time as t? and is dependent on the size of the mixing zone and the balance between turbulence, rotation, and stratification. The recirculation cell is confined within the channel, and export of mixed fluid into the basin is restricted to the weak boundary current. As horizontal entrainment is shut down, long-term production of mixed fluid relies more on vertical entrainment. However, the scalings indicate that short-term dynamics are the most applicable to oceanic conditions.

  8. Ancient impact structures on modern continental shelves: The Chesapeake Bay, Montagnais, and Toms Canyon craters, Atlantic margin of North America

    USGS Publications Warehouse

    Poag, C. Wylie; Plescia, J.B.; Molzer, P.C.

    2002-01-01

    Three ancient impact craters (Chesapeake Bay - 35.7 Ma; Toms Canyon - 35.7 Ma; Montagnais - 51 Ma) and one multiring impact basin (Chicxulub - 65 Ma) are currently known to be buried beneath modern continental shelves. All occur on the passive Atlantic margin of North America in regions extensively explored by seismic reflection surveys in the search for oil and gas reserves. We limit our discussion herein to the three youngest structures. These craters were created by submarine impacts, which produced many structural and morphological features similar in construction, composition, and variability to those documented in well-preserved subaerial and planetary impact craters. The subcircular Chesapeake Bay (diameter 85 km) and ovate Montagnais (diameter 45-50 km) structures display outer-rim scarps, annular troughs, peak rings, inner basins, and central peaks similar to those incorporated in the widely cited conceptual model of complex impact craters. These craters differ in several respects from the model, however. For example, the Montagnais crater lacks a raised lip on the outer rim, the Chesapeake Bay crater displays only small remnants of a raised lip, and both craters contain an unusually thick body of impact breccia. The subtriangular Toms Canyon crater (diameter 20-22 km), on the other hand, contains none of the internal features of a complex crater, nor is it typical of a simple crater. It displays a prominent raised lip on the outer rim, but the lip is present only on the western side of the crater. In addition, each of these craters contains some distinct features, which are not present in one or both of the others. For example, the central peak at Montagnais rises well above the elevation of the outer rim, whereas at Chesapeake Bay, the outer rim is higher than the central peak. The floor of the Toms Canyon crater is marked by parallel deep troughs and linear ridges formed of sedimentary rocks, whereas at Chesapeake Bay, the crater floor contains concentric faults and compression ridges formed in rocks of the crystalline basement. The Chesapeake Bay crater is distinguished further by its cluster of at least 23 adjacent secondary craters. The North American tektite strewn field, a widespread deposit of distal ejecta, is thought to be derived from the Chesapeake Bay impact, perhaps with a small contribution from the Toms Canyon impact. No ejecta field is known to be associated with the Montagnais impact. No immediate major extinction event is directly linked to any of these three impacts. There is evidence, however, that the Chesapeake Bay and Toms Canyon impacts helped initiate a long-term pulse of warm global climate, whose eventual dissipation coincided with an early Oligocene mass extinction event, 2 Ma after the impacts.

  9. Submarine thermal sprirngs on the galapagos rift.

    PubMed

    Corliss, J B; Dymond, J; Gordon, L I; Edmond, J M; von Herzen, R P; Ballard, R D; Green, K; Williams, D; Bainbridge, A; Crane, K; van Andel, T H

    1979-03-16

    The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis. PMID:17776033

  10. Underwater splice for submarine coaxial cable

    SciTech Connect

    Inouye, A.T.; Roe, T. Jr.; Tausing, W.R.; Wilson, J.V.

    1984-10-30

    The invention is a device for splicing submarine coaxial cable underwater on the seafloor with a simple push-on operation to restore and maintain electrical and mechanical strength integrity; the splice device is mateable directly with the severed ends of a coaxial cable to be repaired. Splicing assemblies comprise a dielectric pressure compensating fluid filled guide cavity, a gelled castor oil cap and wiping seals for exclusion of seawater, electrical contacts, a cable strength restoration mechanism, and a pressure compensation system for controlled extrusion of and depletion loss prevention of dielectric seal fluid during cable splicing. A splice is made underwater by directly inserting prepared ends of coaxial cable, having no connector attachments, into splicing assemblies.

  11. Real-time inspection by submarine images

    NASA Astrophysics Data System (ADS)

    Tascini, Guido; Zingaretti, Primo; Conte, Giuseppe

    1996-10-01

    A real-time application of computer vision concerning tracking and inspection of a submarine pipeline is described. The objective is to develop automatic procedures for supporting human operators in the real-time analysis of images acquired by means of cameras mounted on underwater remotely operated vehicles (ROV) Implementation of such procedures gives rise to a human-machine system for underwater pipeline inspection that can automatically detect and signal the presence of the pipe, of its structural or accessory elements, and of dangerous or alien objects in its neighborhood. The possibility of modifying the image acquisition rate in the simulations performed on video- recorded images is used to prove that the system performs all necessary processing with an acceptable robustness working in real-time up to a speed of about 2.5 kn, widely greater than that the actual ROVs and the security features allow.

  12. Submarine thermal springs on the Galapagos Rift

    USGS Publications Warehouse

    Corliss, J.B.; Dymond, J.; Gordon, L.I.; Edmond, J.M.; Von Herzen, R. P.; Ballard, Richard D.; Green, K.; Williams, D.; Bainbridge, A.; Crane, K.; Van Andel, T. H.

    1979-01-01

    The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis

  13. A contaminant monitor for submarine atmospheres.

    NASA Technical Reports Server (NTRS)

    Ruecker, M. R.

    1973-01-01

    A requirement for monitoring selected atmospheric constituents on board nuclear powered submarines has been met by the development of the Central Atmosphere Monitoring System, Mark I. This system employs a mass spectrometer to monitor H2, H2O, N2, O2, CO2, Freon 11, Freon 12, and Freon 114, in addition to an infrared sensor for CO. The CAMS MKI development is discussed, including background, operating fundamentals, principal requirements, functional and physical descriptions, and summarized test results. Each of two prototype units has successfully completed over 9000 hr of operational sea trails, providing the necessary ground work for the manufacture of production units. At the same time, these units, which have benefited extensively from NASA hardware experience, may in turn provide useful data for the development of a new class of maintainable atmospheric monitoring instrumentation for manned spacecraft.

  14. EAARL submarine topography: Biscayne National Park

    USGS Publications Warehouse

    Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Patterson, Judd; Harris, Melanie S.; Mosher, Lance

    2006-01-01

    This lidar-derived submarine topography map was produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs for the purposes of habitat mapping, ecological monitoring, change detection, and event assessment (for example: bleaching, hurricanes, disease outbreaks). As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring water depth and conducting cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to managers of coastal tropical habitats.

  15. Nitrogen biogeochemistry of submarine groundwater discharge

    USGS Publications Warehouse

    Kroeger, K.D.; Charette, M.A.

    2008-01-01

    To investigate the role of the seepage zone in transport, chemical speciation, and attenuation of nitrogen loads carried by submarine groundwater discharge, we collected nearshore groundwater samples (n = 328) and examined the distribution and isotopic signature (??15N) of nitrate and ammonium. In addition, we estimated nutrient fluxes from terrestrial and marine groundwater sources. We discuss our results in the context of three aquifer zones: a fresh groundwater zone, a shallow salinity transition zone (STZ), and a deep STZ. Groundwater plumes containing nitrate and ammonium occurred in the freshwater zone, whereas the deep STZ carried almost exclusively ammonium. The distributions of redox-cycled elements were consistent with theoretical thermodynamic stability of chemical species, with sharp interfaces between water masses of distinct oxidation : reduction potential, suggesting that microbial transformations of nitrogen were rapid relative to dispersive mixing. In limited locations in which overlap occurs between distribution of nitrate with that of ammonium and dissolved Fe2+, changes in concentration and in ??15N suggest loss of all species. Concurrent removal of NO 3- and NH4+, both in freshwater and the deep STZ, might occur through a range of mechanisms, including heterotrophic or autotrophic denitrification, coupled nitrfication : denitrification, anammox, or Mn oxidation of NH4+. Loss of nitrogen was not apparent in the shallow STZ, perhaps because of short water residence time. Despite organic C-poor conditions, the nearshore aquifer and subterranean estuary are biogeochemically active zones, where attenuation of N loads can occur. Extent of attenuation is controlled by the degree of mixing of biogeochemically dissimilar water masses, highlighting the critical role of hydrogeology in N biogeochemistry. Mixing is related in part to thinning of the freshwater lens before discharge and to dispersion at the fresh : saline groundwater interface, features common to all submarine groundwater discharge zones. ?? 2008, by the American Society of Limnology and Oceanography, Inc.

  16. Improved OTEC System for a Submarine Robot

    NASA Technical Reports Server (NTRS)

    Chao, Yi; Jones, Jack; Valdez, Thomas

    2010-01-01

    An ocean thermal energy conversion (OTEC), now undergoing development, is a less-massive, more-efficient means of exploiting the same basic principle as that of the proposed system described in "Alternative OTEC Scheme for a Submarine Robot" (NPO-43500), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 50. The proposed system as described previously would be based on the thawing-expansion/freezing-contraction behavior of a wax or perhaps another suitable phase-change material (PCM). The power generated by the system would be used to recharge the batteries in a battery- powered unmanned underwater vehicle [UUV (essentially, a small exploratory submarine robot)] of a type that has been deployed in large numbers in research pertaining to global warming. A UUV of this type travels between the ocean surface and depths, measuring temperature and salinity. At one phase of its operational cycle, the previously proposed system would utilize the surface ocean temperature (which lies between 15 and 30 C over most of the Earth) to melt a PCM that has a melting/freezing temperature of about 10 C. At the opposite phase of its operational cycle, the system would utilize the lower ocean temperature at depth (e.g., between 4 and 7 C at a depth of 300 m) to freeze the PCM. The melting or freezing would cause the PCM to expand or contract, respectively, by about 9 volume percent. The PCM would be contained in tubes that would be capable of expanding and contracting with the PCM. The PCM-containing tubes would be immersed in a hydraulic fluid. The expansion and contraction would drive a flow of the hydraulic fluid against a piston that, in turn, would push a rack-and-pinion gear system to spin a generator to charge a battery.

  17. Submarine landslides around the Canary Islands

    NASA Astrophysics Data System (ADS)

    Krastel, Sebastian; Schmincke, Hans-Ulrich; Jacobs, Colin L.; Rihm, Roland; Le Bas, Timothy P.; AlibéS, BáRbara

    2001-01-01

    The morphology and structure of the submarine flanks of the Canary Islands were mapped using the GLORIA long-range side-scan sonar system, bathymetric multibeam systems, and sediment echosounders. Twelve young (<2 Ma) giant landslides have been identified on the submarine flanks of the Canary Islands up to now. Older landslide events are long buried under a thick sediment cover due to high sedimentation rates around the Canary Islands. Most slides were found on the flanks of the youngest and most active islands of La Palma, El Hierro, and Tenerife, but young giant landslides were also identified on the flanks of the older (15-20 Ma) but still active eastern islands. Large-scale mass wasting is an important process during all periods of major magmatic activity. The long-lived volcanic constructive history of the islands of the Canary Archipelago is balanced by a correspondingly long history of destruction, resulting in a higher landslide frequency for the Canary Islands compared to the Hawaiian Islands, where giant landslides only occur late in the period of active shield growth. The lower stability of the flanks of the Canaries is probably due to the much steeper slopes of the islands, a result of the abundance of highly evolved intrusive and extrusive rocks. Another reason for the enhanced slope instability is the abundance of pyroclastic deposits on Canary Islands resulting from frequent explosive eruptions due to the elevated volatile contents in the highly alkalic magmas. Dike-induced rifting is most likely the main trigger mechanism for destabilization of the flanks. Flank collapses are a major geological hazard for the Canary Islands due to the sector collapses themselves as well as triggering of tsunamis. In at least one case, a giant lateral blast occurred when an active magmatic or hydrothermal system became unroofed during flank collapse.

  18. Alternative OTEC Scheme for a Submarine Robot

    NASA Technical Reports Server (NTRS)

    Jones, Jack; Chao, Yi

    2009-01-01

    A proposed system for exploiting the ocean thermal gradient to generate power would be based on the thawing-expansion/ freezing-contraction behavior of a wax or perhaps another suitable phase-change material. The power generated by this system would be used to recharge the batteries in a battery-powered unmanned underwater vehicle [UUV (essentially, a small exploratory submarine robot)] of a type that has been deployed in large numbers in research pertaining to global warming. A UUV of this type travels between the ocean surface and various depths, measuring temperature and salinity. This proposed system would be an alternative to another proposed ocean thermal energy conversion (OTEC) system that would serve the same purpose but would utilize a thermodynamic cycle in which CO2 would be the working fluid. That system is described in Utilizing Ocean Thermal Energy in a Submarine Robot (NPO-43304), immediately following this brief. The main advantage of this proposed system over the one using CO2 is that it could derive a useful amount of energy from a significantly smaller temperature difference. At one phase of its operational cycle, the system now proposed would utilize the surface ocean temperature (which lies between 15 and 20 C over most of the Earth) to melt a wax (e.g., pentadecane) that has a melting/freezing temperature of about 10 C. At the opposite phase of its operational cycle, the system would utilize the lower ocean temperature at depth (e.g., between 4 and 7 C at a depth of 300 m) to freeze the wax. The melting or freezing causes the wax to expand or contract, respectively, by about 8 volume percent.

  19. Submarine volcanoes along the Aegean volcanic arc

    NASA Astrophysics Data System (ADS)

    Nomikou, Paraskevi; Papanikolaou, Dimitrios; Alexandri, Matina; Sakellariou, Dimitris; Rousakis, Grigoris

    2013-06-01

    The Aegean volcanic arc has been investigated along its offshore areas and several submarine volcanic outcrops have been discovered in the last 25 years of research. The basic data including swath bathymetric maps, air-gun profiles, underwater photos and samples analysis have been presented along the four main volcanic groups of the arc. The description concerns: (i) Paphsanias submarine volcano in the Methana group, (ii) three volcanic domes to the east of Antimilos Volcano and hydrothermal activity in southeast Milos in the Milos group, (iii) three volcanic domes east of Christiana and a chain of about twenty volcanic domes and craters in the Kolumbo zone northeast of Santorini in the Santorini group and (iv) several volcanic domes and a volcanic caldera together with very deep slopes of several volcanic islands in the Nisyros group. The tectonic structure of the volcanic centers is described and related to the geometry of the arc and the neotectonic graben structures that usually host them. The NE-SW direction is dominant in the Santorini and Nisyros volcanic groups, located at the eastern part of the arc, where strike-slip is also present, whereas NW-SE direction dominates in Milos and Methana at the western part, where co-existence of E-W disrupting normal faults is observed. The volcanic relief reaches 1100-1200 m in most cases. This is produced from the outcrops of the volcanic centers emerging usually at 400-600 m depth and ending either below sea level or at high altitudes of 600-700 m on the islands. Hydrothermal activity at relatively high temperatures observed in Kolumbo is remarkable whereas low temperature phenomena have been detected in the Santorini caldera around Kameni islands and in the area southeast of Milos. In Methana and Nisyros, hydrothermal activity seems to be limited in the coastal areas without other offshore manifestations.

  20. Effect of Submarine Groundwater Discharge on Relict Arctic Submarine Permafrost and Gas Hydrate

    NASA Astrophysics Data System (ADS)

    Frederick, J. M.; Buffett, B. A.

    2014-12-01

    Permafrost-associated gas hydrate deposits exist at shallow depths within the sediments of the circum-Arctic continental shelves. Degradation of this shallow water reservoir has the potential to release large quantities of methane gas directly to the atmosphere. Gas hydrate stability and the permeability of the shelf sediments to gas migration is closely linked with submarine permafrost. Submarine permafrost extent depends on several factors, such as the lithology, sea level variations, mean annual air temperature, ocean bottom water temperature, geothermal heat flux, and the salinity of the pore water. The salinity of the pore water is especially relevant because it partially controls the freezing point for both ice and gas hydrate. Measurements of deep pore water salinity are few and far between, but show that deep off-shore sediments are fresh. Deep freshening has been attributed to large-scale topographically-driven submarine groundwater discharge, which introduces fresh terrestrial groundwater into deep marine sediments. We investigate the role of submarine ground water discharge on the salinity field and its effects on the seaward extent of relict submarine permafrost and gas hydrate stability on the Arctic shelf with a 2D shelf-scale model based on the finite volume method. The model tracks the evolution of the temperature, salinity, and pressure fields given imposed boundary conditions, with latent heat of water ice and hydrate formation included. The permeability structure of the sediments is coupled to changes in permafrost. Results show that pore fluid is strongly influenced by the permeability variations imposed by the overlying permafrost layer. Groundwater discharge tends to travel horizontally off-shore beneath the permafrost layer and the freshwater-saltwater interface location displays long timescale transient behavior that is dependent on the groundwater discharge strength. The seaward permafrost extent is in turn strongly influenced by the salinity field and location of the freshwater-saltwater transition. Our results suggest that the role of salt transport and its effect on permafrost evolution can provide context for the interpretation of recent permafrost maps and methane observations in the Arctic.

  1. Spectral narrowing via quantum coherence

    SciTech Connect

    Mikhailov, Eugeniy E.; Rostovtsev, Yuri V.; Zhang Aihua; Welch, George R.; Sautenkov, Vladimir A.; Zubairy, M. Suhail; Scully, Marlan O.

    2006-07-15

    We have studied the transmission through an optically thick {sup 87}Rb vapor that is illuminated by monochromatic and noise-broadened laser fields in {lambda} configuration. The spectral width of the beat signal between the two fields after transmission through the atomic medium is more than 1000 times narrower than the spectral width of this signal before the medium.

  2. Three-dimensional grid generation about a submarine

    NASA Technical Reports Server (NTRS)

    Abolhassani, Jamshid Samareh; Smith, Robert E.

    1988-01-01

    A systematic multiple-block grid method has been developed to compute grids about submarines. Several topologies are proposed, and an oscillatory transfinite interpolation is used in the grid construction.

  3. View west of reserve basin of submarine trout and frigate ...

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

    View west of reserve basin of submarine trout and frigate Edward E. McDonnell - Naval Base Philadelphia-Philadelphia Naval Shipyard, Reserve Basin & Marine Railway, League Island, Philadelphia, Philadelphia County, PA

  4. Demersal fish distribution and habitat use within and near Baltimore and Norfolk Canyons, U.S. Middle Atlantic Slope

    USGS Publications Warehouse

    Ross, Steve W.; Rhode, Mike; Quattrini, Andrea M.

    2015-01-01

    Numerous submarine canyons along the United States middle Atlantic continental margin support enhanced productivity, diverse and unique habitats, active fisheries, and are vulnerable to various anthropogenic disturbances. During two cruises (15 Aug–2 Oct 2012 and 30 Apr–27 May 2013), Baltimore and Norfolk canyons and nearby areas (including two cold seeps) were intensively surveyed to determine demersal fish distributions and habitat associations. Overall, 34 ROV dives (234–1612 m) resulted in 295 h of bottom video observations and numerous collections. These data were supplemented by 40, 30-min bottom trawl samples. Fish observations were assigned to five general habitat designations: 1) sand-mud (flat), 2) sloping sand-mud with burrows, 3) low profile gravel, rock, boulder, 4) high profile, canyon walls, rocks or ridges, and 5) seep-mixed hard and soft substrata, the later subdivided into seven habitats based on amounts of dead mussel and rock cover. The influence of corals, sponges and live mussels (seeps only) on fish distributions was also investigated. Both canyon areas supported abundant and diverse fish communities and exhibited a wide range of habitats, including extensive areas of deep-sea corals and sponges and two nearby methane seeps (380–430 m, 1455–1610 m). All methods combined yielded a total of 123 species of fishes, 12 of which are either new records for this region or have new range data. Depth was a major factor that separated the fish faunas into two zones with a boundary around 1400 m. Fishes defining the deeper zone included Lycodes sp.,Dicrolene introniger, Gaidropsaurus ensis, Hydrolagus affinis, Antimora rostrata, andAldrovandia sp. Fishes in the deep zone did not exhibit strong habitat affinities, despite the presence of a quite rugged, extensive methane seep. We propose that habitat specificity decreases with increasing depth. Fishes in the shallower zone, characterized by Laemonema sp., Phycis chesteri, Nezumia bairdii, Brosme brosme, and Helicolenus dactylopterus, exhibited a variety of habitat use patterns. In general, fish assemblages in the soft substrata areas (dominated by P. chesteri, N. bairdii, Glyptocephalus cynoglossus, Lophius americanus, Merluccius albidus) were different from those in more complex habitats (dominated by Laemonema spp., Hoplostethus spp., B. brosme,Benthocometes robustus, L. americanus, Dysommina rugosa). Although, when present, the dense coral and sponge cover did not statistically affect general fish assemblage patterns in hard bottom habitats, these sessile organisms markedly increased habitat complexity, and some fish species exhibited close association with them. Fish species compositions in the two canyons were not substantially different from the surrounding slopes. However, the diversity of habitats within both the canyons and seeps exerted an important influence on assemblage structure. At least for some species (e.g., B. brosme) canyon and seep environments may be a refuge from intensive bottom fishing activities. We frequently observed evidence of commercial and recreational fishing activity (lost gear on bottom and fishing boats in the area) throughout the canyons and some resulting habitat damage. Conservation measures for the unique and more vulnerable areas (seep and coral habitats) have recently been approved.

  5. Perspective view over the Grand Canyon, Arizona

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This simulated true color perspective view over the Grand Canyon was created from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data acquired on May 12, 2000. The Grand Canyon Village is in the lower foreground; the Bright Angel Trail crosses the Tonto Platform, before dropping down to the Colorado Village and then to the Phantom Ranch (green area across the river). Bright Angel Canyon and the North Rim dominate the view. At the top center of the image the dark blue area with light blue haze is an active forest fire.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 5 km in foreground to 40 km Location: 36.3 degrees north latitude, 112 degrees west longitude Orientation: North-northeast at top Original Data Resolution: ASTER 15 meters Dates Acquired: May 12, 2000

  6. 20130416_Green Machine Florida Canyon Hourly Data

    DOE Data Explorer

    Vanderhoff, Alex

    2013-04-24

    Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 4/16/13.

  7. River resource management in the Grand Canyon

    SciTech Connect

    1996-07-01

    The objective of GCES was to identify and predict the effects of variations in operating strategies on the riverine environment below Glen Canyon Dam within the physical and legal constraints under which the dam must operate. Critical elements for the development of GCES and other such projects include a list of resources directly or indirectly affected by management, a list of management options, and an ecosystem framework showing the causal connections among system components, potential management strategies that include humans as integral parts of the environment.

  8. Big Canyon Creek Ecological Restoration Strategy.

    SciTech Connect

    Rasmussen, Lynn; Richardson, Shannon

    2007-10-01

    He-yey, Nez Perce for steelhead or rainbow trout (Oncorhynchus mykiss), are a culturally and ecologically significant resource within the Big Canyon Creek watershed; they are also part of the federally listed Snake River Basin Steelhead DPS. The majority of the Big Canyon Creek drainage is considered critical habitat for that DPS as well as for the federally listed Snake River fall chinook (Oncorhynchus tshawytscha) ESU. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resources Management-Watershed (Tribe), in an effort to support the continued existence of these and other aquatic species, have developed this document to direct funding toward priority restoration projects in priority areas for the Big Canyon Creek watershed. In order to achieve this, the District and the Tribe: (1) Developed a working group and technical team composed of managers from a variety of stakeholders within the basin; (2) Established geographically distinct sub-watershed areas called Assessment Units (AUs); (3) Created a prioritization framework for the AUs and prioritized them; and (4) Developed treatment strategies to utilize within the prioritized AUs. Assessment Units were delineated by significant shifts in sampled juvenile O. mykiss (steelhead/rainbow trout) densities, which were found to fall at fish passage barriers. The prioritization framework considered four aspects critical to determining the relative importance of performing restoration in a certain area: density of critical fish species, physical condition of the AU, water quantity, and water quality. It was established, through vigorous data analysis within these four areas, that the geographic priority areas for restoration within the Big Canyon Creek watershed are Big Canyon Creek from stream km 45.5 to the headwaters, Little Canyon from km 15 to 30, the mainstem corridors of Big Canyon (mouth to 7km) and Little Canyon (mouth to 7km). The District and the Tribe then used data collected from the District's stream assessment and inventory, utilizing the Stream Visual Assessment Protocol (SVAP), to determine treatment necessary to bring 90% of reaches ranked Poor or Fair through the SVAP up to good or excellent. In 10 year's time, all reaches that were previously evaluated with SVAP will be reevaluated to determine progress and to adapt methods for continued success. Over 400 miles of stream need treatment in order to meet identified restoration goals. Treatments include practices which result in riparian habitat improvements, nutrient reductions, channel condition improvements, fish habitat improvements, invasive species control, water withdrawal reductions, improved hydrologic alterations, upland sediment reductions, and passage barrier removal. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resource Management Watershed Division (Tribe) developed this document to guide restoration activities within the Big Canyon Creek watershed for the period of 2008-2018. This plan was created to demonstrate the ongoing need and potential for anadromous fish habitat restoration within the watershed and to ensure continued implementation of restoration actions and activities. It was developed not only to guide the District and the Tribe, but also to encourage cooperation among all stakeholders, including landowners, government agencies, private organizations, tribal governments, and elected officials. Through sharing information, skills, and resources in an active, cooperative relationships, all concerned parties will have the opportunity to join together to strengthen and maintain a sustainable natural resource base for present and future generations within the watershed. The primary goal of the strategy is to address aquatic habitat restoration needs on a watershed level for resident and anadromous fish species, promoting quality habitat within a self-sustaining watershed. Seven objectives have been developed to support this goal: (1) Identify factors limiting quality and quantity of steelhead spawning and rearing habitat; (2) Identify targets for optimal conditions within the basin; (3) Identify treatments to address limiting factors and goals for optimal conditions; (4) Prioritize location of restoration activities; (5) Identify information and data gaps; (6) Identify future monitoring strategy to support adaptive management; and (7) Identify opportunities for collaboration with stakeholders.

  9. Green Machine Florida Canyon Hourly Data 20130731

    DOE Data Explorer

    Vanderhoff, Alex

    2013-08-30

    Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 7/1/13 to 7/31/13.

  10. Green Machine Florida Canyon Hourly Data

    DOE Data Explorer

    Vanderhoff, Alex

    2013-07-15

    Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 6/1/13 to 6/30/13

  11. 20140430_Green Machine Florida Canyon Hourly Data

    DOE Data Explorer

    Thibedeau, Joe

    2014-05-05

    Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 01 April to 30 April 2014.

  12. 4. VISTA POINT AND INTERPRETIVE PLAQUE AT LEE VINING CANYON. ...

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

    4. VISTA POINT AND INTERPRETIVE PLAQUE AT LEE VINING CANYON. NOTE ROAD CUT ON CANYON WALL. LOOKING NNE. GIS: N-37 56 30.3 / 119 13 44.8 - Tioga Road, Between Crane Flat & Tioga Pass, Yosemite Village, Mariposa County, CA

  13. 36 CFR 7.70 - Glen Canyon National Recreation Area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Superintendent of Grand Canyon National Park. The National Park Service reserves the right to limit the number of... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT...

  14. 36 CFR 7.70 - Glen Canyon National Recreation Area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Superintendent of Grand Canyon National Park. The National Park Service reserves the right to limit the number of... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT...

  15. 36 CFR 7.70 - Glen Canyon National Recreation Area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Superintendent of Grand Canyon National Park. The National Park Service reserves the right to limit the number of... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT...

  16. 36 CFR 7.70 - Glen Canyon National Recreation Area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Superintendent of Grand Canyon National Park. The National Park Service reserves the right to limit the number of... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT...

  17. 75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-17

    ... Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY: Bureau of Reclamation... Interior (Secretary) is renewing the charter for the Glen Canyon Dam Adaptive Management Work Group. The purpose of the Adaptive Management Work Group is to advise and to provide recommendations to the...

  18. 36 CFR 7.4 - Grand Canyon National Park.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial passenger-carrying motor vehicles....

  19. Cardiometabolic Health in Submariners Returning from a 3-Month Patrol.

    PubMed

    Gasier, Heath G; Young, Colin R; Gaffney-Stomberg, Erin; McAdams, Douglas C; Lutz, Laura J; McClung, James P

    2016-01-01

    Confined space, limited exercise equipment, rotating shift work and reduced sleep may affect cardiometabolic health in submariners. To test this hypothesis, 53 male U.S. Submariners (20-39 years) were studied before and after a 3-month routine submarine patrol. Measures included anthropometrics, dietary and physical activity, biomarkers of cardiometabolic health, energy and appetite regulation, and inflammation. Before deployment, 62% of submariners had a body fat % (BF%) ≥ 25% (obesity), and of this group, 30% met the criteria for metabolic syndrome. In obese volunteers, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), leptin, the leptin/adiponectin ratio, and pro-inflammatory chemokines growth-related oncogene and macrophage-derived chemokine were significantly higher compared to non-obese submariners. Following the patrol, a significant mean reduction in body mass (5%) and fat-mass (11%) occurred in the obese group as a result of reduced energy intake (~2000 kJ) during the patrol; and, independent of group, modest improvements in serum lipids and a mean reduction in interferon γ-induced protein 10 and monocyte chemotactic protein 1 were observed. Since 43% of the submariners remained obese, and 18% continued to meet the criteria for metabolic syndrome following the patrol, the magnitude of weight loss was insufficient to completely abolish metabolic dysfunction. Submergence up to 3-months, however, does not appear to be the cause of obesity, which is similar to that of the general population. PMID:26867201

  20. Cardiometabolic Health in Submariners Returning from a 3-Month Patrol

    PubMed Central

    Gasier, Heath G.; Young, Colin R.; Gaffney-Stomberg, Erin; McAdams, Douglas C.; Lutz, Laura J.; McClung, James P.

    2016-01-01

    Confined space, limited exercise equipm