Sample records for coast range ophiolite
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Shervais, J.W.; Kimbrough, D.L.; Renne, P.; Hanan, B.B.; Murchey, B.; Snow, C.A.; Zoglman, Schuman M.M.; Beaman, J.
2004-01-01
The Coast Range ophiolite of California is one of the most extensive ophiolite terranes in North America, extending over 700 km from the northernmost Sacramento Valley to the southern Transverse Ranges in central California. This ophiolite, and other ophiolite remnants with similar mid-Jurassic ages, represent a major but short-lived episode of oceanic crust formation that affected much of western North America. The history of this ophiolite is important for models of the tectonic evolution of western North America during the Mesozoic, and a range of conflicting interpretations have arisen. Current petrologic, geochemical, stratigraphic, and radiometric age data all favor the interpretation that the Coast Range ophiolite formed to a large extent by rapid extension in the forearc region of a nascent subduction zone. Closer inspection of these data, however, along with detailed studies of field relationships at several locales, show that formation of the ophiolite was more complex, and requires several stages of formation. Our work shows that exposures of the Coast Range ophiolite preserve evidence for four stages of magmatic development. The first three stages represent formation of the ophiolite above a nascent subduction zone. Rocks associated with the first stage include ophiolite layered gabbros, a sheeted complex, and volcanic rocks vith arc tholeiitic or (roore rarely) low-K calc-alkaline affinities. The second stage is characterized by intrusive wehrlite-clinopyroxenite complexes, intrusive gabbros, Cr-rich diorites, and volcanic rocks with high-Ca boninitic or tholeiitic ankaramite affinities. The third stage includes diorite and quartz diorite plutons, felsic dike and sill complexes, and calc-alkaline volcanic rocks. The first three stages of ophiolite formation were terminated by the intrusion of mid-ocean ridge basalt dikes, and the eruption of mid-ocean ridge basalt or ocean-island basalt volcanic suites. We interpret this final magmatic event (MORB
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Scott, T. J.; Arcilla, C. A.; Cardace, D.; Hoehler, T. M.; McCollom, T. M.; Meyer-Dombard, D. R.; Schrenk, M. O.
2013-12-01
The deep biosphere in cold, dark sub-seafloor ultramafic rocks (i.e., those rocks rich in Fe and Mg) is stressed by exceedingly high pH, transient, if any, inorganic carbon availability, and little known organic carbon inventories. As a test of heterotrophic carbon use, serpentinite-associated waters (from groundwater sampling wells and associated surface seepages in tectonically uplifted mantle units in ophiolites) were tested for differences with respect to aqueous geochemistry and performance in EcoPlates™ - Biolog Inc. .. This work focuses on two field locations for water sampling: the Coast Range Ophiolite, CA, USA, and the Zambales Ophiolite, Philippines. Characteristics of each sampling site are presented (pH, mineral substrate, Ca2+/Mg2+ ratio, aqueous metal loads, etc.). Complementary EcoPlate™ results [prefabricated 96-well plates, seeded with triplicate experiments for determining microbiological community response to difference organic carbon sources; a triplicate control experiment with just water is built in to the plate also] are also presented. We found that waters from selected California [groundwater wells (7 discrete wells) and related surface seeps (5 hydrologically connected sites)] and Philippines [4 Zambales Ophiolite springs/seepages] sourced in serpentinites were analyzed. EcoPlate™ average well-color development (AWCD), which demonstrates microbial activities averaged per plate (as in Garland and Mills, 1991), differs across sites. Correlations of AWCD with environmental data (such as pH, oxidation-reduction potential or ORP, Ca2+/Mg2+ ratio, and Fe contents) are evaluated. Clarifying the geochemical-biological relationships that bear out in these analyses informs discourse on the energetic limits of life in serpentinizing systems, with relevance to ultramafic-hosted life on continents and in the seabed.
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Mccann, A. R.; Cardace, D.; Carnevale, D.; Ehlmann, B. L.
2011-12-01
California contains a number of ultramafic (Fe- and Mg rich) rock bodies, including the Coast Range Ophiolite, a block of oceanic crust and upper mantle tectonically emplaced onto land. These ultramafic rocks are primarily composed of olivine and pyroxene, both of which are stable at the high temperatures and pressures in the deep subsurface where they crystallize but become unstable at low temperature and low pressure conditions near the surface. They are highly reduced rocks, creating chemical disequilibria, which can theoretically provide energy to chemoautotrophic organisms. Serpentinization (serpentine-forming) reactions between the rocks and water produce hydrogen molecules, which can be metabolized by diverse organisms. Earth and Mars have shown evidence of similar early geologic histories, possibly with widespread reducing habitable environments (Schulte et al., 2006). Recent data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) have shown serpentine-bearing outcrops near Nili Fossae (21 N, 282 W) and elsewhere in Mars' cratered highlands. Serpentine-bearing outcrops are rare, but their presence confirms that such systems involving the aqueous alteration of ultramafic rocks were active in the past (specifically during the Noachian epoch (older than ~3.7 billion years), possibly producing aqueous habitats suitable for chemoautotrophic life (Ehlmann et al., 2010). Remotely sensed data cannot confirm whether there is active serpentinization on Mars, however exposed, presently serpentinizing ultramafics in terrestrial ophiolites such as those of the California Coast Range provide points of comparison for similar Martian rocks. Volume expansion during serpentinization fractures the host rock, exposing new reaction surfaces, allowing further serpentinization. If subsurface liquid water is present on Mars, serpentinization may still be occurring. We will provide x-ray diffraction and petrographic data for surface serpentinites from the Coast
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Hoehler, T.; Som, S.; Schrenk, M.; McCollom, T.; Cardace, D.
2016-01-01
Metabolic potential and activity associated with hydrogen and carbon monoxide were characterized in fluids sampled from the the Coast Range Ophiolite Microbial Observatory (CROMO). CROMO consists of two clusters of science-dedicated wells drilled to varying depths up to 35m in the actively serpentinizing, Jurassic-age Coast Range Ophiolite of Northern California, along with a suite of pre-existing monitoring wells at the same site. Consistent with the fluid chemistry observed in other serpentinizing systems, CROMO fluids are highly alkaline, with pH up to 12.5, high in methane, with concentrations up 1600 micromolar, and low in dissolved inorganic carbon (DIC), with concentrations of 10's to 100's of micromolar. CROMO is conspicuous for fluid H2 concentrations that are consistently sub-micromolar, orders of magnitude lower than is typical of other systems. However, higher H2 concentrations (10's -100's of micromolar) at an earlier stage of fluid chemical evolution are predicted by, or consistent with: thermodynamic models for fluid chemistry based on parent rock composition equivalent to local peridotite and with water:rock ratio constrained by observed pH; the presence of magnetite at several wt% in CROMO drill cores; and concentrations of formate and carbon monoxide that would require elevated H2 if formed in equilibrium with H2 and DIC. Calculated Gibbs energy changes for reaction of H2 and CO in each of several metabolisms, across the range of fluid composition encompassed by the CROMO wells, range from bioenergetically feasible (capable of driving ATP synthesis) to thermodynamically unfavorable. Active consumption relative to killed controls was observed for both CO and H2 during incubation of fluids from the pre-existing monitoring wells; in incubations of freshly cored solids, consumption was only observed in one sample set (corresponding to the lowest pH) out of three. The specific metabolisms by which H2 and CO are consumed remain to be determined.
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Meyer-Dombard, D'Arcy R; Casar, Caitlin P; Simon, Alexander G; Cardace, Dawn; Schrenk, Matthew O; Arcilla, Carlo A
2018-05-01
Terrestrial serpentinizing systems harbor microbial subsurface life. Passive or active microbially mediated iron transformations at alkaline conditions in deep biosphere serpentinizing ecosystems are understudied. We explore these processes in the Zambales (Philippines) and Coast Range (CA, USA) ophiolites, and associated surface ecosystems by probing the relevance of samples acquired at the surface to in situ, subsurface ecosystems, and the nature of microbe-mineral associations in the subsurface. In this pilot study, we use microcosm experiments and batch culturing directed at iron redox transformations to confirm thermodynamically based predictions that iron transformations may be important in subsurface serpentinizing ecosystems. Biofilms formed on rock cores from the Zambales ophiolite on surface and in-pit associations, confirming that organisms from serpentinizing systems can form biofilms in subsurface environments. Analysis by XPS and FTIR confirmed that enrichment culturing utilizing ferric iron growth substrates produced reduced, magnetic solids containing siderite, spinels, and FeO minerals. Microcosms and enrichment cultures supported organisms whose near relatives participate in iron redox transformations. Further, a potential 'principal' microbial community common to solid samples in serpentinizing systems was identified. These results indicate collectively that iron redox transformations should be more thoroughly and universally considered when assessing the function of terrestrial subsurface ecosystems driven by serpentinization.
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One-carbon (bio ?) Geochemistry in Subsurface Waters of the Serpentinizing Coast Range Ophiolite
Hoehler, Tori M.; Mccollom, Tom; Schrenk, Matt; Cardace, Dawn
2011-01-01
Serpentinization - the aqueous alteration of ultramafic rocks - typically imparts a highly reducing and alkaline character to the reacting fluids. In turn, these can influence the speciation and potential for metabolism of one-carbon compounds in the system. We examined the aqueous geochemistry and assessed the biological potential of one-carbon compounds in the subsurface of the McLaughlin Natural Reserve (Coast Range Ophiolite, California, USA). Fluids from wells sunk at depths of 25-90 meters have pH values ranging from 9.7 to 11.5 and dissolved inorganic carbon (DIC concentrations) generally below 60 micromolar. Methane is present at concentrations up to 1.3 millimolar (approximately one-atmosphere saturation), and hydrogen concentrations are below 15 nanomolar, suggesting active consumption of H2 and production of CH4. However, methane production from CO2 is thermodynamically unfavorable under these conditions. Additionally, the speciation of DIC predominantly into carbonate at these high pH values creates a problem of carbon availability for any organisms that require CO2 (or bicarbonate) for catabolism or anabolism. A potential alternative is carbon monoxide, which is present in these waters at concentrations 2000-fold higher than equilibrium with atmospheric CO. CO is utilized in a variety of metabolisms, including methanogenesis, and bioavailability is not adversely affected by pH-dependent speciation (as for DIC). Methanogenesis from CO under in situ conditions is thermodynamically favorable and would satisfy biological energy requirements with respect to both Gibbs Energy yield and power.
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Hagstrum, J.T.; Murchey, B.L.
1996-01-01
Upper Jurassic red tuffaceous chert above the Coast Range ophiolite at Stanley Mountain, California (lat 35??N, long 240??E), contains three components of remanent magnetization. The first component (A; removed by ???100-???200 ??C) has a direction near the present-day field for southern California and is probably a recently acquired thermoviscous magnetization. A second component (B; removed between ???100 and ???600 ??C) is identical to that observed by previous workers in samples of underlying pillow basalt and overlying terrigenous sedimentary rocks. This component has constant normal polarity and direction throughout the entire section, although these rocks were deposited during a mixed polarity interval of the geomagnetic field. The B magnetization, therefore, is inferred to be a secondary magnetization acquired during accretion, uplift, or Miocene volcanism prior to regional clockwise rotation. The highest temperature component (C; removed between ???480 and 680 ??C) is of dual polarity and is tentatively interpreted as a primary magnetization, although it fails a reversal test possibly due to contamination by B. Separation of the B and C components is best shown by samples with negative-inclination C directions, and a corrected mean direction using only these samples indicates an initial paleolatitude of 32??N ?? 8??. Paleobiogeographic models relating radiolarian faunal distribution patterns to paleolatitude have apparently been incorrectly calibrated using the overprint B component. Few other paleomagnetic data have been incorporated in these models, and faunal distribution patterns are poorly known and mostly unqualified. The available data, therefore, do not support formation of the Coast Range ophiolite at Stanley Mountain near the paleoequator or accretion at ???10??N paleolatitude, as has been previously suggested based on paleomagnetic data, but indicate deposition near expected paleolatitudes for North America (35??N ?? 4??) during Late Jurassic
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Stander, A.; Nelms, M.; Wilkinson, K.; Dyar, M. D.; Cardace, D.
2013-12-01
The reduced status of mantle rocks is a possible controller and indicator of deep life habitat, due to interactions between water and ultramafic (Fe, Mg-rich) minerals, which, under reducing conditions, can yield copious free hydrogen, which is an energy source for rock-hosted chemosynthetic life. In this work, Mössbauer spectroscopy was used to parameterize the redox status of Fe in altering peridotites of the Coast Range Ophiolite (CRO) in California, USA and Zambales Ophiolite (ZO) in the Philippines. Fe-bearing minerals were identified and data were collected for the percentages of Fe(III)and Fe(II)and bulk Fe concentration. Thin section analysis shows that relict primary olivines and spinels generally constitute a small percentage of the ZO and CRO rock, and given satisfactory estimates of the volume of the ultramafic units of the ZO and CRO, a stoichiometric H2 production can be estimated. In addition, ZO serpentinites are ~63,000 ppm Fe in bulk samples; they contain ~41-58% Fe(III)and ~23-34% Fe(II) in serpentine and relict minerals along with ~8-30% of the total Fe as magnetite. CRO serpentinites are ~42,000 ppm Fe in bulk samples; they contain ~15-50% Fe(III), ~22-88% Fe(II) in serpentine and relict minerals, and ~0-52% of total Fe is in magnetite (Fe(II)Fe(III)2O4). Assuming stoichiometric production of H2, and given the following representation of serpentinization 2(FeO)rock + H2O → (Fe2O3)rock +H2, we calculated the maximum quantity of hydrogen released and yet to be released through the oxidation of Fe(II). Given that relatively high Fe(III)/Fetotal values can imply higher water:rock ratios during rock alteration (Andreani et al., 2013), we can deduce that ZO ultramafics in this study have experienced a net higher water:rock ratio than CRO ultramafics. We compare possible H2 yields and contrast the tectonic and alteration histories of the selected ultramafic units. (M. Andreani, M. Muñoz, C. Marcaillou, A. Delacour, 2013, μXANES study of iron
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Cardace, D.; Schrenk, M. O.; McCollom, T. M.; Hoehler, T. M.
2017-12-01
Serpentinization is the aqueous alteration (or hydration) of olivine and pyroxene minerals in ultramafic rocks, occurring in the seabed and ultramafic units on continents, such as at the Coast Range Ophiolite (CRO) in northern California, USA. Mineral products of serpentinization include serpentine, magnetite, brucite, talc, oxyhydroxides, carbonates, and diverse clay minerals. Such mineral transformations generate extremely high pH solutions with characteristic cation and dissolved metal loads, transmitting CH4, H2, and CO gas mixtures from depth; deep life in ultramafic terrains is thought to be fueled by chemical energy derived from these geochemical reactions. The installation of 8 groundwater monitoring wells in the CRO has allowed frequent monitoring since 2011. Influx of deeply sourced, serpentinization-influenced waters is evidenced by related geochemical shifts (e.g., pH, oxidation-reduction potential), but is apparently mixing with other, regionally important groundwater types. Evaluation salinity loads in concert with other parameters, we model the mixing scenario of this site of ongoing scientific study and experimentation.
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Morrison, Jean M.; Goldhaber, Martin B.; Mills, Christopher T.; Breit, George N.; Hooper, Robert L.; Holloway, JoAnn M.; Diehl, Sharon F.; Ranville, James F.
2015-01-01
A soil geochemical study in northern California was done to investigate the role that weathering and transport play in the regional distribution and mobility of geogenic Cr and Ni, which are both potentially toxic and carcinogenic. These elements are enriched in ultramafic rocks (primarily serpentinite) and the soils derived from them (1700–10,000 mg Cr per kg soil and 1300–3900 mg Ni per kg soil) in the Coast Range ophiolite. Chromium and Ni have been transported eastward from the Coast Range into the western Sacramento Valley and as a result, valley soil is enriched in Cr (80–1420 mg kg−1) and Ni (65–224 mg kg−1) compared to median values of U.S. soils of 50 and 15 mg kg−1, respectively. Nickel in ultramafic source rocks and soils is present in serpentine minerals (lizardite, antigorite, and chrysotile) and is more easily weathered compared to Cr, which primarily resides in highly refractory chromite ([Mg,Fe2+][Cr3+,Al,Fe3+]2O4). Although the majority of Cr and Ni in soils are in refractory chromite and serpentine minerals, the etching and dissolution of these minerals, presence of Cr- and Ni-enriched clay minerals and development of nanocrystalline Fe (hydr)oxides is evidence that a significant fractions of these elements have been transferred to potentially more labile phases.
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Ortiz, Estefania; Tominaga, Masako; Cardace, Dawn; Schrenk, Matthew O.; Hoehler, Tori M.; Kubo, Michael D.; Rucker, Dale F.
2018-01-01
Geophysical remote sensing both on land and at sea has emerged as a powerful approach to characterize in situ water-rock interaction processes in time and space. We conducted 2-D Electrical Resistivity Tomography (ERT) surveys to investigate in situ hydrogeological architecture within the Jurassic age tectonic mélange portion of the Coast Range Ophiolite Microbial Observatory (CROMO) during wet and dry seasons, where water-rock interactive processes are thought to facilitate a subsurface biosphere. Integrating survey tracks traversing two previously drilled wells, QV1,1 and CSW1,1 at the CROMO site with wireline and core data, and the Serpentine Valley site, we successfully documented changes in hydrogeologic properties in the CROMO formation, i.e., lateral and vertical distribution of conductive zones and their temporal behavior that are dependent upon seasonal hydrology. Based on the core-log-ERT integration, we propose a hydrogeological architectural model, in which the formation is composed of three distinct aquifer systems: perched serpentinite aquifer without seasonal dependency (shallow system), well-cemented serpentine confining beds with seasonal dependency (intermediate system), serpentinite aquifer (deep system), and the ultramafic basement that acts as a quasi-aquiclude (below the deep system). The stunning contrast between the seasonality in the surface water availability and groundwater storativity in the formation allowed us to locate zones where serpentinite weathering and possibly deeper serpentinization processes might have taken place. We based our findings primarily on lithological composition and the distribution of the conductive formation, our work highlights the link between serpentinite weathering processes and possible sources of water in time and space.
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Origin of Manipur Ophiolite Complex, Indo-Myanmar Range ...
Indian Academy of Sciences (India)
r b
2017-11-20
Nov 20, 2017 ... The Manipur. Ophiolite. Complex: Varying degree of serpentinization and relict pyroxenes. 11/20/2017. 13. Page 14. Serpentinization process preserves the protolith elemental signatures. 11/20/2017. 14 ... The range of Nd isotope ratios in the serpentinized peridotites. 11/20/2017. 17. Kingson et al.
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Watt, Janet Tilden; Ponce, David A.; Graymer, Russell W.; Jachens, Robert C.; Simpson, Robert W.
2014-01-01
While an enormous amount of research has been focused on trying to understand the geologic history and neotectonics of the San Andreas-Calaveras fault (SAF-CF) junction, fundamental questions concerning fault geometry and mechanisms for slip transfer through the junction remain. We use potential-field, geologic, geodetic, and seismicity data to investigate the 3-D geologic framework of the SAF-CF junction and identify potential slip-transferring structures within the junction. Geophysical evidence suggests that the San Andreas and Calaveras fault zones dip away from each other within the northern portion of the junction, bounding a triangular-shaped wedge of crust in cross section. This wedge changes shape to the south as fault geometries change and fault activity shifts between fault strands, particularly along the Calaveras fault zone (CFZ). Potential-field modeling and relocated seismicity suggest that the Paicines and San Benito strands of the CFZ dip 65° to 70° NE and form the southwest boundary of a folded 1 to 3 km thick tabular body of Coast Range Ophiolite (CRO) within the Vallecitos syncline. We identify and characterize two steeply dipping, seismically active cross structures within the junction that are associated with serpentinite in the subsurface. The architecture of the SAF-CF junction presented in this study may help explain fault-normal motions currently observed in geodetic data and help constrain the seismic hazard. The abundance of serpentinite and related CRO in the subsurface is a significant discovery that not only helps constrain the geometry of structures but may also help explain fault behavior and the tectonic evolution of the SAF-CF junction.
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Sousa, A.; Cardace, D.
2017-12-01
Serpentinizing systems hold much promise as potentially habitable environments in diverse planetary settings. They involve abundant and simple ingredients (i.e., the mineral olivine, liquid water), support subsurface microbial communities on Earth (Crespo-Medina et al. 2014; Suzuki et al. 2014; Kelley et al. 2005) and are thought to occur elsewhere in our solar system such as Mars (Schulte et al. 2006; Ehlmann et al. 2010)and possibly ocean worlds (Waite et al. 2017; Vance 2009). Although geochemical and microbial data collection continues in serpentinizing systems, the identification and resolution of potential biosignatures in serpentinites are not yet clear. Specifically, the micro-scale mineralogical contexts in which cell fragments or biofilm residues may be formed and preserved is lacking. Here we report preliminary transmission and reflection mode μ-FTIR spectral maps and XRD diffractograms, obtained with instruments relevant to robotic exploration missions (Blake et al. 2012; Igisu et al. 2009; Leroi et al. 2009). Samples analyzed include ultramafic rock and constituent mineral standards (e.g., olivine) and rocks collected from near surface sites associated with the NASA Astrobiology Institute-funded initiative, the Coast Range Ophiolite Microbial Observatory (CROMO), in Lower Lake, CA (Cardace et al. 2013). These new results provide co-registered, complementary data on astrobiologically important rock and mineral phases related to serpentinization (Crespo-Medina et al. 2014; Twing et al. 2017). Future work will leverage this data set in microbial colonization experiments aimed at parsing background organic loads in serpentinites from surficial/fracture-localized modern biofilm signatures.
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Schrenk, M. O.; Sabuda, M.; Brazelton, W. J.; Twing, K. I.
2017-12-01
The study of serpentinization-influenced microbial ecosystems at and below the seafloor has accelerated in recent years with multidisciplinary drilling expeditions to the Atlantis Massif (X357), Southwest Indian Ridge (X360) and Mariana Forearc (X366). In parallel, a number of studies have surveyed serpentinizing systems in ophiolite complexes which host a range of geologic histories, geochemical characteristics, fluid pathways, and consequently microbiology. As ophiolite complexes originate as seafloor materials, it is likely that a microbiological record of seafloor serpentinization processes is maintained through the emplacement and weathering of continental serpentinites. This hypothesis was evaluated through a global comparison of continental serpentinite springs and groundwater, ranging from highly brackish (saline) to freshwater. One of the most saline sites, known as the Coast Range Ophiolite Microbial Observatory (CROMO), was used as a point-of-comparison to marine serpentinizing systems, such as the Lost City Hydrothermal Field. Although there was little taxonomic overlap between microbial populations in marine and terrestrial systems, both communities harbored an abundance of genes involved in sulfur metabolism, including sulfide oxidation, thiosulfate disproportionation, and sulfate reduction. The phylogeny of key genes involved in these metabolic processes was evaluated relative to published studies and compared between sites. Together, these data provide insights into both the functioning of microbial communities in modern-day serpentinizing systems, and the transport processes that disperse microorganisms between marine and terrestrial serpentinites.
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Masirah – the other Oman ophiolite: A better analogue for mid-ocean ridge processes?
Directory of Open Access Journals (Sweden)
Hugh Rollinson
2017-11-01
Full Text Available Oman has two ophiolites – the better known late Cretaceous northern Oman (or Semail ophiolite and the lesser known and smaller, Jurassic Masirah ophiolite located on the eastern coast of the country adjacent to the Indian Ocean. A number of geological, geochronological and geochemical lines of evidence strongly suggest that the northern Oman ophiolite did not form at a mid-ocean ridge but rather in a supra-subduction zone setting by fast spreading during subduction initiation. In contrast the Masirah ophiolite is structurally part of a series of ophiolite nappes which are rooted in the Indian Ocean floor. There are significant geochemical differences between the Masirah and northern Oman ophiolites and none of the supra-subduction features typical of the northern Oman ophiolite are found at Masirah. Geochemically Masirah is MORB, although in detail it contains both enriched and depleted MORB reflecting a complex source for the lavas and dykes. The enrichment of this source predates the formation of the ophiolite. The condensed crustal section on Masirah (ca. 2 km contains a very thin gabbro sequence and is thought to reflect its genesis from a cool mantle source associated with the early stages of sea-floor spreading during the early separation of eastern and western Gondwana. These data suggest that the Masirah ophiolite is a suitable analogue for an ophiolite created at a mid-ocean ridge, whereas the northern Oman ophiolite is not. The stratigraphic history of the Masirah ophiolite shows that it remained a part of the oceanic crust for ca. 80 Ma. The chemical variability and enrichment of the Masirah lavas is similar to that found elsewhere in Indian Ocean basalts and may simply reflect a similar provenance rather than a feature fundamental to the formation of the ophiolite.
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Directory of Open Access Journals (Sweden)
D. E. Saveliev
2014-03-01
Full Text Available The results of study of rocks of ophiolite assemblage exposed on the east coast of Kasargi Lake are presented. The ophiolite assemblage is formed with the serpentinised ultramafic rocks of dunite-harzburgite association, which are residual and the shlirenbanded gabbros with a number of later dikes of diabases and porphiritic gabbros. The chemical content of mafic and ultramafic rocks of Kasargi massif shows that they are likely the equivalent rocks encountered within the backarc spreading ridges.
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Robertson, Alastair; Avery, Aaron; Carvallo, Claire; Christeson, Gail; Ferré, Eric; Kurz, Walter; Kutterolf, Steffen; Morgan, Sally; Pearce, Julian; Reagan, Mark; Sager, William; Shervais, John; Whattam, Scott; International Ocean Discovery Program Expedition 352 (Izu-Bonin-Mariana Fore Arc), the Scientific Party of
2015-04-01
modern arc formed c. 200 km westwards of the trench. The new drilling evidence proves that both fore arc-type basalt and boninite formed in a fore arc setting soon after subduction initiation (c.52 Ma). Comparisons with ophiolites reveal many similarities, especially the presence of fore arc-type basalts and low calcium boninites. The relative positions of the fore arc basalts, boninites and arc basalts in the Izu Bonin and Mariana forearc (based on previous studies) can be compared with the positions of comparable units in a range of ophiolite complexes in orogenic belts including the Troodos, Oman, Greek (e.g. Vourinos), Albanian (Mirdita), Coast Range (California) and Bay of Islands (Newfoundland) ophiolites. The comparisons support the interpretation that all of the ophiolites formed during intra-oceanic subduction initiation. There are also some specific differences between the individual ophiolites suggesting that ophiolites should be interpreted individually in their regional tectonic settings.
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Godfrey, N.J.; Beaudoin, B.C.; Klemperer, S.L.; Levander, A.; Luetgert, J.; Meltzer, A.; Mooney, W.; Tréhu, A.
1997-01-01
The nature of the Great Valley basement, whether oceanic or continental, has long been a source of controversy. A velocity model (derived from a 200-km-long east-west reflection-refraction profile collected south of the Mendocino triple junction, northern California, in 1993), further constrained by density and magnetic models, reveals an ophiolite underlying the Great Valley (Great Valley ophiolite), which in turn is underlain by a westward extension of lower-density continental crust (Sierran affinity material). We used an integrated modeling philosophy, first modeling the seismic-refraction data to obtain a final velocity model, and then modeling the long-wavelength features of the gravity data to obtain a final density model that is constrained in the upper crust by our velocity model. The crustal section of Great Valley ophiolite is 7-8 km thick, and the Great Valley ophiolite relict oceanic Moho is at 11-16 km depth. The Great Valley ophiolite does not extend west beneath the Coast Ranges, but only as far as the western margin of the Great Valley, where the 5-7-km-thick Great Valley ophiolite mantle section dips west into the present-day mantle. There are 16-18 km of lower-density Sierran affinity material beneath the Great Valley ophiolite mantle section, such that a second, deeper, "present-day" continental Moho is at about 34 km depth. At mid-crustal depths, the boundary between the eastern extent of the Great Valley ophiolite and the western extent of Sierran affinity material is a near-vertical velocity and density discontinuity about 80 km east of the western margin of the Great Valley. Our model has important implications for crustal growth at the North American continental margin. We suggest that a thick ophiolite sequence was obducted onto continental material, probably during the Jurassic Nevadan orogeny, so that the Great Valley basement is oceanic crust above oceanic mantle vertically stacked above continental crust and continental mantle.
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Khattab, M. M.
1993-04-01
The compiled Bouguer gravity anomaly map over parts of the ophiolite rocks of the Northern Oman Mountains suggests the existence of three partially serpentinized nappes: two along the Gulf of Oman coast with axes near Dadnah, near Fujira and the third 17 km SSE of Masafi. Modeling of the subsurface geology, beneath two gravity profiles (Diba-Kalba and Masafi-Fujira), is based on the occurrence (field evidence) of multiphase low-angle thrusting of the members of the Tethyan lithosphere in northern and Oman Mountains. An assumed crustal model at the Arabian continental margin, beneath the Masafi-Fujira profile, is made to explain an intense gravity gradient. Gravity interpretation is not inconsistent with a gliding mechanism for obduction of the ophiolite on this part of the Arabian continental margin.
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Lead isotopic studies of the Samail ophiolite, Oman
Energy Technology Data Exchange (ETDEWEB)
Chen, J.H.; Pallister, J.S.
1981-04-10
The isotopic composition of Pb and the concentrations of U, Th, and Pb have been determined for samples from various lithologic units and massive sulfides of the Samail ophiolite. The observed /sup 206/Pb//sup 204/Pb ratios range from 17.90 to 19.06, /sup 207/Pb//sup 204/Pb ratios from 15.43 to 15.63, and /sup 208/Pb//sup 204/Pb from 37.66 to 38.78. In Pb isotopic evolution diagrams, the initial Pb isotopic compositions of most of the samples from the Samail ophiolite plot within the field of oceanic basalt, clearly distinct from island arc data, and define some of the least radiogenic Pb observed from oceanic rocks. Lead data from the Samail are compatible with a model involving magma generation from an oceanic mantle source and formation of the ophiolite at an oceanic spreading center. U--Th--Pb isotopic systematics demonstrate that vertical heterogeneity in the oceanic crust can be created through differential concentration of U, Th, and Pb during crystal fractionation and alteration at, or near, the spreading ridge. Calcite form amygdules in the ophiolite basalt has similar Pb isotopic composition to the igneous rocks, suggesting precipitation of the calcite from seawater which contained Pb derived mostly from the oceanic crust. Lead isotopic data on Fe--Cu sulfides are also similar to the results from the igneous suite suggesting that the source of the sulfides is predominently from the oceanic crust. Lead data from serpentinized peridotite and a galena sample from below the ophiolite suggest that part of the serpentinization process and the formation of galena could involve addition of radiogenic Pb from either a continental source or from oceanic sediments.
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Ortiz, E.; Vento, N. F. R.; Tominaga, M.; Beinlich, A.; Einsle, J. F.; Buisman, I.; Ringe, E.; Schrenk, M. O.; Cardace, D.
2017-12-01
Serpentinization of mantle peridotite has been recognized as one of the most important energy factories for the deep biosphere. To better evaluate the habitability of the deep biosphere, it is crucial to understand the link between in situ peridotite serpentinization processes and associated magnetite and hydrogen production. Previous efforts in correlating magnetite and hydrogen production during serpentinization processes are based primarily on laboratory experiments and numerical modeling, being challenged to include the contribution of superparamagnetic-sized magnetites (i.e., extremely fine-grained magnetite, petrographically observed as a "pepper flake" like texture in many natural serpentinized rock samples). To better estimate the abundance of superparamagnetic grains, we conducted frequency-dependent susceptibility magnetic measurements at the Institute of Rock Magnetism on naturally serpentinized rock samples from the Coast Range Ophiolite Microbial Observatory (CROMO) in California, USA and the Atlin Ophiolite (British Columbia). In addition, we conducted multiscale EDS phase mapping, BackScattered Electron (BSE) scanning, FIB-nanotomography and STEM-EELS to identify and quantify the superparamagnetic minerals that contribute to the measured magnetic susceptibility signals in our rock samples. Utilizing a multidisciplinary approach, we aim to improve the estimation of hydrogen production based on the abundance of magnetite, that includes the contribution of superparamagnetic particle size magnetite, to ultimately provide a more accurate estimation of bulk deep-biomass hosted by in situ serpentinization processes.
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Robertson, Alastair
2016-04-01
Accretionary orogens, in part, grow as a result of the accretion of oceanic terranes to pre-existing continental blocks, as in the circum-Pacific and central Asian regions. However, the accretionary processes involved remain poorly understood. Here, we consider settings in which oceanic crust formed in a supra-subduction zone setting and later accreted to continental terranes (some, themselves of accretionary origin). Good examples include some Late Cretaceous ophiolites in SE Turkey, the Jurassic Coast Range ophiolite, W USA and the Early Permian Dun Mountain ophiolite of South Island, New Zealand. In the last two cases, the ophiolites are depositionally overlain by coarse clastic sedimentary rocks (e.g. Permian Upukerora Formation of South Island, NZ) that then pass upwards into very thick continental margin fore-arc basin sequences (Great Valley sequence, California; Matai sequence, South Island, NZ). Field observations, together with petrographical and geochemical studies in South Island, NZ, summarised here, provide evidence of terrane accretion processes. In a proposed tectonic model, the Early Permian Dun Mountain ophiolite was created by supra-subduction zone spreading above a W-dipping subduction zone (comparable to the present-day Izu-Bonin arc and fore arc, W Pacific). The SSZ oceanic crust in the New Zealand example is inferred to have included an intra-oceanic magmatic arc, which is no longer exposed (other than within a melange unit in Southland), but which is documented by petrographic and geochemical evidence. An additional subduction zone is likely to have dipped westwards beneath the E Gondwana margin during the Permian. As a result, relatively buoyant Early Permian supra-subduction zone oceanic crust was able to dock with the E Gondwana continental margin, terminating intra-oceanic subduction (although the exact timing is debatable). The amalgamation ('soft collision') was accompanied by crustal extension of the newly accreted oceanic slab, and
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Queaño, Karlo L.; Dimalanta, Carla B.; Yumul, Graciano P.; Marquez, Edanjarlo J.; Faustino-Eslava, Decibel V.; Suzuki, Shigeyuki; Ishida, Keisuke
2017-07-01
The Zambales Ophiolite Complex (ZOC) on the island of Luzon, Philippines is one of the most well-studied crust-mantle sequences in the region. Several massifs comprise the ZOC, one of which is the Coto Block overlain by clastic sedimentary units previously dated as Eocene. Geochronologic studies from diabase, granodiorites and other late-stage magmatic products similarly yielded the same age. Succeeding tectonic models have therefore all been grounded on the assumption that the entire ZOC is Eocene. Recent investigations, however, revealed the presence of chert blocks within the Early to Middle Miocene clastic formation overlying the Acoje Block in the northern part of the ophiolite complex. Radiolarians extracted from the cherts yielded a stratigraphic range that suggests a Late Jurassic to Early Cretaceous age. The recognition of a much older age than previously reported of the ZOC warrants a re-examination of its actual distribution and genesis. Correlating with other similarly-aged ophiolites, we suggest defining a western Mesozoic ophiolite belt, largely extending from the west-central portion of the archipelago to the northeastern tip of Luzon island. Tentatively, we attribute the Mesozoic ophiolitic and associated rocks in western Luzon to an arc-continent collision involving the Philippine Mobile Belt and the Palawan Microcontinental Block. In addition, differences in the clastic compositions of the Cenozoic sedimentary formations provide material not only for deciphering the ZOC's unroofing history but also for constraining the timing of province linkage. The intermittent appearance of lithic fragments and detrital minerals from the ophiolite in the units of the Middle Miocene Candelaria Limestone and the Late Miocene to Early Pliocene Sta. Cruz Formation indicates significant but geographically variable contributions from the ophiolite complex. In the northern Zambales Range, the Sta. Cruz Formation caps the Coto Block and the Acoje Block of the ZOC
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Genetic hitch-hiking extends the range of coast live oak
Richard S. Dodd; Zara Afzal-Rafii; Wasima Mayer
2006-01-01
The northernmost range of coast live oak (Quercus agrifolia) is reported from the Ukiah Valley (Mendocino County, California). Here, field observations suggest that hybridization with interior live oak (Q. wislizeni) is important. Elsewhere in northern California, morphology of coast live oak can be highly variable (particularly...
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Kaneko, R.; Adachi, Y.; Miyashita, S.
2014-12-01
The Oman ophiolite extends along the east coast of Oman, and is the world's largest and best-preserved slice of obducted oceanic lithosphere. The magmatic history of this ophiolite is complex and is generally regarded as having occurred in three stages (MOR magmatism, subduction magmatism and intraplate magmatism). Wehrlitic intrusions constitute an important element of oceanic lower crust of the ophiolite, and numerous intrusions cut gabbro units in the northern Salahi block of this ophiolite. In this study area, we identified two different types of wehrlitic intrusions. One type of the intrusions mainly consists of dunite, plagioclase (Pl) wehrlite and mela-olivine (Ol) gabbro, in which the crystallization sequence is Ol followed by the contemporaneous crystallization of Pl and clinopyroxene (Cpx). This type is called "ordinary" wehrlitic intrusions and has similar mineral compositions to host gabbros (Adachi and Miyashita 2003; Kaneko et al. 2014). Another type of the intrusions is a single intrusion that crops out in an area 250 m × 150 m along Wadi Salahi. This intrusion consists of Pl-free "true" wehrlite, in which the crystallization sequence is Ol and then Cpx. The forsterite contents (Fo%) of Ol from the "ordinary" wehrlitic intrusions and "true" wehrlitic intrusions have ranges of 90.8-87.0 (NiO = 0.36-0.13 wt%) and 84.7 (NiO = 0.31 wt%), respectively. Cr numbers (Cr#) of Cr-spinel from the "true" wehrlitic intrusions show higher Cr# value of 0.85 than those of the "ordinary" wehrlitic intrusions (0.48-0.64). But the former is characterized by very high Fe3+ values (YFe3+ = 0.49-0.68). Kaneko et al. (2014) showed that the "ordinary" ubiquitous type has similar features to MOR magmatism and the depleted type in the Fizh block (Adachi and Miyashita 2003) links to subduction magmatism. These types are distinguished by their mineral chemistries (TiO2 and Na2O contents of Cpx). The TiO2 and Na2O contents of Cpx from the "true" wehrlitic intrusions have 0
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Directory of Open Access Journals (Sweden)
Gawlick Hans-Jürgen
2015-12-01
Full Text Available The causes for the Middle to Late Jurassic tectonic processes in the Northern Calcareous Alps are still controversially discussed. There are several contrasting models for these processes, formerly designated “Jurassic gravitational tectonics”. Whereas in the Dinarides or the Western Carpathians Jurassic ophiolite obduction and a Jurassic mountain building process with nappe thrusting is widely accepted, equivalent processes are still questioned for the Eastern Alps. For the Northern Calcareous Alps, an Early Cretaceous nappe thrusting process is widely favoured instead of a Jurassic one, obviously all other Jurassic features are nearly identical in the Northern Calcareous Alps, the Western Carpathians and the Dinarides. In contrast, the Jurassic basin evolutionary processes, as best documented in the Northern Calcareous Alps, were in recent times adopted to explain the Jurassic tectonic processes in the Carpathians and Dinarides. Whereas in the Western Carpathians Neotethys oceanic material is incorporated in the mélanges and in the Dinarides huge ophiolite nappes are preserved above the Jurassic basin fills and mélanges, Jurassic ophiolites or ophiolitic remains are not clearly documented in the Northern Calcareous Alps. Here we present chrome spinel analyses of ophiolitic detritic material from Kimmeridgian allodapic limestones in the central Northern Calcareous Alps. The Kimmeridgian age is proven by the occurrence of the benthic foraminifera Protopeneroplis striata and Labyrinthina mirabilis, the dasycladalean algae Salpingoporella pygmea, and the alga incertae sedis Pseudolithocodium carpathicum. From the geochemical composition the analysed spinels are pleonastes and show a dominance of Al-chromites (Fe3+–Cr3+–Al3+ diagram. In the Mg/(Mg+ Fe2+ vs. Cr/(Cr+ Al diagram they can be classified as type II ophiolites and in the TiO2 vs. Al2O3 diagram they plot into the SSZ peridotite field. All together this points to a harzburgite
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Ni, Dong-Hong
2017-09-01
We disagree the transitional supra-subduction zone model of Feng et al. (Int J Earth Sci (Geol Rundsch) 105:491-505, 2016) for the tectonic setting of Jifeng ophiolite suite in NE China. Existence of the komatiite in the Jifeng ophiolite indicates an oceanic plateau environment for this ophiolite suite within the so-called Xinlin-Xiguitu ocean.
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Four billion years of ophiolites reveal secular trends in oceanic crust formation
Directory of Open Access Journals (Sweden)
Harald Furnes
2014-07-01
Full Text Available We combine a geological, geochemical and tectonic dataset from 118 ophiolite complexes of the major global Phanerozoic orogenic belts with similar datasets of ophiolites from 111 Precambrian greenstone belts to construct an overview of oceanic crust generation over 4 billion years. Geochemical discrimination systematics built on immobile trace elements reveal that the basaltic units of the Phanerozoic ophiolites are dominantly subduction-related (75%, linked to backarc processes and characterized by a strong MORB component, similar to ophiolites in Precambrian greenstone sequences (85%. The remaining 25% Phanerozoic subduction-unrelated ophiolites are mainly (74% of Mid-Ocean-Ridge type (MORB type, in contrast to the equal proportion of Rift/Continental Margin, Plume, and MORB type ophiolites in the Precambrian greenstone belts. Throughout the Phanerozoic there are large geochemical variations in major and trace elements, but for average element values calculated in 5 bins of 100 million year intervals there are no obvious secular trends. By contrast, basaltic units in the ophiolites of the Precambrian greenstones (calculated in 12 bins of 250 million years intervals, starting in late Paleo- to early Mesoproterozoic (ca. 2.0–1.8 Ga, exhibit an apparent decrease in the average values of incompatible elements such as Ti, P, Zr, Y and Nb, and an increase in the compatible elements Ni and Cr with deeper time to the end of the Archean and into the Hadean. These changes can be attributed to decreasing degrees of partial melting of the upper mantle from Hadean/Archean to Present. The onset of geochemical changes coincide with the timing of detectible changes in the structural architecture of the ophiolites such as greater volumes of gabbro and more common sheeted dyke complexes, and lesser occurrences of ocelli (varioles in the pillow lavas in ophiolites younger than 2 Ga. The global data from the Precambrian ophiolites, representative of nearly 50
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Thermo-mechanical models of obduction applied to the Oman ophiolite
Thibault, Duretz; Philippe, Agard; Philippe, Yamato; Céline, Ducassou; Taras, Gerya; Evguenii, Burov
2015-04-01
During obduction regional-scale fragments of oceanic lithosphere (ophiolites) are emplaced somewhat enigmatically on top of lighter continental lithosphere. We herein use two-dimensional thermo-mechanical models to investigate the feasibility and controlling parameters of obduction. The models are designed using available geological data from the Oman (Semail) ophiolite. Initial and boundary conditions are constrained by plate kinematic and geochronological data and modeling results are validated against petrological and structural observations. The reference model consists of three distinct stages: (1) initiation of oceanic subduction initiation away from Arabian margin, (2) emplacement of the Oman Ophiolite atop the Arabian margin, (2) dome-like exhumation of the subducted Arabian margin beneath the overlying ophiolite. A parametric study suggests that 350-400 km of shortening allows to best fit both the peak P-T conditions of the subducted margin (1.5-2.5 GPa / 450-600°C) and the dimensions of the ophiolite (~170 km width), in agreement with previous estimations. Our results further confirm that the locus of obduction initiation is close to the eastern edge of the Arabian margin (~100 km) and indicate that obduction is facilitated by a strong continental basement rheology.
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Eclogite nappe-stack in the Grivola-Urtier Ophiolites (Southern Aosta Valley, Western Alps)
Tartarotti, Paola
2013-04-01
In the Western Alpine chain, ophiolites represent a section of the Mesozoic Tethys oceanic lithosphere, involved in subduction during the convergence between the paleo-Africa and paelo-Europe continents during the Cretaceous - Eocene. The Western Alpine ophiolites consist of several tectonic units, the most famous being the Zermatt-Saas and Combin nappes, and other major ophiolite bodies as the Voltri, Monviso, and Rocciavrè that show different rock assemblages and contrasting metamorphic imprints. The Grivola-Urtier (GU) unit is exposed in the southern Aosta Valley, covering an area of about 100 km2; it is tectonically sandwiched between the continentally-derived Pennidic Gran Paradiso Nappe below, and the Austroalpine Mount Emilius klippe above. This unit has been so far considered as part of the Zermatt-Saas nappe extending from the Saas-Fee area (Switzerland) to the Aosta Valley (Italy). The GU unit consists of serpentinized peridotites that include pods and boudinaged layers of eclogitic Fe-metagabbro and trondhjemite, rodingites and chloriteschists transposed in the main foliation together with calcschists and micaschists. All rocks preserve particularly fresh eclogitic mineral assemblages. The contact between the serpentinites and calcshists is marked by a tectonic mélange consisting of mylonitic marble and calcschist with stretched and boudinaged serpentinite blocks. Continentally-derived allochthonous blocks ranging in size from100 meters to meters are also included within the ophiolites. New field, petrographic and geochemical data reveal the complex nature of the fossil Tethyan oceanic lithosphere exposed in the southern Aosta Valley, as well as the extent and size of the continental-oceanic tectonic mélange. The geological setting of the GU unit is here inferred as a key tool for understanding the complex architecture of the ophiolites in the Western Alps.
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Neodymium and strontium isotope study of ophiolite and orogenic lherzolite petrogenesis
International Nuclear Information System (INIS)
Richard, P.; Allegre, C.J.; Paris-7 Univ., 75
1980-01-01
Neodymium isotopic analyses have been measured on nine ophiolites and four orogenic lherzolites. Epsilonsub(Nd) varies from +12 to +3 in the ophiolites and from +18 to +2 in the orogenic lherzolites. The majority of the analyses plot on a epsilonsub(Nd)-epsilonsub(Sr) correlation line as defined by Nd and Sr isotopic analyses of oceanic basalts. However, certain ophiolitic and lherzolitic samples exhibit high 87 Sr/ 86 Sr ratios and as such lie to the right of the correlation line towards seawater compositions. From these data one can postulate several origins for ophiolites including that of mid-ocean ridges and ocean islands. If the orogenic lherzolites are interpreted as representative of the mantle occurring below active ridges a more complex model is required involving mantle heterogeneity and multi-episodic chemical fractionation starting prior to 2 Ga ago. (orig.)
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Zeng, Yun-Chuan; Xu, Ji-Feng; Chen, Jian-Lin; Wang, Bao-Di; Kang, Zhi-Qiang; Huang, Feng
2018-02-01
The formation of the Shiquanhe-Yunzhug-Namu Tso ophiolite mélange zone (SNMZ) within the Lhasa Terrane, Tibetan Plateau, is key to understanding the Mesozoic tectonic evolution of this terrane, which remains controversial. We show that the Yunzhug ophiolite in the central segment of the SNMZ formed at 150 Ma, based on U-Pb dating of zircons from a gabbroic sample in a well-developed sheeted dike complex. Geochemically, these mafic rocks are dominated by E-MORB-type compositions, along with minor amounts of rocks with P-MORB-type compositions. The samples also exhibit high εNd(t) values and lack negative Nb and Ta anomalies. Data for all the samples plot within the MORB array on a Th/Yb-Nb/Yb diagram. Therefore, these mafic rocks most likely formed in either a slow spreading oceanic setting or an embryonic ocean, and not in a back-arc basin as has been previously assumed. Taking into account the regional geology, we propose that the Yunzhug ophiolite is part of a distinct ophiolitic belt and represents material formed in an embryonic ocean within the Lhasa Terrane, which provides new insights into the Jurassic tectonic evolution of the Lhasa Terrane.
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Timing of pyroxenite formation in supra-subduction Josephine Ophiolite, Oregon.
Hough, T.; Le Roux, V.; Kurz, M. D.
2017-12-01
The Josephine ophiolite is a partly dismembered ophiolite located in southern Oregon and northwestern California (USA). It displays a large ( 640 km2) mantle section that is mostly composed of depleted spinel harzburgite and lherzolite re-equilibrated at temperatures of 900 °C. In addition, the peridotite section of the ophiolite contains minor dunites and pyroxenite veins ranging from orthopyroxenites to clinopyroxenites. Using field, petrological and geochemical data, previous studies have shown that the peridotite experienced 10-20% of hydrous flux melting. In addition, clinopyroxene and orthopyroxene in harzburgites show variable degrees of light rare-earth element (LREE) enrichment, which suggests percolation and re-equilibration with small fractions of boninite melt. Overall, the trace element concentrations of pyroxenes indicate that the harzburgites experienced particularly high degrees of melting in the mantle wedge. We collected a number of orthopyroxenite and clinopyroxenite veins in the mantle section of the Josephine Ophiolite. Here we present the major and rare-earth element (REE) contents of pyroxene in 4 orthopyroxenites and 2 clinopyroxenites and calculate the major element and REE closure temperatures for individual veins. We show that individual pyroxenites record drastic variations in their degree of REE depletion, indicating that multiple generations of melts percolated the peridotite. The pyroxenite veins also record higher REE closure temperatures (>1200 ºC) compared to the surrounding peridotite, potentially indicating rapid cooling after emplacement. REE closure temperatures are also higher than major element closure temperatures. In parallel, we analyzed Sr isotopes by MC-ICPMS in pyroxene separates from 4 veins. Results indicate that the maximum age of emplacement of orthopyroxenite veins corresponds to the age of exhumation. Some clinopyroxenites may have formed during earlier melt percolation events. This study supports the idea that
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Li, Z.; Zheng, J.; Moskowitz, B. M.; Xiong, Q.; Liu, Q.
2017-12-01
Serpentinized mantle peridotites are widely supposed to be significant sources of the magnetic, gravity and seismic anomalies in mid-oceanic ridges, forearcs and suture zones. However, the relationship between the magnetic properties of variably serpentinized peridotites and the serpentinization process is still under debate. Ophiolite outcrops commonly comprise peridotites in different stages of serpentinization and these ophiolitic peridotites are ideal to investigate the magnetic signatures of suture zones. The Zedong ophiolite locates in the eastern part of the Yarlung-Zangbo suture zone, SE Tibet (China), and the peridotite massif represents the remnants of the Neo-Tethyan lithospheric mantle. The harzburgite and lherzolite samples show densities between 3.316 and 2.593 g cm-3, and vary from the freshest to >90% serpentinized peridotites. The magnetic susceptibility curves from room temperature to 700ºC mainly show the Curie temperatures of 585ºC for pure magnetite. The low-temperature (20-300 K) demagnetization curves show the Verwey transitions at 115-125 K, suggesting that magnetite is also the dominant remanence-carrying phase. The hysteresis data of the peridotites fall in the region of pseudo-single-domain (PSD) and follow the theoretical trends for mixtures of single domain (SD) and multidomain (MD) magnetite. The first-order reversal curve (FORC) diagrams suggest that the magnetite is dominantly interacting SD + PSD particles for S 40% serpentinized samples. The susceptibility and saturation magnetization of the Zedong peridotites range from 0.9 to 30.8 × 10‒3 (SI) and 14.1 to 1318 × 10‒3 Am2 kg‒1, respectively, and both show consistent trends with increasing degrees of serpentinization. The S serpentinization of ophiolitic peridotites, whereas the S > 40% peridotites have higher susceptibilities of 0.02-0.03 (SI) and fall in the region of abyssal peridotites. Our results suggest that the Zedong ophiolitic peridotites probably experienced a
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Geology of the Zambales ophiolite, Luzon, Philippines
Rossman, D.L.; Castanada, G.C.; Bacuta, G.C.
1989-01-01
The Zambales ophiolite of western Luzon, Philippines, exposes a typical succession of basalt flows, diabasic dikes, gabbro and tectonized harzburgite. The age established by limiting strata is late Eocene. Lack of evidence of thrust faulting and the general domal disposition of the lithologie units indicate that the ophiolitic rocks are exposed by uplift. Highly complex internal layered structures within the complex are related to processes developed during formation of the ophiolite and the Zambales ophiolite may be one of the least disturbed (by emplacement) ophiolitic masses known. The exposed mass trends north and the upper surface plunges at low angles (a few degrees) to the north and south. The chemistry and composition of the rocks in the northwest part of the Zambales area (Acoje block) is distinct from that in the southeastern segment (Coto block). The Acoje block, according to Evans (1983) and Hawkins and Evans (1983), resembles (on a chemical basis) arc-tholeiite series rocks from intra-island arcs and the rocks in the Coto block are typical back-arc basin rock series. The present writer believes that the ophiolite composes a single genetic unit and that the changes in composition are the result of changes that took place during the initial formation. The gabbro probably formed below a spreading center in an elongate, in cross section, V-shaped, magma chamber. The gabbro is estimated by the writer to be less than 2 km thick and may be less than 1 km in places. Numerous erosional windows through the gabbro in the northern and eastern side of the Zambales area show that the gabbro remaining in those areas is likely to be only a few hundred meters thick. Harzburgite is exposed to a depth of about 800 m in the Bagsit River area and this may be the deepest part of the ophiolite accessible for study on which there is any control on depth. A transitional zone, about 200 m thick lying between the gabbro and harzburgite, is composed of serpentinized dunite
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Guilmette, C.; Hebert, R.; Wang, C.; Indares, A. D.; Ullrich, T. D.; Dostal, J.; Bedard, E.
2007-12-01
Metre to decameter-size clasts of amphibolite are found embedded in ophiolitic melanges underlying the Yarlung Zangbo Suture Zone Ophiolites, South Tibet, China. These ophiolites and melanges occur at the limit between Indian and Tibetan-derived rocks and represent remnants of an Early Cretaceous intraoceanic supra-subduction zone domain, the Neo-Tethys. In the Saga-Dazuka segment (500 km along-strike), we discovered new occurrences of strongly foliated amphibolites found as clasts in the ophiolitic melange. In garnet-free samples, hornblende is green-blue magnesio-hornblende and cpx is low-Al diopside. In garnet- bearing samples, garnet is almandine with a strong pyrope component (up to 30 mol%) whereas coexisting hornblende is brown Ti-rich tschermakite and clinopyroxene is Al-diopside. Plagioclase composition was ubiquitously shifted to albite during a late metasomatic event. Geochemistry of these rocks indicates that their igneous protoliths crystallized from a slightly differentiated tholeiitic basaltic liquid that did not undergo major fractionation. Trace element patterns reveal geochemical characteristics identical to those of the overlying ophiolitic crust. These are 1) trace element abundances similar to that of N-MORBs or BABBs, 2) a slight depletion of LREE and 3) a moderate to strong Ta-Nb negative anomaly and a slight Ti anomaly. Such characteristics suggest genesis over a spreading center close to a subduction zone, possibly a back-arc basin. Step-heating Ar/Ar plateau ages were obtained from hornblende separates. All ages fall in the range of 123-128 Ma, overlapping the crystallization ages from the overlying ophiolite (126-131 Ma). Pseudosections were built with the THERMOCALC software in the system NCFMASH. Results indicate that the observed assemblage Hb+Pl+Gt+Cpx is stable over a wide range of P-T conditions, between 10-18 kbars and at more than 800°C. Measured mineral modes and solid solution compositions were successfully modeled, indicating
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Stern, R.
2003-04-01
It is now clear that the motive force for plate tectonics is provided by the sinking of dense lithosphere in subduction zones. Correspondingly, the modern tectonic regime is more aptly called ``subduction tectonics" than plate tectonics, which only describes the way Earth's thermal boundary layer adjusts to subduction. The absence of subduction tectonics on Mars and Venus implies that special circumstances are required for subduction to occur on a silicate planet. This begs the question: When did Earth's oceanic lithosphere cool sufficiently for subduction to began? This must be inferred from indirect lines of evidence; the focus here is on the temporal distribution of ophiolites. Well-preserved ophiolites with ``supra-subduction zone" (SSZ) affinities are increasingly regarded as forming when subduction initiates as a result of lithospheric collapse (± a nudge to get it started), and the formation of ophiolitic lithosphere in evolving forearcs favors their emplacement and preservation. The question now is what percentage of ophiolites with ``supra-subduction zone" (SSZ) chemical signatures formed in forearcs during subduction initiation events? Most of the large, well-preserved ophiolites (e.g., Oman, Cyprus, California, Newfoundland) may have this origin. If so, the distribution in space and time of such ophiolites can be used to identify ``subduction initiation" events, which are important events in the evolution of plate tectonics. Such events first occurred at the end of the Archean (˜2.5Ga) and again in the Paleoproterozoic (˜1.8 Ga), but ophiolites become uncommon after this. Well-preserved ophiolites become abundant in Neoproterozoic time, at about 800±50 Ma. Ophiolites of this age are common and well-preserved in the Arabian-Nubian Shield (ANS) of Egypt, Sudan, Ethiopia, Eritrea, and Saudi Arabia. ANS ophiolites mostly contain spinels with high Cr#, indicating SSZ affinities. Limited trace element data on pillowed lavas supports this interpretation
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National Oceanic and Atmospheric Administration, Department of Commerce — Transient killers whales inhabit the West Coast of the United States. Their range and movement patterns are difficult to ascertain, but are vital to understanding...
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The Othris Ophiolite, Greece: A snapshot of subduction initiation at a mid-ocean ridge
Barth, M.G.; Mason, P.R.D.; Davies, G.R.; Drury, M.R.
2008-01-01
The mantle section of the Tethyan-type Othris Ophiolite, Greece, records tectono-magmatic processes characteristic of both mid-ocean ridges and supra-subduction zones. The Othris Ophiolite is a remnant of the Jurassic Neotethys Ocean, which existed between Eurasia and Gondwanaland. Othris
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Directory of Open Access Journals (Sweden)
Cüneyt Güler
2017-01-01
Full Text Available The aim of this study was to investigate natural and anthropogenic processes governing the chemical composition of alkaline groundwater within a fractured rock (ophiolitic mélange aquifer underlying a seasonally inhabited headwater area in the Aladağlar Range (Adana, Turkey. In this aquifer, spatiotemporal patterns of groundwater flow and chemistry were investigated during dry (October 2011 and wet (May 2012 seasons utilizing 25 shallow hand-dug wells. In addition, representative samples of snow, rock, and soil were collected and analyzed to constrain the PHREEQC inverse geochemical models used for simulating water-rock interaction (WRI processes. Hydrochemistry of the aquifer shows a strong interseasonal variability where Mg–HCO3 and Mg–Ca–HCO3 water types are prevalent, reflecting the influence of ophiolitic and carbonate rocks on local groundwater chemistry. R-mode factor analysis of hydrochemical data hints at geochemical processes taking place in the groundwater system, that is, WRI involving Ca- and Si-bearing phases; WRI involving amorphous oxyhydroxides and clay minerals; WRI involving Mg-bearing phases; and atmospheric/anthropogenic inputs. Results from the PHREEQC modeling suggested that hydrogeochemical evolution is governed by weathering of primary minerals (calcite, chrysotile, forsterite, and chromite, precipitation of secondary minerals (dolomite, quartz, clinochlore, and Fe/Cr oxides, atmospheric/anthropogenic inputs (halite, and seasonal dilution from recharge.
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International Nuclear Information System (INIS)
Chapman, H.J.; Spooner, E.T.C.
1977-01-01
The hypothesis that seawater was the source of the hydrothermal fluid which formed the Upper Cretaceous ophiolitic cupriferous pyrite ore deposits of the Troodos Massif (Cyprus) has been tested by analysing the strontium isotopic composition of thirteen mineralized samples from four mines. Initial 87 Sr/ 86 Sr ratios range from 0.7052+-0.0001 to 0.7075+-0.00002, the latter value being indistinguishable from that of Upper Cretaceous seawater at 0.7076+-0.0006 (2 sigma). Hence, the mineralized metabasalt samples have been contaminated with 87 Sr, relative to initial magmatic strontium isotope ratios of the Troodos ophiolitic complex (0.70338+-0.00010 to 0.70365+-0.00005). Since seawater was the only source of strontium available during formation of the Troodos Complex which was isotopically relatively enriched in 87 Sr, the data confirm that seawater was the source of the hydrothermal oreforming fluid. (Auth.)
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Multi-scale Onland-Offshore Investigations of the New Caledonia Ophiolite, SW Pacific
Clerc, C. N.; Collot, J.; Sevin, B.; Patriat, M.; Etienne, S.; Iseppi, M.; Lesimple, S.; Jeanpert, J.; Mortimer, N. N.; Poli, S.; Pattier, F.; Juan, C.; Robineau, B.; Godard, M.; Cluzel, D.
2017-12-01
The Peridotite Nappe of New Caledonia is one of the largest ultramafic ophiolite in the World: it represents about one quarter of the 500 x 80 km island of Grande Terre. This extensive upper mantle unit was tectonically emplaced during the Eocene onto the northeastern edge of Zealandia continent. It is weakly deformed because it was not involved in a collision belt after obduction. A dome-shaped Eocene HP/LT metamorphic complex was exhumed across the fore-arc mantle lithosphere in the northern tip of the island. Post-obduction Miocene to Present coral reefs developed in shallow waters around Grande Terre and surrounding islands. In the perspective of a possible onshore/offshore drilling project (IODP/ICDP), we present recent advances in our understanding of offshore extensions of this ophiolite. To the south of New Caledonia, the offshore continuation of the ultramafic allochthon has been identified by dredges and by its geophysical signature as a continuous linear body that extends over a distance of more than 400 km at about 2000m bsl. Such water depths allow an unprecedented seismic reflection imaging of a drowned and well-preserved ophiolite. Seismic profiles show that the nappe has a flat-top, and is capped by carbonate reefs and dissected by several major normal faults. To the east of this presumed ultramafic body, Felicité Ridge is a 30 km wide, 350 km long, dome-shaped ridge, which may be interpreted as the possible southern extension of the HP/LT metamorphic complex observed onshore. Onshore, several 150 to 200 m long cores were drilled in the ophiolite and airborne electromagnetic allowed high-resolution imaging down to 400 m depth. These recent results allow identification of internal thrusts within the peridotite body and more superficial landslides. The analysis of polyphase fracturation and associated serpentinization brings new constraints on the tectonic evolution of the ophiolite and its subsequent weathering pattern. We integrate these data and
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Bonnemains, D.; Carlut, J. H.; Mevel, C.; Andreani, M.; Escartin, J.; Debret, B.
2015-12-01
We present a petrological and magnetic study of a suite of serpentinized peridotites from the Pindos ophiolite spanning a wide range in the degree of serpentinization (from ~10 to 100%). The Pindos ophiolite, in Northern Greece, is a portion of Late Triassic oceanic lithosphere obducted during the convergence of the Apulian and Pelagonian micro-continents. This ophiolite is interpreted mainly as the result of a supra-subduction zone spreading process but its complete history remains largely unknown. Therefore, it is not clear when the ultramafic section was exposed to fluid circulation that resulted in its serpentinization. Element partitioning during serpentinization reactions is dependent on parameters such as temperature and water-rock ratio. In particular, they affect the behavior of the iron released by olivine, which can be taken up either by magnetite, serpentine and/or brucite. Analyses of the reaction products are therefore a key to constrain the conditions during the main stage of the alteration. Our study was designed to gain insight on the conditions prevailing during hydration. Our results indicate that even fully serpentinized samples have a very low magnetization and magnetite content. Moreover, microprobe and μXanes results show that serpentine is the main host of iron in the divalent but also trivalent form. These results are compared with a set of data from serpentinized ultramafics sampled from the ocean floors, as well as from various other ophiolites. We suggest that serpentinization at Pindos occurred at relatively low-temperature (less than 200 °C), therefore not at a ridge environment. In addition, we stress that the presence of trivalent iron in serpentine indicates that serpentinization may remain a producer of hydrogen even when very little magnetite is formed.
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Hurtado, C.; Bailey, C.; Visokay, L.; Scharf, A.
2017-12-01
The Semail ophiolite is the world's largest and best-exposed ophiolite sequence, however the processes associated with both oceanic detachment and later emplacement onto the Arabian continental margin remain enigmatic. This study examines the upper mantle section of the ophiolite, its associated metamorphic sole, and the autochthonous strata beneath the ophiolite at two locations in northern Oman. Our purpose is to understand the structural history of ophiolite emplacement and evaluate the deformation kinematics of faulted and sheared rocks in the metamorphic sole. At Wadi Hawasina, the base of the ophiolite is defined by a 5- to 15-m thick zone of penetratively-serpentinized mylonitic peridotite. Kinematic indicators record top-to-the SW (reverse) sense-of-shear with a triclinic deformation asymmetry. An inverted metamorphic grade is preserved in the 300- to 500-m thick metamorphic sole that is thrust over deep-water sedimentary rocks of the Hawasina Group. The study site near Buwah, in the northern Jebel Nakhl culmination, contains a N-to-S progression of mantle peridotite, metamorphic sole, and underlying Jurassic carbonates. Liswanite crops out in NW-SE trending linear ridges in the peridotite. The metamorphic sole includes well-foliated quartzite, metachert, and amphibolite. Kinematic evidence indicates that the liswanite and a serpentinized mélange experienced top to-the north (normal) sense-of-shear. Two generations of E-W striking, N-dipping normal faults separate the autochthonous sequence from the metamorphic sole, and also cut out significant sections of the metamorphic sole. Fabric analysis reveals that the metamorphic sole experienced flattening strain (K<0.2) that accumulated during pure shear-dominated general shear (Wk<0.4). Normal faulting and extension at the Buwah site indicates that post-ophiolite deformation is significant in the Jebel Akhdar and Jebel Nakhl culminations.
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Groundwater quality in the Northern Coast Ranges Basins, California
Mathany, Timothy M.; Belitz, Kenneth
2015-01-01
The Northern Coast Ranges (NOCO) study unit is 633 square miles and consists of 35 groundwater basins and subbasins (California Department of Water Resources, 2003; Mathany and Belitz, 2015). These basins and subbasins were grouped into two study areas based primarily on locality. The groundwater basins and subbasins located inland, not adjacent to the Pacific Ocean, were aggregated into the Interior Basins (NOCO-IN) study area. The groundwater basins and subbasins adjacent to the Pacific Ocean were aggregated into the Coastal Basins (NOCO-CO) study area (Mathany and others, 2011).
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Avifauna associated with early growth vegetation on clearcuts in the Oregon coast ranges.
Michael L. Morrison; E. Charles. Meslow
1983-01-01
This paper provides estimates of bird density, diversity, and evenness on 13 clearcut units of the Siuslaw National Forest in the Coast Ranges of Oregon, sampled during 1979,1980, and 1981. Total density of nesting birds ranged from 322 to 588 per 40.5 hectares (100 acres); there were 15 to 19 species nesting on each site.
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Sulfide mineralization in ultramafic rocks of the Faryab ophiolite complex, southern Kerman
Directory of Open Access Journals (Sweden)
Mohammad Ali Rajabzadeh
2015-10-01
Full Text Available Introduction Worldwide, Ni-Cu and PGE magmatic sulfide deposits are confined to the lower parts of stratiform mafic and ultramafic complexes. However, ophiolite mafic and ultramafic complexes have been rarely explored for sulfide deposits despite the fact that they have been extensively explored and exploited for chromite. Sulfide saturation during magmatic evolution is necessary for sulfide mineralization, in which sulfide melts scavenge chalcophile metals from the parent magma and concentrate them in specific lithological zones. The lack of exploration for sulfides in this environment suggests that sulfide saturation is rarely attained in ophiolite-related magmas. Some ophiolites, however, contain sulfide deposits, such as at Acoje in Philippines, and Cliffs in Shetland, U.K. (Evans, 2000; Naldrett, 2004. The Faryab ophiolite complex in southern Kerman Province, the most important mining area for chromite deposits in Iran, is located in the southwest part of the Makran Zone. Evidence of sulfide mineralization has been reported there by some authors (e.g. Rajabzadeh and Moosavinasab, 2013. This paper discusses the genesis of sulfides in the Faryab ophiolite using mineral chemistry of the major mineral phases in different rocks of the ophiolite column in order to determine the possible lithological location of sulfide deposits. Materials and methods Seventy three rock samples from cumulate units were collected from surficial occurrences and drill core. The samples were studied using conventional microscopic methods and the mineralogy confirmed by x-ray diffraction. Electron microprobe analysis was carried out on different mineral phases in order to determine the chemistry of the minerals used in the interpretation of magma evolution in the Faryab ophiolite. Lithologically, the Faryab ophiolite complex is divided into two major parts: the northern part includes magmatic rocks and the southern part is comprised of rocks residual after partial
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Huang, Wentao; van Hinsbergen, Douwe J J; Maffione, Marco; Orme, Devon A.; Dupont-Nivet, Guillaume; Guilmette, Carl; Ding, Lin; Guo, Zhaojie; Kapp, Paul
2015-01-01
The India-Asia suture zone of southern Tibet exposes Lower Cretaceous Xigaze ophiolites and radiolarian cherts, and time-equivalent Asian-derived clastic forearc sedimentary rocks (Xigaze Group). These ophiolites have been interpreted to have formed in the forearc of the north-dipping subduction
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McGoldrick, Siobhan; Canil, Dante; Zagorevski, Alex
2018-03-01
The Permo-Triassic Nahlin ophiolite is the largest and best-preserved ophiolite in the Canadian Cordillera of British Columbia and Yukon, Canada. The ophiolite is well-exposed along its 150 km length with mantle segments divisible into the Hardluck and Menatatuline massifs. Both massifs comprise mostly depleted spinel harzburgite (exchange temperatures in the mantle of the ophiolite also change systematically along strike with the degree of partial melt depletion. The temperatures recorded by REE and Ca-Mg exchange between coexisting pyroxenes require markedly higher peak temperatures and cooling rates for the Menatatuline massif (1250 °C, 0.1-0.01 °C/year) compared to the Hardluck massif (rates controlled by presence or absence of a crustal section above the mantle lithosphere, or by rapid exhumation along a detachment.
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The ophiolitic North Fork terrane in the Salmon River region, central Klamath Mountains, California
Ando, C.J.; Irwin, W.P.; Jones, D.L.; Saleeby, J.B.
1983-01-01
The North Fork terrane is an assemblage of ophiolitic and other oceanic volcanic and sedimentary rocks that has been internally imbricated and folded. The ophiolitic rocks form a north-trending belt through the central part of the region and consist of a disrupted sequence of homogeneous gabbro, diabase, massive to pillowed basalt, and interleaved tectonitic harzburgite. U-Pb zircon age data on a plagiogranite pod from the gabbroic unit indicate that at least this part of the igneous sequence is late Paleozoic in age.The ophiolitic belt is flanked on either side by mafic volcanic and volcaniclastic rocks, limestone, bedded chert, and argillite. Most of the chert is Triassic, including much of Late Triassic age, but chert with uncertain stratigraphic relations at one locality is Permian. The strata flanking the east side of the ophiolitic belt face eastward, and depositional contacts between units are for the most part preserved. The strata on the west side of the ophiolitic belt are more highly disrupted than those on the east side, contain chert-argillite melange, and have unproven stratigraphic relation to either the ophiolitic rocks or the eastern strata.Rocks of the North Fork terrane do not show widespread evidence of penetrative deformation at elevated temperatures, except an early tectonitic fabric in the harzburgite. Slip-fiber foliation in serpentinite, phacoidal foliation in chert and mafic rocks, scaly foliation in argillite, and mesoscopic folds in bedded chert are consistent with an interpretation of large-scale anti-formal folding of the terrane about a north-south hinge found along the ophiolitic belt, but other structural interpretations are tenable. The age of folding of North Fork rocks is constrained by the involvement of Triassic and younger cherts and crosscutting Late Jurassic plutons. Deformation in the North Fork terrane must have spanned a short period of time because the terrane is bounded structurally above and below by Middle or Late
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Nargess Shirdashtzadeh; Ghodrat Torabi; Ramin Samadi
2017-01-01
Introduction Study of the petrology of the ophiolites as the relics of ancient oceanic lithosphere, is a powerful tool to reconstruct Earth’s history. Mantle peridotites have mostly undergone alteration and serpentinization to some extent. Thus, the relics of metamorphic signatures from the upper mantle and crustal processes from most of the peridotites have been ruined. Several recent papers deal with the mantle peridotites of Nain Ophiolite (e.g. Ghazi et al., 2010). However, no scientif...
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Richard E. Miller; Jim Smith; Harry. Anderson
2001-01-01
Fertilizer trials in coast Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) in the Oregon Coast Range usually indicate small and statistically nonsignificant response to nitrogen (N) fertilizers. Inherently weak experimental designs of past trials could make them too insensitive to detect growth differences...
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Tracing alteration of mantle peridotite in the Samail ophiolite using Mg isotopes
de Obeso, J. C.; Kelemen, P. B.; Higgins, J. A.
2017-12-01
Magnesium is one of the main constituents of mantle peridotite ( 22.8 wt%), which has a homogeneous Mg isotopic composition (d26Mg = -0.25 ± 0.04 ‰ (2 sd) DSM3, Teng et al 2010 GCA). Mg isotopes are used as tracers of continental and oceanic weathering as they exhibit variable degrees of fractionation during alteration depending on the lithology. Here we report some of the first Mg isotopic compositions of the mantle section of the Samail ophiolite in Oman and its alteration products. The mantle section of the ophiolite is composed mainly of depleted harzburgites and dunites with mantle-like d26Mg (-0.25, -0.21 ‰). Mantle peridotite is far from equilibrium in near surface conditions leading to rapid, extensive serpentinization, carbonation and oxidation, as well as other geochemical changes. Our analyzed samples encompass most of the alteration of peridotite products observed in Oman including listvenites (completely carbonated peridotite) near the basal thrust of the ophiolite, massive magnesite veins within peridotite outcrops, and heavily altered harzburgites. Magnesite listvenites have d26Mg slightly below mantle values (-0.33, -0.33‰) while dolomite listvenites are significantly lighter (-1.46, -0.89‰). This suggests that heavy Mg isotopes were removed from the listvenites during ophiolite emplacement. Heavily altered peridotite from Wadi Fins exhibit alteration halos with drastic changes in composition. The most oxidized areas are enriched in Fe and depleted in Mg compared to the cores of the samples. These variations in Mg concentrations are complemented by a shift to heavy Mg isotopic compositions (0.74, 0.86‰), among the heaviest d26Mg values that have been reported in altered peridotite. Potential sinks for light isotopes removed from such alteration zones are massive magnesite veins with very light compositions (-3.39, -3.14‰). The fractionation of Mg isotopes observed in the mantle section of the ophiolite spans more than 50% of the known
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The basal part of the Oman ophiolitic mantle: a fossil Mantle Wedge?
Prigent, Cécile; Guillot, Stéphane; Agard, Philippe; Godard, Marguerite; Chauvet, Alain; Dubacq, Benoit; Monié, Patrick; Yamato, Philippe
2014-05-01
Although the Oman ophiolite is classically regarded as being the direct analog of oceanic lithosphere created at fast spreading ridges, the geodynamic context of its formation is still highly debated. The other alternative end-member model suggests that this ophiolite entirely formed in a supra-subduction zone setting. Fluids involved in the hydration of the oceanic lithosphere and in the presence of a secondary boninitic and andesitic volcanism may provide a way to discriminate between these two interpretations: are they descending near-axis hydrothermal fluxes (first model) or ascending from a subducting slab (second model)? We herein focus on the base of the ophiolitic mantle in order to characterize the origin of fluids and decipher hydration processes. Samples were taken along hecto- to kilometre-long sections across the basal banded unit directly overlying the amphibolitic/granulitic metamorphic sole. We carried out a petrological, structural and geochemical study on these rocks and their constitutive minerals. Our results show that, unlike the generally refractory character of Oman harzburgites, all the basal mantle rocks display secondary crystallization of clinopyroxene and amphibole through metasomatic processes. The microstructures and the chronology of these secondary mineralizations (clinopyroxene, pargasitic amphibole, antigorite and then lizardite/chrysotile) suggest that these basal rocks have been affected by cooling from mantle temperatures (serpentines (B, Sr, Rb, Ba, As), are consistent with amphibolite-derived fluids (Ishikawa et al., 2005) and cannot be easily explained by other sources. Based on these observations, we propose a geodynamic model in which intense and continuous metasomatism of the cooling base of the ophiolitic mantle is due to the release of fluids coming from the progressive dehydration of underlying amphibolitic rocks. This process is compatible with the progressive subduction of the Arabian margin during the Upper
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Zhang, Xiu-Zheng; Dong, Yong-Sheng; Wang, Qiang; Dan, Wei; Zhang, Chunfu; Deng, Ming-Rong; Xu, Wang; Xia, Xiao-Ping; Zeng, Ji-Peng; Liang, He
2016-07-01
Reconstructing the evolutionary history of the Paleo-Tethys Ocean remains at the center of debates over the linkage between Gondwana dispersion and Asian accretion. Identifying the remnants of oceanic lithosphere (ophiolites) has very important implications for identifying suture zones, unveiling the evolutionary history of fossil oceans, and reconstructing the amalgamation history between different blocks. Here we report newly documented ophiolite suites from the Longmu Co-Shuanghu Suture zone (LSSZ) in the Xiangtaohu area, central Qiangtang block, Tibet. Detailed geological investigations and zircon U-Pb dating reveal that the Xiangtaohu ophiolites are composed of a suite of Permian (281-275 Ma) ophiolites with a nearly complete Penrose sequence and a suite of Early Carboniferous (circa 350 Ma) ophiolite remnants containing only part of the lower oceanic crust. Geochemical and Sr-Nd-O isotopic data show that the Permian and Carboniferous ophiolites in this study were derived from an N-mid-ocean ridge basalts-like mantle source with varied suprasubduction-zone (SSZ) signatures and were characterized by crystallization sequences from wet magmas, suggesting typical SSZ-affinity ophiolites. Permian and Carboniferous SSZ ophiolites in the central Qiangtang provide robust evidence for the existence and evolution of an ancient ocean basin. Combining with previous studies on high-pressure metamorphic rocks and pelagic radiolarian cherts, and with tectonostratigraphic and paleontological data, we support the LSSZ as representing the main suture of the Paleo-Tethys Ocean which probably existed and evolved from Devonian to Triassic. The opening and demise of the Paleo-Tethys Ocean dominated the formation of the major framework for the East and/or Southeast Asia.
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Postobductional extension along and within the Frontal Range of the Eastern Oman Mountains
Mattern, Frank; Scharf, Andreas
2018-04-01
The Oman Mountains formed by late Cretaceous obduction of the Tethys-derived Semail Ophiolite. This study concerns the postobductional extension on the northern flank of the mountain belt. Nine sites at the northern margins of the Jabal Akhdar/Nakhl and Saih Hatat domes of the Eastern Oman ("Hajar") Mountains were investigated. The northern margins are marked by a system of major interconnected extensional faults, the "Frontal Range Fault". While the vertical displacements along the Saih Hatat and westerly located Jabal Nakhl domes measure 2.25-6.25 km, 0.5-4.5 km and 4-7 km, respectively, it amounts to 1-5 km along the Jabal Akhdar Dome. Extension had started during the late Cretaceous, towards the end of ophiolite emplacement. Two stages of extension can be ascertained (late Cretaceous to early Eocene and probably Oligocene) at the eastern part of the Frontal Range Fault System (Wadi Kabir and Fanja Graben faults of similar strike). Along the intervening and differently striking fault segments at Sad and Sunub the same two stages of deformation are deduced. The first stage is characterized again by extension. The second stage is marked by dextral motion, including local transtension. Probable Oligocene extension affected the Batinah Coast Fault while it also affected the Wadi Kabir Fault and the Fanja Graben. It is unclear whether the western portion of the Frontal Range Fault also went through two stages of deformation. Bedding-parallel ductile and brittle deformation is a common phenomenon. Hot springs and listwaenite are associated with dextral releasing bends within the fault system, as well as a basalt intrusion of probable Oligocene age. A structural transect through the Frontal Range along the superbly exposed Wadi Bani Kharous (Jabal Akhdar Dome) revealed that extension affected the Frontal Range at least 2.5 km south of the Frontal Range Fault. Also here, bedding-parallel shearing is important, but not exclusive. A late Cretaceous thrust was
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Orogenic, Ophiolitic, and Abyssal Peridotites
Bodinier, J.-L.; Godard, M.
2003-12-01
of ophiolites (mid-ocean ridges versus supra-subduction settings - e.g., Nicolas, 1989). In addition, the mantle structures and mineralogical compositions of tectonically emplaced mantle rocks may be obscured by deformation and metamorphic recrystallization during shallow upwelling, exhumation, and tectonic emplacement. Metamorphic processes range from high-temperature recrystallization in the stability field of plagioclase peridotites ( Rampone et al., 1993) to complete serpentinization (e.g., Burkhard and O'Neill, 1988). Some garnet peridotites record even more complex evolutions. They were first buried to, at least, the stability field of garnet peridotites, and, in some cases to greater than 150 km depths ( Dobrzhinetskaya et al., 1996; Green et al., 1997; Liou, 1999). Then, they were exhumed to the surface, dragged by buoyant crustal rocks ( Brueckner and Medaris, 2000).Alternatively, several peridotite massifs are sufficiently well preserved to allow the observation of structural relationships between mantle lithologies that are larger than the sampling scale of mantle xenoliths. It is possible in these massifs to evaluate the scale of mantle heterogeneities and the relative timing of mantle processes such as vein injection, melt-rock reaction, deformation, etc… Detailed studies of orogenic and ophiolitic peridotites on centimeter- to kilometer-scale provide invaluable insights into melt transfer mechanisms, such as melt flow in lithospheric vein conduits and wall-rock reactions (Bodinier et al., 1990), melt extraction from mantle sources via channeled porous flow ( Kelemen et al., 1995) or propagation of kilometer-scale melting fronts associated with thermalerosion of lithospheric mantle ( Lenoir et al., 2001). In contrast, mantle xenoliths may be used to infer either much smaller- or much larger-scale mantle heterogeneities, such as micro-inclusions in minerals ( Schiano and Clocchiatti, 1994) or lateral variations between lithospheric provinces ( O
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Deformation of the Songshugou ophiolite in the Qinling orogen
Sun, Shengsi; Dong, Yunpeng
2017-04-01
The Qinling orogen, middle part of the China Central Orogenic Belt, is well documented that was constructed by multiple convergences and subsequent collisions between the North China and South China Blocks mainly based on geochemistry and geochronology of ophiolites, magmatic rocks as well as sedimentary reconstruction. However, this model is lack of constraints from deformation of subduction/collision. The Songshugou ophiolite outcropped to the north of the Shangdan suture zone represents fragments of oceanic crust and upper mantle. Previous works have revealed that the ophiolite was formed at an ocean ridge and then emplaced in the northern Qinling belt. Hence, deformation of the ophiolite would provide constraints for the rifting and subduction processes. The ophiolite consists chiefly of metamorphosed mafic and ultramafic rocks. The ultramafic rocks contain coarse dunite, dunitic mylonite and harzburgite, with minor diopsidite veins. The mafic rocks are mainly amphibolite, garnet amphibolite and amphibole schist, which are considered to be eclogite facies and retrograde metamorphosed oceanic crust. Amphibole grains in the mafic rocks exhibit a strong shape-preferred orientation parallel to the foliation, which is also parallel to the lithologic contacts between mafic and ultramafic rocks. Electron backscattered diffraction (EBSD) analyses show strong olivine crystallographic preferred orientations (CPO) in dunite including A-, B-, and C-types formed by (010)[100], (010)[001] and (100)[001] dislocation slip systems, respectively. A-type CPO suggests high temperature plastic deformation in the upper mantle. In comparison, B-type may be restricted to regions with significantly high water content and high differential stress, and C-type may also be formed in wet condition with lower differential stress. Additionally, the dunite evolved into amphibolite facies metamorphism with mineral assemblages of olivine + talc + anthophyllite. Assuming a pressure of 1.5 GPa
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Weber, Sebastian; Martinez, Raul
2016-04-01
The Western Alpine Penninic domain is a classical accretionary prism that formed after the closure of the Penninic oceans in the Paleogene. Continental and oceanic nappes were telescoped into the Western Alpine stack associated with continent-continent collision. Within the Western Alpine geologic framework, the ophiolite nappes of the Zermatt-Saas Zone and the Tsate Unit are the remnants of the southern branch of the Piemonte-Liguria ocean basin. In addition, a series of continental basement slices reported as lower Austroalpine outliers have preserved an eclogitic high-pressure imprint, and are tectonically sandwiched between these oceanic nappes. Since the outliers occur at an unusual intra-ophiolitic setting and show a polymetamorphic character, this group of continental slices is of special importance for understanding the tectono-metamorphic evolution of Western Alps. Recently, more geochronological data from the Austroalpine outliers have become available that make it possible to establish a more complete picture of their complex geological history. The Lu-Hf garnet-whole rock ages for prograde growth of garnet fall into the time interval of 52 to 62 Ma (Weber et al., 2015, Fassmer et al. 2015), but are consistently higher than the Lu-Hf garnet-whole rock ages from several other locations throughout the Zermatt-Saas zone that range from 52 to 38 Ma (Skora et al., 2015). This discrepancy suggests that the Austroalpine outliers may have been subducted earlier than the ophiolites of the Zermatt-Saas Zone and therefore have been tectonically emplaced into their present intra-ophiolite position. This points to the possibility that the Zermatt-Saas Zone consists of tectonic subunits, which reached their respective pressure peaks over a prolonged time period, approximately 10-20 Ma. The pressure-temperature estimates from several members of the Austroalpine outliers indicate a complex distribution of metamorphic peak conditions, without ultrahigh
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Directory of Open Access Journals (Sweden)
Farhad Ghaseminejad
2014-10-01
Full Text Available Introduction Geological background Ophiolites have played a major role in our understanding of Earth’s processes ranging from seafloor spreading, melt evolution and magma transport in oceanic spreading centers, and hydrothermal alteration and mineralization of oceanic crust to collision tectonics, mountain building processes, and orogeny. They provide the essential structural, petrological, geochemical, and geochronological evidence to document the evolutionary history of ancient continental margins and ocean basin. Ophiolites include a peridotitic mantle sequence, generally characterized by high-temperature plastic deformation and residual chemistry, and a comagmatic crustal sequence (gabbros, diabase dikes, and submarine basalts, weakly or not deformed. According to this interpretation, ophiolites were allochthonous with respect to their country rocks. They were assembled during a primary accretion stage at an oceanic spreading center, and later tectonically emplaced on a continental margin or island arc (Dilek, 2003. The indigenous dikes of pyroxenites and gabbros that were injected into a melting peridotite, or intrusive dikes of pyroxenite and gabbro that injected when the peridotite was fresh and well below its solidus, are discussed in different ophiolite papers. Pyroxenite formation and contact of gabbro and mantle peridotite are discussed in different articles (Dilek, 2003. When a gabbro intrude a fresh mantle peridotite could not significantly react with it, but if intrusion occurs during the serpentinization, the gabbro will change to rodingite. Geological setting The Naein ophiolitic melanges comprise the following rock units: mantle peridotites (harzburgite, lherzolite, dunite, with associated chromitite, gabbro, pyroxenite, sheeted and swarm dikes, massive basalts, pillow lava, plagiogranite, radiolarian chert, glaubotruncana limestone, rodingite, listvenite, and metamorphic rocks (foliated amphibolitic dike, amphibolite, skarn
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Rollinson, H. R.
2014-12-01
Granitoid dykes up to several hundred metres wide and 2 km long are found in depleted harzburgites in the mantle section of the Oman ophiolite. They vary in composition from tonalite to potassic granite and are generally more potassic than the crustal plagiogranites found within the sheeted dyke complex higher up within the ophiolite stratigraphy. Some granites are strongly peraluminous and contain garnet and andalusite. They are geochemically variable, some with REE that are relatively unfractionated ((La/Yb)n= 3.5-6.0, flat middle to heavy REE, steep light REE) to those which are highly fractionated ((La/Yb)n= 28-220). On primitive-mantle normalised plots some have very high concentrations of fluid-mobile elements - Cs, Rb, Th, U and Pb. Few have significant Ta-Nb anomalies. On the Ca-Fe-Mg-Ti discrimination diagram of Patino Douce (J. Petrol., 1999) whole-rock compositions define a spectrum between felsic-pelite derived melts and amphibolite-derived melts. There is a chemical similarity between the least REE fractionated plagiogranites (generally tonalites and granodiorites) and melts of an amphibolitic parent. This is supported by the occurrence of mafic xenoliths in some dykes, the presence of hornblende and highly calcic cores (up to An85) in some plagioclase grains. Trace element modelling using Oman Geotimes lavas as the starting composition indicates that melting took place in the garnet stability field, although enrichment in the melt in Cs, Rb, Ba and Pb suggests that there was another component present in addition to the mafic parent. Other plagiogranites (trondhjemites and granites) have a strongly peraluminous chemistry and mineralogy and geochemical similarities with the Himalayan leucogranites implying that they were derived from a sedimentary protolith. These mantle plagiogranites are more prevalent in the northern outcrops of the ophiolite. The volume of granitoid melt and the depth of melting preclude their derivation from the sole of the
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Directory of Open Access Journals (Sweden)
D. E. Saveliev
2015-12-01
Full Text Available This article presents the results of structural, petrographic, mineralogical and chemical studies of dunite veinlets in spinel peridotite from the Kraka ophiolites. It is demonstrated that plastic deformation of polycrystalline olivine, which form dunite, was accompanied by precipitation of impurities (aluminum and chrome as newly formed chrome spinels. The thinnest acicular inclusions of 0.3-0.5 micron thick are aligned in olivine grains along [010] axis. Bigger elongated irregular chrome spinel grains usually occur along grain and sub-grain olivine boundaries, and, occasionally, inside the grains along [100] axis. Alteration from the fine xenomorphic grains of chrome spinels to the bigger idiomorphic crystals was observed. Analogically to dynamic ageing (dispersion hardening in metals, the structural and chemical alterations in dunites are interpreted as deformation induced segregation of impurities. It is suggested that the euhedral chrome spinel grains typical for ophiolitic dunites were formed by coalescence and spheroidization. This process may be a key factor in the formation of ophiolitic chrome ore deposits.
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Garcia, A.F.; Mahan, S.A.
2012-01-01
A fundamental geological tenet is that as landscapes evolve over graded to geologic time, geologic structures control patterns of topographic distribution in mountainous areas such that terrain underlain by competent rock will be higher than terrain underlain by incompetent rock. This paper shows that in active orogens where markedly weak and markedly strong rocks are juxtaposed along contacts that parallel regional structures, relatively high topography can form where strain is localized in the weak rock. Such a relationship is illustrated by the topography of the central Coast Ranges between the Pacific coastline and the San Andreas fault zone (SAFZ), and along the length of the Gabilan Mesa (the "Gabilan Mesa segment" of the central Coast Ranges). Within the Gabilan Mesa segment, the granitic upper crust of the Salinian terrane is in contact with the accretionary-prism m??lange upper crust of the Nacimiento terrane along the inactive Nacimiento fault zone. A prominent topographic lineament is present along most of this lithologic boundary, approximately 50 to 65. km southwest of the SAFZ, with the higher topography formed in the m??lange on the southwest side of the Nacimiento fault. This paper investigates factors influencing the pattern of topographic development in the Gabilan Mesa segment of the central Coast Ranges by correlating shortening magnitude with the upper-crust compositions of the Salinian and Nacimiento terranes. The fluvial geomorphology of two valleys in the Gabilan Mesa, which is within the Salinian terrane, and alluvial geochronology based on optically-stimulated luminescence (OSL) age estimates, reveal that the magnitude of shortening accommodated by down-to-the-southwest tilting of the mesa since 400ka is less than 1 to 2m. Our results, combined with those of previous studies, indicate that at least 63% to 78% of late-Cenozoic, northeast-southwest directed, upper-crustal shortening across the Gabilan Mesa segment has been accommodated
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Bonev, Nikolay; Filipov, Petyo
2017-12-01
In the Hellenides of northern Greece, the Sithonia back-arc ophiolite constitute an element of the Vardar suture zone against the Chortiatis island arc magmatic suite, the Melissochori Formation and the Serbo-Macedonian Massif further north at the Mesozoic continental margin of Eurasia. A granodiorite from the Chortiatis island arc magmatic suite crystallized at 160 Ma as derived from new U-Pb zircon geochronology and confirms the end of arc magmatic activity that started at around 173 Ma. Located southerly of the Chortiatis island arc magmatic suite, the Sithonia ophiolite had igneous life from 159 to 149 Ma, and the ophiolite interfinger with clastic-carbonate Kimmeridgian sediments. Magmatic structures (i.e., sheeted dykes) in the ophiolite witness for NE-trending rift axis, while the transform faults and fracture zones sketch NW-SE transcurrent transtension-like propagation of the rift-spreading center at Sithonia that is consistent with a dextral wrench corridor already proposed for the ophiolite origin in the eastern Vardar zone. The tectonic emplacement of the Sithonia ophiolite involved dextral ENE to SE strike-slip sense of shear and SW and NE reverse thrust sense of shear on mostly steep foliation S1, subhorizontal lineation L1 and associated variably inclined F1 fold axes. This structural grain and kinematics are shared by adjacent Chortiatis island arc magmatic suite and the Melissochori Formation. The coexistence of strike-parallel and thrust components of displacement along discrete dextral strike-slip shear zones and internal deformation of the mentioned units is interpreted to result from a bulk dextral transpressive deformation regime developed in greenschist-facies metamorphic conditions. The back-arc ocean floor previous structural architecture with faults and fracture zones where Kimmeridgian sediments deposited in troughs was used by discrete strike-slip shear zones in which these sediments involved, and the shear zones become the sites for
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Vasey, Michael C; Parker, V Thomas; Holl, Karen D; Loik, Michael E; Hiatt, Seth
2014-09-01
We investigated the hypothesis that maritime climatic factors associated with summer fog and low cloud stratus (summer marine layer) help explain the compositional diversity of chaparral in the coast range of central California. We randomly sampled chaparral species composition in 0.1-hectare plots along a coast-to-interior gradient. For each plot, climatic variables were estimated and soil samples were analyzed. We used Cluster Analysis and Principle Components Analysis to objectively categorize plots into climate zone groups. Climate variables, vegetation composition and various diversity measures were compared across climate zone groups using ANOVA and nonmetric multidimensional scaling. Differences in climatic variables that relate to summer moisture availability and winter freeze events explained the majority of variance in measured conditions and coincided with three chaparral assemblages: maritime (lowland coast where the summer marine layer was strongest), transition (upland coast with mild summer marine layer influence and greater winter precipitation), and interior sites that generally lacked late summer water availability from either source. Species turnover (β-diversity) was higher among maritime and transition sites than interior sites. Coastal chaparral differs from interior chaparral in having a higher obligate seeder to facultative seeder (resprouter) ratio and by being dominated by various Arctostaphylos species as opposed to the interior dominant, Adenostoma fasciculatum. The maritime climate influence along the California central coast is associated with patterns of woody plant composition and β-diversity among sites. Summer fog in coastal lowlands and higher winter precipitation in coastal uplands combine to lower late dry season water deficit in coastal chaparral and contribute to longer fire return intervals that are associated with obligate seeders and more local endemism. Soil nutrients are comparatively less important in explaining plant
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Qiu, Tian; Zhu, Yongfeng
2018-06-01
The Sartohay ophiolitic mélange is located in western Junggar (Xinjiang province, NW China), which is a major component of the core part of the Central Asian Orogenic Belt (CAOB). Chromian spinels in serpentinite, talc schist, carbonate-talc schist and listwaenite in Sartohay ophiolitic mélange retain primary compositions with Cr# of 0.39-0.65, Mg# = 0.48-0.67, and Fe3+# evolution of chromian spinels in highly altered ultramafic rocks from the Sartohay ophiolitic mélange. Chromian spinels in serpentinite and talc schist were rimmed by Cr-magnetite, which was dissolved completely during transformation from serpentinite/talc schist to listwaenite. Chromian spinels were then transformed into Fe2+-rich chromite in shear zones, which characterized by high fluid/rock ratios. This Fe2+-rich chromite and/or chromian spinels could then be transformed into Fe3+-rich chromite in oxidizing conditions at shallow levels.
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Complejo Ojosmin: fragment of ophiolite transamazonian
International Nuclear Information System (INIS)
Bossi, J.; Pineyro, D. . Email geologia@fagro.edu.uy
2004-01-01
A preliminary geological survey of a previously unknown basic igneous complex in the Padre Alta Terrane (Pat) is presented. We report petrographic, geochemical and stratigraphic data for more than 200 outcrops. Geological evolution of the complex can be described in terms of four main events: (1) formation Pat units around 2000 Ma; (2) granodiorite thrusting onto possible ophiolite ca 1900 Ma ; (3) granophyric magmatism around 1700 Ma(4) intrusion of trachyte dykes. Data available suggest thrusting onto fragment of oceanic crust. Since the described structure presupposes the existence of pre transamazonian continental fragments in the TPA, it is very important to study the area in detail in the future [es
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Ishizuka, O.; Tani, K.; Reagan, M. K.; Kanayama, K.; Umino, S.; Harigane, Y.; Sakamoto, I.
2014-12-01
The Izu-Bonin-Mariana (IBM) forearc preserves the earliest arc magmatic history from subduction initiation to the establishment of the arc. Recent investigations have established a bottom to top igneous stratigraphy of: 1) mantle peridotite, 2) gabbroic rocks, 3) a sheeted dyke complex, 4) basaltic pillow lavas (forearc basalts: FAB), 5) boninites and magnesian andesites, 6) tholeiites and calcalkaline arc lavas. This stratigraphy has many similarities to supra-subduction zone (SSZ) ophiolites. One of the most important common characteristics between the SSZ ophiolites and the forearc crust is the occurrence of MORB-like basaltic lavas underlying or accompanying boninites and early arc volcanic suites. A key observation from the IBM forearc is that FAB differs from nearby back-arc lavas in chemical characteristics, including a depletion in moderately incompatible elements. This indicates that FAB is not a pre-existing oceanic basement of the arc, but the first magmatic product after subduction initiation. Sheeted dikes of FAB composition imply that this magmatism was associated with seafloor spreading, possibly triggered by onset of slab sinking. Recognition of lavas with transitional geochemical characteristics between the FAB and the boninites strongly implies genetic linkage between these two magma types. The close similarity of the igneous stratigraphy of SSZ ophiolites to the IBM forearc section strongly implies a common magmatic evolutionary path, i.e., decompressional melting of a depleted MORB-type mantle is followed by melting of an even more depleted mantle with the addition of slab-derived fluid/melt to produce boninite magma. Similarity of magmatic process between IBM forearc and Tethyan ophiolites appears to be reflected on common characteristics of upper mantle section. Peridotite from both sections show more depleted characteristics compared to upper mantle rocks from mid-ocean ridges. Age determinations reveal that first magmatism at the IBM arc
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Maffione, Marco; van Hinsbergen, Douwe J. J.; de Gelder, Giovanni I. N. O.; van der Goes, Freek C.; Morris, Antony
2017-05-01
Formation of new subduction zones represents one of the cornerstones of plate tectonics, yet both the kinematics and geodynamics governing this process remain enigmatic. A major subduction initiation event occurred in the Late Cretaceous, within the Neo-Tethys Ocean between Gondwana and Eurasia. Suprasubduction zone ophiolites (i.e., emerged fragments of ancient oceanic lithosphere formed at suprasubduction spreading centers) were generated during this subduction event and are today distributed in the eastern Mediterranean region along three E-W trending ophiolitic belts. Several models have been proposed to explain the formation of these ophiolites and the evolution of the associated intra-Neo-Tethyan subduction zone. Here we present new paleospreading directions from six Upper Cretaceous ophiolites of Turkey, Cyprus, and Syria, calculated by using new and published paleomagnetic data from sheeted dyke complexes. Our results show that NNE-SSW subduction zones were formed within the Neo-Tethys during the Late Cretaceous, which we propose were part of a major step-shaped subduction system composed of NNE-SSW and WNW-ESE segments. We infer that this subduction system developed within old (Triassic?) lithosphere, along fracture zones and perpendicular weakness zones, since the Neo-Tethyan spreading ridge formed during Gondwana fragmentation would have already been subducted at the Pontides subduction zone by the Late Cretaceous. Our new results provide an alternative kinematic model of Cretaceous Neo-Tethyan subduction initiation and call for future research on the mechanisms of subduction inception within old (and cold) lithosphere and the formation of metamorphic soles below suprasubduction zone ophiolites in the absence of nearby spreading ridges.
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Petrographical and geochemical properties of plagiogranites and gabbros in Guleman ophiolite
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Ayşe Didem KILIÇ
2009-06-01
Full Text Available Petrographical and geochemical properties of gabbros and plagiogranites of Guleman ophiolite are determined. It was concluded that gabbros can be basic rocks on subduction zone and plagioclase-rich leucocratic rocks (plagiogranite are differentiation products of fractional crystallization of a basic magma in the magma chamber.
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An alkaline spring system within the Del Puerto ophiolite (California USA): A Mars analog site
Energy Technology Data Exchange (ETDEWEB)
Blank, J.G.; Green, S.; Blake, D.; Valley, J.; Kita, N.; Treiman, A.; Dobson, P.F.
2008-10-01
Mars appears to have experienced little compositional differentiation of primitive lithosphere, and thus much of the surface of Mars is covered by mafic lavas. On Earth, mafic and ultramafic rocks present in ophiolites, oceanic crust and upper mantle that have been obducted onto land, are therefore good analogs for Mars. The characteristic mineralogy, aqueous geochemistry, and microbial communities of cold-water alkaline springs associated with these mafic and ultramafic rocks represent a particularly compelling analog for potential life-bearing systems. Serpentinization, the reaction of water with mafic minerals such as olivine and pyroxene, yields fluids with unusual chemistry (Mg-OH and Ca-OH waters with pH values up to {approx}12), as well as heat and hydrogen gas that can sustain subsurface, chemosynthetic ecosystems. The recent observation of seeps from pole-facing crater and canyon walls in the higher Martian latitudes supports the hypothesis that even present conditions might allow for a rockhosted chemosynthetic biosphere in near-surface regions of the Martian crust. The generation of methane within a zone of active serpentinization, through either abiogenic or biogenic processes, could account for the presence of methane detected in the Martian atmosphere. For all of these reasons, studies of terrestrial alkaline springs associated with mafic and ultramafic rocks are particularly timely. This study focuses on the alkaline Adobe Springs, emanating from mafic and ultramafic rocks of the California Coast Range, where a community of novel bacteria is associated with the precipitation of Mg-Ca carbonate cements. The carbonates may serve as a biosignature that could be used in the search for evidence of life on Mars.
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Sr isotopic tracer study of the Samail ophiolite, Oman
International Nuclear Information System (INIS)
Lanphere, M.A.; Coleman, R.G.; Hopson, C.A.
1981-01-01
We have measured Rb and Sr concentrations and Sr isotopic compositions in 41 whole-rock samples and 12 mineral separates from units of the Samail ophiolite, including peridotite, gabbro, plagiogranite diabase dikes, and gabbro and websterite dikes within the metamorphic peridotite. Ten samples of cummulate gabbro from the Wadir Kadir section and nine samples from the Wadi Khafifah section have mean 87 Sr/ 86 Sr ratios and standard deviations of 0.70314 +- 0.00030 and 0.70306 +- 0.00034, respectively. The dispersion in Sr isotopic composition may reflect real heterogeneities in the magma source region. The average Sr isotopic composition of cumulate gabbro falls in the range of isotopic compositions of modern midocean ridge basalt. The 87 Sr/ 86 Sr ratios of noncumulate gabbro, plagiogranite, and diabase dikes range from 0.7034 to 0.7047, 0.7038 to 0.7046, and 0.7037 to 0.7061, respectively. These higher 87 Sr/ 86 Sr ratios are due to alteration of initial magmatic compositions by hydrothermal exchange with seawater. Mineral separates from dikes that cut harzburgite tectonite have Sr isotopic compositions which agree with that of cumulate gabbro. These data indicate that the cumulate gabbro and the different dikes were derived from partial melting of source regions that had similar long-term histories and chemical compositions
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Alteration, age, and emplacement of the Tangihua Complex ophiolite, New Zealand
International Nuclear Information System (INIS)
Nicholson, K.N.; Black, P.M.; Picard, C.; Cooper, P.; Hall, C.M.; Itaya, T.
2007-01-01
The Tangihua Complex, New Zealand, represents an upper sequence of Late Cretaceous oceanic crustal material: massive basalt flows, pillow lavas, and dolerites. Three phases of alteration are preserved within the complex, each characterised by zeolite precipitation, which correlate to stratigraphic position. The mylonitised sole contains greenschist assemblages (c. 325 degrees C) grading upwards into the initial phase of alteration (250-300 degrees C), and is characterised by actinolite, epidote, albite, and Na-rich zeolites. This phase is cut by lower temperature veins of chlorite-smectite and Ca-rich zeolites. The final alteration phase ( + and Ca 2+ rich minerals, including apophyllite and calcite. Disruption of Ar/Ar spectra around 50 Ma correlate with rifting in the Loyalty Basin and initiation of obduction along the Loyalty-Three Kings Ridge system. We suggest that these events resulted in initial dismemberment, alteration, and movement of the ophiolite, whereas Ar/Ar plateaux at 25-35 Ma correspond to ophiolite emplacement and the last phases of alteration. (author). 49 refs., 5 figs., 3 tabs
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Calibrating and testing a gap model for simulating forest management in the Oregon Coast Range
Pabst, R.J.; Goslin, M.N.; Garman, S.L.; Spies, T.A.
2008-01-01
The complex mix of economic and ecological objectives facing today's forest managers necessitates the development of growth models with a capacity for simulating a wide range of forest conditions while producing outputs useful for economic analyses. We calibrated the gap model ZELIG to simulate stand-level forest development in the Oregon Coast Range as part of a landscape-scale assessment of different forest management strategies. Our goal was to incorporate the predictive ability of an empirical model with the flexibility of a forest succession model. We emphasized the development of commercial-aged stands of Douglas-fir, the dominant tree species in the study area and primary source of timber. In addition, we judged that the ecological approach of ZELIG would be robust to the variety of other forest conditions and practices encountered in the Coast Range, including mixed-species stands, small-scale gap formation, innovative silvicultural methods, and reserve areas where forests grow unmanaged for long periods of time. We parameterized the model to distinguish forest development among two ecoregions, three forest types and two site productivity classes using three data sources: chronosequences of forest inventory data, long-term research data, and simulations from an empirical growth-and-yield model. The calibrated model was tested with independent, long-term measurements from 11 Douglas-fir plots (6 unthinned, 5 thinned), 3 spruce-hemlock plots, and 1 red alder plot. ZELIG closely approximated developmental trajectories of basal area and large trees in the Douglas-fir plots. Differences between simulated and observed conifer basal area for these plots ranged from -2.6 to 2.4 m2/ha; differences in the number of trees/ha ???50 cm dbh ranged from -8.8 to 7.3 tph. Achieving these results required the use of a diameter-growth multiplier, suggesting some underlying constraints on tree growth such as the temperature response function. ZELIG also tended to overestimate
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The recycling of chromitites in ophiolites from southwestern North America
González-Jiménez, José M.; Camprubí, Antoni; Colás, Vanessa; Griffin, William L.; Proenza, Joaquín A.; O'Reilly, Suzanne Y.; Centeno-García, Elena; García-Casco, Antonio; Belousova, Elena; Talavera, Cristina; Farré-de-Pablo, Júlia; Satsukawa, Takako
2017-12-01
Podiform chromitites occur in mantle peridotites of the Late Triassic Puerto Nuevo Ophiolite, Baja California Sur State, Mexico. These are high-Cr chromitites [Cr# (Cr/Cr + Al atomic ratio = 0.61-0.69)] that contain a range of minor- and trace-elements and show whole-rock enrichment in IPGE (Os, Ir, Ru). That are similar to those of high-Cr ophiolitic chromitites crystallised from melts similar to high-Mg island-arc tholeiites (IAT) and boninites in supra-subduction-zone mantle wedges. Crystallisation of these chromitites from S-undersaturated melts is consistent with the presence of abundant inclusions of platinum-group minerals (PGM) such as laurite (RuS2)-erlichmanite (OsS2), osmium and irarsite (IrAsS) in chromite, that yield TMA ≈ TRD model ages peaking at 325 Ma. Thirty-three xenocrystic zircons recovered from mineral concentrates of these chromitites yield ages (2263 ± 44 Ma to 278 ± 4 Ma) and Hf-O compositions [ɛHf(t) = - 18.7 to + 9.1 and 18O values the mantle via subduction. They were captured by the parental melts of the chromitites when the latter formed in a supra-subduction zone mantle wedge polluted with crustal material. In addition, the Puerto Nuevo chromites have clinopyroxene lamellae with preferred crystallographic orientation, which we interpret as evidence that chromitites have experienced high-temperature and ultra high-pressure conditions (the formation of chromitite in the supra-subduction zone mantle wedge underlying the Vizcaino intra-oceanic arc ca. 250 Ma ago, deep-mantle recycling, and subsequent diapiric exhumation in the intra-oceanic basin (the San Hipólito marginal sea) generated during an extensional stage of the Vizcaino intra-oceanic arc ca. 221 Ma ago. The TRD ages at 325 Ma record a partial melting event in the mantle prior to the construction of the Vizcaino intra-oceanic arc, which is probably related to the Permian continental subduction, dated at 311 Ma.
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Spring and surface water quality of the Cyprus ophiolites
Directory of Open Access Journals (Sweden)
C. Neal
2002-01-01
Full Text Available A survey of surface, spring and borehole waters associated with the ophiolite rocks of Cyprus shows five broad water types (1 Mg-HCO3, (2 Na-SO4-Cl-HCO3, (3 Na-Ca-Cl-SO4-OH-CO3, (4 Na-Cl-SO4 and (5 Ca-SO4. The waters represent a progression in chemical reactivity from surface waters that evolve within a groundwater setting due to hydrolysis of the basic/ultrabasic rock as modified by CO2-weathering. An increase in salinity is also observed which is due to mixing with a saline end-member (modified sea-water and dissolution of gypsum/anhydrite. In some cases, the waters have pH values greater than 11. Such high values are associated with low temperature serpentinisation reactions. The system is a net sink for CO2. This feature is related not only to the hydrolysis of the primary minerals in the rock, but also to CaCO3 or Ca-Mg-CO3 solubility controls. Under hyperalkaline conditions, virtually all the carbon dioxide is lost from the water due to the sufficiently high calcium levels and carbonate buffering is then insignificant. Calcium sulphate solubility controls may also be operative when calcium and sulphate concentrations are particularly high. Keywords: Cyprus, Troodos, ophiolite, serpentinisation, spring, stream, water quality, bromide, iodine, boron, trace elements, hyperalkaline.
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Yang, Hsiaochin; Chen, Wenshan
2013-04-01
According to the collision of Philippine Sea plate and Eurasia plate, a series of left-lateral active faults with reverse sense exists in the Longitudinal Valley of east Taiwan. The Holocene marine terraces along the east coast of the Coastal Range in Taiwan are well known for their very rapid uplift and record tectonic history of this active collision boundary. The Holocene marine terrace sequence resulting from successive sea level change and tectonic activation is subdivided into several steps where the highest and oldest terrace, back to ca 13,000yr BP, reaches up to ca 80 m above sea level, and the lower terraces are mostly erosional ones, overlain by less than 1m thick coral beds in situ. The uplift of the coast is very high, ranging from 5 to 10 m/ka. According to the fabrics of potsherds and geochronological data, the prehistoric cultures in eastern Taiwan could be classified into three stages: Fushan (ca 5000-3500yr BP), Peinan/Chilin (ca3500-2000yr BP), Kweishan (ca2000-1000 yr BP) and Jinpu (ca 1000-400yr BP) cultural assemblages respectively. A great difference exists between the various cultural stage, not only the pottery making techniques, but also the distributions of archaeological sites. Combined with the dynamic geomorphic evolution of marine terraces and the distribution of prehistoric culture sites on the east coast of the Coastal Range, a coastal migration trend could be established.
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Colgan, Joseph P.; McPhee, Darcy K.; McDougall, Kristin; Hourigan, Jeremy K.
2013-01-01
We synthesized data from geologic maps, wells, seismic-reflection profiles, potential-field interpretations, and low-temperature thermochronology to refine our understanding of late Cenozoic extension and shortening in the Salinian block of the central California Coast Ranges. Data from the La Panza Range and southern Salinas Basin document early to middle Miocene extension, followed by Pliocene and younger shortening after a period of little deformation in the late Miocene. Extension took place on high-angle normal faults that accommodated ∼2% strain at the scale of the ∼50-km-wide Salinian block (oriented perpendicular to the San Andreas fault). Shortening was accommodated by new reverse faults, reactivation of older normal faults, and strike-slip faulting that resulted in a map-view change in the width of the Salinian block. The overall magnitude of shortening was ∼10% strain, roughly 4–5 times greater than the amount of extension. The timing and magnitude of deformation in our study area are comparable to that documented in other Salinian block basins, and we suggest that the entire block deformed in a similar manner over a similar time span. The timing and relative magnitude of extension and shortening may be understood in the context of central Coast Range tectonic boundary conditions linked to rotation of the western Transverse Ranges at the south end of the Salinian block. Older models for Coast Range shortening based on balanced fault-bend fold-style cross sections are a poor approximation of Salinian block deformation, and may lead to mechanically improbable fault geometries that overestimate the amount of shortening.
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Vacquand, Christèle; Deville, Eric; Beaumont, Valérie; Guyot, François; Sissmann, Olivier; Pillot, Daniel; Arcilla, Carlo; Prinzhofer, Alain
2018-02-01
This paper proposes a comparative study of reduced gas seepages occurring in ultrabasic to basic rocks outcropping in ophiolitic complexes based on the study of seepages from Oman, the Philippines, Turkey and New Caledonia. This study is based on analyses of the gas chemical composition, noble gases contents, stable isotopes of carbon, hydrogen and nitrogen. These seepages are mostly made of mixtures of three main components which are H2, CH4 and N2 in various proportions. The relative contents of the three main gas components show 4 distinct types of gas mixtures (H2-rich, N2-rich, N2-H2-CH4 and H2-CH4). These types are interpreted as reflecting different zones of gas generation within or below the ophiolitic complexes. In the H2-rich type, associated noble gases display signatures close to the value of air. In addition to the atmospheric component, mantle and crustal contributions are present in the N2-rich, N2-H2-CH4 and H2-CH4 types. H2-bearing gases are either associated with ultra-basic (pH 10-12) spring waters or they seep directly in fracture systems from the ophiolitic rocks. In ophiolitic contexts, ultrabasic rocks provide an adequate environment with available Fe2+ and alkaline conditions that favor H2 production. CH4 is produced either directly by reaction of dissolved CO2 with basic-ultrabasic rocks during the serpentinization process or in a second step by H2-CO2 interaction. H2 is present in the gas when no more carbon is available in the system to generate CH4. The N2-rich type is notably associated with relatively high contents of crustal 4He and in this gas type N2 is interpreted as issued mainly from sediments located below the ophiolitic units.
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Perez, Americus d. C.; Faustino-Eslava, Decibel V.; Yumul, Graciano P.; Dimalanta, Carla B.; Tamayo, Rodolfo A.; Yang, Tsanyao Frank; Zhou, Mei-Fu
2013-03-01
The volcanic section of the Middle Oligocene Amnay Ophiolite in Mindoro, Philippines has previously been shown to be of normalmid-oceanic ridge basalt (NMORB) composition. Here we report for the first time an enriched mantle component that is additionally recorded in this crustal section. New whole rock major and trace element data are presented for nine mafic volcanic rocks from a section of the ophiolite that has not been previously examined. These moderately evolved tholeiitic basalts were found to have resulted from the bulk mixing of ˜10% ocean island basalt components with depleted mantle. Drawing together various geochemical characteristics reported for different rock suites taken as representatives of the South China Sea crust, including the enriched MORB (EMORB) and NMORB of the East Taiwan Ophiolite, the NMORB from previous studies of the Amnay Ophiolite and the younger ocean floor eruptives of the Scarborough Seamount-Reed Bank region, a veined mantle model is proposed for the South China Sea mantle. The NMORB magmatic products are suggested to have been derived from the more depleted portions of the mantle whereas the ocean island basalt (OIB) and EMORB-type materials from the mixing of depleted and veined/enriched mantle regions.
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Methane Dynamics in a Tropical Serpentinizing Environment: The Santa Elena Ophiolite, Costa Rica
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Melitza Crespo-Medina
2017-05-01
Full Text Available Uplifted ultramafic rocks represent an important vector for the transfer of carbon and reducing power from the deep subsurface into the biosphere and potentially support microbial life through serpentinization. This process has a strong influence upon the production of hydrogen and methane, which can be subsequently consumed by microbial communities. The Santa Elena Ophiolite (SEO on the northwestern Pacific coast of Costa Rica comprises ~250 km2 of ultramafic rocks and mafic associations. The climatic conditions, consisting of strongly contrasting wet and dry seasons, make the SEO a unique hydrogeological setting, where water-rock reactions are enhanced by large storm events (up to 200 mm in a single storm. Previous work on hyperalkaline spring fluids collected within the SEO has identified the presence of microorganisms potentially involved in hydrogen, methane, and methanol oxidation (such as Hydrogenophaga, Methylobacterium, and Methylibium spp., respectively, as well as the presence of methanogenic Archaea (such as Methanobacterium. Similar organisms have also been documented at other serpentinizing sites, however their functions have not been confirmed. SEO's hyperalkaline springs have elevated methane concentrations, ranging from 145 to 900 μM, in comparison to the background concentrations (<0.3 μM. The presence and potential activity of microorganisms involved in methane cycling in serpentinization-influenced fluids from different sites within the SEO were investigated using molecular, geochemical, and modeling approaches. These results were combined to elucidate the bioenergetically favorable methane production and/or oxidation reactions in this tropical serpentinizing environment. The hyperalkaline springs at SEO contain a greater proportion of Archaea and methanogens than has been detected in any terrestrial serpentinizing system. Archaea involved in methanogenesis and anaerobic methane oxidation accounted from 40 to 90% of total
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Ambrose, T. K.; Wallis, D.; Hansen, L. N.; Waters, D. J.; Searle, M. P.
2017-12-01
Studies of experimentally deformed rocks and small-scale natural shear zones have demonstrated that volumetrically minor phases can control strain localisation by limiting grain growth and promoting grain-size sensitive deformation mechanisms. Such studies are often used to infer a critical role for minor phases in the development of plate boundaries. However, the role of of minor phases in strain localisation at plate boundaries remains to be tested by direct observation. To test the hypothesis that minor phases control strain localisation at plate boundaries, we conducted microstructural analyses of peridotite samples collected across the base of the Oman-UAE ophiolite. The base of the ophiolite is marked by the Semail thrust, which represents the now exhumed contact between subducted oceanic crust and the overlying mantle wedge. As such, the base of the ophiolite provides the opportunity to directly examine a former plate boundary. Our results demonstrate that the mean olivine grain size is inversely proportional to the abundance of minor phases (primarily pyroxene), consistent with suppression of grain growth by grain-boundary pinning. Our results also reveal that mean olivine grain size is proportional to CPO strength, suggesting that the fraction of strain accommodated by different deformation mechanisms varied spatially. Experimentally-derived flow laws indicate that under the inferred deformation conditions the viscosity of olivine was grain-size sensitive. As such, grain size, and thereby the abundance of minor phases, influenced viscosity during subduction-related deformation along the base of the mantle wedge. We calculate that viscosity and strain rate respectively decrease and increase by approximately an order of magnitude towards the base of the ophiolite. Our data indicate that this rheological weakening was primarily the result of more abundant secondary phases near the base of the ophiolite. Our interpretations are consistent with those of
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Dixon, S.; Rutherford, M. J.
1979-01-01
A study of relationships between basic and acidic rocks was made by fractionating primitive basalt at low pressure anhydrous conditions at various fugacities. Fractionally crystallized basalt became increasingly enriched in iron which became silicate liquid immiscible, producing Fe-enriched basaltic and granitic liquids. The latter is similar to plagiogranites found in mid-oceanic rift (MOR) regions, showing that silicate liquid immiscibility could be the petrogenic process which produces plagiogranites in some MOR regions and ophiolites. The major problem in considering plagiogranites as products of silicate liquid immiscibility is absence of any description of the Fe-enriched conjugate liquid in the ophiolite or MOR literature, and the identification of this magma is essential for a definite case of silicate liquid immiscibility.
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Page, Norman J; Talkington, Raymond W.
1984-01-01
Samples of spinel lherzolite, harzburgite, dunite, and chromitite from the Bay of Islands, Lewis Hills, Table Mountain, Advocate, North Arm Mountain, White Hills Periodite Point Rousse, Great Bend and Betts Cove ophiolite complexes in Newfoundland were analyzed for the platinum-group elements (PGE) Pd, Pt, Rh, Ru and Ir. The ranges of concentration (in ppb) observed for all rocks are: less than 0. 5 to 77 (Pd), less than 1 to 120 (Pt), less than 0. 5 to 20 (Rh), less than 100 to 250 (Ru) and less than 20 to 83 (Ir). Chondrite-normalized PGE ratios suggest differences between rock types and between complexes. Samples of chromitite and dunite show relative enrichment in Ru and Ir and relative depletion in Pt and Pd.
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Maffione, Marco; van Hinsbergen, Douwe J. J.
2018-03-01
Jurassic subduction initiation in the Neo-Tethys Ocean eventually led to the collision of the Adria-Africa and Eurasia continents and the formation of an 6,000 km long Alpine orogen spanning from Iberia to Iran. Reconstructing the location and geometry of the plate boundaries of the now disappeared Neo-Tethys during the initial moments of its closure is instrumental to perform more realistic plate reconstructions of this region, of ancient ocean basins in general, and on the process of subduction initiation. Neo-Tethyan relics are preserved in an ophiolite belt distributed above the Dinaric-Hellenic fold-thrust belt. Here we provide the first quantitative constraints on the geometry of the spreading ridges and trenches active in the Jurassic Neo-Tethys using a paleomagnetically based net tectonic rotation analysis of sheeted dykes and dykes from the West and East Vardar Ophiolites of Serbia (Maljen and Ibar) and Greece (Othris, Pindos, Vourinos, and Guevgueli). Based on our results and existing geological evidence, we show that initial Middle Jurassic ( 175 Ma) closure of the western Neo-Tethys was accommodated at a N-S trending, west dipping subduction zone initiated near and parallel to the spreading ridge. The West Vardar Ophiolites formed in the forearc parallel to this new trench. Simultaneously, the East Vardar Ophiolites formed above a second N-S to NW-SE trending subduction zone located close to the European passive margin. We tentatively propose that this second subduction zone had been active since at least the Middle Triassic, simultaneously accommodating the closure of the Paleo-Tethys and the back-arc opening of Neo-Tethys.
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International Nuclear Information System (INIS)
Tilton, G.R.; Hopson, C.A.; Wright, J.E.
1981-01-01
Plagiogranites are a minor but widespread component of the Samail ophiolite plutonic member. They crystallized from the most fractionated melts generated by magmatic crystallization and differentiation of a steady state magma chamber beneath the Tethyan spreading ocean ridge, and their ages are thought to mark the time of ocean crust formation. Isotopic U--Pb ages of zircons from 13 plagiogranites collected along a 270-km segment of the Samail ophiolite subparallel to the regional trend of the sheeted dike complex (the former spreading ridge axis direction) define a narrow time interval of 93.5--97.9 m.y., with a pronounced clustering about 95 m.y. The zircon ages of the plagiogranites agree remarkably well with the early Cenomanian to early Turonian biostratigraphic ages of sediments that are intercalated within the ophiolite pillow lavas and that lie just above them (Tippit et al., 1981). The agreement of radiometric and biostratigraphic ages provides strong support for the conclusion that the plagiogranite U--Pb ages closely date the time span of ocean crust formation. No step changes in age patterns are observed along the ridge axis (sheeted dike) direction, suggesting that there are no major internal offsets of the ophiolite by transform or other faults along most of the traverse. One possible exception occurs at the southeastern end of the sampled interval (Ibra area), where a 3 m.y. discontinuity might be caused by an unmapped fault. Assuming that the regional trend of the sheeted dikes (N10 0 --25 0 W) marks the direction of the former spreading ridge axis, the present array of sample localities spans a distance of 130 to 195 km normal to that axis (i.e., in the spreading direction). The data as a whole do not define a clear-cut age trend normal to the spreading axis, but by eliminating samples that may be aberrant due to faulting, the data array suggests a pattern of increasing ages from east to west
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Ramos, Rodrigo Chaves; Koester, Edinei; Porcher, Carla Cristine
2017-12-01
The present paper shows a mineral chemistry study in chromites found in serpentine-talc schists of the Arroio Grande Ophiolite, located in the southeastern Dom Feliciano Belt, near the Brazil/Uruguay border. Using electron microscope scanning and electron microprobe techniques, this study found a supra-subduction zone signature in the chromites, together with evidence of metasomatism. It corroborates previous hypothesis that suggested a supra-subduction zone origin for the protoliths of the Arroio Grande meta-igneous rocks and a metasomatic origin for the chromite-bearing magnesian schists. The studied chromites present high Cr# (0.65-0.77) and Fe2+# (0.88-0.95), low MgO (0.85-2.47 wt%) and TiO2 (0.01-0.19 wt%) and anomalous high concentration of ZnO (up to 1.97 wt%). The results were compared with chemical data from detrital chromites from the Schwarzrand and Fish River Subgroups of the Nama Group (Namibia), demonstrating that they are compositionally similar with those found in the latter. These chromites, in turn, are believed to have been derived from the oceanic Marmora Terrane (Gariep Belt) in the west (present-day coordinates). Taking into consideration that oceanic metamafites from both the latter and the Arroio Grande Ophiolite share common bulk-rock geochemical features (in this paper interpreted as fragments of the same paleo-ocean floor - the Marmora back-arc basin), it is possible to raise the hypothesis that detrital material derived from the studied ophiolite might also be found in Nama Group. It is reinforced by the fact that sediments (related to the Pelotas-Aiguá Batholith granitoids) derived from the easternmost Dom Feliciano Belt, i.e. the region where Arroio Grande Ophiolite is located, is found in both Schwarzrand and Fish River Subgroups. Thus, we suggest that Arroio Grande Ophiolite detrital sediments might also have contributed to the Nama Basin infilling during Late Ediacaran-Lower Cambrian.
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Synthesis of inverse ringwoodite sheds light on the subduction history of Tibetan ophiolites.
Bindi, Luca; Griffin, William L; Panero, Wendy R; Sirotkina, Ekaterina; Bobrov, Andrey; Irifune, Tetsuo
2018-04-03
Tibetan ophiolites are shallow mantle material and crustal slabs that were subducted as deep as the mantle transition zone, a conclusion supported by the discovery of high-pressure phases like inverse ringwoodite in these sequences. Ringwoodite, Mg 2 SiO 4 , exhibits the normal spinel structure, with Mg in the octahedral A site and Si in the tetrahedral B site. Through A and B site-disorder, the inverse spinel has four-coordinated A cations and the six-coordinated site hosts a mixture of A and B cations. This process affects the density and impedance contrasts across the boundaries in the transition zone and seismic-wave velocities in this portion of the Earth. We report the first synthesis at high pressure (20 GPa) and high temperature (1600 °C) of a Cr-bearing ringwoodite with a completely inverse-spinel structure. Chemical, structural, and computational analysis confirm the stability of inverse ringwoodite and add further constraints to the subduction history of the Luobusa peridotite of the Tibetan ophiolites.
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Directory of Open Access Journals (Sweden)
Nargess Shirdashtzadeh
2017-07-01
Full Text Available Introduction Study of the petrology of the ophiolites as the relics of ancient oceanic lithosphere, is a powerful tool to reconstruct Earth’s history. Mantle peridotites have mostly undergone alteration and serpentinization to some extent. Thus, the relics of metamorphic signatures from the upper mantle and crustal processes from most of the peridotites have been ruined. Several recent papers deal with the mantle peridotites of Nain Ophiolite (e.g. Ghazi et al., 2010. However, no scientific work has been carried out on the metamorphosed mantle peridotites. The study area of the Darreh Deh that is located in the east of the Nain Ophiolite, is composed of huge massifs of metamorphosed mantle peridotites (i.e. lherzolite, clinopyroxene-bearing harzburgite, and harzburgite, and small volumes of dunite, characterized by darker color, higher topographic relief, smaller number of basic intrusives, lower serpentinization degree, and amphibolite-facies metamorphism. In this study, the petrography and mineralogy of metamorphosed peridotites in the Darreh Deh has been considered based on geochemical data. Geological Setting The Mesozoic ophiolitic mélange of Nain is located in the west of CEIM, along the Nain-Baft fault. As a part of a metamorphosed oceanic crust, it is mainly composed of harzburgite, lherzolite, dunite and their serpentinized varieties, chromitite, pyroxenite, gabbro, diabasic dike, spilitized pillow lava, plagiogranite, amphibolite, metaperidotites, schist, skarn, marble, rodingite, metachert and listwaenite (Shirdashtzadeh et al., 2010, 2014a, 2014b. Geochemical investigations indicate a suprasubduction zone in the eastern branch of the Neo-Tethys Ocean (Ghasemi and Talbot, 2006; Shirdashtzadeh et al., 2010, 2014a, 2014b. Materials and Methods Chemical analyses of mineral compositions were carried out using a JEOL JXA8800R wavelength-dispersive electron probe micro-analyzer (accelerating voltage of 15 kV and a beam current of 15 n
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Directory of Open Access Journals (Sweden)
Pearlyn C. Manalo
2015-01-01
Full Text Available This paper presents the first field, geochemical and geophysical information on the recently recognized Early Cretaceous Balud Ophiolitic Complex (BOC in the island of Masbate in the Central Philippines. Mapping of the western limb of the island revealed that only the upper crustal section of the BOC is exposed in this area. Geochemically, the pillow basalts are characterized by transitional mid-oceanic ridge basalt-island arc tholeiitic compositions. Gravity surveys yielded low Bouguer anomaly values that are consistent with the highly dismembered nature of the BOC. Short wavelength, high amplitude magnetic anomalies registered across the study area are attributed to shallow magnetic sources. This is taken to support the model that the ophiolitic complex occurs as thin crustal slivers that are not deeply-rooted in the mantle. Comparing BOC with other ophiolites in the Central Philippines, such as those in the islands of Sibuyan, Leyte and Bohol, suggests the possibility of a common or contiguous source for similarly-aged and geochemically composed crust-mantle sequences in the region.
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Randall J. Wilk; Jeffrey D. Ricklefs; Martin G. Raphael
2014-01-01
We evaluated the effect of forest riparian alternative tree buffer designs on Western Red-backed Salamanders (Plethodon vehiculum) along headwater stream banks in managed forests of the Washington Coast Range. We used pit trap live removals in early autumn to estimate relative abundances of surface-active salamanders before and after 3 levels of riparian buffer...
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Ishimaru, Satoko; Arai, Shoji; Tamura, Akihiro
2017-11-01
We found clinopyroxenite dykes in a banded harzburgite block within the Sumeini area in the uppermost part of the metamorphic sole of the northern part of the Oman ophiolite. The dykes clearly cut the deformational structure of the harzburgite and contain its fragments, indicating dyke formation during obduction of the ophiolite. The Mg# [= Mg / (Mg + total Fe)] of clinopyroxenes in the dykes ranges from 0.81 to 0.91, and increases up to 0.93 proximal to harzburgite fragments. Mantle minerals in the harzburgite fragments were modified chemically through interaction with the magma that formed the dyke, yielding lower clinopyroxene and spinel Mg#, and spinels with higher TiO2 contents than those in the unaltered harzburgite. These geochemical features indicate that the clinopyroxenite dykes are cumulates derived from a relatively deep-seated primitive magma enriched in light rare earth elements (LREE) with an ocean island basalt (OIB)-like affinity, geochemically similar to the V3 lavas of an off-ridge origin. Combining these data with geological observations suggests that the clinopyroxenite dykes represent root system of the V3 lavas. Our analyses of the clinopyroxenite dykes testify to the external nature of the V3 magmas, which was added to the sliced oceanic lithosphere from the outside. It is likely that the V3 magma underwent deep-seated crystallization of clinopyroxene and had limited interaction with mantle peridotite en route to the surface. The mode of occurrence of the Sumeini clinopyroxenites (i.e., emplaced into a banded harzburgite block surrounded by garnet amphibolite) is consistent with the generation of OIB-like magmas (V3 lava) beneath the Oman ophiolite resulting from the break-off of the "subducting slab" and subsequent infiltration of hot asthenospheric mantle. This view is consistent with the limited distribution of V3-related rocks in the Oman ophiolite. The production of such OIB-like magmas during ophiolite obduction is not a rare event
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Directory of Open Access Journals (Sweden)
Gawlick Hans-Jürgen
2017-08-01
Full Text Available Oceanic radiolarite components from the Middle Jurassic ophiolitic mélange between Trnava and Rožanstvo in the Zlatibor Mountains (Dinaridic Ophiolite Belt west of the Drina–Ivanjica unit yield Late Triassic radiolarian ages. The microfacies characteristics of the radiolarites show pure ribbon radiolarites without crinoids or thin-shelled bivalves. Beside their age and the preservation of the radiolarians this points to a deposition of the radiolarites on top of the oceanic crust of the Neo-Tethys, which started to open in the Late Anisian. South of the study area the ophiolitic mélange (Gostilje–Ljubiš–Visoka–Radoševo mélange contains a mixture of blocks of 1 oceanic crust, 2 Middle and Upper Triassic ribbon radiolarites, and 3 open marine limestones from the continental slope. On the basis of this composition we can conclude that the Upper Triassic radiolarite clasts derive either from 1 the younger parts of the sedimentary succession above the oceanic crust near the continental slope or, more convincingly 2 the sedimentary cover of ophiolites in a higher nappe position, because Upper Triassic ribbon radiolarites are only expected in more distal oceanic areas. The ophiolitic mélange in the study area overlies different carbonate blocks of an underlying carbonate-clastic mélange (Sirogojno mélange. We date and describe three localities with different Upper Triassic radiolarite clasts in a mélange, which occurs A on top of Upper Triassic fore-reef to reefal limestones (Dachstein reef, B between an Upper Triassic reefal limestone block and a Lower Carnian reef limestone (Wetterstein reef, and C in fissures of an Upper Triassic lagoonal to back-reef limestone (Dachstein lagoon. The sedimentary features point to a sedimentary and not to a tectonic emplacement of the ophiolitic mélange (= sedimentary mélange filling the rough topography of the topmost carbonate-clastic mélange below. The block spectrum of the underlying and
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Gawlick, Hans-Jürgen; Djerić, Nevenka; Missoni, Sigrid; Bragin, Nikita Yu.; Lein, Richard; Sudar, Milan; Jovanović, Divna
2017-08-01
Oceanic radiolarite components from the Middle Jurassic ophiolitic mélange between Trnava and Rožanstvo in the Zlatibor Mountains (Dinaridic Ophiolite Belt) west of the Drina-Ivanjica unit yield Late Triassic radiolarian ages. The microfacies characteristics of the radiolarites show pure ribbon radiolarites without crinoids or thin-shelled bivalves. Beside their age and the preservation of the radiolarians this points to a deposition of the radiolarites on top of the oceanic crust of the Neo-Tethys, which started to open in the Late Anisian. South of the study area the ophiolitic mélange (Gostilje-Ljubiš-Visoka-Radoševo mélange) contains a mixture of blocks of 1) oceanic crust, 2) Middle and Upper Triassic ribbon radiolarites, and 3) open marine limestones from the continental slope. On the basis of this composition we can conclude that the Upper Triassic radiolarite clasts derive either from 1) the younger parts of the sedimentary succession above the oceanic crust near the continental slope or, more convincingly 2) the sedimentary cover of ophiolites in a higher nappe position, because Upper Triassic ribbon radiolarites are only expected in more distal oceanic areas. The ophiolitic mélange in the study area overlies different carbonate blocks of an underlying carbonate-clastic mélange (Sirogojno mélange). We date and describe three localities with different Upper Triassic radiolarite clasts in a mélange, which occurs A) on top of Upper Triassic fore-reef to reefal limestones (Dachstein reef), B) between an Upper Triassic reefal limestone block and a Lower Carnian reef limestone (Wetterstein reef), and C) in fissures of an Upper Triassic lagoonal to back-reef limestone (Dachstein lagoon). The sedimentary features point to a sedimentary and not to a tectonic emplacement of the ophiolitic mélange (= sedimentary mélange) filling the rough topography of the topmost carbonate-clastic mélange below. The block spectrum of the underlying and slightly older
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Kapsiotis, Argirios; Grammatikopoulos, Tassos A.; Tsikouras, Basilios; Hatzipanagiotou, Konstantin; Zaccarini, Federica; Garuti, Giorgio
2011-01-01
The Pindos ophiolite complex, located in the northwestern part of continental Greece, hosts various chromite deposits of both metallurgical (high-Cr) and refractory (high-Al) type. The Pefki chromitites are banded and sub-concordant to the surrounding serpentinized dunites. The Cr# [Cr/(Cr + Al)] of magnesiochromite varies between 0.75 and 0.79. The total PGE grade ranges from 105.9 up to 300.0 ppb. IPGE are higher than PPGE, typical of mantle hosted ophiolitic chromitites. The PGM assemblage in chromitites comprises anduoite, ruarsite, laurite, irarsite, sperrylite, hollingworthite, Os-Ru-Ir alloys including osmium and rutheniridosmine, Ru-bearing oxides, braggite, paolovite, platarsite, cooperite, vysotskite, and palladodymite. Iridarsenite and omeiite were also observed as exsolutions in other PGM. Rare electrum and native Ag are recovered in concentrates. This PGM assemblage is of great petrogenetic importance because it is significantly different from that commonly observed in podiform mantle-hosted and banded crustal-hosted ophiolitic chromitites. PGE chalcogenides of As and S are primary, and possibly crystallized directly from a progressively enriched in As boninitic melt before or during magnesiochromite precipitation. The presence of Ru-bearing oxides implies simultaneous desulfurization and dearsenication processes. Chemically zoned laurite and composite paolovite-electrum intergrowths are indicative of the relatively high mobility of certain PGE at low temperatures under locally oxidizing conditions. The PGM assemblage and chemistry, in conjunction with geological and petrologic data of the studied chromitites, indicate that it is characteristic of chromitites found within or close to the petrologic Moho. Furthermore, the strikingly different PGM assemblages between the high-Cr chromitites within the Pindos massif is suggestive of non-homogeneous group of ores.
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Geochemistry of reduced gas related to serpentinization of the Zambales ophiolite, Philippines
Abrajano, T.A.; Sturchio, N.C.; Kennedy, B.M.; Lyon, G.L.; Muehlenbachs, K.; Böhlke, J.K.
1990-01-01
Methane-hydrogen gas seeps with mantle-like C and noble gas isotopic characteristics issue from partially serpentinized ultramafic rocks in the Zambales ophiolite, Philippines. New measurements of noble gas and 14C isotope abundances, rock/mixed-volatile equilibrium calculations, and previous chemical and isotopic data suggest that these reduced gases are products of periodotite hydration. The gas seeps are produced in rock-dominated zones of serpentinization, and similar gases may be ubiquitous in ultramafic terranes undergoing serpentinization.
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Thermo-mechanical modeling of the obduction process based on the Oman ophiolite case
Duretz , Thibault; Agard , Philippe; Yamato , Philippe; Ducassou , Céline; Burov , Evgenii ,; Gerya , T. V.
2016-01-01
International audience; Obduction emplaces regional-scale fragments of oceanic lithosphere (ophiolites) over continental lithosphere margins of much lower density. For this reason, the mechanisms responsible for obduction remain enigmatic in the framework of plate tectonics. We present two-dimensional (2D) thermo-mechanical models of obduction and investigate possible dynamics and physical controls of this process. Model geometry and boundary conditions are based on available geological and g...
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Allahyari, Khalil; Saccani, Emilio; Rahimzadeh, Bahman; Zeda, Ottavia
2014-01-01
The Sarve-Abad (Sawlava) ophiolitic complex consists of several tectonically dismembered ophiolitic sequences. They are located along the Main Zagros Thrust Zone, which marks the ophiolitic suture between the Arabian and Sanandaj-Sirjan continental blocks. They represent a portion of the southern Neo-Tethyan oceanic lithosphere, which originally existed between the Arabian (to the south) and Eurasian (to the north) continental margins. The Sarve-Abad ophiolites include cumulitic lherzolites bearing minor dunite and chromitite lenses in places. The main rock-forming minerals in ultramafic cumulates are cumulus olivine and inter-cumulus clinopyroxene and orthopyroxene. Minor (<5%) chromian spinel occurs as both cumulus and inter-cumulus phases.
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Hässig, Marc; Rolland, Yann; Sosson, Marc; Hassani, Riad; Topuz, Gultekin; Faruk Çelik, Ömer; Gerbault, Muriel; Galoyan, Ghazar; Müller, Carla; Sahakyan, Lilit; Avagyan, Ara
2013-04-01
In the Lesser Caucasus three main domains are distinguished from SW to NE: (1) the South Armenian Block (SAB), a Gondwanian-derived continental terrane; (2) scattered outcrops of ophiolites coming up against the Sevan-Akera suture zone; and (3) the Eurasian plate. The Armenian ophiolites represent remnants of an oceanic domain which disappeared during Eurasia-Arabia convergence. Previous works using geochemical whole-rock analyses, 40Ar/39Ar and paleontological dating have shown that the ophiolite outcrops throughout this area were emplaced during the Late Cretaceous as one non-metamorphic preserved ophiolitic nappe of back-arc origin that formed during Middle to Late Jurassic. From these works, tectonic reconstructions include two clearly identified subductions, one related to the Neotethys subduction beneath the Eurasian margin and another to intra-oceanic subduction responsible for the opening of the back-arc basin corresponding to the ophiolites of the Lesser Caucasus. The analysis of the two stages of metamorphism of the garnet amphibolites of the ophiolite obduction sole at Amasia (M1: HT-LP peak of P = 6-7 kbar and T > 630°C; M2; MP-MT peak at P = 8-10 kbar and T = 600°C) has allowed us to deduce the onset of subduction of the SAB at 90 Ma for this locality, which age coincides with other paleontological ages at the obduction front. A preliminary paleomagnetic survey has also brought quantification to the amount of oceanic domain which disappeared by subduction between the SAB and Eurasia before collision. We propose a dynamic finite element model using ADELI to test the incidence of parameters such as the density of the different domains (or the interval between the densities), closing speed (or speeds if sporadic), the importance and interactions of mantle discontinuities with the subducting lithosphere and set a lithospheric model. Our field observations and analyses are used to validate combinations of factors. The aim is to better qualify the
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Making a report of a short trip in an ophiolitic complex with Google Earth
Aubret, Marianne
2017-04-01
Plate tectonics is taught in French secondary school (lower and upper-sixth). According to the curriculum, the comprehension of plate-tectonic processes and concepts should be based on field data. For example, the Alpine's ocean history is studied to understand how mountain ranges are formed. In this context, Corsica is a great open-air laboratory, but unfortunately, the traffic conditions are very difficult in the island and despite the short distances, it's almost impossible for teachers to take their students to the remarkable geologic spots. The «défilé de l'Inzecca» is one of them: there you can see a part of the alpine's ophiolitic complex. The aim of this activity is to elaborate a « KMZ folder » in Google Earth as a report of a short trip thanks to the students' data field; it is also the occasion to enrich the Google Earth KMZ folder already available for our teaching.
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Directory of Open Access Journals (Sweden)
O. Kiseleva
2017-07-01
Full Text Available The Ospino-Kitoi and Kharanur ultrabasic massifs represent the northern and southern ophiolite branches respectively of the Upper Onot ophiolitic nappe and they are located in the southeastern part of the Eastern Sayan (SEPES ophiolites. Podiform chromitites with PGE mineralization occur as lensoid pods within dunites and rarely in harzburgites or serpentinized peridotites. The chromitites are classified into type I and type II based on their Cr#. Type I (Cr# = 59–85 occurs in both northern and southern branches, whereas type II (Cr# = 76–90 occurs only in the northern branch. PGE contents range from ∑PGE 88–1189 ppb, Pt/Ir 0.04–0.42 to ∑PGE 250–1700 ppb, Pt/Ir 0.03–0.25 for type I chromitites of the northern and southern branches respectively. The type II chromitites of the northern branch have ∑PGE contents higher than that of type I (468–8617 ppb, Pt/Ir 0.1–0.33. Parental melt compositions, in equilibrium with podiform chromitites, are in the range of boninitic melts and vary in Al2O3, TiO2 and FeO/MgO contents from those of type I and type II chromitites. Calculated melt compositions for type I chromitites are (Al2O3melt = 10.6–13.5 wt.%, (TiO2melt = 0.01–0.44 wt.%, (Fe/Mgmelt = 0.42–1.81; those for type II chromitites are: (Al2O3melt = 7.8–10.5 wt.%, (TiO2melt = 0.01–0.25 wt.%, (Fe/Mgmelt = 0.5–2.4. Chromitites are further divided into Os-Ir-Ru (I and Pt-Pd (II based on their PGE patterns. The type I chromitites show only the Os-Ir-Ru pattern whereas type II shows both Os-Ir-Ru and Pt-Pd patterns. PGE mineralization in type I chromitites is represented by the Os-Ir-Ru system, whereas in type II it is represented by the Os-Ir-Ru-Rh-Pt system. These results indicate that chromitites and PGE mineralization in the northern branch formed in a suprasubduction setting from a fluid-rich boninitic melt during active subduction. However, the chromitites and PGE mineralization of the southern
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Boschman, L.; Van Hinsbergen, D. J. J.; Langereis, C. G.; Molina-Garza, R. S.; Kimbrough, D. L.
2017-12-01
The North American Cordillera has been shaped by a long history of accretion of arcs and other buoyant crustal fragments to the western margin of the North American Plate since the Early Mesozoic. Accretion of these terranes resulted from a complex tectonic history interpreted to include episodes of both intra-oceanic subduction within the Panthalassa/Pacific Ocean, as well as continental margin subduction along the western margin of North America. Western Mexico, at the southern end of the Cordillera, contains a Late Cretaceous-present day long-lived continental margin arc, as well as Mesozoic arc and SSZ ophiolite assemblages of which the origin is under debate. Interpretations of the origin of these subduction-related rock assemblages vary from far-travelled exotic intra-oceanic island arc character to autochthonous or parautochthonous extended continental margin origin. We present new paleomagnetic data from four localities: (1) the Norian SSZ Vizcaíno peninsula Ophiolite; (2) its Lower Jurassic sedimentary cover; and (3) Barremian and (4) Aptian sediments derived from the Guerrero arc. The data show that the Mexican ophiolite and arc terranes have a paleolatitudinal plate motion history that is equal to that of the North American continent. This suggests that these rock assemblages were part of the overriding plate and were perhaps only separated from the North American continent by temporal fore- or back-arc spreading. These spreading phases resulted in the temporal existence of tectonic plates between the North American and Farallon Plates, and upon closure of the basins, in the growth of the North American continent without addition of any far-travelled exotic terranes.
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Randall J. Wilk; Martin G. Raphael; Christopher S. Nations; Jeffrey D. Ricklefs
2010-01-01
We assessed the short-term effects of alternative designs of forested buffer treatments along headwater streams on small ground-dwelling mammals in managed forests in western Washington, USA. Over three summers (one pretreatment and two posttreatment), we trapped 19 mammalian species along 23 streams in the northern Coast Range. We compared faunal communities in...
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Topuz, Gültekin; Okay, Aral I.; Schwarz, Winfried H.; Sunal, Gürsel; Altherr, Rainer; Kylander-Clark, Andrew R. C.
2018-02-01
The Eastern Mediterranean region within the Tethyan belt is characterised by two main pulses of suprasubduction-zone ophiolite formation during the Early-Middle Jurassic and Late Cretaceous. Despite vast exposures of the Permo-Triassic accretionary complexes, related suprasubduction-zone ophiolites and the timing of subduction initiation leading to the formation of Permo-Triassic accretionary complexes are unknown so far. Here we report on a 40 km long and 0.3 to 1.8 km wide metaophiolite fragment within transitional greenschist- to blueschist-facies oceanic rocks from NW Turkey. The metaophiolite fragment is made up mainly of serpentinite and minor dykes or stocks of strongly sheared metagabbro with mineral assemblages involving actinolite/winchite, chlorite, epidote, albite, titanite and phengite. The metagabbro displays (i) variable CaO and MgO contents, (ii) anomalously high Mg# (= 100 ∗ molar MgO/(MgO + FeOtot)) of 75-88, and (iii) positive Eu anomalies, together with low contents of incompatible elements such as Ti, P and Zr, suggesting derivation from former plagioclase cumulates. The serpentinites comprise serpentine, ± chlorite, ± talc, ± calcite and relict Cr-Al spinel surrounded by ferrichromite to magnetite. Relict Cr-Al spinels are characterised by (i) Cr/(Cr + Al) ratios of 0.45-0.56 and Mg/(Mg + Fe2 +) ratio of 0.76-0.22, (ii) variable contents of ZnO and MnO, and (iii) extremely low TiO2 contents. Zn and Mn contents are probably introduced into Cr-Al spinels during greenschist- to blueschist metamorphism. Compositional features of the serpentinite such as (i) Ca- and Al-depleted bulk compositions, (ii) concave U-shaped, chondrite-normalised rare earth element patterns (REE) with enrichment of light and heavy REEs, imply that serpentinites were probably derived from depleted peridotites which were refertilised by light rare earth element enriched melts in a suprasubduction-zone mantle wedge. U-Pb dating on igneous zircons from three metagabbro
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International Nuclear Information System (INIS)
Fujii, N.; Yanakawa, M.; Arcilla, C.A.; Pascua, C.; Namiki, K.; Sato, T.; Shikazono, N.; Alexander, W.R.
2011-01-01
Bentonite is one of the safety-critical components of the engineered barrier system for the disposal concepts developed for many types of radioactive waste. However, bentonite - especially the swelling clay component that contributes to its essential barrier functions - is unstable at high pH. To date, results from laboratory tests on bentonite degradation have been ambiguous as the reaction rates are so slow as to be difficult to observe. As such, a key goal in this project is to examine the reaction of natural bentonites in contact with natural hyperalkaline groundwaters to determine if any long-term alteration of the bentonite occurs. Ophiolites have been identified as sources of hyperalkaline groundwaters that can be considered natural analogues of the leachates produced by some cementitious materials in repositories for radioactive waste. At the Zambales ophiolite in the Philippines, widespread active serpentinisation results in hyperalkaline groundwaters with measured pH values of up to 11.7, falling into the range typical of low-alkali cement porewaters. These cements are presently being developed worldwide to minimise the geochemical perturbations which are expected to result from the use of OPC-based concretes (see Kamei et al., this conference, for details). In particular, it is hoped that the lower pH of the low-alkali cement leachates will reduce, or even avoid entirely, the potential degradation of the bentonite buffer which is expected at the higher pH levels (12.5 and above) common to OPC-based concretes. During recent field campaigns at two sites in the Zambales ophiolite (Mangatarem and Bigbiga), samples of bentonite and the associated hyperalkaline groundwaters have been collected by drilling and trenching. At Mangatarem, qualitative data from a 'fossil' (i.e. no groundwater is currently present) reaction zone indicates some alteration of the bentonite to zeolite, serpentine and CSH phases. Preliminary reaction path modelling suggests that the
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MacDonald, J. H., Jr.; Milliken, S. H.; Zalud, K. M.
2017-12-01
The Jurassic Ingalls ophiolite complex is located in the central Cascades, Washington State. This ophiolite predominantly consists of three variably serpentinized mantle units. Serpentinite occurs as massive replacing peridotite, or as highly sheared fault zones cutting other rocks. Mylonitic serpentinite forms a large-scale mélange in the middle of the ophiolite, and is interpreted as a fracture zone. Whole-rock and mineral geochemistry of the massive serpentinite was done to understand the metasomatic process and identify the possible protoliths of these rocks. Whole-rock major and trace elements of the massive serpentinite are similar to modern peridotites. The majority of samples analyzed are strongly serpentinized, while a few were moderately to weakly altered. Ca, Mg, and Al suggest these rocks formed from serpentinized harzburgite and dunite with minor lherzolite. All samples have positive Eu/Eu*. Serpentinites plot in fields defined by modern abyssal and forearc peridotites. Trace elements suggests the protoliths underwent variable amounts of mantel depletion (5-20%). Serpentine and relic igneous minerals were analyzed by EPMA at the Florida Center for Analytical Electron Microscopy. The serpentine dose not chemically display brucite mixing, has minor substitution of Fe, Ni, and Cr for Mg, and minor Al substitution for Si. Bastites have higher Ni than replaced olivine. Mineral chemistry, high LOI, and X-ray diffraction suggest lizardite is the primary serpentine polymorph, with minor chrysotile also occurring. Relic Al-chromite and Cr-spinel commonly have Cr-magnetite rims. These relic cores have little SiO2 and Fe3+, suggesting the spinels are well preserved. Most spinels plot in overlap fields defined by abyssal and arc peridotite, while two samples plot entirely in arc fields. Relic olivine have Fo90 to Fo92 and plot along the mantle array. Relic pyroxene are primarily enstatite, with lesser high-Ca varieties. Relic minerals plot near fields defined by
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Genesis and transport of hexavalent chromium in the system ophiolitic rocks - groundwater
Shchegolikhina, Anastasia; Guadagnini, Laura; Guadagnini, Alberto
2015-04-01
Our study aims at contributing to the quantification and characterization of chromium transport processes from host rocks and soil matrices to groundwater. We focus on dissolved hexavalent chromium detected in groundwaters of geological regions with ophiolitic rocks (ophiolites and serpentinites) inclusions due to its critical ecological impact. (Oze et al., 2004). Despite the large number of analyses on the occurrence of high concentrations of hazardous hexavalent chromium ions in natural waters, only few studies were performed with the objective of identifying and investigating the geochemical reactions which could occur in the natural system rock - groundwater - dissolved chromium (Fantoni et al., 2002, Stephen and James, 2004, Lelli et al., 2013). In this context, there is a need for integration of results obtained from diverse studies in various regions and settings to improve our knowledge repository. Our theoretical analyses are grounded and driven by practical scenarios detected in subsurface reservoirs exploited for civil and industrial use located in the Emilia-Romagna region (Italy). Available experimental datasets are complemented with data from other international regional-scale settings (Altay mountains region, Russia). Modeling of chromium transformation and migration particularly includes characterization of the multispecies geochemical system. A key aspect of our study is the analysis of the complex competitive sorption processes governing heavy metal evolution in groundwater. The results of the research allow assessing the critical qualitative features of the mechanisms of hexavalent chromium ion mobilization from host rocks and soils and the ensuing transformation and migration to groundwater under the influence of diverse environmental factors. The study is then complemented by the quantification of the main sources of uncertainty associated with prediction of heavy metal contamination levels in the groundwater system explored. Fantoni, D
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Hydrogen Gas from Serpentinite, Ophiolites and the Modern Ocean Floor as a Source of Green Energy
Coveney, R. M.
2008-12-01
Hydrogen gas is emitted by springs associated with serpentinites and extensive carbonate deposits in Oman, The Philippines, the USA and other continental locations. The hydrogen springs contain unusually alkaline fluids with pH values between 11 and 12.5. Other workers have described off-ridge submarine springs with comparably alkaline fluid compositions, serpentinite, abundant free hydrogen gas, and associated carbonate edifices such as Lost City on the Atlantis Massif 15 km west of the Mid-Atlantic Ridge (D.S. Kelley and associates, Science 2005). The association of hydrogen gas with ultramafites is a consistent one that has been attributed to a redox couple involving oxidation of divalent iron to the trivalent state during serpentinization, although other possibilities exist. Some of the hydrogen springs on land are widespread. For example in Oman dozens of alkaline springs (Neal and Stanger, EPSL 1983) can be found over thousands of sq km of outcropping ophiolite. While the deposits in Oman and the Philippines are well-known to much of the geochemical community, little interest seems to have been displayed toward either the ophiolitic occurrences or the submarine deposits for energy production. This may be a mistake as the showings because they could lead to an important source of green energy. Widespread skepticism currently exists about hydrogen as a primary energy source. It is commonly said that free hydrogen does not occur on earth and that it is therefore necessary to use other sources of energy to produce hydrogen, obviating the general environmental benefit. However the existence of numerous occurrences of hydrogen gas associated with ophiolites and submarine occurrences of hydrogen suggests the likelihood that natural hydrogen gas may be an important source of clean energy for modern society remaining to be tapped. Calculations in progress should establish whether or not this is likely to be the case.
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Ambrose, Tyler K.; Wallis, David; Hansen, Lars N.; Waters, Dave J.; Searle, Michael P.
2018-06-01
Studies of experimentally deformed rocks and small-scale natural shear zones have demonstrated that volumetrically minor phases can control strain localisation by limiting grain growth and promoting grain-size sensitive deformation mechanisms. These small-scale studies are often used to infer a critical role for minor phases in the development of plate boundaries. However, the role of minor phases in strain localisation at an actual plate boundary remains to be tested by direct observation. In order to test the hypothesis that minor phases control strain localisation at plate boundaries, we conducted microstructural analyses of peridotite samples collected along a ∼1 km transect across the base of the Oman-United Arab Emirates (UAE) ophiolite. The base of the ophiolite is marked by the Semail thrust, which represents the now exhumed contact between subducted oceanic crust and the overlying mantle wedge. As such, the base of the ophiolite provides the opportunity to directly examine a former plate boundary. Our results demonstrate that the mean olivine grain size is inversely proportional to the abundance of minor phases (primarily orthopyroxene, as well as clinopyroxene, hornblende, and spinel), consistent with suppression of grain growth by grain-boundary pinning. Our results also reveal that mean olivine grain size is proportional to CPO strength (both of which generally decrease towards the metamorphic sole), suggesting that the fraction of strain produced by different deformation mechanisms varied spatially. Experimentally-derived flow laws indicate that under the inferred deformation conditions, the viscosity of olivine was grain-size sensitive. As such, grain size, and thereby the abundance of minor phases, influenced viscosity during subduction-related deformation along the base of the mantle wedge. We calculate an order of magnitude decrease in the viscosity of olivine towards the base of the ophiolite, which suggests strain was localised near the
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Savov, Ivan; Ryan, Jeff; Haydoutov, Ivan; Schijf, Johan
2001-10-01
The Balkan-Carpathian ophiolite (BCO), which outcrops in Bulgaria, Serbia and Romania, is a Late Precambrian (563 Ma) mafic/ultramafic complex unique in that it has not been strongly deformed or metamorphosed, as have most other basement sequences in Alpine Europe. Samples collected for study from the Tcherni Vrah and Deli Jovan segments of BCO include cumulate dunites, troctolites, wehrlites and plagioclase wehrlites; olivine and amphibole-bearing gabbros; anorthosites; diabases and microgabbros; and basalts representing massive flows, dikes, and pillow lavas, as well as hyaloclastites and umbers (preserved sedimentary cover). Relict Ol, Cpx and Hbl in cumulate peridotites indicate original orthocumulate textures. Plagioclase in troctolites and anorthosites range from An60 to An70. Cumulate gabbro textures range from ophitic to poikilitic, with an inferred crystallization order of Ol-(Plag+Cpx)-Hbl. The extrusive rocks exhibit poikilitic, ophitic and intersertal textures, with Cpx and/or Plag (Oligoclase-Andesine) phenocrysts. The major opaques are Ti-Magnetite and Ilmenite. The metamorphic paragenesis in the mafic samples is Chl-Trem-Ep, whereas the ultramafic rocks show variable degrees of serpentinization, with lizardite and antigorite as dominant phases. Our samples are compositionally and geochemically similar to modern oceanic crust. Major element, trace element and rare earth element (REE) signatures in BCO basalts are comparable to those of MORB. In terms of basalt and dike composition, the BCO is a 'high-Ti' or 'oceanic' ophiolite, based on the classification scheme of Serri [Earth Planet. Sci. Lett. 52 (1981) 203]. Our petrologic and geochemical results, combined with the tectonic position of the BCO massifs (overlain by and in contact with Late Cambrian island arc and back-arc sequences), suggest that the BCO may have formed in a mid-ocean ridge setting. If the BCO records the existence of a Precambrian ocean basin, then there may be a relationship
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Neubeck, Anna; Sun, Li; Müller, Bettina; Ivarsson, Magnus; Hosgörmez, Hakan; Özcan, Dogacan; Broman, Curt; Schnürer, Anna
2017-06-15
The surface waters at the ultramafic ophiolitic outcrop in Chimaera, Turkey, are characterized by high pH values and high metal levels due to the percolation of fluids through areas of active serpentinization. We describe the influence of the liquid chemistry, mineralogy, and H 2 and CH 4 levels on the bacterial community structure in a semidry, exposed, ultramafic environment. The bacterial and archaeal community structures were monitored using Illumina sequencing targeting the 16S rRNA gene. At all sampling points, four phyla, Proteobacteria , Actinobacteria , Chloroflexi , and Acidobacteria , accounted for the majority of taxa. Members of the Chloroflexi phylum dominated low-diversity sites, whereas Proteobacteria dominated high-diversity sites. Methane, nitrogen, iron, and hydrogen oxidizers were detected as well as archaea and metal-resistant bacteria. IMPORTANCE Our study is a comprehensive microbial investigation of the Chimaera ophiolite. DNA has been extracted from 16 sites in the area and has been studied from microbial and geochemical points of view. We describe a microbial community structure that is dependent on terrestrial, serpentinization-driven abiotic H 2 , which is poorly studied due to the rarity of these environments on Earth. Copyright © 2017 Neubeck et al.
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Chapter 9: The rock coast of the USA
Hapke, Cheryl J.; Adams, Peter N.; Allan, Jonathan; Ashton, Andrew; Griggs, Gary B.; Hampton, Monty A.; Kelly, Joseph; Young, Adam P.
2014-01-01
The coastline of the USA is vast and comprises a variety of landform types including barrier islands, mainland beaches, soft bluffed coastlines and hard rocky coasts. The majority of the bluffed and rocky coasts are found in the northeastern part of the country (New England) and along the Pacific coast. Rocky and bluffed landform types are commonly interspersed along the coastline and occur as a result of relative lowering of sea level from tectonic or isostatic forcing, which can occur on timescales ranging from instantaneous to millenia. Recent research on sea cliffs in the contiguous USA has focused on a broad range of topics from documenting erosion rates to identifying processes and controls on morphology to prediction modelling. This chapter provides a detailed synthesis of recent and seminal research on rocky coast geomorphology along open-ocean coasts of the continental United States (USA).
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Energy Technology Data Exchange (ETDEWEB)
Montero Cabrera, M.E. E-mail: montero@yakko.cimav.edu.mx; Ortueta Milan, M.; Herrera Peraza, E.F.; Herrera Hernandez, H.; Rodriguez Martinez, N.; Olivares Rieumont, S.; Lopez Reyes, M.C
2001-01-15
Concentrations of 16 elements from 14 serpentinitic samples from Basilio and Cantel petroleum fields were obtained by instrumental neutron activation analysis (INAA): Cr, Co, Ni, La, Nd, Sm, Eu, Gd, Tb, Ce Yb, Lu, Rb, Cs, Hf and Th. Relative INAA was performed using certified reference materials and laboratory standards. Average elemental concentrations showed that the ophiolites have a basic character, suggesting the use of a well-logging method designed for volcano-sedimentary petroleum fields.
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International Nuclear Information System (INIS)
Montero Cabrera, M.E.; Ortueta Milan, M.; Herrera Peraza, E.F.; Herrera Hernandez, H.; Rodriguez Martinez, N.; Olivares Rieumont, S.; Lopez Reyes, M.C.
2001-01-01
Concentrations of 16 elements from 14 serpentinitic samples from Basilio and Cantel petroleum fields were obtained by instrumental neutron activation analysis (INAA): Cr, Co, Ni, La, Nd, Sm, Eu, Gd, Tb, Ce Yb, Lu, Rb, Cs, Hf and Th. Relative INAA was performed using certified reference materials and laboratory standards. Average elemental concentrations showed that the ophiolites have a basic character, suggesting the use of a well-logging method designed for volcano-sedimentary petroleum fields
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Xiong, Fahui; Yang, Jingsui; Dilek, Yildirim; Wang, ChunLian; Hao, Xiaolin; Xu, Xiangzhen; Lian, Dongyang
2018-03-01
Ophiolites exposed across the western Tauride belt in Turkey represent tectonically emplaced fragments of oceanic lithosphere obducted onto the continental margin following the closure of the Neotethys Ocean during the Late Cretaceous. The ultramafic massif of Köycegiz, which is located in the ophiolitic belt of southwestern Turkey, is a major source of metallurgical chromitite ore. The massif comprises a base of tectonized harzburgite with minor dunite overlain by a magmatic sequence of wehrlite, pyroxenite, troctolite and gabbro. Only sparse refractory chromitites occur within the harzburgites; in contrast, the upper and middle sections of the peridotite sequence contain abundant metallurgical chromitites. The peridotites record abundant evidence of mantle metasomatism on various scales, as the Fo values of olivine in harzburgite are 90.1-95.4, whereas those in dunite are 90.1-91.8. The compositions of the melts passing through the peridotites changed gradually from arc tholeiite to boninite due to melt-rock reactions, thus producing more Cr-rich chromitites in the upper part of the body. Most of the chromitites have high Cr numbers (77-78), although systematic changes in the compositions of the olivine and chromian spinel occur from the harzburgites to the dunite envelopes to the chromitites, reflecting melt-rock reactions. The calculated ΔlogfO2 (FMQ) values range from - 2.77 to + 1.03 in the chromitites, - 2.73 to -0.01 in the harzburgites, and - 1.65 to + 0.45 in the dunites. All of the available evidence suggests that the Köycegiz ophiolite formed in a supra-subduction zone (SSZ) mantle wedge. These models indicate that the harzburgites represent the products of first-stage melting and low degrees of melt-rock interaction that occurred in a mid-ocean ridge (MOR) environment. In contrast, the chromitites and dunites represent the products of second-stage melting and related refertilization, which occurred in an SSZ environment.
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Raymond, Loren A.; Merschat, Arthur J.; Vance, R. Kelly
2016-01-01
Metaultramafic rocks (MUR) in the Ashe Metamorphic Suite (AMS) of northwestern North Carolina include quartz ± feldspar-bearing QF-amphibolites and quartz-deficient, locally talc-, chlorite-, and/or Mg-amphibole-bearing TC-amphibolites. Some workers divide TC-amphibolites into Todd and Edmonds types, based on mineral and geochemical differences, and we provisionally add a third type – olivine ± pyroxene-rich, Rich Mountain-type rocks. Regionally, MUR bodies range from equant, Rich Mountain- to highly elongate, Todd-TC-amphibolite-type bodies. The MURs exhibit three to five mineral associations containing assemblages with olivine, anthophyllitic amphibole, Mg-hornblende, Mg-actinolite, cummingtonite, and serpentine representing decreasing eclogite to greenschist facies grades of metamorphism over time. MUR protoliths are difficult to determine. Southwestern MUR bodies have remnant olivine ± pyroxene-rich assemblages representing ultrabasic-basic, dunite-peridotite-pyroxenite protoliths. Northeastern TC-amphibolite MURs contain hornblende and actinolitic amphiboles plus chlorites – aluminous and calcic assemblages suggesting to some that metasomatism of basic, QF-amphibolites yields all TC-amphibolites. Yet MgO-CaO-Al2O3 and trace element chemistries of many TC-amphibolites resemble compositions of plagioclase peridotites. We show that a few AMS TC-amphibolites had basaltic/gabbroic protoliths, while presenting arguments opposing application of the metasomatic hypothesis to all TC-amphibolites. We establish that MUR bodies are petrologically heterolithic and that TC-amphibolites are in contact with many rock types; that those with high Cr, Ni, and Mg have olivine- or pyroxene-dominated protoliths; that most exhibit three or more metamorphic mineral associations; and that contacts thought to be metasomatic are structural. Clearly, different MUR bodies have different chemistries representing various protoliths, and have different mineral assemblages, reflecting
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A stable isotope study of serpentinization in the Fengtien ophiolite, Taiwan
Energy Technology Data Exchange (ETDEWEB)
Tzen-Fu Yui; Hsueh-Wen Yeh (Univ. of Hawaii, Honolulu (USA)); Chihming Wang Lee (National Taiwan Univ. (Taiwan))
1990-05-01
Detailed H- and O-isotopic studies of serpentinites of Fengtien ophiolite have been made in order to enhance our knowledge on the process of serpentinization. Pseudomorphic lizardites have {delta}{sup 18}O = +3.6{per thousand} and {delta}D = {minus}48 to {minus}49{per thousand}; bladed-mat and foliated antigorites have {delta}{sup 18}O = +3.5 to +5.8{per thousand} and {delta}D = {minus}45 to {minus}69{per thousand}; slickensided antigorites have {delta}{sup 18}O = +4.1 to +4.9{per thousand} and {delta}D = {minus}46 to {minus}50{per thousand}; picrolites have {delta}{sup 18}O = +4.2 to +4.3{per thousand} and {delta}D = {minus}65 to {minus}67{per thousand}; and slickensided chrysotiles have {delta}{sup 18}O = +4.1 to +4.5{per thousand} and {delta}D = {minus}80{per thousand}. It is suggested that lizardite might have formed in an oceanic environment, whereas antigorite and chrysotile have formed in continental environments. These results depict complicated multiple serpentinization processes. Isotopic temperatures calculated using {delta}{sup 18}O values of coexisting fissure-filling minerals range from 325 to 370{degree}C, which are consistent with those derived from phase equilibria involving serpentines. The narrow range of {delta}{sup 18}O and wide range of {delta}D values for antigorite and chrysotile also demonstrate that water/rock ratios during these serpentinizations should not have been high. These Fengtien serpentines fall outside either of the continental domains described by Wenner and Taylor (1973, 1974); and fall within their oceanic domain. We suggest that the domains proposed by Wenner and Taylor (1973, 1974) should be extended and that the terms, especially the continental antigorite and the continental lizardite-chrysotile, should be purely occurrence-descriptive.
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International Nuclear Information System (INIS)
Sivell, W.J.
2002-01-01
. Metalliferous contributions to red and green TA in the overlying terrigenous sedimentary sequence also link these facies to early DMOB back-arc eruptives. The red and green TA pass upwards into ungraded Atomodesmid-bearing grey TA, implying turbidite deposition in a shallowing marine environment. The (mainly andesitic) TA show systematic trends of decreasing Eu/Eu* and ε Nd (T) with increasing Ε-REE, La/Y, Th/Sc, and SiO 2 . Th abundances and Th/Sc ratios (up to 1.6) in the TA are akin to those of calc-alkaline magmas in continental arcs, and are significantly greater than island-arc or ophiolitic volcanics. A narrow range of positive ε Nd (T) values (+0.5 to +2.0) for the TA suggests a young differentiated continental arc source, less dissected than the quartzofeldspathic plutonic provenance for the Torlesse (ε Nd (T) N /Yb N = 2.5-2.8) in the sandstones resemble island-arc tholeiites (IAT). The breccias have low Eu/Eu* (c. 0.72), Ce N /Yb N = 1.6, Th/Sc (0.1-0.2), and Tb N /Yb N c. 1.0, features transitional between the sandstones and DMOB plagiogranites. Importantly, the sandstones and breccias show high positive initial Nd ratios (ε Nd (T) = +5 to +8) akin to values for Brook Street IAT (ε Nd (T) = +9). This implies juvenile (mantle-derived) source rocks for both the mafic and felsic younger terrigenous sediments, compatible with crustal residence (mean provenance) ages less than for the TA. Little continental input is permitted by Nd-isotopic data for these rocks. Whereas the early DMOB pillow basalt - chemical sediment - TA assemblage was emplaced in a back-arc setting, with influx of detritus in part from an active continental margin (possibly within the New England Orogen), the younger DMOB terrigenous sediment association shows a close kinship with bimodal DMOB magmatism related to infant arc volcanic centres in an extensional forearc regime. Turbidite sands and mass-flow deposits were shed into proximal fault-bound basins isolated from continental clastic
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Abdel-Karim, Abdel-Aal M.; Ali, Shehata; El-Shafei, Shaimaa A.
2018-03-01
This study is focused on ophiolitic metaultramafics from Um Halham and Fawakhir, Central Eastern Desert of Egypt. The rocks include serpentinized peridotites, serpentinites together with talc- and quartz-carbonates. The primary spinel relict is Al-chromite [Cr# > 60], which is replaced by Cr-magnetite during metamorphism. The high Cr# of Al-chromites resembles supra-subduction zone (SSZ) peridotites and suggests derivation from the deeper portion of the mantle section with boninitic affinity. These mantle rocks equilibrated with boninitic melt have been generated by high melting degrees. The estimated melting degrees ( 19-24%) lie within the range of SSZ peridotites. The high Cr# of spinel and Fo content of olivine together with the narrow compositional range suggest a mantle residual origin. Serpentinized peridotite and serpentinites have low Al2O3/SiO2 ratios (mostly serpentinization process. Moreover, they have very low Nb, Ta, Zr and Hf concentrations along with sub-chondritic Nb/Ta (0.3-16) and Zr/Hf (mostly 1-20) ratios further confirming that their mantle source was depleted by earlier melting extraction event. The high chondrite normalized (La/Sm)N ratios (average 10) reflect input of subduction-related slab melts/fluids into their mantle source.
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International Nuclear Information System (INIS)
Kananian, A.; Juteau, Th.; Bellon, H.; Darvishzadeh, A.; Sabzehi, M.; Whitechurch, H.; Ricou, L.E.
2001-01-01
The ophiolite massif of Kahnuj (600 km 2 ) consists, from bottom to top, of layered gabbros, isotropic gabbros and ouralite gabbros, agmatites of dioritic to plagio-granitic composition, a sheeted dyke complex and lastly a basaltic pillow lava unit. Amphiboles from gabbros were dated ( 40 K- 40 Ar ages) between 156 and 139 Ma and the agmatites are nearly contemporaneous. Potassic granitic veins dated at 93-88 Ma are related to the development of the Ganj arc complex. (authors)
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Gianola, Omar; Schmidt, Max W.; Jagoutz, Oliver; Sambuu, Oyungerel
2017-12-01
The 570 Ma old Khantaishir ophiolite is built by up to 4 km harzburgitic mantle with abundant pyroxenites and dunites followed by 2 km of hornblende-gabbros and gabbronorites and by a 2.5 km thick volcanic unit composed of a dyke + sill complex capped by pillow lavas and some volcanoclastics. The volcanics are mainly basaltic andesites and andesites (or boninites) with an average of 58.2 ± 1.0 wt% SiO2, X Mg = 0.61 ± 0.03 ( X Mg = molar MgO/(MgO + FeOtot), TiO2 = 0.4 ± 0.1 wt% and CaO = 7.5 ± 0.6 wt% (errors as 2 σ). Normalized trace element patterns show positive anomalies for Pb and Sr, a negative Nb-anomaly, large ion lithophile elements (LILE) concentrations between N- and E-MORB and distinctly depleted HREE. These characteristics indicate that the Khantaishir volcanics were derived from a refractory mantle source modified by a moderate slab-component, similar to boninites erupted along the Izu-Bonin-Mariana subduction system and to the Troodos and Betts Cove ophiolites. Most strikingly and despite almost complete outcrops over 260 km2, there is no remnant of any pre-existing MORB crust, suggesting that the magmatic suite of this ophiolite formed on completely denudated mantle, most likely upon subduction initiation. The architecture of this 4-5 km thick early arc crust resembles oceanic crust formed at mid ocean ridges, but lacks a sheeted dyke complex; volcanic edifices are not observed. Nevertheless, low melting pressures combined with moderate H2O-contents resulted in high-Si primitive melts, in abundant hornblende-gabbros and in a fast enrichment in bulk SiO2. Fractional crystallization modeling starting from the observed primitive melts (56.6 wt% SiO2) suggests that 25 wt% pyroxene + plagioclase fractionation is sufficient to form the average Khantaishir volcanic crust. Most of the fractionation happened in the mantle, the observed pyroxenite lenses and layers in and at the top of the harzburgites account for the required cumulate volumes. Finally
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A deep hydrothermal fault zone in the lower oceanic crust, Samail ophiolite Oman
Zihlmann, B.; Mueller, S.; Koepke, J.; Teagle, D. A. H.
2017-12-01
Hydrothermal circulation is a key process for the exchange of chemical elements between the oceans and the solid Earth and for the extraction of heat from newly accreted crust at mid-ocean ridges. However, due to a dearth of samples from intact oceanic crust, or continuous samples from ophiolites, there remain major short comings in our understanding of hydrothermal circulation in the oceanic crust, especially in the deeper parts. In particular, it is unknown whether fluid recharge and discharge occurs pervasively or if it is mainly channeled within discrete zones such as faults. Here, we present a description of a hydrothermal fault zone that crops out in Wadi Gideah in the layered gabbro section of the Samail ophiolite of Oman. Field observations reveal a one meter thick chlorite-epidote normal fault with disseminated pyrite and chalcopyrite and heavily altered gabbro clasts at its core. In both, the hanging and the footwall the gabbro is altered and abundantly veined with amphibole, epidote, prehnite and zeolite. Whole rock mass balance calculations show enrichments in Fe, Mn, Sc, V, Co, Cu, Rb, Zr, Nb, Th and U and depletions of Si, Ca, Na, Cr, Zn, Sr, Ba and Pb concentrations in the fault rock compared to fresh layered gabbros. Gabbro clasts within the fault zone as well as altered rock from the hanging wall show enrichments in Na, Sc, V, Co, Rb, Zr, Nb and depletion of Cr, Ni, Cu, Zn, Sr and Pb. Strontium isotope whole rock data of the fault rock yield 87Sr/86Sr ratios of 0.7046, which is considerably more radiogenic than fresh layered gabbro from this locality (87Sr/86Sr = 0.7030 - 0.7034), and similar to black smoker hydrothermal signatures based on epidote, measured elsewhere in the ophiolite. Altered gabbro clasts within the fault zone show similar values with 87Sr/86Sr ratios of 0.7045 - 0.7050, whereas hanging wall and foot wall display values only slightly more radiogenic than fresh layered gabbro.The secondary mineral assemblages and strontium isotope
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Stern, Michelle A.; Anderson, Frank A.; Flint, Lorraine E.; Flint, Alan L.
2018-05-03
In situ soil moisture datasets are important inputs used to calibrate and validate watershed, regional, or statewide modeled and satellite-based soil moisture estimates. The soil moisture dataset presented in this report includes hourly time series of the following: soil temperature, volumetric water content, water potential, and total soil water content. Data were collected by the U.S. Geological Survey at five locations in California: three sites in the central Sierra Nevada and two sites in the northern Coast Ranges. This report provides a description of each of the study areas, procedures and equipment used, processing steps, and time series data from each site in the form of comma-separated values (.csv) tables.
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Directory of Open Access Journals (Sweden)
Antonella Campopiano
2015-01-01
Full Text Available The aim of this study is to identify the infrared absorption band suitable for quantifying tremolite in three powdered samples (fine, medium, and large size classes coming from a quarry of ophiolitic friable rocks in the western part of the Calabria region of Italy. Three IR bands were considered: OH stretching band between 3700 and 3650 cm−1, the stretching bands of the Si-O-Si linkage between 1200 and 900 cm−1, and the absorbance band at 756 cm−1 attributable to tremolite. The amount of tremolite in the test samples was quantified by using the curve parameters of the three analytical bands. The quantitative analysis of tremolite using the band due to OH stretchings (3700–3650 cm−1 and the bands attributed to the Si-O-Si stretchings (1200–900 cm−1 showed high values for all test samples. Their use overestimated the tremolite amount because both bands were affected at the interfering mineral silicates such as talc, kaolinite, chlorite, and serpentinites. The abundant presence of antigorite in studied samples mainly in medium size class sample had a key role in our findings. The band at 756 cm−1 was not affected at the interfering minerals and can be used for quantitative analysis of tremolite in sample coming from ophiolitic deposits.
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The geomagnetic coast effect at two 80° S stations in Antarctica, observed in the ULF range
Directory of Open Access Journals (Sweden)
M. Regi
2018-02-01
Full Text Available We examined the coast effect in Antarctica along the 80° S magnetic parallel. We used the geomagnetic field measurements at the two coastal stations of Mario Zucchelli Station and Scott Base, and, as a reference, at the inland temporary station Talos Dome, during 18 January–14 March 2008. Spectral analysis in the Pc5 frequency range (1–7 mHz revealed large differences between coastal and inland stations, such as higher spectral power levels in the vertical component and higher coherence between horizontal and vertical components at coastal stations. Using the interstation method on selected active time intervals, with Talos Dome as a remote reference station, we found that remote reference induction arrows are directed almost perpendicularly with respect to their respective coastlines. Moreover, the single-station analysis shows that at Talos Dome the amplitude of the induction arrows is much smaller than at coastal stations. These results clearly indicate that coast effect at a few hundred kilometers from the coastline is relatively small. The coast effect on polarization parameters was examined, for a Pc5 event that occurred on 11 March 2008. The results evidenced that the azimuthal angle of polarized signals at one of the coastal stations is largely different with respect to the inland station (by ∼ 110°, while the polarization ratio and ellipticity attain comparable values. We proposed a correction method of the polarization parameters, which operates directly in the frequency domain, obtaining comparable azimuthal angles at coastal and inland stations.
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Mathany, Timothy M.; Dawson, Barbara J.; Shelton, Jennifer L.; Belitz, Kenneth
2011-01-01
Groundwater quality in the 633-square-mile Northern Coast Ranges (NOCO) study unit was investigated by the U.S. Geological Survey (USGS) from June to November 2009, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program's Priority Basin Project (PBP) and the U.S. Geological Survey National Water-Quality Assessment Program (NAWQA). The GAMA-PBP was developed in response to the California Groundwater Quality Monitoring Act of 2001 and is being conducted in collaboration with the SWRCB and Lawrence Livermore National Laboratory (LLNL). The NOCO study unit was the thirtieth study unit to be sampled as part of the GAMA-PBP.
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Ichiyama, Yuji; Ito, Hisatoshi; Hokanishi, Natsumi; Tamura, Akihiro; Arai, Shoji
2017-06-01
A Paleogene accretionary complex, the Mineoka-Setogawa Belt, is distributed around the Izu Collision Zone, central Japan. Plutonic rocks of gabbro, diorite and tonalite compositions are included as fragments and dykes in an ophiolitic mélange in this belt. Zircon U-Pb dating of the plutonic rocks indicates that they were formed at ca. 35 Ma simultaneously. These ages are consistent with Eocene-Oligocene tholeiite and calc-alkaline arc magmatism in the Izu-Bonin-Mariana (IBM) Arc and exclude several previous models for the origin of the Mineoka-Setogawa ophiolitic rocks. The geochemical characteristics of these plutonic rocks are similar to those of the Eocene-Oligocene IBM tholeiite and calc-alkaline volcanic rocks as well as to the accreted middle crust of the IBM Arc, the Tanzawa Plutonic Complex. Moreover, their lithology is consistent with those of the middle and lower crust of the IBM Arc estimated from the seismic velocity structure. These lines of evidence strongly indicate that the plutonic rocks in the Mineoka-Setogawa ophiolitic mélange are fragments of the middle to lower crust of the IBM Arc. Additionally, the presence of the Mineoka-Setogawa intermediate to felsic plutonic rocks supports the hypothesis that intermediate magma can form continental crust in intra-oceanic arcs.
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Directory of Open Access Journals (Sweden)
Emilio Saccani
2015-07-01
Full Text Available In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to post-Archean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram was obtained using >2000 known ophiolitic basalts and was tested using ∼560 modern rocks from known tectonic settings. Ten different basaltic varieties from worldwide ophiolitic complexes have been examined. They include two basaltic types that have never been considered before, which are: (1 medium-Ti basalts (MTB generated at nascent forearc settings; (2 a type of mid-ocean ridge basalts showing garnet signature (G-MORB that characterizes Alpine-type (i.e., non volcanic rifted margins and ocean-continent transition zones (OCTZ. In the Th-Nb diagram, basalts generated in oceanic subduction-unrelated settings, rifted margins, and OCTZ can be distinguished from subduction-related basalts with a misclassification rate <1%. This diagram highlights the chemical variation of oceanic, rifted margin, and OCTZ basalts from depleted compositions to progressively more enriched compositions reflecting, in turn, the variance of source composition and degree of melting within the MORB-OIB array. It also highlights the chemical contributions of enriched (OIB-type components to mantle sources. Enrichment of Th relative to Nb is particularly effective for highlighting crustal input via subduction or crustal contamination. Basalts formed at continental margin arcs and island arc with a complex polygenetic crust can be distinguished from those generated in intra-oceanic arcs in supra-subduction zones (SSZ with a misclassification rate <1%. Within the SSZ group, two sub-settings can be recognized with a misclassification rate <0.5%. They are: (1 SSZ influenced by chemical contribution from subduction-derived components (forearc and intra-arc sub-settings characterized by island arc tholeiitic (IAT and boninitic basalts; (2 SSZ with no contribution from subduction
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Mayhew, Lisa E.; Ellison, Eric T.; Miller, Hannah M.; Kelemen, Peter B.; Templeton, Alexis S.
2018-02-01
Partially serpentinized peridotites in the Samail ophiolite in the Sultanate of Oman currently undergo low temperature alteration and hydration both at shallow levels, with water recently in contact with the atmosphere, and at depth, with anoxic, reducing fluids. However, it is unclear how changes in the distribution and oxidation state of Fe are driving the production of energy-rich gases such as hydrogen and methane detected in peridotite catchments. We track the Fe transformations in a suite of outcrop samples representing a subset of the spectrum of least to most altered end-members of the Oman peridotites. We use microscale mineralogical and geochemical analyses including QEMSCAN, Raman spectroscopy, synchrotron radiation X-ray fluorescence (XRF) mapping, and electron microprobe wavelength dispersive spectroscopy. The less-altered peridotites possess a diversity of Fe-bearing phases including relict primary minerals (e.g. olivine, pyroxene, chromite) and secondary phases (e.g. serpentine and brucite). Raman spectroscopy and electron microprobe data (Si/(Mg + Fe)) indicate that much of the serpentine is significantly intergrown with brucite on the sub-micron scale. These data also indicate that the Fe content of the brucite ranges from 10 to 20 wt% FeO. The mineral assemblage of the highly reacted rocks is less diverse, dominated by serpentine and carbonate while olivine and brucite are absent. Magnetite is relatively rare and mainly associated with chromite. Goethite and hematite, both Fe(III)-hydroxides, were also identified in the highly altered rocks. Whole rock chemical analyses reflect these mineralogical differences and show that Fe in the partially serpentinized samples is on average more reduced (∼0.40-0.55 Fe3+/FeTotal) than Fe in the highly reacted rocks (∼0.85-0.90 Fe3+/FeTotal). We propose that olivine, brucite, chromite and, perhaps, serpentine in the less-altered peridotites act as reactive phases during low temperature alteration of the Oman
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Quantifying Cr(VI) Production and Export from Serpentine Soil of the California Coast Range.
McClain, Cynthia N; Fendorf, Scott; Webb, Samuel M; Maher, Kate
2017-01-03
Hexavalent chromium (Cr(VI)) is generated in serpentine soils and exported to surface and groundwaters at levels above health-based drinking water standards. Although Cr(VI) concentrations are elevated in serpentine soil pore water, few studies have reported field evidence documenting Cr(VI) production rates and fluxes that govern Cr(VI) transport from soil to water sources. We report Cr speciation (i) in four serpentine soil depth profiles derived from the California Coast Range serpentinite belt and (ii) in local surface waters. Within soils, we detected Cr(VI) in the same horizons where Cr(III)-minerals are colocated with biogenic Mn(III/IV)-oxides, suggesting Cr(VI) generation through oxidation by Mn-oxides. Water-extractable Cr(VI) concentrations increase with depth constituting a 7.8 to 12 kg/km 2 reservoir of Cr(VI) in soil. Here, Cr(VI) is produced at a rate of 0.3 to 4.8 kg Cr(VI)/km 2 /yr and subsequently flushed from soil during water infiltration, exporting 0.01 to 3.9 kg Cr(VI)/km 2 /yr at concentrations ranging from 25 to 172 μg/L. Although soil-derived Cr(VI) is leached from soil at concentrations exceeding 10 μg/L, due to reduction and dilution during transport to streams, Cr(VI) levels measured in local surface waters largely remain below California's drinking water limit.
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Carr, D.; Loocke, M. P.; Snow, J. E.; Gazel, E.
2017-12-01
The Santa Elena Ophiolite (SEO), located on the northwestern coast of Costa Rica, consists primarily of preserved oceanic mantle and crustal rocks thrust above an accretionary complex. The SEO is predominantly characterized by mantle peridotites (i.e., primarily spinel lherzolite with minor amounts of harzburgite and dunite) cut and intruded by minor pegmatitic gabbros, layered gabbros, plagiogranites, and doleritic and basaltic dykes. Previous studies have concluded that the complex formed in a suprasubduction zone (SSZ) setting based on the geochemical nature of the layered gabbros and plagiogranites (i.e., depleted LREE and HFSE and enriched LILE and Pb), as well, as the peridotites (i.e., low-TiO2, Zr, and V, and high MgO, Cr, and Ni)(Denyer and Gazel, 2009). Eighteen ultramafic samples collected during the winter 2010/2011 field season (SECR11) exhibit abundant evidence for melt-rock reaction (e.g., disseminated plagioclase and plagioclase-spinel, clinopyroxene-spinel, and plagioclase-clinopyroxene symplectites) and provide a unique opportunity to characterize the textural and chemical nature of melt-rock reaction in the SEO. We present the results of a petrologic investigation (i.e., petrography and electron probe microanalysis) of 28 thin sections (19 spinel lherzolites, of which 14 are plagioclase-bearing, 4 pyroxenite veins, and 5 harzburgites) derived from the SECR11 sample set. The results of this investigation have the potential to better our understanding of the nature of melt generation and migration and melt-rock interaction in the SEO mantle section and shed further light on the complex petrogenetic history of the SEO. Denyer, P., Gazel, E., 2009, Journal of South American Earth Sciences, 28:429-442.
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Snavely, Parke D.; Niem, Alan; Wong, Florence L.; MacLeod, Norman S.; Calhoun, Tracy K.; Minasian, Diane L.; Niem, Wendy
1996-01-01
The geology of the Cascade Head area bridges the geology in the Tillamook Highlands to the north (Wells and others, 1994; 1995) with that of the Newport Embayment on the south (Snavely and others, 1976 a,b,c). The four 7.5-minute quadrangles (Neskowin, Nestucca Bay, Hebo, and Dolph) which comprise the Cascade Head area include significant stratigraphic, structural, and igneous data that are essential in unraveling the geology of the northern and central part of the Oregon Coast Range and of the adjacent continental shelfEarlier studies (Snavely and Vokes, 1949) were of a broad reconnaissance nature because of limited access in this rugged, densely forested part of the Siuslaw National Forest. Also, numerous thick sills of late middle Eocene diabase and middle Miocene basalt mask the Eocene stratigraphic relationships. Previous mapping was hampered by a lack of precise biostratigraphic data. However, recent advances in biostratigraphy and radiometric age dating and geochemistry have provided the necessary tools to decipher stratigraphic and structural relationships in the Eocene sedimentary and volcanic rock sequences (W.W. Rau, personal communication, 1978 to 1988; Bukry and Snavely, 1988). Many important stratigraphic and igneous relationships are displayed within the Casacde Head area: (1) turbidite sandstone of the middle Eocene Tyee Formation, which is widespread in the central and southern part of the Oregon Coast Range (Snavely and others, 1964), was not deposited in the western part of the Cascade Head, and is of limited extent north of the map area (Wells and others, 1994); (2) the late middle Eocene Yamhill Formation, which crops out along the west and east flank of the Oregon Coast Range, overlaps older strata and overlies an erosional unconformity on the lower Eocene Siletz River Volcanics (Snavely and others, 1990; 1991); (3) thick sills of late middle Eocene diabase (43 Ma) are widespread in the Cascade Head area and also form much of the eastern
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Kurz, W.; Quandt, D.; Micheuz, P.; Krenn, K.
2017-12-01
The Troodos ophiolite, Cyprus, is one of the best preserved ophiolites. Based on geochemical data a supra-subduction zone (SSZ) setting was proposed. Microtextures and fluid inclusions of veins and vesicles within the Pillow Lavas record the post-magmatic structural and geochemical evolution of this SSZ beginning at 75 Ma. Three different vein types from the Upper and Lower Pillow Lavas are distinguished and imply vein precipitation under a dominant extensional regime: (1) syntaxial calcite-, quartz- and zeolite-bearing veins are interpreted as mineralized extension fractures that were pervaded by seawater. This advective fluid flow in an open system changed later into a closed system characterized by geochemical self-organization. (2) Blocky and (3) antitaxial fibrous calcite veins are associated with brecciation due to hydrofracturing and diffusion-crystallization processes, respectively. Based on aqueous fluid inclusion chemistry with seawater salinities in all studied vein types, representative fluid inclusion isochores crossed with calculated litho- and hydrostatic pressure conditions yield mineral precipitation temperatures between 180 and 210 °C, for veins and vesicles hosted in the Upper and Lower Pillow Lavas. This points to a heat source for the circulating seawater and implies that vein and vesicle minerals precipitated shortly after pillow lava crystallization under dominant isobaric cooling conditions. Compared to previous suggestions derived from secondary mineralization a less steep geothermal gradient of 200 °C from the Sheeted Dyke Complex to the Pillow Lavas of the Troodos SSZ is proposed. Further fossil and recent SSZ like the Mirdita ophiolite, Albania, the South-Anatolian ophiolites, Turkey, and the Izu-Bonin fore arc, respectively, reveal similar volcanic sequences. Vein samples recovered during International Ocean Discovery Program expedition 351 and 352 in the Izu-Bonin back and fore arc, respectively, indicate also seawater infiltration
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Sonzogni, Yann; Treiman, Allan H.; Schwenzer, Susanne P.
2017-01-01
A partially serpentinized peridotite from the Josephine ophiolite has been studied in detail in order to characterize the chemical processes of its serpentinization. The original rock was harzburgite, and its olivine and orthopyroxene are partially replaced by veins and patches of lizardite serpentine and magnetite; brucite and talc are completely absent from the serpentinite, regardless of whether the precursor mineral was olivine or pyroxene. Petrographic and mineral-chemical data suggest a...
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Mathany, Timothy M.; Belitz, Kenneth
2015-01-01
Groundwater quality in the 633-square-mile (1,639-square-kilometer) Northern Coast Ranges (NOCO) study unit was investigated as part of the Priority Basin Project (PBP) of the Groundwater Ambient Monitoring and Assessment (GAMA) Program and the U.S. Geological Survey (USGS) National Water-Quality Assessment Program. The study unit is composed of two study areas (Interior Basins and Coastal Basins) and is located in northern California in Napa, Sonoma, Lake, Colusa, Mendocino, Glenn, Humboldt, and Del Norte Counties. The GAMA-PBP is being conducted by the California State Water Resources Control Board in collaboration with the USGS and the Lawrence Livermore National Laboratory.
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Directory of Open Access Journals (Sweden)
Morovvat Faridazad
2017-02-01
Full Text Available Introduction Khoy ophiolite at the global scale is in the middle part of the Alp-Himalaya orogenic belt and it is extended over 3900 Km2 which indicates remnant Neotethys oceanic lithosphere in the Mesozoic era (Kananian et al., 2010. In this paper, in addition to a review of previous investigations about Khoy ophiolite, we will try to determine the nature and kind of minerals, origin and partial melting rate as well as the equilibrium pressure and temperature of harzburgites from the Eastern Metamorphic Complex of Khoy ophiolite. Materials and methods Thin sections microscopy studies were carried out following field investigations. EPMA analysis was carried out with using a Superprobe JEOL, JXA 8200 Microprobe unit at the state of WDS and under condition of 15kv accelerating voltage, 10nA current beam, 1µm beam diameter and collection of natural and synthetic standards for calibration. Results The study area is located at the NW of Iran and north of the Khoy city in the west Azarbaijan province. This area is part of the ophiolitic complex of NW Iran and belongs to its Eastern Metamorphic Complex. This metamorphic zone has large tectonically segments of the metamorphic ophiolites which mainly include serpentinized peridotites with associated metagabbros. There are three types of peridotitic rocks in this area which are: Lherzolites, harzburgites and dunites. Lherzolites are composed of olivine (60-70%, orthopyroxene (10-30% and clinopyroxene (~10-20% with minor amounts (~2% of Cr-spinel mineral. Harzburgites are composed of olivine (70-80%, orthopyroxene (10-20% and clinopyroxene (~5% with minor amounts (~2% of Cr-spinel mineral. Dunites are composed of olivine (90-95%, orthopyroxene (5-10% with minor amounts (~1-2% of Cr-spinel mineral. Composition range of olivines is between Fo89.46 Fa10.37 to Fo89.86 Fa10.0 as well as NiO content range is 018-046 (wt %. The calculated Mg# of olivines is 0.90 and the composition of olivines in Fo-Fa diagram
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Derbyshire, E. J.; O'Driscoll, B.; Lenaz, D.; Gertisser, R.; Kronz, A.
2013-03-01
The mantle sequence of the ~ 492 Ma Shetland Ophiolite Complex (SOC; Scotland) contains abundant compositionally heterogeneous podiform chromitite bodies enclosed in elongate dunite lenses in the vicinity of the petrological Moho. Chromitite petrogenesis and late-stage alteration events recorded in these seams are examined here using petrography, mineral chemistry and crystal structural data. The resistant nature of Cr-spinel to serpentinisation and other late-stage alteration means that primary igneous compositions are preserved in unaltered crystal cores. Chromitite mineralogy and texture from five sampled localities at The Viels, Hagdale, Harold's Grave, Nikka Vord and Cliff reveal significant inter-pod chemical heterogeneity. The Cr-spinel mineral chemistry is consistent with supra-subduction zone melt extraction from the SOC peridotites. The occurrence of chromitite seams in the centres of the dunite lenses combined with variable Cr-spinel compositions at different chromitite seam localities supports a model of chromitite formation from spatially (and temporally?) fluctuating amounts of melt-rock interaction through channelised and/or porous melt flow. Pervasive serpentinisation of the SOC has led to the almost complete replacement of the primary (mantle) silicate mineral assemblages with serpentine (lizardite with minor chrysotile and antigorite). Magmatic sulphide (e.g., pentlandite) in dunite and chromitite is locally converted to reduced Ni-sulphide varieties (e.g., heazlewoodite and millerite). A post-serpentinisation (prograde) oxidisation event is recorded in the extensively altered Cliff chromitite seams in the west of the studied area, where chromitite Cr-spinel is extensively altered to ferritchromit. The ferritchromit may comprise > 50% of the volume of the Cliff Cr-spinels and contain appreciable quantities of 1-2 μm inclusions of sperrylite (PtAs2) and Ni-arsenide, signifying the coeval formation of these minerals with ferritchromit at
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Autotrophic Ecosystems on the Early Earth
Schulte, M.
2003-01-01
Ophiolite sequences, sections of lower oceanic crust and upper mantle that have been thrust onto continental craton, are located in northern and central California and provide easily accessible areas that serve as good analogs for similar, more extensive areas of the early Earth. We have begun investigating and characterizing these sites in order to understand better the processes that may be responsible for the water chemistry, mineralogy and biology of similar environments on the early Earth. The geophysical and geochemical processes in these terranes provide niches for unique communities of extremeophiles and likely provide a good analog to the location that first gave rise to life on Earth. The ophiolites found in northern and central California include the Trinity, Josephine, Coast Range and Point Sal, all of which are approximately 160 million years old. Fluids from serpentinizing springs are generally alkaline with high pH and H2 contents, indicating that the mafic rock compositions control the fluid composition through water-rock reactions during relatively low-grade hydrothermal processes. There are significant amounts of primary mineralogy remaining in the rocks, meaning that substantial alteration processes are still occurring in these terranes. The general reaction for serpentinization of olivine is given by one of the authors. olivine + H2O = serpentine + brucite + magnetite + H2. We have analyzed the mineralogical composition of several rock samples collected from the Coast Range Ophiolite near Clear Lake, CA by electron microprobe. The remnant primary mineralogy is fairly urnform in composition, with an olivine composition of Fo(sub 90), and with pyroxene compositions of En(sub 90) for orthopyroxene and En(sub 49)Wo(sub 48)Fs(sub 03) for the clinopyroxene. Other primary phases observed include chromites and other spinels. Examination of petrographic thin sections reveals that serpentinization reactions have occurred in these locations. The serpentine
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Gordon H. Reeves; Jon B. Grunbaum; Dirk W. Lang
2009-01-01
The seasonal diel behaviour of age 1+ steelhead from Coast and Cascade Range streams in Oregon was examined in the field and in laboratory streams. During the summer, fish from both areas were active during the day in natural streams: they held position in the water column in moderate velocities and depths. At night, fish were in slower water, closer to the bottom...
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Harutyunyan, A. V.; Petrosyan, H. M.
2010-05-01
In the basis of multiple geological and geophysical data, also on the results of investigations seismic and density properties of rocks at high termobaric conditions, we proposed the petrophisical section and model of evolution of Earth crust of the territory of Armenia. On the proposed model the following interrelated problems are debated: forming of ophiolite belts and volcanic centers, genesis of hydrocarbons by organic and inorganic ways, and also reasons of originating of seismic centers. The reasons of originating of seismic centers in different depths of Earth crust, are miscellaneous. According to the model of Earth crust evolution the ophiolite belts are formed due to permanent protrusive intrusion of serpentinized masses from the foot of the crust (35-50km) into upper horizons. It is natural to assume, that the permanent intrusion of serpentinizd masses through deep faults has drastically occurred accompanying with seismic shakings. This process encourages the development of deep faults. The protrusive intrusion of serpentinized masse accompanied with partial dehydration of serpentinites and serpentinized ultrabasites and new mineral formation. The processes was accompanied also with drastic change of seismic waves and volumes up to 30%. Experiments at high termobaric conditions show, that some minerals undergone polymorphous transformations, accompanied with phase change and drastic change of rocks volume. Particularly plastic calcite, included in the composition of metamorphic rocks to run into the cracks expends and diversifies them. The process described cause some general effects similar to those of the process of dilatancy. Therefore, the protrusive intrusion of serpentinized masses into upper horizons, it dehydrations and polymorphous transformations in different minerals, may be cause of geo-dynamic processes at different depths of Earth crust. It may be assumed, that those processes permanently occur nowadays as well. Comparing the maps of
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Graymer, R.W.; Langenheim, V.E.; Roberts, M.A.; McDougall, Kristin
2014-01-01
The Cambria 30´ x 60´ quadrangle comprises southwestern Monterey County and northwestern San Luis Obispo County. The land area includes rugged mountains of the Santa Lucia Range extending from the northwest to the southeast part of the map; the southern part of the Big Sur coast in the northwest; broad marine terraces along the southwest coast; and broadvalleys, rolling hills, and modest mountains in the northeast. This report contains geologic, gravity anomaly, and aeromagnetic anomaly maps of the eastern three-fourths of the 1:100,000-scale Cambria quadrangle and the associated geologic and geophysical databases (ArcMap databases), as well as complete descriptions of the geologic map units and the structural relations in the mapped area. A cross section is based on both the geologic map and potential-field geophysical data. The maps are presented as an interactive, multilayer PDF, rather than more traditional pre-formatted map-sheet PDFs. Various geologic, geophysical, paleontological, and base map elements are placed on separate layers, which allows the user to combine elements interactively to create map views beyond the traditional map sheets. Four traditional map sheets (geologic map, gravity map, aeromagnetic map, paleontological locality map) are easily compiled by choosing the associated data layers or by choosing the desired map under Bookmarks.
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Directory of Open Access Journals (Sweden)
Tracey Goldstein
Full Text Available Interspecies transmission of influenza A is an important factor in the evolution and ecology of influenza viruses. Marine mammals are in contact with a number of influenza reservoirs, including aquatic birds and humans, and this may facilitate transmission among avian and mammalian hosts. Virus isolation, whole genome sequencing, and hemagluttination inhibition assay confirmed that exposure to pandemic H1N1 influenza virus occurred among free-ranging Northern Elephant Seals (Mirounga angustirostris in 2010. Nasal swabs were collected from 42 adult female seals in April 2010, just after the animals had returned to the central California coast from their short post-breeding migration in the northeast Pacific. Swabs from two seals tested positive by RT-PCR for the matrix gene, and virus was isolated from each by inoculation into embryonic chicken eggs. Whole genome sequencing revealed greater than 99% homology with A/California/04/2009 (H1N1 that emerged in humans from swine in 2009. Analysis of more than 300 serum samples showed that samples collected early in 2010 (n = 100 were negative and by April animals began to test positive for antibodies against the pH1N1 virus (HI titer of ≥1∶40, supporting the molecular findings. In vitro characterizations studies revealed that viral replication was indistinguishable from that of reference strains of pH1N1 in canine kidney cells, but replication was inefficient in human epithelial respiratory cells, indicating these isolates may be elephant seal adapted viruses. Thus findings confirmed that exposure to pandemic H1N1 that was circulating in people in 2009 occurred among free-ranging Northern Elephant Seals in 2010 off the central California coast. This is the first report of pH1N1 (A/Elephant seal/California/1/2010 in any marine mammal and provides evidence for cross species transmission of influenza viruses in free-ranging wildlife and movement of influenza viruses between humans and wildlife.
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Smith, C. N.; Kesler, S. E.; Blum, J. D.; Rytuba, J. J.
2007-12-01
We present here the first study of the isotopic composition of Hg in rocks, ore deposits, and active hydrothermal systems from the California Coast Ranges, one of Earth's largest Hg-depositing systems. The Franciscan Complex and Great Valley Sequence, which form the bedrock in the California Coast Ranges, are intruded and overlain by Tertiary volcanic rocks including the Clear Lake Volcanic Sequence. These rocks contain two types of Hg deposits, hot-spring deposits that form at shallow depths (<300 m) and silica-carbonate deposits that extend to greater depths (200 to 1000 m), as well as active springs and geothermal systems that release Hg to the present surface. The Franciscan Complex and Great Valley Sequence contain clastic sedimentary rocks with higher concentrations of Hg than volcanic rocks of the Clear Lake Volcanic Field. Mean Hg isotope compositions for all three rock units are similar, although the range of values in Franciscan Complex rocks is greater than in either Great Valley or Clear Lake rocks. Hot spring and silica-carbonate Hg deposits have similar average isotopic compositions that are indistinguishable from averages for the three rock units, although δ202Hg values for the Hg deposits have a greater variance than the country rocks. Precipitates from dilute spring and saline thermal waters in the area have similarly large variance and a mean δ202Hg value that is significantly lower than the ore deposits and rocks. These observations indicate there is little or no isotopic fractionation during release of Hg from its source rocks into hydrothermal solutions. Isotopic fractionation does appear to take place during transport and concentration of Hg in deposits, especially in their uppermost parts. Boiling of hydrothermal fluids is likely the most important process causing of the observed Hg isotope fractionation. This should result in the release of Hg with low δ202Hg values into the atmosphere from the top of these hydrothermal systems and a
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Mineral compositions of plutonic rocks from the Lewis Hills massif, Bay of Islands ophiolite
Smith, Susan E.; Elthon, Don
1988-01-01
Mineral compositions of residual and cumulate rocks from the Lewis Hills massif of the Bay of Islands ophiolite complex are reported and interpreted in the context of magnetic processes involved in the geochemical evolution of spatially associated diabase dikes. The mineral compositions reflect greater degrees of partial melting than most abyssal peridotites do and appear to represent the most depleted end of abyssal peridotite compositions. Subsolidus equilibration between Cr-Al spinal and olivine generally has occurred at temperatures of 700 to 900 C. The spinel variations agree with the overall fractionation of basaltic magmas producing spinels with progressively lower Cr numbers. The compositions of clinopyroxenes suggest that the fractionation of two different magma series produced the various cumulate rocks.
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Vogel, Monica; Früh-Green, Gretchen L.; Boschi, Chiara; Schwarzenbach, Esther M.
2014-05-01
The Bracco-Levanto ophiolitic complex (Eastern Liguria) represents one of the largest and better-exposed ophiolitic successions in the Northern Apennines. It is considered to be a fragment of heterogeneous Jurassic lithosphere that records tectono-magmatic and alteration histories similar to those documented along the Mid-Atlantic Ridge, such as at the 15°20'N area and the Atlantis Massif at 30°N. Structural and petrological studies on these rocks provide constraints on metamorphic/deformation processes during formation and hydrothermal alteration of the Jurassic oceanic lithosphere. We present a petrological and geochemical study of deformation processes and fluid-rock interaction in the Bracco-Levanto ophiolitic complex and compare these to modern oceanic hydrothermal systems, such as the Lost City Hydrothermal Field hosted in ultramafic rocks on the Atlantis Massif. A focus is on investigating mass transfer and fluid flow paths during high and low temperature hydrothermal activity, and on processes leading to hydrothermal carbonate precipitation and the formation of ophicalcites, which are characteristic of the Bracco-Levanto sequences. Major element and mineral compositional data allow us to distinguish a multiphase history of alteration characterized by: (1) widespread SiO2 metasomatism during progressive serpentinization, and (2) multiple phases of veining and carbonate precipitation associated with circulation of seawater and high fluid-rock ratios in the shallow ultramafic-dominated portions of the Jurassic seafloor. We observe regional variations in MgO, SiO2 and Al2O3, suggesting Si-flux towards stratigraphically higher units. In general, the ophicalcites have higher Si, Al and Fe concentrations and lower Mg than the serpentinite basement rocks or serpentinites with minimal carbonate veins. Bulk rock trace element data and Sr isotope ratios indicate seawater reacting with rocks of more mafic composition, then channeled towards stratigraphically higher
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Moertle, J.; Holk, G. J.
2015-12-01
Stable isotope geochemistry reveals a complex fluid evolution for the Western Metamorphic Belt (WMB), Coast Ranges Batholith (CRB), Central Gneiss Complex (CGC) and Coast Ranges Megalineament (CRM). These fluids are a product of a complex tectonic history related to terrane accretion that includes oblique convergence, metamorphism, magmatism, and orogenic collapse. From W-to-E, these fluid systems are as follows. High-pressure greenschist-to-amphibolite facies metasedimentary rocks of the WMB record variable mineral δD (-61 to -104‰) and δ18O (e.g., quartz +9.6 to +13.4‰) values with multiple minerals in apparent isotopic equilibrium (T ~ 450-550°C) suggest a low W/R system dominated by metamorphic fluids. Variable and non-equilibrium δD (-53 to -143‰) and δ18O (e.g., biotite +2.3 to +5.3‰) values from diorites of the Quottoon pluton affected by the ductile CRM suggest a complex evolution that involved both metamorphic and meteoric-hydrothermal fluids in this dextral shear zone; these results differ from those 300 km along strike to the north that documented only metamorphic fluids in the CRM (Goldfarb et al., 1988). Our data and those of Magaritz and Taylor (1976) from granulite facies metasediments of the CGC and plutons of the western CRB reveal homogeneous δD values (-62 to -78‰) and a restricted range of δ18O values (e.g., quartz +8.5 to +11.5‰) with all minerals in equilibrium at T > 570°C indicate a system dominated by magmatic fluids. Calculated whole-rock δ18O values (~ +7‰) for the Quottoon pluton and CRB intrusive rocks suggest a mantle origin for these magmas. Reinterpretation of very low δD (< -150‰) and quartz-feldspar δ18O pairs that display extreme disequilibrium (feldspar δ18O values as low as -5‰) from the Ponder pluton, eastern CRB, and Hazelton Group point reveals that the major meteoric-hydrothermal system that affected these rocks was related to Eocene detachment faulting along the Shames Lake fault system, a
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Directory of Open Access Journals (Sweden)
Bahram Bahrambeygi
2017-06-01
Full Text Available Ophiolitic regions are one of the most complex geology settings. Mapping in these parts need broad and precise studies and tools because of the mixture rocks and confusion units. Hyperion hyperspectral sensor data are one of the advanced tools for earth surface mapping that containing rich information of shallow electromagnetic reflection in 242 continuous bands. Because of some contaminated noise in tens of these bands we removed 87 most noisy bands and focused our study on 155 low noisy bands. In present study, tow spectral based classification algorithms of support vector machine and neutral network are compared on hyperion image for classification of cluttered units in an ophiolite set. Study area is Mesina region in collision ophiolitic belt of south east of Iran. In this region for design processing results validation rate, lots of random locations and control points were studied in field scale and were sampled for laboratory surveys. Samples were investigated in microscopic section and by electron microprobe system. Based on laboratory-field studies, the lithology of this area can divided into five general groups: (Melange series, metamorphic units, Oligocene – Miocene to Quaternary volcanic units, lime and flysch units. Based on field-laboratory works, some standard points defined for validate processing results accuracy rate. Therefore, the Support Vector Machine and neutral network method as advanced hyperspectral image processing methods respectively have overall accuracies of 52% and 65%. Consequently the method based neutral network theory for hyperspectral classification have acceptable ratio in separation of blended complicated units.
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Tectonic Evolution of Jabal Tays Ophiolite Complex, Eastern Arabian Shield, Saudi Arabia
AlHumidan, Saad; Kassem, Osama; Almutairi, Majed; Al-Faifi, Hussain; Kahal, Ali
2017-04-01
Microstructural analysis is important for investigation of tectonic evaluation of Jable Tays area. Furthermore, the Jable Tays ophiolite complex is effected by Al Amar -Idsas fault. The nature of the Al Amar-Idsas fault is a part of the Eastern Arabian Shield, which was subjected to multiple interpretations. Through fieldwork investigation, microscopic examination, and microstructural analysis, we aim to understand the evolution and tectonic setting of the Jable Tays area. Finite-strain data displays that the Abt schist, the metavolcanics and the metagranites are highly to moderately deformed. The axial ratios in the XZ section range from 1.40 to 2.20. The long axes of the finite-strain ellipsoids trend NW- SE and W-E in the Jable Tays area while, their short axes are subvertical to subhorizontal foliations. The strain magnitude does not increase towards the tectonic contacts between the Abt schist and metavolcano-sedimentary. While majority of the obtained data indicate a dominant oblate with minor prolate strain symmetries in the Abt schist, metavolcano-sedimentary and metagranites. The strain data also indicate flattening with some constriction. We assume that the Abt schist and the metavolcano-sedimentry rocks have similar deformation behavior. The finite strain in the studied rocks accumulated during the metamorphism that effected by thrusting activity. Based on these results, we finally concluded that the contact between Abt schist and metavolcano-sedimentary rocks were formed during the progressive thrusting under brittle to semi-ductile deformation conditions by simple shear that also involved a component of vertical shortening, causing subhorizontal foliation in Jable Tays area.
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Beaumont, Valérie; Vacquand, Christèle; Deville, Eric; Prinzhofer, Alain
2013-04-01
H2-rich gas seepages in ultrabasic to basic contexts both in marine and continental environment are by-products of serpentinisation. Hydrothermal systems at MOR expose ultrabasic rocks to thermodynamic conditions favouring oxidation of FeII bearing minerals and water reduction. In continental context such thermodynamic conditions do not exist although active serpentinisation occurs in all known ophiolitic complexes (Barnes et al., 1978; Bruni et al., 2002; Cipolli et al., 2004; Boschetti and Toscani, 2008; Marques et al., 2008). Hyperalkaline springs are reported in these contexts as evidence of this active serpentinisation (Barnes et al., 1967) and are often associated with seepages of reduced gases (Neal and Stanger, 1983; Sano et al., 1993). Dry gas seepages are also observed (Abrajano et al., 1988, 1990; Hosgörmez, 2007; Etiope et al., 2011) Such H2-rich gases from ophiolite complexes were sampled in the Sultanate of Oman, the Philippines and Turkey and were analysed for chemical composition, noble gases contents, stable isotopes of carbon, hydrogen and nitrogen. The conditions for present-day serpentinisation in ophiolites were recognised as low temperature processes in Oman with high rock/water ratios (Neal and Stanger, 1985), while the origin of gases is not as univocal for Philippines and Turkey gas seepages. Although, H2 generation is directly linked with FeII oxidation, different reactions can occur during peridotite hydration (McCollom and Bach, 2009; Marcaillou et al., 2011) and serpentine weathering. Produced H2 can react with carbonate species to produce methane via processes that could be biological or abiotic, while carbon availability depends on water recharge chemistry. In the present study, the geochemical properties of gases sampled from three different ophiolite complexes are compared and provide evidence that weathering reactions producing H2 depend on structural, geological, geomorphologic and hydrological local features. REFERENCES Abrajano
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Deville, E. P.; Prinzhofer, A.; Vacquand, C.; Chavagnac, V.; Monnin, C.; Ceuleneer, G.; Arcilla, C. A.
2009-12-01
We compare the geological environments of sites of emission of natural hydrogen in the Oman ophiolite and the Zambales ophiolite (Luzon, Philippines). The genesis of natural H2 results from the interaction between ultrabasic rocks and aqueous solutions circulating in deep fracture networks, by oxidation of metals (Fe2+, Mn2+) and reduction of water, probably under high temperature conditions. This process generates very reducing conditions capable of destabilizing other molecules (notably reduction of deep CO2 being transformed into CH4 by Fisher-Tropsch type reactions). Nitrogen is also commonly associated to the H2-rich fluids. H2 flows are associated with the expulsion of hyperalkaline waters rich in ions OH- and Ca2+ and characterized by high pH (between 11 and 12). Most alkaline springs are found in the vicinity of major faults and/or lithological discontinuities like the basal thrust plane of the ophiolites and the peridotite-gabbro contact (Moho). Within the fracture networks, gas and water separate probably at shallow depth, i.e. close to the top of the upper aquifer level. Locally high flows of gas migrate vertically through fracture pathways and they are able to inflame spontaneously on the surface. Aqueous fluids tends to migrate laterally in the fracture network toward the creeks where most of the hyperalkaline springs are found. This water circulation induces a chain of diagenetic reactions starting in the fracture systems and continuing at the surface where it leads to the precipitation of calcite, aragonite, brucite and more rarely portlandite. This chain of diagenetic reactions is associated with the capture of the atmospheric CO2 during the precipitation of carbonates.
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Ishimaru, Satoko; Arai, Shoji; Tamura, Akihiro
2013-04-01
Oman ophiolite is one of the well-known ophiolites for excellent exposures not only of the mantle section but also of the crustal section including effusive rocks and the underlying metamorphic rocks. In the Oman ophiolite, three types of effusive rocks (V1, V2 and V3 from the lower sequences) are recognized: i.e., V1, MORB-like magma, V2, island-arc type lava, and V3, intra-plate lava (Godard et al., 2003 and references there in). V1 and V2 lavas are dominant (> 95 %) as effusive rocks and have been observed in almost all the blocks of northern part of the Oman ophiolite (Godard et al., 2003), but V3 lava has been reported only from Salahi area (Alabaster et al., 1982). It is clear that there was a time gap of lava eruption between V1-2 and V3 based on the presence of pelagic sediments in between (Godard et al., 2003). In addition, V3 lavas are fed by a series of doleritic dikes crosscutting V2 lava (Alley unit) (Alabaster et al., 1982). We found clinopyroxenite (CPXITE) dikes crosscutting deformation structure of basal peridotites just above the metamorphic sole in Wadi Ash Shiyah. The sole metamorphic rock is garnet amphibolite, which overlies the banded and deformed harzburgite and dunite. The CPXITE is composed of coarse clinopyroxene (CPX) with minor amount of chlorite, garnet (hydrous/anhydrous grossular-andradite) with inclusions of titanite, and serpentine formed at a later low-temperature stage. The width of the CPXITE dikes is 2-5 cm (10 cm at maximum) and the dikes contain small blocks of wall harzburgite. Almost all the silicates are serpentinized in the harzburgite blocks except for some CPX. The Mg# (= Mg/(Mg + Fe) atomic ratio) of the CPX is almost constant (= 0.94-0.95) in the serpentinite blocks but varies within the dikes, highest at the contact with the block (0.94) and decreasing with the distance from the contact to 0.81 (0.85 on average). The contents of Al2O3, Cr2O3, and TiO2 in the CPX of the dikes are 0.5-2.0, 0.2-0.6, and 0
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Palandzhyan, S.A.; Layer, P.W.; Patton, W.W.; Khanchuk, A.I.
2011-01-01
Isotope datings of amphibole-bearing mafics and metamafics in the northern part of the Anadyr-Koryak region allow clarification of the time of magmatic and metamorphic processes, which are synchronous with certain stages of the geodynamic development of the northwest segment of the Pacific mobile belt in the Phanerozoic. To define the 40Ar/39Ar age of amphiboles, eight samples of amphibole gabbroids and metamafics were selected during field work from five massifs representing ophiolites and mafic plutons of the island arc. Rocks from terranes of three foldbelts: 1) Pekulnei (Chukotka region), 2) Ust-Belaya (West Koryak region), and 3) the Tamvatnei and El'gevayam subterranes of the Mainits terrane (Koryak-Kamchatka region), were studied. The isotope investigations enabled us to divide the studied amphiboles into two groups varying in rock petrographic features. The first was represented by gabbroids of the Svetlorechensk massif of the Pekulnei Range and by ophiolites of the Tamvatnei Mts.; their magmatic amphiboles show the distribution of argon isotopes in the form of clearly distinguished plateau with an age ranging within 120-129 Ma. The second group includes metamorphic amphiboles of metagabbroids and apogabbro amphibolites of the Ust-Belaya Mts., Pekulnei and Kenkeren ranges (El'gevayam subterranes). Their age spectra show loss of argon and do not provide well defined plateaus the datings obtained for them are interpreted as minimum ages. Dates of amphiboles from the metagabbro of the upper tectonic plate of the Ust-Belaya allochthon points to metamorphism in the suprasubduction environment in the fragment of Late Neoproterozoic oceanic lithosphere in Middle-Late Devonian time, long before the Uda-Murgal island arc system was formed. The amphibolite metamorphism in the dunite-clinopyroxenite-metagabbro Pekulnei sequence was dated to occur at the Permian-Triassic boundary. The age of amphiboles from gabbrodiorites of the Kenkeren Range was dated to be Early
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Mineral textures in Serpentine-hosted Alkaline Springs from the Oman ophiolite
Giampouras, Manolis; Garcia-Ruiz, Juan Manuel; Bach, Wolfgang; Garrido, Carlos J.; Los, Karin; Fussmann, Dario; Monien, Monien
2017-04-01
Meteoric water infiltration in ultramafic rocks leads to serpentinization and the formation of subaerial, low temperature, hydrothermal alkaline springs. Here, we present a detailed investigation of the mineral precipitation mechanisms and textural features of mineral precipitates, along as the geochemical and hydrological characterization, of two alkaline spring systems in the Semail ophiolite (Nasif and Khafifah sites, Wadi Tayin massif). The main aim of the study is to provide new insights into mineral and textural variations in active, on-land, alkaline vents of the Oman ophiolite. Discharge of circulating fluids forms small-scale, localized hydrological catchments consisting in unevenly interconnected ponds. Three different types of waters can be distinguished within the pond systems: i) Mg-type; alkaline (7.9 11.6), Ca-OH-rich waters; and iii) Mix-type waters arising from the mixing of Mg-type and Ca-type waters (9.6 ponds were carried out by X-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscopy coupled to dispersive energy spectroscopy (FE-SEM-EDS). Aragonite and calcite are the dominant minerals (95 vol.%) of the total mineralogical index in all sites. Mg-type waters host hydrated magnesium carbonates (nesquehonite) and magnesium hydroxycarbonate hydrates (artinite) due to evaporation. Brucite, hydromagnesite and dypingite presence in Mix-type waters is spatially controlled by the hydrology of the system and is localized around mixing zones between Ca-type with Mg-type waters. Residence time of discharging waters in the ponds before mixing has an impact on fluid chemistry as it influences the equilibration time with the atmosphere. Acicular aragonite is the main textural type in hyper-alkaline Ca-type waters, acting as a substratum for the growth of calcite and brucite crystals. Low crystallinity, dumbbell shaped and double pyramid aragonite dominates in Mix-type water precipitates. Rate of supersaturation is essential
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Coast redwood science symposium—2016: Past successes and future direction
Richard B. Standiford; Yana Valachovic
2017-01-01
There is no more iconic tree or more closely watched forest ecosystem than coast redwood. With its limited range and high value, the coast redwood forest is a microcosm of many of the emerging science and management issues facing todayâs forested landscapes. As new information is collected and new management approaches and treatments tried, it is critical that policies...
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Grajales-Nishimura, José Manuel; Ramos-Arias, Mario Alfredo; Solari, Luigi; Murillo-Muñetón, Gustavo; Centeno-García, Elena; Schaaf, Peter; Torres-Vargas, Ricardo
2018-04-01
The Juchatengo complex (JC) suite is located between the Proterozoic Oaxacan complex to the north and the Xolapa complex to the south, and was amalgamated by late Paleozoic magmatism. It consists of mafic and sedimentary rocks that have oceanic affinities, with internal pseudostratigraphic, structural and metamorphic characteristics, which resemble a typical upper-level ophiolite assemblage. New U-Pb zircon and previous hornblende K-Ar analyses yield ages of ca. 291-313 Ma (U-Pb) for plagiogranites and ca. 282-277 Ma for tonalites intruding the entire sequence, including pelagic sediments at the top, with a maximum deposition age of ca. 278 Ma and noteworthy local provenance. These data constrain the age of the JC to the Late Pennsylvanian-Early Permian period. Hf isotopic analyses obtained from zircons in the JC plagiogranite and tonalite show that they come from a similar primitive mantle source (176Hf/177Hf: 0.282539-0.283091; ƐHf(t): + 3.2 to + 15.0). ƐHf(t) values from near 0 to - 2.8 in the tonalites indicate a contribution from the continental crust. Trace elements and REE patterns in whole rock and zircons point to a primitive mantle source for differentiated mafic, plagiogranite dykes and tonalitic plutons. Geochronological and geochemical data address the generation of new oceanic crust above the subduction zone, probably in a backarc setting. In this tectonic scenario, the JC ophiolite originated due to the convergence of the paleo-Pacific plate below the already integrated Oaxacan and Acatlán complexes in western Pangea. The dextral displacement places the deformation in a transtensional regime during the late Paleozoic age.
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Maffione, M.; Morris, A.; Anderson, M.
2010-12-01
Oceanic core complexes (OCCs) are dome-shaped massifs commonly associated with the inside corners of the intersection of transform faults and slow (and ultra-slow) spreading centres. They represent the uplifted footwalls of large-slip oceanic detachment faults (e.g. Cann et al., 1997; Blackman et al., 1998) and are composed of mantle and lower crustal rocks exhumed during fault displacement (Smith et al., 2006, 2008). Recent paleomagnetic studies of core samples from OCCs in the Atlantic Ocean (Morris et al., 2009; MacLeod et al., in prep) have confirmed that footwall sections undergo substantial rotation around (sub-) horizontal axes. These studies, therefore, support “rolling hinge” models for the evolution of OCCs, whereby oceanic detachment faults initiate at a steep angle at depth and then “roll-over” to their present day low angle orientations during unroofing (Buck, 1988; Wernicke & Axen, 1988; Lavier et al., 1999). However, a fully integrated paleomagnetic and structural analysis of this process is hampered by the one-dimensional sampling provided by ocean drilling of OCC footwalls. Therefore, ancient analogues for OCCs in ophiolites are of great interest, as these potentially provide 3-D exposures of these important structures and hence a more complete understanding of footwall strain and kinematics (providing that emplacement-related phases of deformation can be accounted for). Recently, the relationship between outcropping crustal and upper mantle rocks led Tremblay et al. (2009) to propose that an OCC is preserved within the Mirdita ophiolite of the Albanian Dinarides (northern Albania). This is a slice of Jurassic oceanic lithosphere exposed along a N-S corridor which escaped the main late Cenozoic Alpine deformation (Robertson, 2002, 2004; Dilek et al., 2007). Though in the eastern portion of the Mirdita ophiolite a Penrose-type sequence is present, in the western portion mantle rocks are in tectonic contact with upper crustal lithologies
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Canovas, Peter A.; Hoehler, Tori; Shock, Everett L.
2017-07-01
Various classes of microbial and biomolecular evidence from global studies in marine and continental settings are used to identify a set of reactions that appear to support microbial metabolism during serpentinization of ultramafic rocks. Geochemical data from serpentinizing ecosystems in the Samail ophiolite of Oman are used to evaluate the extent of disequilibria that can support this set of microbial metabolisms and to provide a ranking of potential metabolic energy sources in hyperalkaline fluids that are direct products of serpentinization. Results are used to construct hypotheses for how microbial metabolism may be supported in the subsurface for two cases: ecosystems hosted in rocks that have already undergone significant serpentinization and those hosted by deeper, active serpentinization processes.
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Sheridan, Christopher D.; Puettmann, Klaus J.; Huso, Manuela M.P.; Hagar, Joan C.; Falk, Kristen R.
2013-01-01
Many land managers in the Pacific Northwest have the goal of increasing late-successional forest structures. Despite the documented importance of Douglas-fir tree bark structure in forested ecosystems, little is known about factors influencing bark development and how foresters can manage development. This study investigated the relative importance of tree size, growth, environmental factors, and thinning on Douglas-fir bark furrow characteristics in the Oregon Coast Range. Bark furrow depth, area, and bark roughness were measured for Douglas-fir trees in young heavily thinned and unthinned sites and compared to older reference sites. We tested models for relationships between bark furrow response and thinning, tree diameter, diameter growth, and environmental factors. Separately, we compared bark responses measured on trees used by bark-foraging birds with trees with no observed usage. Tree diameter and diameter growth were the most important variables in predicting bark characteristics in young trees. Measured environmental variables were not strongly related to bark characteristics. Bark furrow characteristics in old trees were influenced by tree diameter and surrounding tree densities. Young trees used by bark foragers did not have different bark characteristics than unused trees. Efforts to enhance Douglas-fir bark characteristics should emphasize retention of larger diameter trees' growth enhancement.
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Directory of Open Access Journals (Sweden)
HARTMANN LÉO A.
2003-01-01
Full Text Available Valuable information is retrieved from the integrated investigation of the field relationships, microstructure and mineral compositions of harzburgites from the Neoproterozoic Cerro Mantiqueiras Ophiolite. This important tectonic marker of the geological evolution of southernmost Brazilian Shield was thoroughly serpentinized during progressive metamorphism, because the oldest mineral assemblage is: olivine + orthopyroxene + tremolite + chlorite + chromite. This M1 was stabilized in mid amphibolite facies - 550-600ºC as calculated from mineral equilibria. No microstructural (e.g. ductile deformation of olivine or chromite or compositional (e.g. mantle spinel remnant of mantle history was identified. A metamorphic event M2 occurred in the low amphibolite facies along 100 m-wide shear zones, followed by intense serpentinization (M3 and narrow 1-3 m-wide shear zones (M4 containing asbestos.
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International Nuclear Information System (INIS)
Olive, V.; Hebert, R.; Loubet, M.
1997-01-01
The Mont Ham Massif (part of the Thetford Mines ophiolite, south Quebec) represents a magmatic sequence made up of tholeiitic and boninitic derived products. A geochemical study confirms the multicomponent mixing models that have been classically advanced for the source of boninites, with slab-derived components added to the main refractory harzburgitic peridotite. An isochron diagram of the boninitic rocks is interpreted as a mixing trend between two components: (i) a light rare earth element (LREE) enriched component (A), interpreted as slab-derived fluid-melts equilibrated with sedimentary materials (ε Nd = -3, 147 Sm/ 144 Nd = 0.140), and (ii) a LREE-depleted component (B) (0.21 147 Sm/ 144 Nd Nd = 9). A multicomponent source is also necessary to explain the Nd-isotope and trace element composition of the tholeiites, which are explained by the melting of a more fertile, Iherzolitic mantle and (or) mid-ocean ridge basalt source (component C), characterized by a large-ion lithophile element depicted pattern and an lapetus mantle Nd isotopic composition (ε Nd = 9), mixed in adequate proportions with the two previously infered slab-derived components (A and B). The genesis of the boninites of Mont Ham is not significantly different from those of boninites located in the Pacific. An intraoceanic subduction zone appears to be an appropriate geodynamic environment for the Mont Ham ophiolitic sequence. (author)
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Qiu, Tian; Zhu, Yongfeng
2018-03-01
Listwaenite lenses in the Sartohay ophiolitic mélange (Xinjiang, China) were formed via reactions between serpentinite and metasomatic fluids. First, serpentinite changed into talc schist via the reaction of serpentine + CO2 → talc + magnesite + H2O. Second, talc schist changed into listwaenite via the reaction of talc + CO2 → magnesite + quartz + H2O. Magnetite was progressively destroyed during transformation from serpentinite to talc schist, and completely consumed in listwaenite. Zircon crystals 30-100 μm long, disseminating in talc schist, undeformed listwaenite and mylonitized listwaenite, coexist with talc, quartz and magnesite, while micron-sized zircon grains (ages (302.9 ± 6.8 Ma, 299.7 ± 5.5 Ma and 296.5 ± 3.5 Ma), and are thought to represent the age of formation of the talc schist and listwaenite. These ages are indistinguishable within errors and suggest a rapid transformation from talc schist to listwaenite. Some zircon rims in samples of the undeformed listwaenite and mylonitized listwaenite give much younger apparent U-Pb ages (280-277 Ma), which could be interpreted as a recrystallization age reflecting late-stage shearing in the Sartohay ophiolitic mélange.
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Weber, Sebastian; Bucher, Kurt
2015-09-01
The Theodul Glacier Unit (TGU) at "Trockener Steg" represents a continental slice, embedded within the ophiolitic Zermatt-Saas Zone. The Zermatt-Saas Zone is the remnant of the Piemonte-Liguria oceanic lithosphere, formed in the middle Jurassic and subducted up to eclogite facies conditions in the Early Tertiary. The close spatial association of the TGU to the Zermatt-Saas Zone permits a comparison of the metamorphic evolution of the units by detailed field mapping and a petrological investigation of eclogites. The eclogites from both tectono-metamorphic units can be clearly distinguished by their textures, mineral assemblages and by mineral and bulk-rock composition. Geothermobarometry and computed assemblage stability diagrams for the TGU eclogites indicate P-T conditions of 2.2 ± 0.1 GPa and 580 ± 50 °C. These derived P-T conditions must be considered as minimum peak metamorphic conditions the rocks achieved during subduction. The P-T data are different from those derived for eclogites of Zermatt-Saas Zone adjacent to the Theodul Glacier Unit, that reached maximal burial depths at 2.3-2.4 GPa and 500 ± 50 °C. While the estimates of the eclogites of Zermatt-Saas Zone are in good agreement with some of the previous studies, the contrasting P-T estimates for the TGU eclogites suggest that the Zermatt-Saas complex must be subdivided into several tectonic subunits. The non-uniform peak conditions over the "Trockener Steg" area and the maximum pressures conditions reported from ultra-high pressure localities within Zermatt-Saas Zone suggest, that individual tectonic slices have been assembled after detachment from the slab at the return-point, i.e. along the exhumation path. Detached packages of rocks may range from small tectonic slices up to several kilometer-sized fragments. The TGU is separated from the surrounding rocks of the ophiolite unit by two major tectonic contacts. In addition, the formation of biotite-rich crusts along the basal contact of the TGU
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First Record of Invasive Lionfish (Pterois volitans) for the Brazilian Coast.
Ferreira, Carlos E L; Luiz, Osmar J; Floeter, Sergio R; Lucena, Marcos B; Barbosa, Moysés C; Rocha, Claudia R; Rocha, Luiz A
2015-01-01
The invasion of the northwestern Atlantic by the Indo-Pacific lionfish has developed extraordinarily fast, and is expected to cause one of the most negative ecological impacts among all marine invasions. In less than 30 years, lionfish have dramatically expanded their distribution range to an area encompassing the eastern coast of the USA, Bermuda, the entire Caribbean region and the Gulf of Mexico. The rapidity of the lionfish spread has raised concerns in other parts of the Atlantic that may be under the reach of the invasion. Despite the anticipation that lionfish would eventually extend their range throughout most of the eastern coast of South America, it had not been recorded in Brazil until now. Here we report the first lionfish appearance for the Brazilian coast and show that the individual collected by us is genetically linked to the invasive Caribbean population. Since small-range endemics are found in several locations in Brazil and are among the species that are most vulnerable to extinction, we recommend urgent control, management and education measures aimed at minimizing the effects of this impending invasion.
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Chavagnac, Valérie; Ceuleneer, Georges; Monnin, Christophe; Lansac, Benjamin; Hoareau, Guilhem; Boulart, Cédric
2013-07-01
We report on the mineralogical assemblages found in the hyperalkaline springs hosted on Liguria and Oman ophiolites based on exhaustive X-ray diffraction and scanning electron microprobe analyses. In Liguria, hyperalkaline springs produce a thin brownish calcite precipitate that covers the bedrock due to the concomitant atmospheric CO2 uptake and neutralization of the hyperalkaline waters. No brucite and portlandite minerals are observed. The discharge of alkaline waters in Oman ophiolite forms white-orange precipitates. Calcium carbonate minerals (calcite and/or aragonite) are the most abundant and ubiquitous precipitates and are produced by the same mechanism as in Liguria. This process is observed as a thin surface crust made of rhombohedral calcite. Morphological features of aragonite vary from needle-, bouquet-, dumbbell-, spheroidal-like habitus according to the origin of carbon, temperature, and ionic composition of the hyperalkaline springs, and the biochemical and organic compounds. Brucite is observed both at hyperalkaline springs located at the thrust plane and at the paleo-Moho. The varying mixing proportions between the surface runoff waters and the hyperalkaline ones control brucite precipitation. The layered double hydroxide minerals occur solely in the vicinity of hyperalkaline springs emerging within the bedded gabbros. Finally, the dominant mineralogical associations we found in Oman (Ca-bearing carbonates and brucite) in a serpentinizing environment driven by the meteoric waters are surprisingly the same as those observed at the Lost City hydrothermal site in a totally marine environment.
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Karrasch, A. K.; Farough, A.; Lowell, R. P.
2017-12-01
Hydration and serpentinization of oceanic lithosphere influences its strength and behavior under stress. Serpentine content is the limiting factor in deformation and the correlation between crustal strength and the degree of serpentinization is not linear. Escartin et al., [2001] shows that the presence of only 10% serpentine results in a nominally non-dilatant mode of brittle deformation and reduces the strength of peridotites dramatically. In this study, we measured density and porosity of ophiolite samples from Point Sal, CA that had various degrees of serpentinization. The densities ranged between 2500- 3000 kg/m3 and porosities ranged between 2.1-4.8%. The degree of serpentinization was estimated from mineralogical analysis, and these data were combined with that of 4 other samples analyzed by Farough et al., [2016], which were obtained from various localities. The degree of serpentinization varied between 0.6 and 40%. We found that degree of serpentinization was inversely correlated with density with a slope of 7.25 (kg/m3)/%. Using Horen et al., [1996] models, estimated P-wave velocity of the samples ranged between 6.75-7.90 km/s and S-wave velocity ranged between 3.58-4.35 km/s. There were no distinguishable difference in the results between olivine-rich or pyroxene-rich samples. These results, along with correlations to strength and deformation style, can be used as a reference for mechanical properties of the crust at depth, analysis of deep drill cores and to estimate the rate of weakening of the oceanic crust after the onset of serpentinization reactions.
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Radiological assessment of coastal marine sediment and water samples, Karachi coast, Pakistan
International Nuclear Information System (INIS)
Qureshi, R.M.; Mashiatullah, A.; Akram, M.; Sajjad, M.I.; Shafiq, M.; Javed, T.; Aslam, M.
1999-04-01
Concentrations of selective natural radionuclides (/sup 226/Ra, /sup 228/Ra, /sup 40/K) in shallow marine coastal sediments and sea water off Karachi coast, Pakistan, were measured with a hyper pure germanium (HPGe) gamma spectrometer. Sediment and water samples were collected from polluted Layari and Malire River downstream (pre-out fall), Gizri Creek, Layari River out fall in Karachi harbor, Karachi Harbor/ Manora Channel Mains, as well as from open sea (South-East Coast and North-West Coast) within the 10m depth contour. No artificial radionuclides (e.g. /sup 60/Co, /sup 137/Cs and /sup 134/Cs were detected in both water and sediment samples at any of these locations. The activity of /sup 226/Ra in coastal river sediments is found below its limit of detection (<18.35 Bqkg/sup -1/). Activity of /sup 228/Ra in sediments off Karachi Coast ranges between 11.80 +- 3.60 to 37.27+- 4.31 Bqkg/sup -1/. The highest activity was found south of Nuclear Power Station (KANUPP) and the lowest activity was found in the vicinity of Oyster Rocks (open sea). The /sup 226/Ra activity ranges from 19.40+- 5.88 to 67.14 +- 10.02 Bqkg/sup -1/. The activity of /sup 228/Ra in sediments of Manora Channel, South-east Coast of Karachi and the North west coast of Karachi are also in agreement with the IAEA marine sediment standard namely: IAEA-135 (/sup 228/Ra = 36.7 +- 3 Bqkg/sup -1/). The activity of /sup 226/Ra for the South East Coast of Karachi and the North west coast of Karachi are also in agreement with the IAEA marine sediment standard namely: IAEA 135(/sup 226/Ra=23.9 +- 1.1 Bqkg/sup -1/) and Pacific Ocean sediment standard namely: IAEA-368 (/sup 226/Ra=21.4+- 1.1 Bqkg/sup -1/). The /sup 40/K activity in sea sediments varies from 197.7+- 44.24 to 941.90 +- 39.00 Bqkg-1). The highest activity is observed in the vicinity of Oyster Rocks (open sea) along the Clifton coast (South-East Cost of Karachi) and the lowest activity is found south of Nuclear Power Station (KANUPP) along the
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Directory of Open Access Journals (Sweden)
Wenyan Ge
2018-04-01
Full Text Available As a source of data continuity between Landsat and SPOT, Sentinel-2 is an Earth observation mission developed by the European Space Agency (ESA, which acquires 13 bands in the visible and near-infrared (VNIR to shortwave infrared (SWIR range. In this study, a Sentinel-2A imager was utilized to assess its ability to perform lithological classification in the Shibanjing ophiolite complex in Inner Mongolia, China. Five conventional machine learning methods, including artificial neural network (ANN, k-nearest neighbor (k-NN, maximum likelihood classification (MLC, random forest classifier (RFC, and support vector machine (SVM, were compared in order to find an optimal classifier for lithological mapping. The experiment revealed that the MLC method offered the highest overall accuracy. After that, Sentinel-2A image was compared with common multispectral data ASTER and Landsat-8 OLI (operational land imager for lithological mapping using the MLC method. The comparison results showed that the Sentinel-2A imagery yielded a classification accuracy of 74.5%, which was 2.5% and 5.08% higher than those of the ASTER and OLI imagery, respectively, indicating that Sentinel-2A imagery is adequate for lithological discrimination, due to its high spectral resolution in the VNIR to SWIR range. Moreover, different data combinations of Sentinel-2A + ASTER + DEM (digital elevation model and OLI + ASTER + DEM data were tested on lithological mapping using the MLC method. The best mapping result was obtained from Sentinel-2A + ASTER + DEM dataset, demonstrating that OLI can be replaced by Sentinel-2A, which, when combined with ASTER, can achieve sufficient bandpasses for lithological classification.
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Schmidt, K.M.; Roering, J.J.; Stock, J.D.; Dietrich, W.E.; Montgomery, D.R.; Schaub, T.
2001-01-01
Decades of quantitative measurement indicate that roots can mechanically reinforce shallow soils in forested landscapes. Forests, however, have variations in vegetation species and age which can dominate the local stability of landslide-initiation sites. To assess the influence of this variability on root cohesion we examined scarps of landslides triggered during large storms in February and November of 1996 in the Oregon Coast Range and hand-dug soil pits on stable ground. At 41 sites we estimated the cohesive reinforcement to soil due to roots by determining the tensile strength, species, depth, orientation, relative health, and the density of roots ???1 mm in diameter within a measured soil area. We found that median lateral root cohesion ranges from 6.8-23.2 kPa in industrial forests with significant understory and deciduous vegetation to 25.6-94.3 kPa in natural forests dominated by coniferous vegetation. Lateral root cohesion in clearcuts is uniformly ???10 kPa. Some 100-year-old industrial forests have species compositions, lateral root cohesion, and root diameters that more closely resemble 10-year-old clearcuts than natural forests. As such, the influence of root cohesion variability on landslide susceptibility cannot be determined solely from broad age classifications or extrapolated from the presence of one species of vegetation. Furthermore, the anthropogenic disturbance legacy modifies root cohesion for at least a century and should be considered when comparing contemporary landslide rates from industrial forests with geologic background rates.
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Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range
Cross, Alison; Perakis, Steven S.
2011-01-01
Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species – soil relationships in ecosystems that have developed without significant human disturbance. We characterized foliage, forest floor, and mineral soil nutrients associated with four canopy tree species (Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and bigleaf maple (Acer macrophyllum Pursh)) in eight old-growth forests of the Oregon Coast Range. The greatest forest floor accumulations of C, N, P, Ca, Mg, and K occurred under Douglas-fir, primarily due to greater forest floor mass. In mineral soil, western hemlock exhibited significantly lower Ca concentration and sum of cations (Ca + Mg + K) than bigleaf maple, with intermediate values for Douglas-fir and western redcedar. Bigleaf maple explained most species-based differences in foliar nutrients, displaying high concentrations of N, P, Ca, Mg, and K. Foliar P and N:P variations largely reflected soil P variation across sites. The four tree species that we examined exhibited a number of individualistic effects on soil nutrient levels that contribute to biogeochemical heterogeneity in these ecosystems. Where fire suppression and long-term succession favor dominance by highly shade-tolerant western hemlock, our results suggest a potential for declines in both soil Ca availability and soil biogeochemical heterogeneity in old-growth forests.
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Growth of Douglas-fir near equipment trails used for commercial thinning in the Oregon Coast Range.
Richard E. Miller; Jim Smith; Paul W. Adams; Harry W. Anderson
2007-01-01
Soil disturbance is a visually apparent result of using heavy equipment to harvest trees. Subsequent consequences for growth of remaining trees, however, are variable and seldom quantified. We measured tree growth 7 and 11 years after thinning of trees in four stands of coast Douglas-fir (Pseudotsuga menziesii var. menziesii(...
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International Nuclear Information System (INIS)
Alvarado, Guillermo E.; Denyer, Perci; Gazel, Esteban
2009-01-01
Studies on the radiolarite igneous (ophiolitic) complexes were done for more than one century in Costa Rica that range from Jurassic to Eocene. These studies can be grouped in four stages of knowledge: 1) from 1904 to 1957 were recognized the cherts, and the mafic and ultramafic igneous complexes, the first regional maps were done, and the first time were recognized ellipsoidal basalts, now widely known as pillow lavas. 2) From 1958 to 1978 the complexes were seen under the concept of the association of ophiolites (serpentine, gabbro, diabase, basalts, and related rocks) and interpreted the radiolarites as deep-sea sediments. The stage is characterized by the seminal work of Gabriel Dengo and by the first geochemical analyses in the framework of the plate tectonics. 3) A huge amount of geochemical data, paleontological and K/Ar ages were published from 1979 to 1994 and it was the stage of more controversial papers, their interpretation varied for the same locality (i.e. (Nicoya Peninsula) from relative simple stratigraphic model to a very complex nappe slices, and from a simple tectonic evolution (in situ and formed by a mid oceanic ridge volcanism) to a multistage evolution (terrains, and mid oceanic ridge, aseismic ridge, intraplate and island arc volcanism). The situation was similar in the other Costa Rican oceanic complexes. 4) The outlook for 1995 to the present it has been clarified and mutual agreement between the different groups. The stage is characterized by joint collaboration, the use of modern laboratory techniques as Sr, Nd, and Pb isotopes, major, trace and complete rare earth elements. 40A r/ 39 Ar dating, and volcanological criteria, together with detailed field mapping. The main new result of these studies was that the radiolarites (164-84 Ma) in the Nicoya Peninsula were significatively older than the basic igneous rocks (140-84 Ma), indicating a complex magmatic event intruding and erupting into the thick sedimentary sequence. For other areas
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First Record of Invasive Lionfish (Pterois volitans for the Brazilian Coast.
Directory of Open Access Journals (Sweden)
Carlos E L Ferreira
Full Text Available The invasion of the northwestern Atlantic by the Indo-Pacific lionfish has developed extraordinarily fast, and is expected to cause one of the most negative ecological impacts among all marine invasions. In less than 30 years, lionfish have dramatically expanded their distribution range to an area encompassing the eastern coast of the USA, Bermuda, the entire Caribbean region and the Gulf of Mexico. The rapidity of the lionfish spread has raised concerns in other parts of the Atlantic that may be under the reach of the invasion. Despite the anticipation that lionfish would eventually extend their range throughout most of the eastern coast of South America, it had not been recorded in Brazil until now. Here we report the first lionfish appearance for the Brazilian coast and show that the individual collected by us is genetically linked to the invasive Caribbean population. Since small-range endemics are found in several locations in Brazil and are among the species that are most vulnerable to extinction, we recommend urgent control, management and education measures aimed at minimizing the effects of this impending invasion.
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Noël, J.; Godard, M.; Martinez, I.; Oliot, E.; Williams, M. J.; Rodriguez, O.; Chaduteau, C.; Gouze, P.
2017-12-01
Carbon trapping in ophiolitic peridotites contributes to the global carbon cycle between solid Earth and its outer envelopes (through subduction and/or modern alteration). To investigate this process, we performed petro-structural (microtomography, EBSD, EPMA) and geochemical studies (LA-ICP-MS, carbon and oxygen isotopes on bulk and minerals using SHRIMP) of harzburgites cored in the Oman Ophiolite. Studied harzburgites are highly serpentinized (> 90 %) and crosscut by 3 generations of carbonates (> 20 Vol%) with compositions from calcite to dolomite (Mg/Ca = 0-0.85). Type 1 carbonates are fine penetrative veinlets and mesh core after olivine. They have low REE (e.g., Yb = 0.08-0.23 x CI-chondrite) and negative Ce anomalies. They have δ13CPDB = -15.2 to 1.10‰ and δ18OSMOW = 17.5 to 33.7‰, suggesting precipitation temperatures up to 110°C. Type 2 carbonates are pluri-mm veins bounded by cm-thick serpentinized vein selvages, oriented dominantly parallel to mantle foliation. Dynamic recrystallization is observed, indicating polygenetic formation: well crystallized calcite with REE abundances similar to Type 1 carbonates are locally replaced by small dolomite and calcite grains with higher REE (e.g., Yb = 0.35-1.0 x CI-chondrite) and positive Gd anomaly. Type 2 carbonates have δ13CPDB = -12.6 to -4.1‰ and δ18OSMOW = 25.0 to 32.7‰, suggesting precipitation temperatures from 10 to 60°C. Type 3 carbonates are late pluri-mm to cm veins reactivating Type 2 veins. They consist of small grains of dolomite and calcite with REE abundances similar to recrystallized Type 2 carbonates. Type 3 carbonates have δ13CPDB = -8.3 to -5.8‰ and δ18OSMOW = 28.8 to 32.7‰, suggesting precipitation temperatures 100°C). Formation of carbonate veins (Type 2) indicates localization of fluid flux, while serpentinization remains the dominant alteration process. Low T carbonate veins (Type 3) remain the main flow path through ophiolitic peridotites. Our study suggests that
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Deans, J. R.; Crispini, L.; Cheadle, M. J.; Harris, M.; Kelemen, P. B.; Teagle, D. A. H.; Matter, J. M.; Takazawa, E.; Coggon, J. A.
2017-12-01
Oman Drilling Project Holes GT1A and GT2A were drilled into the Wadi Tayin massif, Samail ophiolite and both recovered ca. 400 m of continuous core through a section of the layered gabbros and the foliated-layered gabbro transition. Hole GT1A is cut by a discrete fault system including localized thin ultracataclastic fault zones. Hole GT2A is cut by a wider zone of brittle deformation and incipient brecciation. Here we report the structural history of the gabbros reflecting formation at the ridge to later obduction. Magmatic and high temperature history- 1) Both cores exhibit a pervasive, commonly well-defined magmatic foliation delineated by plagioclase, olivine and in places clinopyroxene. Minor magmatic deformation is present. 2) The dip of the magmatic foliation varies cyclically, gradually changing dip by 30o from gentle to moderate over a 50 m wavelength. 3) Layering is present throughout both cores, is defined by changes in mode and grain size ranging in thickness from 2 cm to 3 m and is commonly sub-parallel to the foliation. 4) There are no high temperature crystal-plastic shear zones in the core. Key observations include: no simple, systematic shallowing of dip with depth across the foliated-layered gabbro transition and layering is continuous across this transition. Cyclic variation of magmatic foliation dip most likely reflects the process of plate separation at the ridge axis. Near-axis faulting- i) On or near-axis structures consist of epidote-amphibole bearing hydraulic breccias and some zones of intense cataclasis with intensely deformed epidote and seams of clay and chlorite accompanied by syntectonic alteration of the wall rock. Early veins are filled with amphibole, chlorite, epidote, and anhydrite. ii) The deformation ranges from brittle-ductile, causing local deflection of the magmatic foliation, to brittle offset of the foliation and core and mantle structures in anhydrite veins. iii) The prevalent sense of shear is normal and slickenfibers
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Vallalar, B.; Meyer-Dombard, D. R.; Cardace, D.; Arcilla, C. A.
2016-12-01
Serpentinization involves hydrologic alteration of ultramafic mantle rocks containing olivine and pyroxene to produce serpentine minerals. The fluids resulting from this reaction are reduced, extremely depleted in dissolved inorganic carbon, and are highly alkaline with pH values typically exceeding 10. Major byproducts of the serpentinizing reaction include iron oxides, hydrogen, methane, and small amounts of organic molecules that provide chemosynthetic energy for subsurface microbial communities. In addition, weathering of serpentine rocks often produces fluids and sediments that have elevated concentrations of various toxic heavy metals such as chromium, nickel, cobalt, copper, and zinc. Thus, microorganisms inhabiting these unique ecological niches must be adapted to a variety of physicochemical extremes. The purpose of this study is to isolate bacteria that are capable of withstanding extremely high concentrations of multiple heavy metals from serpentine fluid-associated sediments. Fluid and sediment samples for microbial culturing were collected from Manleluag Spring National Park located on the island of Luzon, Philippines. The area is part of the Zambales ophiolite range, and hosts several serpentinizing fluid seeps. Fluid emanating from the source pool of the spring, designated Manleluag 2 (ML2), has a pH of 10.83 and temperature of 34.4 °C. Luria-Bertani agar medium was supplemented with varying concentrations of five trace elements - Cu, Cr, Co, Ni, and Zn. Environmental samples were spread on each of these media and colony forming units were subsequently chosen for isolation. In all, over 20 isolates were obtained from media with concentrations ranging from 25 mg/L - 400 mg/L of each metal. Taxonomic identity of each isolate was determined using 16S rRNA gene sequences. The isolates were then tested for tolerance to alkaline conditions by altering LB medium to pH values of 8, 9, 10, 11, and 12. The majority of strains exhibit growth at the highest p
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Kondolf, G. M.; Oreilly, C.
2010-12-01
Water-supply reservoirs in the actively eroding California Coast Ranges are vulnerable to sediment filling, thus creating obsolete impounding dams (Minear & Kondolf 2009). Once full of sediment, there is more impetus to remove dams for public safety and fish passage, but managing accumulated sediments becomes a dominant issue in dam removal planning. We analyzed the planning process and sediment management analyses for five dams, all of which have important ecological resources but whose dam removal options are constrained by potential impacts to downstream urban populations. Ringe Dam on Malibu Ck, Matilija Dam on the Ventura River, Searsville Dam on San Francisquito Ck, and Upper York Creek Dam on York Ck cut off important habitat for anadromous steelhead trout (Oncorhynchus mykiss). San Clemente Dam on the Carmel River has a working fish ladder, but only some of the migratory steelhead use it. By virtue of having filled with sediment, all five dams are at greater risk of seismic failure. San Clemente Dam is at greater risk because its foundation is on alluvium (not bedrock), and the poor-quality concrete in Matilija Dam is deteriorating from an akali-aggregate reaction. Simply removing the dams and allowing accumulated sediments to be transported downstream is not an option because all these rivers have extremely expensive houses along downstream banks and floodplains, so that allowing the downstream channel to aggrade with dam-dervied sediments could expose agencies to liability for future flood losses. Analyses of potential sediment transport have been based mostly on application of tractive force models, and have supported management responses ranging from in-situ stabilization (San Clemente and Matilija) to removal of stored sediment (York) to annual dredging to maintain capacity and prevent sediment passing over the dam (proposed for Searsville).
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International Nuclear Information System (INIS)
1991-09-01
The 11-million gallon Exxon Valdez oil spill highlighted deficiencies in the nation's ability to contain and recover spilled oil. The Oil Pollution Act of 1990 represents a major effort by Congress to address these deficiencies and to clarify the roles and responsibilities of the private sector and the federal government in preventing, preparing for, and responding to oil spills. This report examines the Coast Guard's efforts to avoid unnecessary and wasteful duplication by coordinating with the private sector and others, including federal and state agencies, its plans to buy oil spill response equipment and the new responsibilities the act places on the private sector and the Coast Guard and if these responsibilities call for a shift in emphasis in Coast Guard oil spill response activities
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Burton, Carmen
2018-05-30
The Monterey-Salinas Shallow Aquifer study unit covers approximately 7,820 square kilometers (km2) in Santa Cruz, Monterey, and San Luis Obispo Counties in the Central Coast Hydrologic Region of California. The study unit was divided into four study areas—Santa Cruz, Pajaro Valley, Salinas Valley, and Highlands. More than 75 percent of the water used for drinking-water supply in the Central Coast Hydrologic Region of California is groundwater, and there are more than 8,000 well driller’s logs for domestic wells (California Department of Water Resources, 2013).
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Rebay, G.; Tiepolo, M.; Zanoni, D.; Langone, A.; Spalla, M. I.
2015-12-01
The Zermatt-Saas (ZS) Zone, formerly part of Tethyan oceanic crust and variously affected by oceanic metamorphism, is now part of the orogenic suture that developed in the Western European Alps during the Alpine subduction and collision. The ZS rocks preserve a dominant HP to UHP metamorphic imprint overprinted by greenschist facies metamorphism. The age of the oceanic protoliths is considered to be middle to upper Jurassic whereas the HP metamorphism is mostly considered to be Eocene. In upper Valtournanche ZS ophiolites, the dominant regional S2 foliation is mapped with spatial continuity in serpentinite, metarodingite and eclogite and is defined by HP/UHP parageneses in all lithotypes. It developed at 2.5 ± 0.3 GPa and 600 ± 20°C during Alpine subduction. S2 foliation of serpentinites wraps rare clinopyroxene and zircon relics. Trace element composition of clinopyroxene suggests that they crystallised from a melt in equilibrium with plagioclase: they most likely represent relicts of gabbroic assemblages. The clinopyroxene porphyroclasts have rims indented within S2 and compositions similar to fine-grained clinopyroxeneII defining S2, suggesting that they recrystallised during Alpine subduction. Zircon cores show, under CL, sector zoning typical of magmatic growth. U-Pb dates suggest their crystallisation during Middle Jurassic. Magmatic cores have thin fringe overgrowths parallel to the S2 foliation. U-Pb concordant analyses on these domains reveal an Upper Cretaceous-Paleocene crystallization most likely representing the HP to UHP Alpine re-equilibration. This suggests that some sections of the ZS have experienced HP to UHP metamorphism earlier than previously thought, opening new interpretative geodynamic scenarios. Remarkably, these new dates are similar to those recorded for the HP re-equilibration in the continental crust of the adjacent Austroalpine units (upper plate of the Alpine subduction system) and to those recorded for prograde metamorphism in
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Reid, Mark E.; Coe, Jeffrey A.; Brien, Dianne
2016-01-01
Many debris flows increase in volume as they travel downstream, enhancing their mobility and hazard. Volumetric growth can result from diverse physical processes, such as channel sediment entrainment, stream bank collapse, adjacent landsliding, hillslope erosion and rilling, and coalescence of multiple debris flows; incorporating these varied phenomena into physics-based debris-flow models is challenging. As an alternative, we embedded effects of debris-flow growth into an empirical/statistical approach to forecast potential inundation areas within digital landscapes in a GIS framework. Our approach used an empirical debris-growth function to account for the effects of growth phenomena. We applied this methodology to a debris-flow-prone area in the Oregon Coast Range, USA, where detailed mapping revealed areas of erosion and deposition along paths of debris flows that occurred during a large storm in 1996. Erosion was predominant in stream channels with slopes > 5°. Using pre- and post-event aerial photography, we derived upslope contributing area and channel-length growth factors. Our method reproduced the observed inundation patterns produced by individual debris flows; it also generated reproducible, objective potential inundation maps for entire drainage networks. These maps better matched observations than those using previous methods that focus on proximal or distal regions of a drainage network.
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Role of storms and forest practices in sedimentation of an Oregon Coast Range lake
Richardson, K.; Hatten, J. A.; Wheatcroft, R. A.; Guerrero, F. J.
2014-12-01
The design of better management practices in forested watersheds to face climate change and the associated increase in the frequency of extreme events requires a better understanding of watershed responses to extreme events in the past and also under management regimes. One of the most sensitive watershed processes affected is sediment yield. Lake sediments record events which occur in a watershed and provide an opportunity to examine the interaction of storms and forest management practices in the layers of the stratigraphy. We hypothesize that timber harvesting and road building since the 1900s has resulted in increases in sedimentation; however, the passage of the Oregon Forest Practices Act (OFPA) in 1972 has led to a decrease in sedimentation. Sediment cores were taken at Loon Lake in the Oregon Coast Range. The 32-m deep lake captures sediment from a catchment highly impacted by recent land use and episodic Pacific storms. We can use sedimentological tools to measure changes in sediment production as motivated by extreme floods before settlement, during a major timber harvesting period, and after installation of forestry Best Management Practices. Quantification of changes in particle size and elemental composition (C, N, C/N) throughout the cores can elucidate changes in watershed response to extreme events, as can changes in layer thickness. Age control in the cores is being established by Cesium-137 and radiocarbon dating. Given the instrumental meteorological data and decadal climate reconstructions, we will disentangle climate driven signals from changes in land use practices. The sediment shows distinct laminations and varying thickness of layers throughout the cores. Background deposition is composed of thin layers (events to determine if the OFPA is having an effect on reducing sedimentation rates as a result of extreme magnitude storm events.
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VanTongeren, J. A.
2017-12-01
Oceanic crust is formed when mantle-derived magmas are emplaced at the ridge axis, a zone of intense rifting and extension. Magmas begin to cool and crystallize on-axis, forming what is termed the "Mush Zone", a region of partially molten rocks. Several attempts have been made to understand the nature of the Mush Zone at fast spreading mid-ocean ridges, specifically how much partial melt exists and how far off-axis the Mush Zone extends. Geophysical estimates of P-wave velocity perturbations at the East Pacific Rise show a region of low velocity approximately 1.5-2.5 km off-axis, which can be interpreted to be the result of higher temperature [e.g. Dunn et al., 2000, JGR] or the existence of partial melt. New petrological and geochemical data and methods allow for the calculation of the lateral extent of the Mush Zone in the lower oceanic crust on exposed sections collected from the Oman ophiolite, a paleo-fast/intermediate spreading center. I will present new data quantifying the crystallization temperatures of gabbros from the Wadi Khafifah section of lower oceanic gabbros from the Oman ophiolite. Crystallization temperatures are calculated with the newly developed plagioclase-pyroxene REE thermometer of Sun and Liang [2017, Contrib. Min. Pet.]. There does not appear to be any systematic change in the crystallization temperature of lower crustal gabbros with depth in the crust. In order to quantify the duration of crystallization and the lateral extent of the Mush Zone of the lower crust, crystallization temperatures are paired with estimates of the solidus temperature and cooling rate determined from the same sample, previously constrained by the Ca diffusion in olivine geothermometer/ geospeedometer [e.g. VanTongeren et al., 2008 EPSL]. There is no systematic variation in the closure temperature of Ca in olivine, or the cooling rate to the 800°C isotherm. These results show that gabbros throughout the lower crust of the Oman ophiolite remain in a partially
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Follicular aspiration versus coasting for ovarian hyper-stimulation syndrome prevention
Bushaqer, Nayla J.; Dayoub, Nawal M.; AlHattali, Khalsa K.; Ayyoub, Hisham A.; AlFaraj, Samaher S.; Hassan, Samar N.
2018-01-01
Objectives: To compare follicular reduction prior to human chorionic gonadotropin (HCG) trigger and coasting in terms of ovarian hyper-stimulation syndrome (OHSS) reduction, pregnancy, and cancellation rates in in vitro fertilization/ intracytoplasmic sperm injection (IVF/ICSI) cycles. Methods: This study was designed as a prospective study. The setting was the IVF unit at King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia. A total of 39 patients undergoing IVF/ICSI cycles, who were at risk of OHSS, 20 were put into a coasting group and 19 had follicular reduction instead. This occurred between October 2010 and January 2011. Our main outcome was OHSS reduction. Results: Six (30%) women developed OHSS in the coasting group and 2 (10.5%) women developed OHSS in the follicular group (p-value=0.235). The pregnancy rates in the cycles were similar for both groups: 4/20 (20%) in the coasting group and 3/19 (15.8%) in the follicular group (p-value=1.000). The cancellation rate of the cycles was similar for both groups, 6/20 (30%) in the coasting group and 1/19 (5.3%) in the follicular group (p-value=0.09). The median number of punctured follicles was significantly lower in the follicular group (16 follicles, interquartile range (IQR)=21-12) compared to the coasting group (29 follicles, IQR=37.8-19.8, p-value=0.001). The retrieved, fertilized, and cleaved oocytes, as well as the number of embryos transferred, were similar amongst both groups. Conclusion: There was no difference between follicular reduction prior to HCG and coasting, in terms of OHSS reduction, pregnancy, and cancellation rates in both the IVF and ICSI cycles. PMID:29543308
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2012-11-06
...-XC165 Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program... implemented as part of the trawl rationalization program. FOR FURTHER INFORMATION CONTACT: Jamie Goen, phone..., NMFS implemented a trawl rationalization program, a catch share program, for the Pacific coast...
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Sulphide mineralization and wall-rock alteration in ophiolites and modern oceanic spreading centres
Koski, R.A.
1983-01-01
Massive and stockwork Fe-Cu-Zn (Cyprus type) sulphide deposits in the upper parts of ophiolite complexes represent hydrothermal mineralization at ancient accretionary plate boundaries. These deposits are probable metallogenic analogues of the polymetallic sulphide deposits recently discovered along modern oceanic spreading centres. Genetic models for these deposits suggest that mineralization results from large-scale circulation of sea-water through basaltic basement along the tectonically active axis of spreading, a zone of high heat flow. The high geothermal gradient above 1 to 2 km deep magma chambers emplaced below the ridge axis drives the convective circulation cell. Cold oxidizing sea-water penetrating the crust on the ridge flanks becomes heated and evolves into a highly reduced somewhat acidic hydrothermal solvent during interaction with basaltic wall-rock. Depending on the temperature and water/rock ratio, this fluid is capable of leaching and transporting iron, manganese, and base metals; dissolved sea-water sulphate is reduced to sulphide. At the ridge axis, the buoyant hydrothermal fluid rises through permeable wall-rocks, and fluid flow may be focussed along deep-seated fractures related to extensional tectonic processes. Metal sulphides are precipitated along channelways as the ascending fluid undergoes adiabatic expansion and then further cooling during mixing with ambient sub-sea-floor water. Vigorous fluid flow results in venting of reduced fluid at the sea-floor/sea-water interface and deposition of massive sulphide. A comparison of sulphide mineralization and wall-rock alteration in ancient and modern spreading centre environments supports this genetic concept. Massive sulphide deposits in ophiolites generally occur in clusters of closely spaced (stacked sequences of pillow basalt and sheet flows, the sea-floor underlying numerous deposits in Guaymas Basin consists of diatomaceous ooze and terrigenous clastic sediment that is intruded by diabase
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Longshore sediment transport along the Indian coast
Digital Repository Service at National Institute of Oceanography (India)
Chandramohan, P.; Nayak, B.U.
Coast. Maharashtra Coast and the part between Pondicherry and Point Calimere in Tamilnadu, show negligible order of annual net transport. Annual net transport along the east coast is in north and along the west coast in south but for South Gujarat Coast....
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Ichthyofauna of the Eastern Coast Bays of the Novaya Zemlya Archipelago
Bolshakova, Ya. Yu.; Bolshakov, D. V.
2018-03-01
Based on 2014-2016 studies and published data on the ichthyofauna composition near the eastern coast of Novaya Zemlya, a revised list of fish fauna has been compiled. It includes 30 species from 23 genera and 13 families. The taxonomic diversity of ichthyofauna, its characteristics in respect to geographic range and biotopic groups of fish are considered. In general, ichthyological communities in bays off the eastern coast are similar in the species ratio to the communities in the open Kara Sea, and do not demonstrate any essential features of isolation.
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Ground water pollution due to aquaculture in east coast region of ...
African Journals Online (AJOL)
Abstract. Ground water quality parameters were studied for pollution due to aquaculture in the east coast region of district Andhrapradesh, India. Over a period of two years, 46 groundwater samples were collected for analyses. The results showed that the alkalinity ranged from 120 - 482 mg/L, and pH ranged from 7.1 to 8.6.
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Sapwood area - leaf area relationships for coast redwood
Stancioiu, P T; O'Hara, K L
2005-01-01
Coast redwood (Sequoia sempervirens (D. Don) Endl.) trees in different canopy strata and crown positions were sampled to develop relationships between sapwood cross-sectional area and projected leaf area. Sampling occurred during the summers of 2000 and 2001 and covered tree heights ranging from 7.7 to 45.2 m and diameters at breast height ranging from 9.4 to 92.7 cm. Foliage morphology varied greatly and was stratified into five types based on needle type (sun or shade) and twig color. A str...
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looks on as Adm. Charles Ray thanks Adm. Chuck Michel for his service as the 30th vice commandant of the commandant Adm. Charles W. Ray relieved Adm. Charles D. Michel as vice commandant of the U.S. Coast Guard by . Following graduation and commissioning as an officer in the Coast Guard, Wright will be heading to the
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Scolelepis (Polychaeta: Spionidae from the Brazilian coast with a diagnosis of the genus
Directory of Open Access Journals (Sweden)
Marcelo Borges Rocha
2012-08-01
Full Text Available Five species of Scolelepis have been reported for the Brazilian coast. This study raises this number, with two new records: S. acuta Treadwell, 1914, originally from Eastern Pacific, and Scolelepis andradei Delgado-Blas, Díaz & Liñero-Arana, 2009, from the Caribbean Sea. Furthermore, two species were found to have an expanded geographic range along the Brazilian coast: Scolelepis lighti Delgado-Blas, 2006 and Scolelepis goodbodyi Jones, 1962.
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Saccani, Emilio; Allahyari, Khalil; Rahimzadeh, Bahman
2014-05-01
The Sarve-Abad (Sawlava) ophiolites crop out in the Main Zagros Thrust Zone and represent remnants of the Mesozoic southern Neo-Tethys Ocean that was located between the Arabian shield and Sanandaj-Sirjan continental block. They consist of several incomplete ophiolitic sequences including gabbroic bodies, a dyke complex, and pillow lava sequences. These rocks generally range from sub-alkaline to transitional character. Mineral chemistry and whole-rock geochemistry indicate that they have compositions akin to enriched-type mid-ocean ridge basalts (E-MORB) and plume-type MORB (P-MORB). Nonetheless, the different depletion degrees in heavy rare earth elements (HREE), which can be observed in both E-MORB like and P-MORB like rocks enable two main basic chemical types of rocks to be distinguished as Type-I and Type-II. Type-I rocks are strongly depleted in HREE (YbN 9.0). Petrogenetic modeling shows that Type-I rocks originated from 7 to 16% polybaric partial melting of a MORB-type mantle source, which was significantly enriched by plume-type components. These rocks resulted from the mixing of variable fractions of melts generated in garnet-facies and the spinel-facies mantle. In contrast, Type-II rocks originated from 5 to 8% partial melting in the spinel-facies of a MORB-type source, which was moderately enriched by plume-type components. A possible tectono-magmatic model for the generation of the southern Neo-Tethys oceanic crust implies that the continental rift and subsequent oceanic spreading were associated with uprising of MORB-type asthenospheric mantle featuring plume-type component influences decreasing from deep to shallow mantle levels. These deep plume-type components were most likely inherited from Carboniferous mantle plume activity that was associated with the opening of Paleo-Tethys in the same area.
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Climate change at the coast: from global to local
International Nuclear Information System (INIS)
Watkinson, A.R.
2009-01-01
The IPCC has recently documented substantial changes in the global heat content of the oceans, salinity, sea level, thermal expansion and biogeochemistry. Over the 21. century anticipated climate related changes include: a rise in sea level of up to 0.6 m or more; increases in sea surface temperatures up to 3 deg. C; an intensification of tropical and extra tropical cyclones; larger extreme waves and storm surges; altered precipitation/ run-off; and ocean acidification. The Tyndall Centre has been exploring how to down-scale the global analysis to the local level within the framework of a coastal simulator. The simulator provides information on possible future states of the coast through the 21. Century under a range of climate and socio-economic futures and shoreline management options. It links models within a nested framework, recognizing three scales: (1) global, (2) regional, and (3) local. The linked models describe a range of processes, including marine climate (waves, surges and mean sea level), sand bank morpho-dynamics, wave transformation, shoreline morpho-dynamics, built environment scenarios, ecosystem change, and erosion and flood risk. Analyses from the simulator reinforce conclusions from IPCC WG2: coasts will be exposed to increasing risks over coming decades due to many compounding climate-change factors; the impact of climate change on coasts will be exacerbated by increasing human induced pressures; the unavoidability of sea-level rise even in the longer-term frequently conflicts with present day human development patterns and trends. (author)
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Small protohistoric sites (fishing villages?) on the saurashtra coast, West Coast of India
Digital Repository Service at National Institute of Oceanography (India)
Gaur, A.S.; Sundaresh
During the maritime archaeological explorations a few sites of protohistoric in nature have been noticed along the saurashtra coast. the trial excavations of a few sites namely Bet Dwarka and Bhokhira on the western saurashtra coast yielded...
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Coast Live Oak Thinning Study in the Central Coast of California
Norman H. Pillsbury; Michael J. DeLasaux; Timothy R. Plumb
1987-01-01
Abstract: Along-term thinning study was established in ten stands of coast live oak (Quercus agrifolia N in the Central Coast of California. Information about diameter, basal area, and volume growth and yield is being obtained from unthinned control plots and from plots thinned to 50 and 100 square feet of basal area per acre. Descriptive information was also collected...
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Screening of some marine plants from the Indian coast for biological activity
Digital Repository Service at National Institute of Oceanography (India)
Naqvi, S.W.A.; Solimabi; Kamat, S.Y.; DeSouza, L.; Reddy, C.V.G.; Bhakuni, D.S.; Dhawan, B.N.
Extracts of twenty five seaweeds from Indian coast have been put through a broad biological screen which includes tests for antiviral, antibacterial, antifungal, antiprotozoal, antifertility activities and a wide range of pharmacological activities...
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Inglis, E.; Bouilhol, P.; Burton, K. W.; Debret, B.; Millet, M. A.; Williams, H. M.
2016-12-01
During subduction the destabilisation of hydrous serpentine group phases can generate significant fluid fluxes between the subducting slab and the overlying mantle wedge. Despite our knowledge of this, the exact process and nature of the fluids released during serpentinite devolatilisation remain poorly understood. This study presents new field observations alongside petrographic and geochemical data for metamorphic veins and host serpentinite from the Zermatt-Saas ophiolite from the Swiss Alps, which underwent high-pressure metamorphism during the Alpine orogeny. Samples were collected from the serpentinised ultramafic section of the Zermatt-Saas ophiolite, which is mainly comprised of variably foliated and sheared antigorite serpentine. High-pressure metamorphic veins hosted within the antigorite serpentinite, are observed within the least deformed part of the massif, occurring as cm scale laterally continuous channels or mm scale interconnected anastomosing networks. Preliminary high-precision Fe isotope data for the host antigorite serpentine yield a mean δ56Fe value of -0.09‰ ± 0.04‰ (n=3), notably lighter than previously measured Alpine and abyssal serpentinites (Debret et al., 2016). In contrast, samples of cm scale olivine-bearing veins display a mean δ56Fe value of 0.07 ± 0.05‰ (n=3), resolvably heavier than that of the host serpentinite. These preliminary results suggest preferential mobility of isotopically heavy Fe within the vein forming fluids, but at this stage it is unclear if this fluid is related to local devolatilisation of the host serpentinite or input from an external source. Debret et al., 2016. Isotopic evidence for iron mobility during subduction. Geology, v. 44, no. 3, pp. 215 -218.
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Hahm, W. J.; Dietrich, W. E.; Dawson, T. E.; Lovill, S.; Rempe, D.
2016-12-01
Water availability regulates ecosystem function, particularly in seasonally dry climates where lack of moisture in the growing season acts as an ecological bottleneck. Water within hillslopes is extracted by plants during transpiration and also delivered to streams to support baseflow for riparian ecosystems and human use. How water is stored and then released from hillslopes is strongly influenced by the structure of the critical zone (CZ) that emerges from the complex interaction of lithology, climate, and tectonics. Here we show how contrasting CZ development has extreme ecohydrological consequences in the seasonally dry climate of the Northern California Coast Ranges. To explore how the CZ transmits and stores water, we studied hydrologic dynamics at two sites with similar climate across belts of the Franciscan Formation in the Eel River CZO. We monitored plant water use, precipitation inputs and stream runoff, groundwater and vadose zone moisture dynamics and documented near-surface hydraulic conductivity and runoff-generation processes. We investigated CZ structure via boreholes and geophysical methods. We find that CZ thickness determines the extent to which hillslopes `shed' or `store' wet season precipitation, and fundamentally controls the structure of plant communities and summer low-flows. In a climate where winter precipitation regularly exceeds 2000 mm, the thin CZ of the sheared argillite matrix Central belt rapidly fills, resulting in wet-season saturation overland flow that drives flashy winter runoff in channels that then quickly run dry in the early summer. The maximum unsaturated moisture storage of approximately 200 mm is sufficient to host an ecologically diverse yet sparsely forested oak savanna. In contrast, the thick CZ of the interbedded argillite and greywacke Coastal belt stores up to 600 mm of winter precipitation in the unsaturated zone and a seasonal groundwater system within fractured bedrock provides year-round flow to channels
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A coastal hazards data base for the US Gulf Coast
Energy Technology Data Exchange (ETDEWEB)
Daniels, R.C. [ed.] [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center]|[Univ. of Tennessee, Knoxville, TN (United States). Energy, Environment and Resources Center; Gornitz, V.M. [National Aeronautics and Space Administration, New York, NY (United States). Goddard Inst. for Space Studies; White, T.W. [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center
1994-06-01
This document describes the contents of a digital data base that may be used to identify coastlines along the US Gulf Coast at risk to sea-level rise. The data base integrates point, line, and polygon data for the US Gulf Coast into 0.25{degree} latitude by 0.25{degree} longitude grid cells and into 1:2,000,000 digitized line segments that can be used by raster or vector geographic information systems (GIS) as well as by non-GIS data base systems. Each coastal grid cell and line segment contains data on elevation, geology, geomorphology, sea-level trends, shoreline displacement (erosion/accretion), tidal ranges, and wave heights. To allow for the identification of coastlines at risk from sea-level rise, 7 of the 22 original data variables in this data base were classified by vulnerability and used to create 7 relative risk variables. These relative risk variables range in value from 1 to 5 and may be used to calculate a coastal vulnerability index for each grid cell and/or line segment. The data for these 29 variables (i.e., the 22 original variables and 7 risk variables) have been placed into the following data formats: (1) Gridded polygon data for the 22 original data variables. Data include elevation, geology, geomorphology, sea-level trends, shoreline displacement (erosion/accretion), tidal ranges, and wave heights. (2) Gridded polygon data for the seven classified risk variables. The risk variables are classified versions of: mean coastal elevation, geology, geomorphology, local subsidence trend, mean shoreline displacement, maximum tidal range, and maximum significant wave height. (3) 1:2,000,000 line segment data containing the 29 data variables (the 22 original data variables and the seven classified risk variables). (4) Supplemental point data for the stations used in calculating the sea-level trend and tidal range data sets. (5) Supplemental line segment data containing a 1:2,000,000 digitized coastline of the US Gulf Coast as defined by this document.
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Spectra of currents and temperature off Godavari (east coast of India)
Digital Repository Service at National Institute of Oceanography (India)
Sarma, M.S.S; Rao, L.V.G.
Time series data of currents and temperature obtained from a mooring of current meters off Godavari (East Coast of India) during September 1980 are analysed to study the space scales of semidiurnal and internal oscillations in the range of buoyancy...
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Pirates, ports, and coasts in Asia: historical and contemporary perspectives
Kleinen, J.; Osseweijer, M.
2010-01-01
Pirates, Ports and Coasts in Asia aims to fill in some of the historical gaps in the coverage of maritime piracy and armed robbery in Asia. The authors highlight a variety of activities ranging from raiding, destroying and pillaging coastal villages and capturing inhabitants to attacking and taking
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Spatial Reconnaissance : Technical Report ComCoast
Verhagen, H.J.; Ahlhorn, F.
2005-01-01
ComCoast (Combined Functions in Coastal Defence Zones) is an INTERREG IIIB project funded by the EU. ComCoast aims to develop and demonstrate innovative solutions for flood protection in coastal areas. In ComCoast, five countries from the North Sea Region are involved: Belgium, Denmark, The
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USGS science for the Nation's changing coasts; shoreline change assessment
Thieler, E. Robert; Hapke, Cheryl J.
2011-01-01
The coastline of the United States features some of the most popular tourist and recreational destinations in the world and is the site of intense residential, commercial, and industrial development. The coastal zone also has extensive and pristine natural areas, with diverse ecosystems providing essential habitat and resources that support wildlife, fish, and human use. Coastal erosion is a widespread process along most open-ocean shores of the United States that affects both developed and natural coastlines. As the coast changes, there are a wide range of ways that change can affect coastal communities, habitats, and the physical characteristics of the coast?including beach erosion, shoreline retreat, land loss, and damage to infrastructure. Global climate change will likely increase the rate of coastal change. A recent study of the U.S. Mid-Atlantic coast, for example, found that it is virtually certain that sandy beaches will erode faster in the future as sea level rises because of climate change. The U.S. Geological Survey (USGS) is responsible for conducting research on coastal change hazards, understanding the processes that cause coastal change, and developing models to predict future change. To understand and adapt to shoreline change, accurate information regarding the past and present configurations of the shoreline is essential. A comprehensive, nationally consistent analysis of shoreline movement is needed. To meet this national need, the USGS is conducting an analysis of historical shoreline changes along open-ocean coasts of the conterminous United States and parts of Alaska and Hawaii, as well as the coasts of the Great Lakes.
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Origin of multiple serpentinization events in New Caledonia
Ulrich, M.; Guillot, S.; Muñoz, M.; Picard, C.
2011-12-01
Studies on serpentinites around the world have shown that various polymorphs can coexist depending on the temperature, pressure and chemistry of the formation environment. Identifying serpentine polymorphs can thus provide significant constrains on the geodynamic environment at the time of formation. The New Caledonia ophiolite (Southwest Pacific) is one of the world's largest (500 km long, 50 km wide and 2 km thick). Emplaced during Eocene, it is thrust upon the continental Norfolk ridge, which derived from the splitting of the East Gondwana margin during Lower Late Cretaceous. The ophiolite consists of a large continuous massif occurring in the south of the island and some smaller isolated klippes located along the West coast. The peridotites are mostly harzburgite, related to a supra-subduction zone environment. The northernmost massifs are also composed of lherzolites, inherited from the opening of the South Loyalty Basin where the ophiolite was formed. Serpentinization is ubiquitous (usually >50%) independently from the nature of the peridotite. However, numerous studies have focused on the ophiolite but very few on the serpentinite. In this study, we use the Raman spectroscopy to identify serpentine polymorph in each part of the ophiolite. In situ trace element measurements were performed to constrain the behavior of fluid mobile element (FME: As, Sb, B, Li, Cs, Pb, U, Ba, Sr), and we are currently analyzing stable isotopic ratios to investigate the origin of fluids. Our results show that lizardite represents ~90% of the serpentine in the New Caledonia ophiolite. Only the serpentine sole has recorded multiple serpentinization events. In this horizon, the lizardite is crosscut by millimeter to centimeter antigorite veins. Chrysotile is the last polymorph to crystallize in millimeter crackseals. If the formation of the lizardite can be easily related to abyssal history of the ophiolite for the lherzolite and its supra-subduction history for the harzburgite, the
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Directory of Open Access Journals (Sweden)
Federica Zaccarini
2016-10-01
Full Text Available An electron microprobe study has been carried out on platinum-group minerals, accessory phases, and chromite in several chromite deposits of the Alapaevsk ophiolite (Central Urals, Russia namely the Bakanov Kluch, Kurmanovskoe, Lesnoe, 3-d Podyony Rudnik, Bol’shaya Kruglyshka, and Krest deposits. These deposits occur in partially to totally serpentinized peridotites. The microprobe data shows that the chromite composition varies from Cr-rich to Al-rich. Tiny platinum-group minerals (PGM, 1–10 µm in size, have been found in the chromitites. The most abundant PGM is laurite, accompanied by minor cuproiridsite and alloys in the system Os–Ir–Ru. A small grain (about 20 μm was found in the interstitial serpentine of the Bakanov Kluch chromitite, and its calculated stoichiometry corresponds to (Ni,Fe5P. Olivine, occurring in the silicate matrix or included in fresh chromite, has a mantle-compatible composition in terms of major and minor elements. Several inclusions of amphibole, Na-rich phlogopite, and clinopyroxene have been identified. The bimodal Cr–Al composition of chromite probably corresponds to a vertical distribution in the ophiolite sequence, implying formation of Cr-rich chromitites in the deep mantle, and Al-rich chromitites close to the Moho-transition zone, in a supra-subduction setting. The presence of abundant hydrous silicate inclusions, such as amphibole and phlogopite, suggests that the Alapaevsk chromitites crystallized as a result of the interaction between a melt enriched in fluids and peridotites. Laurite and cuproiridsite are considered to be magmatic in origin, i.e., entrapped as solid phases during the crystallization of chromite at high temperatures. The sulfur fugacity was relatively high to allow the precipitation of Ir-bearing sulfides, but below the Os–OsS2 buffer. The alloys in the system Os–Ir–Ru are classified as secondary PGM, i.e., formed at low temperature during the serpentinization process. The
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Lower crustal section of the Oman Ophiolite drilled in Hole GT1A, ICDP Oman Drilling Project
Umino, S.; Kelemen, P. B.; Matter, J. M.; Coggon, J. A.; Takazawa, E.; Michibayashi, K.; Teagle, D. A. H.
2017-12-01
Hole GT1A (22° 53.535'N, 58° 30.904'E) was drilled by the Oman Drilling Project (OmDP) into GT1A of the Samail ophiolite, Oman. OmDP is an international collaboration supported by the International Continental Scientific Drilling Program, the Deep Carbon Observatory, NSF, IODP, JAMSTEC, and the European, Japanese, German and Swiss Science Foundations, with in-kind support in Oman from the Ministry of Regional Municipalities and Water Resources, Public Authority of Mining, Sultan Qaboos University, and the German University of Technology. Hole GT1A was diamond cored in 22 Jan to 08 Feb 2017 to a total depth of 403.05 m. The outer surfaces of the cores were imaged and described on site before being curated, boxed and shipped to the IODP drill ship Chikyu, where they underwent comprehensive visual and instrumental analysis. Hole GT1A drilled the lower crustal section in the southern Oman Ophiolite and recovered 401.52 m of total cores (99.6% recovery). The main lithology is dominated by olivine gabbro (65.9%), followed in abundance by olivine-bearing gabbro (21.5%) and olivine melagabbro (3.9%). Minor rock types are orthopyroxene-bearing olivine gabbro (2.4%), oxide-bearing olivine gabbro (1.5%), gabbro (1.1%), anorthositic gabbro (1%), troctolitic gabbro (0.8%); orthopyroxene-bearing gabbro (0.5%), gabbronorite (0.3%); and dunite (0.3%). These rocks are divided into Lithologic Unit I to VII at 26.62 m, 88.16 m, 104.72 m, 154.04 m, 215.22 m, 306.94 m in Chikyu Curated Depth in descending order; Unit I and II consist of medium-grained olivine gabbro with lower olivine abundance in Unit II. Unit III is medium-grained olivine melagabbros, marked by an increase in olivine. Unit IV is relatively homogenous medium-grained olivine gabbros with granular textures. Unit V is identified by the appearance of fine-grained gabbros, but the major rocktypes are medium grained olivine gabbros. Unit VI is medium-grained olivine gabbro, marked by appearance of orthopyroxene. Unit VII
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Power Scaling of the Mainland Shoreline of the Atlantic Coast of the United States
Vasko, E.; Barton, C. C.; Geise, G. R.; Rizki, M. M.
2017-12-01
The fractal dimension of the mainland shoreline of the Atlantic coast of the United Stated from Maine to Homestead, FL has been measured in 1000 km increments using the box-counting method. The shoreline analyzed is the NOAA Medium Resolution Shoreline (https://shoreline.noaa.gov/data/datasheets/medres.html). The shoreline was reconstituted into sequentially numbered X-Y coordinate points in UTM Zone 18N which are spaced 50 meters apart, as measured continuously along the shoreline. We created a MATLAB computer code to measure the fractal dimension by box counting while "walking" along the shoreline. The range of box sizes is 0.7 to 450 km. The fractal dimension ranges from 1.0 to1.5 along the mainland shoreline of the Atlantic coast. The fractal dimension is compared with beach particle sizes (bedrock outcrop, cobbles, pebbles, sand, clay), tidal range, rate of sea level rise, rate and direction of vertical crustal movement, and wave energy, looking for correlation with the measured fractal dimensions. The results show a correlation between high fractal dimensions (1.3 - 1.4) and tectonically emergent coasts, and low fractal dimensions (1.0 - 1.2) along submergent and stable coastal regions. Fractal dimension averages 1.3 along shorelines with shoreline protection structures such as seawalls, jetties, and groins.
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Vehicle test report: South Coast technology electric conversion of a Volkswagen Rabbit
Price, T. W.; Shain, T. W.; Bryant, J. A.
1981-01-01
The South Coast Technology Volkswagen Rabbit, was tested at the Jet Propulsion Laboratory's (JPL) dynamometer facility and at JPL's Edwards Test Station (ETS). The tests were performed to characterize certain parameters of the South Coast Rabbit and to provide baseline data that will be used for the comparison of near term batteries that are to be incorporated into the vehicle. The vehicle tests were concentrated on the electrical drive system; i.e., the batteries, controller, and motor. The tests included coastdowns to characterize the road load, maximum effort acceleration, and range evaluation for both cyclic and constant speed conditions. A qualitative evaluation of the vehicle was made by comparing its constant speed range performance with those vehicles described in the document 'state of the Art assessment of Electric and Hybrid Vehicles'. The Rabbit performance was near to the best of the 1977 vehicles.
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33 CFR 23.10 - Coast Guard emblem.
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Coast Guard emblem. 23.10 Section... DISTINCTIVE MARKINGS FOR COAST GUARD VESSELS AND AIRCRAFT § 23.10 Coast Guard emblem. (a) The distinctive emblem of the Coast Guard shall be as follows: On a disc the shield of the Coat of Arms of the United...
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Rigby, Elizabeth A.; Haukos, David A.
2015-01-01
Mottled ducks (Anas fulvigula) on the western Gulf Coast have exhibited a steep population decline since the mid 1990s. Low rates of breeding incidence and nest success have been implicated in this decline, but duckling survival and the habitat needs of broods have not been previously investigated in this region. We fitted mottled duck ducklings and adult females with radio transmitters and tracked broods to estimate duckling survival and brood habitat selection on the upper Texas Gulf Coast. Duckling survival to 30 days was high (range among models 0.354–0.567) compared to other dabbling duck species. Estimated fecundity was low, (range among models 0.398–0.634) however, indicating that overall reproductive output is low. Within coastal marsh, broods selected home ranges with more water cover and less upland and fresh marsh landcover than was available in the study area. Within coastal marsh home ranges, broods selected for water cover relative to other landcover types, and there was some evidence that broods avoided unvegetated landcover. Although high quality brood habitat is undeniably important, management efforts to increase mottled duck population growth on the western Gulf Coast may best be spent on increasing nesting habitat quality to increase nest success and breeding incidence.
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The Coast Artillery Journal. Volume 86, Number 3, May-June 1943
1943-06-01
range is approximately 8,000 meters. d. Air obstacles (barrage balloons and kites ) supple- ment the defense capabilities of antiaircraft artillery around...presented letters of commendation from the training center com- 19-13 COAST ARTILLERY ACTI\\’ITIES 85 mander. Runners -up received passes and commenda
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2012 Oregon Department of Geology and Mineral Industries (DOGAMI) Oregon Lidar: Central Coast
National Oceanic and Atmospheric Administration, Department of Commerce — WSI has collected Light Detection and Ranging (LiDAR) data of the Oregon Central Coast Study Area for the Oregon Department of Geology and Mineral Industries...
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2012-12-19
.... 120813333-2647-01] RIN 0648-BC28 Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 17 to the Salmon Fishery Management Plan AGENCY: National Marine Fisheries Service (NMFS), National.... SUMMARY: NMFS proposes regulations to implement Amendment 17 to the Pacific Coast Salmon Fishery...
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Nearshore marine benthic invertebrates moving north along the U.S. Atlantic coast
Numerous species have shifted their ranges north in response to global warming. We examined 21 years (1990-2010) of marine benthic invertebrate data from the National Coastal Assessment’s monitoring of nearshore waters along the US Atlantic coast. Data came from three bioge...
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South Oregon Coast Reinforcement.
Energy Technology Data Exchange (ETDEWEB)
United States. Bonneville Power Administration.
1998-05-01
The Bonneville Power Administration is proposing to build a transmission line to reinforce electrical service to the southern coast of Oregon. This FYI outlines the proposal, tells how one can learn more, and how one can share ideas and opinions. The project will reinforce Oregon`s south coast area and provide the necessary transmission for Nucor Corporation to build a new steel mill in the Coos Bay/North Bend area. The proposed plant, which would use mostly recycled scrap metal, would produce rolled steel products. The plant would require a large amount of electrical power to run the furnace used in its steel-making process. In addition to the potential steel mill, electrical loads in the south Oregon coast area are expected to continue to grow.
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2011-12-29
.... 101206604-1758-02] RIN 0648-BA55 Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 16 to the Salmon Fishery Management Plan AGENCY: National Marine Fisheries Service (NMFS), National...) to implement Amendment 16 to the Pacific Coast Salmon Fishery Management Plan for Commercial and...
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2011-10-24
.... 101206604-1620-01] RIN 0648-BA55 Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 16 to the Salmon Fishery Management Plan AGENCY: National Marine Fisheries Service (NMFS), National... implement Amendment 16 to the Pacific Coast Salmon Fishery Management Plan for Commercial and Recreational...
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2013-02-14
.... 120813333-3107-02] RIN 0648-BC28 Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 17 to the Salmon Fishery Management Plan AGENCY: National Marine Fisheries Service (NMFS), National... implement Amendment 17 to the Pacific Coast Salmon Fishery Management Plan for Commercial and Recreational...
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Indian Ocean coasts, coastal ecology
Digital Repository Service at National Institute of Oceanography (India)
Ingole, B.S.
stream_size 9 stream_content_type text/plain stream_name Encycl_Coast_Sci_2005_546.pdf.txt stream_source_info Encycl_Coast_Sci_2005_546.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...
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Deville, E. P.; Prinzhofer, A.; Pillot, D.; Vacquand, C.; Sissmann, O.
2010-12-01
The occurrence of H2 flows which were punctually known notably in the ophiolites of Oman, Zambales (Philippines) and Antalya (Turkey) appears to be a widespread phenomenon in these major peridotite massifs associated with ancient or active subduction processes. Similar H2-rich gas flows have been discovered also in the peridotite of New-Caledonia. H2 concentrations are locally high (commonly 60 to90% in Oman). H2 is frequently degassing in hyperalkaline springs but the highest flows were found directly expelled from fractures in the peridotites. Obviously, within the fracture systems, gas and associated hyperalkaline water separate at shallow depth close to the top of the upper aquifer level. Locally high flows of gas migrate vertically in the fractures, whereas water with degassing H2 tends to migrate laterally in the fracture network toward the creeks where most of the hyperalkaline springs are found. The genesis of natural H2 is interpreted as the result of the interaction, at depth, between ultrabasic mantle rocks in the upper plate and water expelled by the subducted sediments by oxidation of metals (Fe2+, Mn2+) and reduction of water during serpentinisation. CH4 is commonly associated to the H2-rich fluids and it is interpreted as the result of the reduction of available CO2 at depth. N2 is also commonly associated to the H2-rich fluids in the ophiolites, whereas N2 flows (within H2) were found in the subducted sediments (below the sole décollement of the peridotite) where it can be observed (Oman and New-Caledonia). Within the peridotites, the hyperalkaline water is rich in ions OH- and Ca2+ and characterized by high pH (between 11 and 12). Most alkaline springs are found in the vicinity of major faults and/or lithological discontinuities like the basal décollement of the ophiolites and the peridotite-gabbro contact (Moho). This hyperalkaline water migration induces a chain of diagenetic reactions starting at depth within the fracture systems by the
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2010-03-18
... West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program AGENCY: National... proposed Trawl Rationalization Program. We are interested in feedback concerning proposed regulations to... Pacific Fishery Management Council (Council) has been developing a trawl rationalization program that...
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Legal ecotones: A comparative analysis of riparian policy protection in the Oregon Coast Range, USA.
Boisjolie, Brett A; Santelmann, Mary V; Flitcroft, Rebecca L; Duncan, Sally L
2017-07-15
Waterways of the USA are protected under the public trust doctrine, placing responsibility on the state to safeguard public resources for the benefit of current and future generations. This responsibility has led to the development of management standards for lands adjacent to streams. In the state of Oregon, policy protection for riparian areas varies by ownership (e.g., federal, state, or private), land use (e.g., forest, agriculture, rural residential, or urban) and stream attributes, creating varying standards for riparian land-management practices along the stream corridor. Here, we compare state and federal riparian land-management standards in four major policies that apply to private and public lands in the Oregon Coast Range. We use a standard template to categorize elements of policy protection: (1) the regulatory approach, (2) policy goals, (3) stream attributes, and (4) management standards. All four policies have similar goals for achieving water-quality standards, but differ in their regulatory approach. Plans for agricultural lands rely on outcome-based standards to treat pollution, in contrast with the prescriptive policy approaches for federal, state, and private forest lands, which set specific standards with the intent of preventing pollution. Policies also differ regarding the stream attributes considered when specifying management standards. Across all policies, 25 categories of unique standards are identified. Buffer widths vary from 0 to ∼152 m, with no buffer requirements for streams in agricultural areas or small, non-fish-bearing, seasonal streams on private forest land; narrow buffer requirements for small, non-fish-bearing perennial streams on private forest land (3 m); and the widest buffer requirements for fish-bearing streams on federal land (two site-potential tree-heights, up to an estimated 152 m). Results provide insight into how ecosystem concerns are addressed by variable policy approaches in multi-ownership landscapes, an
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Cabira rangarajani n. sp. (Polychaeta: Pilargidae) from the Goa coast, central west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Mandal, Sumit; Harkantra, S.N.; Salazar-Vallejo, S.I.
Cabira rangarajani n. sp., is described from the Goa coast, in central west coast of India. It differs from C. brevicirris (Rangarajan, 1964), by having a single type of neurochaetae while the other species has three types. The new species also...
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Prigent, C.; Guillot, S.; Agard, P.; Lemarchand, D.; Soret, M.; Ulrich, M.
2018-02-01
The basal part of the Semail ophiolitic mantle was (de)formed at relatively low temperature (LT) directly above the plate interface during "nascent subduction" (the prelude to ophiolite obduction). This subduction-related LT deformation was associated with progressive strain localization and cooling, resulting in the formation of porphyroclastic to ultramylonitic shear zones prior to serpentinization. Using petrological and geochemical analyses (trace elements and B isotopes), we show that these basal peridotites interacted with hydrous fluids percolating by porous flow during mylonitic deformation (from ∼850 down to 650 °C). This process resulted in 1) high-T amphibole crystallization, 2) striking enrichments of minerals in fluid mobile elements (FME; particularly B, Li and Cs with concentrations up to 400 times those of the depleted mantle) and 3) peridotites with an elevated δ11B of up to +25‰. These features indicate that the metasomatic hydrous fluids are most likely derived from the dehydration of subducting crustal amphibolitic materials (i.e., the present-day high-T sole). The rapid decrease in metasomatized peridotite δ11B with increasing distance to the contact with the HT sole (to depleted mantle isotopic values in <1 km) suggests an intense interaction between peridotites and rapid migrating fluids (∼1-25 m.y-1), erasing the initial high-δ11B subduction fluid signature within a short distance. The increase of peridotite δ11B with increasing deformation furthermore indicates that the flow of subduction fluids was progressively channelized in actively deforming shear zones parallel to the contact. Taken together, these results also suggest that the migration of subduction fluids/melts by porous flow through the subsolidus mantle wedge (i.e., above the plate interface at sub-arc depths) is unlikely to be an effective mechanism to transport slab-derived elements to the locus of partial melting in subduction zones.
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COAST code conversion from Cyber to HP
International Nuclear Information System (INIS)
Lee, Hae Cho
1996-04-01
The transient thermal hydraulic behavior of reactor coolant system in a nuclear power plant following loss of coolant flow is analyzed by use of COAST digital computer code. COAST calculates individual loop flow rates and steam generator pressure drops is a function of time following coast-down of any number of reactor coolant pumps. This report firstly describes detailed work carried out for installation of COAST on HP 9000/700 series and code validation results after installation. Secondly, a series of work is also describes in relation to installation of COAST on Apollo DN10000 series as well as relevant code validation results. Attached is a report on software verification and validation results. 7 refs. (Author) .new
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2010-10-04
... opportunities to harvest available healthy stocks and meet the objective of the Pacific Coast Groundfish FMP to... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 660 [Docket No... Coast Groundfish Fishery; Inseason Adjustments to Fishery Management Measures AGENCY: National Marine...
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Energy Technology Data Exchange (ETDEWEB)
Kananian, A. [University of Tarbiat Modarress, Geological Dept., Faculty of Science, Teheran (Iran, Islamic Republic of); Juteau, Th.; Bellon, H. [Universite de Bretagne Occidentale, IUEM, 29 - Brest (France); Darvishzadeh, A. [University of Teheran, Geological Dept., Faculty of Science, Teheran (Iran, Islamic Republic of); Sabzehi, M. [Geological Survey of Iran, Teheran (Iran, Islamic Republic of); Whitechurch, H. [Universite Louis Pasteur, EOST, Institut de Physique du Globe, 67 - Strasbourg (France); Ricou, L.E. [Institut de Physique du Globe, 75 - Paris (France)
2001-05-01
The ophiolite massif of Kahnuj (600 km{sup 2}) consists, from bottom to top, of layered gabbros, isotropic gabbros and ouralite gabbros, agmatites of dioritic to plagio-granitic composition, a sheeted dyke complex and lastly a basaltic pillow lava unit. Amphiboles from gabbros were dated ({sup 40}K-{sup 40}Ar ages) between 156 and 139 Ma and the agmatites are nearly contemporaneous. Potassic granitic veins dated at 93-88 Ma are related to the development of the Ganj arc complex. (authors)
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National Oceanic and Atmospheric Administration, Department of Commerce — The imagery posted on this site is of the North Carolina coast after Hurricane Ophelia made landfall. The regions photographed range from Hubert, North Carolina to...
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Surf zone dynamics along the south Karnataka Coast between Bhatkal and Ullal, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Chandramohan, P.; SanilKumar, V.; Nayak, B.U.; Raju, N.S.N.
stronger in June, and relatively low and steady during the rest of the year. Coast between Padubidri and Ullal experienced relatively stronger longshore currents than the coast between Maravanthe and Malpe. Longshore sediment transport rate was relatively...
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A coastal hazards data base for the U.S. West Coast
Energy Technology Data Exchange (ETDEWEB)
Gornitz, V.M. [Columbia Univ., New York, NY (United States). Center for Climate Systems Research]|[National Aeronautics and Space Administration, New York, NY (United States). Goddard Inst. for Space Studies; Beaty, T.W. [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center; Daniels, R.C. [Univ. of Tennessee, Knoxville, TN (United States). Energy, Environment and Resources Center
1997-12-01
This document describes the contents of a digital data base that may be used to identify coastlines along the US West Coast that are at risk to sea-level rise. This data base integrates point, line, and polygon data for the US West Coast into 0.25{degree} latitude by 0.25{degree} longitude grid cells and into 1:2,000,000 digitized line segments that can be used by raster or vector geographic information systems (GIS) as well as by non-GIS data bases. Each coastal grid cell and line segment contains data variables from the following seven data sets: elevation, geology, geomorphology, sea-level trends, shoreline displacement (erosion/accretion), tidal ranges, and wave heights. One variable from each data set was classified according to its susceptibility to sea-level rise and/or erosion to form 7 relative risk variables. These risk variables range in value from 1 to 5 and may be used to calculate a Coastal Vulnerability Index (CVI). Algorithms used to calculate several CVIs are listed within this text.
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46 CFR 50.10-25 - Coast Guard Symbol.
2010-10-01
... 46 Shipping 2 2010-10-01 2010-10-01 false Coast Guard Symbol. 50.10-25 Section 50.10-25 Shipping... Definition of Terms Used in This Subchapter § 50.10-25 Coast Guard Symbol. (a) The term Coast Guard Symbol... impression of the Coast Guard Symbol for stamping nameplates and specimens is shown in Figure 50.10-25(b...
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A longshore sediment transport estimation for the Indian coast
Digital Repository Service at National Institute of Oceanography (India)
Nayak, B.U.; Chandramohan, P.
in Tamilnadu, and the Maharashtra Coast experience negligible annual net transport. The direction of annual net transport along the east coast is towards north and along the west coast towards south except at south Gujarat Coast...
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Sustainability of future coasts and estuaries: A synthesis
Newton, Alice; Harff, Jan; You, Zai-Jin; Zhang, Hua; Wolanski, Eric
2016-12-01
Coasts are at the nexus of the Anthropocene, where land, marginal seas and atmosphere meet along a thin strip that is inhabited by nearly half the human population (Wolanski and Elliott, 2015). Coasts are often fringed by rich habitats such as mangroves, salt-marshes, inter-tidal mud and sand flats, seagrass meadows, kelp forests and coral reefs that provide a valuable range of ecosystem services to humans and to the adjacent marginal seas (Van den Belt and Costanza, 2011). It is the highly dynamic system that is constantly being reshaped by changing natural forces and anthropogenic activities. Coastal systems and human societies form coastal social-ecological systems that increasingly face multiple pressures, which threaten their ecological and economical sustainability. Common pressures include changes to land use and hydrology, land reclamation, coastal sand mining, harbour dredging, pollution and eutrophication, overexploitation such as overfishing, all in the context of climate change. During the 20th Century, coastal scientists studied the problems and issues arising along the coasts (Ramesh et al., 2015). Now, in the 21st Century, their focus must increasingly be about how to solve these problems and issues through better management and innovative approaches. To study these matters, two workshops were held in Yantai, P.R. China, in September 2015, hosted by the Yantai Institute of Coastal Zone Research, CAS. The outcome of these workshops is this special issue of Estuarine, Coastal and Shelf Science.
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Rollinson, Hugh; Mameri, Lucan; Barry, Tiffany
2018-06-01
Polymineralic inclusions interpreted as melt inclusions in chromite from the dunitic Moho Transition Zone in the Maqsad area of the Oman ophiolite have been analysed and compositions integrated using a rastering technique on the scanning electron microscope. The inclusions now comprise a range of inter-grown hydrous phases including pargasite, aspidolite, phlogopite and chlorite, indicating that the parental melts were hydrous. Average inclusion compositions for seven samples contain between 23.1 and 26.8 wt% MgO and 1.7-3.6 wt% FeO. Compositions were corrected to allow for the low FeO concentrations using coexisting olivine compositions. These suggest that the primary melt has between 20 and 22 wt% MgO and 7-9.7 wt% FeO and has an affinity with boninitic melts, although the melts have a higher Ti content than most boninites. Average rare earth element concentrations suggest that the melts were derived from a REE depleted mantle source although fluid-mobile trace elements indicate a more enriched source. Given the hydrous nature of the inclusions this enrichment could be fluid driven. An estimate of the melt temperature can be made from the results of homogenisation experiments on these inclusions and suggests 1300 °C, which implies for a harzburgite solidus, relatively shallow melting at depths of <50 km and is consistent with a boninitic origin. The current "basaltic" nature of the chromite host to highly magnesian melt inclusions suggests that the dunitic Moho Transition Zone operated as a reaction filter in which magnesian melts were transformed into basalts by the removal of high magnesian olivines, particularly in areas where the Moho Transition Zone is unusually thick. We propose therefore that podiform mantle chromitites, even those with an apparent MORB-like chemical signature, have crystallised from a highly magnesian parental melt. The data presented here strongly support the view that this took place in a subduction initiation setting.
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Pirnia, Tahmineh; Saccani, Emilio; Arai, Shoji
2018-06-01
The Nain ophiolites crop out along the western border of the central East Iran Microcontinent (CEIM) and consist of an ophiolitic mélange in which pargasite-bearing spinel and plagioclase mantle lherzolites are largely represented. Whole-rock and mineral chemistry data suggest that these rocks record the complex history of the asthenospheric and lithospheric mantle evolution. The spinel lherzolites have experienced low-degree ( 5%) partial melting and contain clinopyroxenes with positive Eu anomalies (Eu/Eu* = 1.10-1.48) suggesting that the partial melting occurred under oxidized conditions (fayalite-magnetite-quartz -0.8 to +1.3). The pargasite and coexisting clinopyroxene in these rocks are depleted in light rare earth elements (LREE) (mean chondrite-normalized CeN/SmN = 0.045). The depleted chemistry of this amphibole reflects metasomatism during interaction with H2O-rich subalkaline mafic melts, most likely concurrently with or after the partial melting of the spinel lherzolites. The plagioclase lherzolites were subsequently formed by the subsolidus recrystallization of spinel lherzolites under plagioclase facies conditions as a result of mantle uprising, as evidenced by: (1) the development of plagioclase rims around the spinels; (2) plagioclase + orthopyroxene exsolution textures within some clinopyroxene grains; (3) an increase in plagioclase modal content coupled with an increase in modal olivine and a decrease in modal pyroxene and pargasite; (4) coincident decreases in Al, Mg, and Ni, and increases in Cr, Ti, and Fe in spinel, as well as decreases in Al and Ca, and increases in Cr and Ti in pyroxene and pargasite; and (5) the identical whole rock compositions of the spinel and plagioclase lherzolites, which rules out a magmatic origin for the plagioclase in these units. The Nain lherzolites have similar whole-rock and mineral geochemical compositions to subcontinental peridotites that are typically representative of Iberia-type rifted continental margins
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Zooplankton along the Tamil Nadu coast
Digital Repository Service at National Institute of Oceanography (India)
Santhakumari, V.; Saraswathy, M.
Zooplankton abundance along two sectors at Cape Comorin and Tuticorin of Tamil Nadu Coast, southeast coast of India was studied. High biomass contributed by Ostracods, Salps, Chaetognaths etc., were observed along Tuticorin transect. In the Cape...
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International Nuclear Information System (INIS)
Mohd Suhaimi Elias; Abdul Khalik Wood; Zaleha Hashim; Wee Boon Siong; Mohd Suhaimi Hamzah; Shamsiah Abdul Rahman; Nazaratul Ashifa Abdullah Salim; Ariffin Talib
2007-01-01
The polycyclic hydrocarbons (PAHs) are pollutants of concern due to their persistent in the marine ecosystem, thus its can cause long-term adverse effect to the marine life. In this study the concentrations of PAHs in east coast Peninsular Malaysia sediments were determined. About ten stations along the east coast of the coastal area were selected to collect sediments sample using grab sampler. The PAHs from the sediment samples were soxhlet extracted using mixture of hexane and dichloromethane (DCM). Fractionation was done using the silica-alumina column. About 17 compounds of the PAHs were determined using the Gas Chromatography-Mass Spectrometer (GCMS model QP5050A). The Σ PAHs was found in the range between 0.26 μg/ g to 0.59 μg/ g dry weight. The data from the study signified that the main source of PAHs in the sediment of the east coast peninsular Malaysia is originated from the pyrolytic source. (author)
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Alternative Fuels Data Center: Hybrid and Electric Vehicles Boom Coast to
Coast Hybrid and Electric Vehicles Boom Coast to Coast to someone by E-mail Share Alternative Fuels Data Center: Hybrid and Electric Vehicles Boom Coast to Coast on Facebook Tweet about Alternative Fuels Data Center: Hybrid and Electric Vehicles Boom Coast to Coast on Twitter Bookmark Alternative
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Digital Repository Service at National Institute of Oceanography (India)
Aboobacker, V.M.; Vethamony, P.; Samiksha, S.V.; Rashmi, R.; Jyoti, K.
] “Impact of sea-breeze on wind-seas off Goa, west coast of India,” Journal of Earth System Science,115(2), 229-234. Rani, S.I., Radhika, R., Subrahamanyam, D.B., Denny, P.A., Kunhikrishnan, P.K. [2010] “Characterization of sea/land breeze circulation...., Praveena, K. [2001] “Study of sea breeze and land breeze along the west coast of Indian sub-continent over the latitude range 15°N to 8°N during INDOEX IFP-99 (SK-141) cruise,”Current Science, 80, 85-88. Sullivan, P.P., Edson. J.B., Hristov, T., Mc...
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FutureCoast: "Listen to your futures"
Pfirman, S. L.; Eklund, K.; Thacher, S.; Orlove, B. S.; Diane Stovall-Soto, G.; Brunacini, J.; Hernandez, T.
2014-12-01
Two science-arts approaches are emerging as effective means to convey "futurethinking" to learners: systems gaming and experiential futures. FutureCoast exemplifies the latter: by engaging participants with voicemails supposedly leaking from the cloud of possible futures, the storymaking game frames the complexities of climate science in relatable contexts. Because participants make the voicemails themselves, FutureCoast opens up creative ways for people to think about possibly climate-changed futures and personal ways to talk about them. FutureCoast is a project of the PoLAR Partnership with a target audience of informal adult learners primarily reached via mobile devices and online platforms. Scientists increasingly use scenarios and storylines as ways to explore the implications of environmental change and societal choices. Stories help people make connections across experiences and disciplines and link large-scale events to personal consequences. By making the future seem real today, FutureCoast's framework helps people visualize and plan for future climate changes. The voicemails contributed to FutureCoast are spread through the game's intended timeframe (2020 through 2065). Based on initial content analysis of voicemail text, common themes include ecosystems and landscapes, weather, technology, societal issues, governance and policy. Other issues somewhat less frequently discussed include security, food, industry and business, health, energy, infrastructure, water, economy, and migration. Further voicemail analysis is examining: temporal dimensions (salient time frames, short vs. long term issues, intergenerational, etc.), content (adaptation vs. mitigation, challenges vs. opportunities, etc.), and emotion (hopeful, resigned, etc. and overall emotional context). FutureCoast also engaged audiences through facilitated in-person experiences, geocaching events, and social media (Tumblr, Twitter, Facebook, YouTube). Analysis of the project suggests story
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Zooplankton standing stock and composition in coastal waters of Goa, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Goswami, S.C.
Temporal and spatial variability in standing stock and zooplankton composition at 5 stations along the Goa Coast, India during 1975-76 were studied. Standing stock values ranged from 22.81 to 53.65 mg C.m/3. Zooplankton community was diverse...
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Rangewide Genetic Variation in Coast Redwood Populations at a Chloroplast Microsatellite Locus
Chris Brinegar
2012-01-01
Old growth and second growth populations of coast redwood (Sequoia sempervirens) were sampled at 10 locations throughout its range and analyzed at a highly variable chloroplast microsatellite locus. Very low FST values indicated that there was no significant genetic differentiation between adjacent old growth and second growth populations at each location. Genetic...
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Embling, Laura A K; Zagami, Debbie; Sriram, Krishna Bajee; Gordon, Robert J; Sivakumaran, Pathmanathan
2016-12-01
The categorisation of lung disease into obstructive ventilatory defect (OVD) and tendency to a restrictive ventilatory defect (TRVD) patterns using spirometry is used to guide both prognostication and treatment. The effectiveness of categorisation depends upon having reference ranges that accurately represent the population they describe. The Global Lung Initiative 2012 (GLI 2012) has spirometry reference ranges drawn from the largest sample size to date. This study aimed to determine whether using spirometry reference ranges from the new GLI 2012 dataset, compared to the previously used National Health and Nutritional Examination Survey III (NHANES III) dataset, resulted in a change in diagnosis between OVD, TRVD and normal ventilatory pattern (NVP). Spirometry data were collected from 301 patients, aged 18-80 years, undergoing investigation at the Gold Coast Hospital and Health Service (GCHHS) throughout February and March 2014. OVD was defined as a forced expiratory volume in 1 second (FEV 1 ) divided by forced vital capacity (FVC) less than lower limit of normal (LLN). TRVD was defined as FEV 1 /FVC ≥ LLN, FEV 1 reference range resulted in a change in diagnosis of lung disease in 5.9% of the individuals included in this study. This variance in diagnosis when changing reference ranges should be taken into account by clinicians as it may affect patient management.
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Ribeiro, Mónica; Taborda, Rui; Lira, Cristina; Bizarro, Aurora; Oliveira, Anabela
2014-05-01
Headland sediment bypassing plays a major role in definition of coastal sedimentary budget and consequently in coastal management. This process is particularity important at headland-bay beaches on rocky coasts. However, headland-bay beach research is usually focused on the beach rotation since these beaches are generally regarded as closed systems. The sediment bypassing mechanisms have been extensively studied in the context of artificial structures (e.g. groins and jetties) but studies of natural headland sediment bypassing are scarce and usually applied to decadal time scales. This work aims to contribute to the understanding of headland sediment bypassing processes in non-artificial environments, taking as a case study a natural coastal stretch at the Portuguese west coast. The study is supported on the analysis of planform beach changes using Landsat satellite images (with an acquisition frequency of 16 days) complemented with field surveys with DGPS-RTK and ground-based photographic monitoring. The study area can be described as a cliffed rocky coast that accommodates a series of headland-bay beaches with different geometries: some are encased in the dependence of fluvial streams, while others correspond to a narrow and elongated thin sand strip that covers a rocky shore platform. This coast is generally characterized by a weak, but active, sediment supply and high levels of wave energy due to the exposure to the swells generated in the North Atlantic. The long-term stability of the beaches in conjunction with active sediment supply along the study area (from streams and cliff erosion) and a sink at the downdrift end of this coastal stretch (an active dune system) support the existence of headland sediment bypassing. The analysis of planform beach changes show a coherent signal in time but with a range that depends on the orientation of the stretch where each beach is included. In general, beaches displays a clockwise rotation during summer related to the NW
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Yeasts from the sediment samples of the EEZ along the southwest coast of India
Digital Repository Service at National Institute of Oceanography (India)
Prabhakaran, N.; Gupta, R.
Fiftyeight yeast isolates were obtained from the benthic sediment samples of 19 stations during R.V. Gaveshani Cruise No. 187 of the Exclusive Economic Zone along the southwest coast of India. The depths ranged from 20 to 1,055 m. Asporogenous yeast...
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Influence of eastern Arabian Sea on summer monsoon rainfall over west coast of India
Digital Repository Service at National Institute of Oceanography (India)
RameshBabu, V.; Rao, M.S.; Rao, M.V.
and distant nature. In order to realise the model results and the influence of Arabian sea in the context of long range forecasting of monsoon rainfall, we have examined the correlation between the rainfall over west coast of India and premonsoon thermal...
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Tsunami impacts on morphology of beaches along south Kerala coast, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Rasheed, K.A.A.; Das, V.K.; Revichandran, C.; Vijayan, P.R.; Thottam, T.J.
TSUNAMI IMPACTS ON MORPHOLOGY OF BEACHES ALONG SOUTH KERALA COAST, WEST COAST OF INDIA K. A. Abdul Rasheed *, V. Kesava Das, C. Revichandran, P. R. Vijayan and Tony. J. Thottam National Institute of Oceanography (NIO), Regional Centre (RC... large waves of height 11 to 11.5m in Kutch region (Pendse 1945). Most of the tsunamis are generated by the earthquake-initiated seabed displacements. Landslides (including underwater landslides), volcanic eruptions, impact of large objects (such...
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National Oceanic and Atmospheric Administration, Department of Commerce — Aerial surveys are conducted along the US west coast to determine distribution and abundance of endangered leatherback turtles (Dermochelys coriacea), loggerhead...
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Directory of Open Access Journals (Sweden)
Eugenio E Veloso
2009-01-01
Full Text Available The repeated north and southward migration of the Chile Triple junction, offshore the Península de Taitao, is expected to have imposed contrasting stress fields in the forearc for the last 6 Ma because of changes in convergence direction and rate of subducting plates. NNW-SSE to E-W and minor NE-SW striking brittle faults developed in the plutonic units of the Mio-Pliocene Taitao Ophiolite, whereas NNE-SSW and minor NW-SE trending faults developed in its eastern border (Bahía Barrientes fault-zone. These brittle faults are studied to elucídate the style of ophiolite emplacement and the tectonic effects resulting from the alternated migration of the Chile Triple junction in the área. Analyses of heterogeneous fault-slip data on both áreas suggest that faults were activated by different stress fields. Two different compressional stress fields were identified in the plutomc units (A and B, whereas three different stress fields, ranging from compressional to strike-slip, were identified in the BahíaBarrientos fault-zone (C, D and E. Calculated directions of Oj axes for A, C, D and E solutions are mostly E-W trending, roughly similar to the convergence direction of subducting plates, whereas that for B solution is counterclockwise rotated ca. 60° with respect to the previous E-W trend. Brittle structures related to solution B were attributed to an early deformation of the ophiolite, most probably developed shortly after its emplacement {ca. 6 Ma. These structures were further counterclockwise rotated, while new structures (related to solution A developed in the plutomc units in order to absorb the continuous deformation. In the eastern margin of the ophiolite, the stress field divided inte compressional and strike-slip components. During periods of relatively strong compression (fast subduction of the Nazca píate, the fault-zone experienced well defined compressional and strike-slip movements (solutions C and D. In contrast, during periods of
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Xu, Yang; Liu, Chuan-Zhou; Chen, Yi; Guo, Shun; Wang, Jian-Gang; Sein, Kyaing
2017-07-01
Centimeter-size intrusions of gabbros and plagiogranites occur in mantle peridotites of the Myitkyina ophiolite, Myanmar. The gabbros mainly consist of plagioclase and clinopyroxene, whereas orthopyroxene occasionally occurs. The plagiogranites are mainly composed of plagioclase, quartz and amphibole, with small amount of accessory minerals, such as zircon, apatite and rutile. Plagioclase in the gabbros varies from andesine to anorthite (An37-91), whereas plagioclase in the plagiogranites is less calcic (An1-40). Clinopyroxene in the gabbros is pervasively altered to hornblende. The gabbros contain 42.97-52.88 wt% SiO2, which show negative correlations with Al2O3, CaO and MgO, but positive correlations with Na2O, P2O5 and TiO2. Microtextural relations reveal the crystallization of clinopyroxene prior to plagioclase in the Myitkyina gabbros. This suggests that the gabbros were crystallized from hydrous melts, which is also supported by the occurrence of orthopyroxene and anorthitic plagioclase in some gabbros. The gabbros have slightly enriched Sr-Nd isotopes, with initial 87Sr/86Sr ratios of 0.703938-0.706609 and εNd(t) values of + 2.4-+7.2, and relatively variable Hf isotopes, with εHf(t) values of + 13.4-+24.9. A subduction component is required to explain the decoupled Nd-Hf isotopes of the gabbros. Binary mixing suggests that addition of ca 2% subducted sediments to a depleted mantle can account for the Nd-Hf decoupling. Therefore, both petrological and geochemical data of the gabbros support that the Myitkyina ophiolite was originated in a supra-subduction zone setting. The plagiogranites have compositions of tonalites and trondhjemites, containing 56.93-77.93 wt% SiO2, 1.27-10.79 wt% Na2O and 0.05-0.71 wt% K2O. They are slightly enriched in LREE over HREE and display positive anomalies in Eu, Zr, Hf but negative Nb anomalies. Very low TiO2 contents (0.03-0.2 wt%) of the plagiogranites suggest that they were not products of fractional crystallization of MORB
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Active Microbial Sulfate Reduction in Serpentinization Fluids of the Semail Ophiolite in Oman
Glombitza, C.; Rempfert, K. R.; Templeton, A. S.; Hoehler, T. M.
2017-12-01
Dissimilatory sulfate reduction (SR) is among the oldest known microbial processes on Earth. It is the predominant anaerobic microbial process in sulfur-rich marine sediments but it also occurs in subsurface lithoautotrophic ecosystems, where it is driven by radiolytically produced H2 and sulfate [1]. Serpentinization is a process by which H2 is generated in a reaction of water with peridotite rock. This abiotic generation of H2 suggests its potential to power life in rocks as a stand-alone process, independent of the photosynthetic biosphere, because the generated H2 is a key energy source for microbial metabolism. This is of particular interest in understanding the role of water-rock reactions in generating habitable conditions on and beyond Earth. Sulfate is plausibly available in several of the water-bearing environments now known beyond Earth, making SR a potentially important metabolism in those systems. Sulfate minerals are abundant on the surface of Mars [2], suggesting that Martian groundwaters may be sulfate-rich. Sulfate is also postulated to be a component of the oceans of Europa and Enceladus [3, 4]. The inferred presence of both sulfate and peridotite rocks in these environments points toward a potential niche for sulfate reducers and highlights the need to understand how and where SR occurs in serpentinizing systems on Earth. We incubated formation fluids sampled from in the Semail Ophiolite in Oman with a 35-S labelled sulfate tracer and determined the rates of in-situ microbial sulfate reduction. The selected fluids represent different environmental conditions, in particular varying substrate concentrations (sulfate, H2 and CH4) and pH (pH 8.4 to pH 11.2). We found active microbial SR at very low rates in almost all fluids, ranging from 2 fmol mL-1 d-1 to 2 pmol mL-1 d-2. Lowest rates were associated with the hyperalkaline fluids (pH > 10), that had also the lowest sulfate concentration (50-90 µmol L-1). In line with previously determined species
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Polonium-210 in dried fin fishes of Tuticorin, Southeast coast of India
International Nuclear Information System (INIS)
Carol, R.; Wesley, S.G.
2013-01-01
Tuticorin is one of the major sea-ports and fish-landing centres in the southeastern coast of India. Most of the fishes landed in this coast are consumed fresh and 40% of the fishes are used in the dried form. 210 Po (t 1/2 = 138.4 days) in marine food has received much interest from the scientific community because of its high toxicity and the radioactive dose it delivers to marine organisms and human beings when compared to anthropogenic radionuclides released into coastal waters. Although many studies have been conducted in fresh fishes from various coasts concerning 210 Po, sufficient data are not available for value-added dried marine fish products. In the present study, 210 Po and 210 Pb were quantified in some commercially important dried fishes and their exposure to humans studied. Polonium-210 was determined after wet digestion and counted using an alpha probe. Overall, the concentration of 210 Po in the dried fish muscle tissue ranged from 1.45 ± 0.82 to 559.23 ± 5.45 Bq kg -1 . The highest concentration in the muscle tissue was recorded for the species Stolephorus brevisensis (559.23 ± 8.9 Bq kg -1 ) belonging to the group Clupeidae and the lowest in Harpodon sp. (Bombay duck). The 210 Po dose receive by the public due to consumption of the dried fishes was found to be in the range of 25.2-350.3 μSV yr -1 and the fish samples were found to be radiologically safe. (author)
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An overview of EPA’s oceans, coasts, estuaries and beaches programs and the regulatory (permits/rules) and non-regulatory approaches for managing their associated environmental issues, such as water pollution and climate change.
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Distribution of natural radionuclides and hot points in coasts of Hormozgan, Persian Gulf, Iran
International Nuclear Information System (INIS)
Abdi, M.R.; Mostajaboddavati, M.; Hasanzadeh, A.; Faghihian, H.; Kamali, M.
2006-01-01
A reconnaissance study has been made on the distribution of 238 U, 232 Th, 40 K, 137 Cs and geochemical features in soil and sediment samples at various locations in the coast of Persian Gulf. Activity concentration levels due to radionuclides were measured in 50 samples of soils and sediments collected from the coast of Hormozgan. From the measured spectra, activity concentrations were determined for 40 K (range from 140 to 1172 Bq x kg -1 ), 137 Cs (from 0 to 15 Bq x kg -1 ), 238 U (from 29 to 385 Bq x kg -1 ) and 2321 Th (from 9 to 156 Bq x kg -1 ) with the lowest limit of detection (LLD) of 68, 3.2, 4.3 and 4.3 Bq x kg -1 , respectively. The dose rate from ambient air at the soil ranges was between 23 to 177 nGy x h -1 with an average of 60±7.86 nGy x h -1 . (author)
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Moore, Diane E.; Lockner, David A.; Ponce, David A.
2010-01-01
Serpentinized ophiolitic rocks are juxtaposed against quartzofeldspathic rocks at depth across considerable portions of the Hayward and Calaveras Faults. The marked compositional contrast between these rock types may contribute to fault creep that has been observed along these faults. To investigate this possibility, we are conducting hydrothermal shearing experiments to look for changes in frictional properties resulting from the shear of ultramafic rock juxtaposed against quartzose rock units. In this paper we report the first results in this effort: shear of bare-rock surfaces of serpentinite and granite, and shear of antigorite-serpentinite gouge between forcing blocks of granitic rock. All experiments were conducted at 250°C. Serpentinite sheared against granite at 50 MPa pore-fluid pressure is weaker than either rock type separately, and the weakening is significantly more pronounced at lower shearing rates. In contrast, serpentinite gouge sheared dry between granite blocks is as strong as the bare granite surface. We propose that the weakening is the result of a solution-transfer process involving the dissolution of serpentine minerals at grain-to-grain contacts. Dissolution of serpentine is enhanced by modifications to pore-fluid chemistry caused by interaction of the fluid with the quartz-bearing rocks. The compositional differences between serpentinized ultramafic rocks of the Coast Range Ophiolite and quartzofeldspathic rock units such as those of the Franciscan Complex may provide the mechanism for aseismic slip (creep) in the shallow crust along the Hayward, Calaveras, and other creeping faults in central and northern California.
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National Oceanic and Atmospheric Administration, Department of Commerce — The imagery posted on this site is of the Texas and Louisiana Gulf Coast after Hurricane Rita made landfall. The regions photographed range from San Luis Pass, Texas...
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South Coast Air Quality Management District Truck Testing | Transportation
Research | NREL South Coast Air Quality Management District Truck Evaluation South Coast Air Quality Management District Truck Evaluation Photo of heavy-duty truck cab. Electric drayage truck Cargo Transportation project, conducted in partnership with the South Coast Air Quality Management
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Marine fishery possibilities of the west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Panikkar, N.K.
Marine fishery activity of the west coast of India is discussed. Sea fish production from the west coast of India makes three fourths of total fish production from Indian coasts. Kerala accounts for the largest production of fish in India...
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International Nuclear Information System (INIS)
Sivell, W.J.; McCulloch, M.T.
2000-01-01
Magmatic suites with contrasting isotopic and geochemical compositions, sequentially emplaced in different tectonic regimes, comprise the Dun Mountain Ophiolite Belt (DMOB), New Zealand. At D'Urville Island, the northernmost exposure of the DMOB, earliest erupted (stage 1) pillow basalts ε Nd (T) = +6.3 to +7.5, and are incompatible element enriched, like basalts from geochemically anomalous ridge segments. Overlying stage 2 basalts (sheeted flows) show a narrow range of ε Nd (T) = +8.3 + or -0.2, with chemical characteristics of depleted backarc basin basalts. These rocks are intruded by mafic to silicic stage 3 magmas, which have high uniform initial 143 Nd/ 144 Nd ratios (ε Nd (T) = +9.3 + or -0.2) over a wide range of 147 Sm/ 144 Nd values (yielding a precise Early Permian Nd-isotope age of 278 ± 4 Ma (MSWD = 0.48)). Stage 3 magmas show pronounced subduction-related geochemical signatures similar to island arc tholeiites (IAT) from immature arcs. They are closely analogous to some (boninite)-IAT magmas which characterise 'infant arc' eruptive activity in forearc basins of present-day Western Pacific island arc systems. A wide variety of stage 3 magma compositions, ranging from near-primary basaltic dikes (Mg = 74) to extremely fractionated silicic plagiogranites with uniformly very depleted isotopic ratios, is consistent with slow spreading rates which gave rise to polybaric, closed-system fractionation of magmas and periodic chamber abandonment. Some stage 3 rocks with SiO 2 levels in the andesite range have low-TiO 2 contents and high Mg, and may be fractionated equivalents of boninites. High ε Nd (T) values of stage 3 magmas indicate a lack of subducted sediment with inherited crustal residence signatures, and reflect the extent of supra-subduction zone (SSZ) mantle wedge depletion. DMOB stage 3 magmas may represent foreac magmatism that was the precursor to normal subduction-related volcanism established by c. 265 Ma in the Brook Street Arc and derived
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Perkins, T.; Wilson, M.
2005-01-01
Invasive plants can threaten diversity and ecosystem function. We examined the relationship between the invasive Phalaris arundinacea (reed canarygrass) and species richness in beaver wetlands in Oregon, USA. Four basins (drainages) were chosen and three sites each of beaver impoundments, unimpounded areas and areas upstream of debris jams were randomly chosen in each basin for further study (n = 36). Analysis of covariance (ANCOVA) showed that the relationship between Phalaris and species richness differed significantly (p = 0.01) by site type. Dam sites (beaver impoundments) exhibited a strong inverse relationship between Phalaris and species richness (bD = a??0.15), with one species lost for each 7% increase in Phalaris cover. In contrast, there was essentially no relationship between Phalaris cover and species richness in jam sites (debris jam impoundments formed by flooding; bJ = +0.01) and unimpounded sites (bU = a??0.03). The cycle of beaver impoundment and abandonment both disrupts the native community and provides an ideal environment for Phalaris, which once established tends to exclude development of herbaceous communities and limits species richness. Because beaver wetlands are a dominant wetland type in the Coast Range, Phalaris invasion presents a real threat to landscape heterogeneity and ecosystem function in the region.
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International Nuclear Information System (INIS)
Gao, Yongwen; Svec, Russell A.; Wallace, Farron R.
2013-01-01
Highlights: ► Otoliths of 120 canary rockfish were analyzed for δ 18 O and δ 13 C. ► δ 18 O and δ 13 C values of the otoliths ranged from −0.2‰ to +1.7‰ and −5.4‰ to −1.4‰. ► No separation was observed from the isotopic data and δ 18 O vs. δ 13 C correlation. ► No significant difference was computed between WA and OR samples especially in δ 13 C. ► Canary rockfish may belong to a single spawning stock or population coast-wide. - Abstract: Canary rockfish are one of the commercially important rockfish species along the US Pacific coast. Yet little is known about their life history and stock structure. In this study 120 canary rockfish otoliths were collected from waters off the Washington and Oregon coast and subjected to stable O and C isotope (δ 18 O and δ 13 C) analyses. One powder sample was taken from the nucleus of each otolith, and the other from the 5th annual ring. Data from otolith nuclei can provide information on the natal sources and spawning stock separations, while data from age-1 to age-5 may indicate changes in fish habitat. Overall the δ 18 O values in otoliths of canary rockfish ranged from −0.2‰ to +1.7‰, whereas δ 13 C values of the same samples ranged from −5.4‰ to −1.4‰. The isotopic data and correlation of δ 18 O versus δ 13 C did not show clear separation between Washington and Oregon samples, similar to those for a previous study on yelloweye rockfish from the same region. These results suggest that canary rockfish may belong to a single spawning stock or population along the Washington and Oregon coast
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Upwelling along the east coast of India
Digital Repository Service at National Institute of Oceanography (India)
Murty, C.S.; Varadachari, V.V.R.
the premonsoon and monsoon periods. Waters from deeper layers of the shelf appear to reach the surface causing considerable fall of surface temperature near the coast. The probable causes for these differences in upwelling along the coast are discussed...
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Quantification of tsunami hazard on Canada's Pacific Coast; implications for risk assessment
Evans, Stephen G.; Delaney, Keith B.
2015-04-01
including life-loss risk. Our analysis further indicates that in terms of life-loss risk, communities on Canada's Pacific Coast that are exposed to high tsunami hazard, experience the highest natural risk in Canada. Although sparsely populated, the (outer) coast of British Columbia has important critical infrastructure that includes port developments, shoreline facilities related to forest resource exploitation, a large number of First Nations Reserves, small municipal centres, towns, and villages, (some of which are ecotourism and sport fishing centres), and a limited number of industrial facilities. For selected areas on the west coast of Vancouver Island inundation maps have been prepared for a range of tsunami scenarios. We find that key facilities and critical infrastructure are exposed to the hazards associated with tsunami inundation.
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West Coast DA Event data - West Coast Toxic Pseudo-nitzschia bloom
National Oceanic and Atmospheric Administration, Department of Commerce — Beginning in the spring of 2015 the US West Coast began to experience the most wide-spread toxic Pseudo-nitzschia bloom to date, after approximately eight years...
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Natural History of Oregon Coast Mammals
Chris Maser; Bruce R. Mate; Jerry F. Franklin; C.T. Dyrness
1981-01-01
The book presents detailed information on the biology, habitats, and life histories of the 96 species of mammals of the Oregon coast. Soils, geology, and vegetation are described and related to wildlife habitats for the 65 terrestrial and 31 marine species. The book is not simply an identification guide to the Oregon coast mammals but is a dynamic portrayal of their...
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Kiseleva, Olga; Zhmodik, Sergei
2015-04-01
New study of PGE in restitic ultrabasic (Kharanur and Ospin-Kitoi) massifs from North and South branches (Dobretsov et al., 1985) of the ophiolite complexes in south-eastern part of the Eastern Sayan show their presence in chromitites of both branches belonging to the different geodynamic settings. Modern concepts model includes several mechanisms of podiform chromitite origin reflected in the chemistry of Cr-spinels (Arai, Yurimoto, 1994; Ballhaus, 1998; Uysal et al., 2009 et al.): 1) partial melting of upper mantle rocks, 2) mixing of primitive melts with melts enriched in SiO2, 3) melt-rock interaction. We estimated the types of interaction of mafic melts with mantle peridotites, with the formation of chromite bodies. For ore chrome spinelides from northern branch (Al2O3) melt = 8 - 14 wt%, (TiO2) melt = 0 - 0,4 wt%, (Fe/Mg) melt = 0,5 - 2,4; Southern branch (Al2O3) melt = 10 - 13 wt%, (TiO2) melt = 0,1 wt%, (Fe/Mg) melt = 0,3 - 1 (Kiseleva, 2014). There are two types of PGE distribution Os-Ir-Ru (I) and Pt-Pd (II). Type I chromitites (mid-Al#Cr-spinels) revealed only Os-Ir-Ru distributions; type II (low-Al#Cr spinelides) show both Os-Ir-Ru and (Pt-Pd) distributions (Kiseleva et al., 2012, 2014). PGE distribution in ultramafic peridotites and chromitites reflects PGE fractionation during partial melting (Barnes et al., 1985; Rehkämper et al., 1997). Processes bringing to extreme fractionation of PGE, may be associated with fluid-saturated supra subduction environment where melting degree near 20% and above is sufficient for the release of PGE from the mantle source (Dick, Bullen, 1984; Naldrett, 2010). Enrichment in PPGE together with a high content of IPGE in same chromite bodies is attributed to the second step of melting, and formation of S-enriched and saturated in PGE melts (Hamlyn, Keays, 1986; Prichard et al., 1996). For type I chromitites platinum group minerals (PGM) are presented by Os-Ir-Ru system. In type II chromitites PGM are represented by Os
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Beach rocks of the central west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Wagle, B.G.
rocks of the central west coast of India. Vol. 10, No.2, 1990 bonate and Miliolite Problems of Gujarat, PRL Ahmedabad:41 42 Kale VS, RajagllIU SN (1985) Neogene and Quaternary transgres sional and regressional history of the west coast of India... (1990) 10: 111-115 Geo-Marine Letters ~1990 Springtr-Vtrlng Ntw Yolldnc. Beach Rocks of the Central West Coast of India B. G. Wagle National Institute of Oceanography, Dona Paula, Goa, India, 403004 Abstract Along the central west coast of India several...
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Studies on sediment transport along Kerala Coast, south west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Sajeev, R.; Chandramohan, P.; Josanto, V.; Sanakaranarayanan, V.N.
Longshore sediment transport characteristics of the Kerala Coast have been examined to delineate various physical processes affecting the different coastal environments. Monthly averages of the daily LEO (Littoral Environmental Observation) data...
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Subtidal benthic macrofauna of the Mangalore Coast, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Gopalakrishnan, T.C.; Nair, K.K.C.
Subtidal macrobenthic fauna from the Mangalore Coast was studied from the shelf areas between the old Mangalore Port and Suratkal, covering an area of approximately 40 km sup(2). Benthic bivalves were the most abundant group, (36160/m sup(2...
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Marine archaeological investigations along the Saurashtra coast, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Gaur, A.S.; Sundaresh; Tripati, S.
Utilization of the ocean resources on the Saurashtra coast is dating back to the Harappan period (3rd millennium BC) and evidences on the same have been recorded from various archaeological sites such as Lothal, Padri, Nageshwar and Bet Dwarka...
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Bavestrello, Giorgio; Bo, Marzia; Betti, Federico; Canessa, Martina; Gaggero, Laura; Rindi, Fabio; Cattaneo-Vietti, Riccardo
2018-01-01
On marine rocky shores, several physical, chemical and biological processes operate to maintain the benthic assemblages' heterogeneity, but among the abiotic factors, the composition and texture of the rocky substrata have been only sporadically considered. However, biomineralogical studies have demonstrated an unsuspected ability of the benthic organisms to interact at different levels with rocky substrata. Therefore, the mineralogy of the substratum can affect the structure of benthic communities. To evaluate this hypothesis, the macrobenthic assemblages developed on two different ophiolitic rocks (serpentinites and metagabbros) in contact at a restricted stretch of the western Ligurian Riviera (western Mediterranean Sea), with identical environmental and climatic conditions, were analysed. Samplings were carried out at four bathymetric levels (+1m, 0m, -1m, and -3m respect to the mean sea level) and the analysis of the data evidenced differences in terms of species distribution and percent coverage. Algal communities growing on metagabbros were poorer in species richness and showed a much simpler structure when compared to the assemblages occurring on the serpentinites. The most widely distributed animal organism, the barnacle Chthamalus stellatus, was dominant on serpentinites, and virtually absent on metagabbros. Our results suggest a complex pattern of interactions between lithology and benthic organisms operating through processes of inhibition/facilitation related to the mineral properties of the substratum.
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Southern right whales Eubalaena australis visit the coasts of ...
African Journals Online (AJOL)
spamer
Counts and photographs of right whales Eubalaena australis taken on aerial surveys of the southern coast of. South Africa between ... of 0.08–2.89 km.h-1. Theodolite tracking of undisturbed groups of right whales from Cape Columbine produced ...... right whales on the coast of Argentina (Outer Coast) between 1971 and ...
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Hydrodynamic modeling along the southern tip of India: A special emphasis on Kanyakumari coast
Directory of Open Access Journals (Sweden)
K. Gurumoorthi
2017-12-01
Full Text Available Hydrodynamic models are important to many coastal engineering designs and application, especially addressing sediment and water quality. In this study, MIKE 21 two-dimensional (2D hydrodynamic model based on the flexible mesh (FM technique was used to simulate the surface currents forced by tides and winds in Kanyakumari coast. The model results of the tidal level along shore and cross shore currents are agreed well with measured data in Kanyakumari coast. The major components of tides and currents are analyzed by harmonic analysis methods. Root mean square error (RMSE values for the measured and model tides (0.017 m and 0.079 m and currents (0.025 m/s and 0.009 m/s during the northeast (NE and southwest (SW monsoon period are calculated. A series of scenario runs for NE and SW monsoon season are used to understand the regional circulation. The model result shows that the Kanyakumari coast is dominated by tides and surface currents flow, which are influenced by the seasonal reversal wind pattern. Flows around this coastal water have been evidenced small scale cyclonic and anti-cyclonic eddies ranged from ∼55 to 120 km in diameter. The cyclonic and anti-cyclonic eddies are mostly appeared in near Kanyakumari and SE coast of Kerala due to local/ remotely generated forces.
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Radionuclide accumulation in green and brown macroalgae at the Bulgarian Black Sea coast
International Nuclear Information System (INIS)
Strezov, A.; Nonova, T.
2005-01-01
The concentration of technogenic and natural radionuclides were measured in brown and green macroalgae from the Bulgarian Black Sea coast for the period 1996 and 2003 using low-level gamma spectroscopy. Mean values and concentration range for the studied species enables the comparison of the nuclide content in macroalgae showing that brown algae accumulate the studied radionuclides to a higher extent. (author)
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Estimation of 226Ra and U(Nat) in sediment off Mumbai coast
International Nuclear Information System (INIS)
Sugandhi, S.; Ravi, P.M.; Wankhede, Sonal
2012-01-01
Bottom sediment in a marine system is formed from organic and inorganic particles which settle from water of aquatic media. The sediment compartment is the receptor of radionuclides and it indicates the impact of pollution. Radioactive materials like Ra and U are normal constituents of earths crust. The present study was done to estimate 226 Ra and U(Nat) from various locations in sediment off Mumbai coast. The levels of 226 Ra in sediments of Mumbai coast has been observed to be between 3.8 to 26.0 Bq/kg with a mean averaged value of 13.3 Bq/kg which is similar to the sediment at Bay of Bengal (13.9 to 25.9 Bq/kg), Indian Ocean (13.8 Bq/kg), Arabian Sea (16.9 to 31.7 Bq/kg), Egyptian Red sea coast (27.4 Bq/kg). Uranium content in sediment was found to be in the range of 16.3 to 56.3 Bq/kg with an averaged mean of 32.2 Bq/kg. It is observed that, uranium concentration is higher than radium concentration in sediment. This may be attributed to the relatively higher mobility of radium as compared to uranium in an aquatic environment
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National Oceanic and Atmospheric Administration, Department of Commerce — The imagery posted on this site is of the Gulf Coast of Louisiana, Mississippi and Alabama after Hurricane Katrina made landfall. The regions photographed range from...
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Near-coast tsunami waveguiding: phenomenon and simulations
van Groesen, Embrecht W.C.; Adytia, D.; Adytia, D.; Andonowati, A.
2008-01-01
In this paper we show that shallow, elongated parts in a sloping bottom toward the coast will act as a waveguide and lead to large enhanced wave amplification for tsunami waves. Since this is even the case for narrow shallow regions, near-coast tsunami waveguiding may contribute to an explanation
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Directory of Open Access Journals (Sweden)
Kevin L. O’Hara
2017-04-01
Full Text Available Coast redwood (Sequoia sempervirens (Lamb. ex. D. Don Endl. is unique among conifer species because of its longevity, the great sizes of individual trees, and its propensity to reproduce through sprouts. Timber harvesting in the native redwood range along the coast of the western United States has necessitated restoration aimed to promote old forest structures to increase the total amount of old forest, the connectivity between old forests, and to enhance the resiliency of these ecosystems. After disturbance or harvest, healthy redwood stumps sprout vigorously, often producing dozens of sprouts within two years of disturbance. These sprouts form highly aggregated spatial patterns because they are clustered around stumps that may number less than 50 ha−1. Thinning of sprouts can accelerate individual tree growth, providing an effective restoration strategy to accelerate formation of large trees and old forest structures or increase stand growth for timber production. However, management, including restoration activities, is a contentious issue throughout the native range of redwood because of the history of overexploitation of this resource and perceptions that overexploitation is continuing. This paper reviews the science of early stand dynamics in coast redwood and their implications for restoration and other silvicultural strategies.
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Resolving orographic rainfall on the Indian west coast
Digital Repository Service at National Institute of Oceanography (India)
Suprit, K.; Shankar, D.
We discuss a method to obtain the spatial estimates of rainfall on the Indian west coast for calculating the surface water budget. The region includes the basin of the Mandovi River, a typical west-coast river whose catchment area includes...
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Directory of Open Access Journals (Sweden)
Elisha Mrabu Jenoh
Full Text Available Insect infestation of mangroves currently threatens mangrove forest health and management. In the Western Indian Ocean region, little is known about insect damage to mangroves despite the fact that numerous infestations have occurred. In Kenya, infestations of Sonneratia alba have persisted for almost two decades, yet the taxonomic identity of the infesting pest(s, the extent of infestation, the pests' biology, the impacts of infestation on host and the ecosystem, the host's defensive strategies to the infestation are poorly understood. S. alba is a ubiquitous, pioneer mangrove species of the Indo-Pacific, occurring along the waterfront in a variety of mangrove ecosystem settings. Our main objectives were to identify the pest(s responsible for the current dieback of S. alba in Kenya, and to determine the extent of infestation. To identify the pests responsible for infestation, we trapped emergent insects and reared larvae in the laboratory. To determine the overall extent of infestation within the S. alba zone, we assessed nine sites along the entire Kenyan coastline for the presence or absence of infested mangroves. Insect infestation in two mangrove embayments (Gazi and Mida was quantified in depth. Two wood-boring insects were identified: a metarbelid moth (Lepidoptera, Cossoidea of undescribed genus and the beetle Bottegia rubra (Cerambycidae, Lamiinae.The metarbelid moth infests mangroves in both northern (from Ngomeni to Kiunga and southern regions (from Vanga to Mtwapa of the Kenyan coast. B. rubra appeared in low density in Gazi, and in high density in Mida, Kilifi, and Ngomeni, with densities gradually decreasing northward. Insect infestation levels reached 18% in Gazi and 25% of S. alba stands in Mida. Our results indicate that B. rubra has the ability to infest young mangrove trees and expand its range, posing a danger to rehabilitation efforts where plantations have been established. Thus, there is great need for forest managers to
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From the African Coast, the invention of two territories: Equatorial Guinea and Ivory Coast
Directory of Open Access Journals (Sweden)
Adjoa Nathalie Chiyé Kessé
2014-08-01
Full Text Available From the African coast starts Latin American history and part of Europe’s. This article includes a comprehensive analysis on the cultural influence of Africa especially Equatorial Guinea and Côte d’Ivoire in Latin America. From the first European incursions into African coast (xvi century and throughout the colonial era, the paper highlights interethnic relations that occurred following the meeting and coexistence between cultures of both continents, an analysis that is essential to study the survival of traditions, beliefs and African customs that survive today in many regions of Latin America. Considering the importance now given to the recovery of identity traits of the past for studies of multi-ethnicity and re-construction of identities, this article can be used by researchers at Afro-descendance, notable in Latin America, whose research is related to African identity traits in their respective nations. Equatorial Guinea was a Spanish colony along with the Protectorate of Morocco and Western Sahara. The duration of this colony ran from 1885 to 1968. In 1926, it became the Spanish Guinea, and in 1968 it acquired its independance from Spain while retaining the Spanish cultural architecture. Furthermore, the French presence in this first stage of the conquest in Côte d’Ivoire, is provided by the army. The colonial authorities in Paris were not yet sufficiently organized to move their representatives to what was then known as the Poor or Bad People Coast or Coast of teeth. It was the military from Senegal, as base of the French colonial army who assumed the conquest and organization of the Ivorian territory for immediate exploitation of economic resources. It is this improvised framework without legal planning, which led to the idea of the invention of Africa supported by Valentin Mudimbe (1988 and Achille Mbembe (2000.
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Pollution Levels in Fog at the Chilean Coast
Sträter, E.; Klemm, O.; Westbeld, A.
2010-07-01
During July and August 2008 fog water was collected for chemical analysis in Patache, at the coast of northern Chile, 60 km south of Iquique (20°49’S, 70°09’W). Advective fog events occur regularly at the cliff in the coastal range at about 800 m above MSL. People collect these types of fog water at some places along the coast with Large Fog Collectors (LFC) for domestic use and for watering field crops. So far, no chemical analysis of fog water was performed in Patache. Pure fogwater samples (38 samples from 8 fog events) were taken by using a passive Scientific Cylindrical Fog Collector. Major ions and trace metals were quantified. The analyses indicate very high ionic concentrations (mean 3500 µeq/l) and very low pH values (mean 3.3). The mean H+-concentration represents 16 % of the total ionic equivalent concentration. Sulfate is the anion exhibiting the highest concentrations. A mean value of 880 µeq/l was found, which accounts for 24 % of the total mean concentration. In contrast to sulfate, nitrate shows only a low percentage of 8.1 %. Further major ions are sodium (20%) and chloride (19 %), which are typical seasalt ions in coastal fog. High correlations between the measured ions suggest a causal link between concentration in the fog samples and the liquid water content (LWC) of the cloud. The higher the liquid water content the lower are the ionic concentrations. Enrichment factors with sodium as reference ion were calculated to identify potential emission sources contributing to the observed pollutant levels. We found that K+, Na+, Mg2+ and Cl- mainly result from seaspray. Sulfate, however, is enriched by a factor of 13. The measured trace elements are highly enriched by factors up to hundreds of thousands (Zn: 50, Ni: 1800, As: 2400, Cd: 3900, Fe: 100000, Cu: 96000, Pb: 250000). A cluster analysis supports the conclusion that sulfate and the trace elements originate from anthropogenic activities. The sulfate cannot primarily originate from
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Page, N.J.; Pallister, J.S.; Brown, M.A.; Smewing, J.D.; Haffty, J.
1982-01-01
30 samples of chromitite and chromite-rich rocks from two stratigraphic sections, 250 km apart, through the basal ultramafic member of the Samail ophiolite were spectrographically analysed for platinum-group elements (PGE) and for Co, Cu, Ni and V. These data are reported as are Cr/(Cr + Al), Mg/(Mg + Fe) and wt.% TiO2 for most samples. The chromitite occurs as pods or lenses in rocks of mantle origin or as discontinuous layers at the base of the overlying cumulus sequence. PGE abundances in both sections are similar, with average contents in chromite-rich rocks: Pd 8 ppb, Pt 14 ppb, Rh 6 ppb, Ir 48 ppb and Ru 135 ppb. The PGE data, combined with major-element and petrographic data on the chromitite, suggest: 1) relatively larger Ir and Ru contents and highest total PGE in the middle part of each section; 2) PGE concentrations and ratios do not correlate with coexisting silicate and chromite abundances or chromite compositions; 3) Pd/PGE, on average, increases upward in each section; 4) Samail PGE concentrations, particularly Rh, Pt and Pd, are lower than the average values for chromite-rich rocks in stratiform intrusions. 2) suggests that PGEs occur in discrete alloy or sulphide phases rather than in the major oxides or silicates, and 4) suggests that chromite-rich rocks from the oceanic upper mantle are depleted in PGE with respect to chondrites. L.C.C.
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Directory of Open Access Journals (Sweden)
Esteban A. Agudo
2014-09-01
Full Text Available The recent invasion of lionfish (Pterois volitans in the Atlantic is considered a new threat to benthic and fish communities in the Caribbean region. This species was first reported in Venezuela in 2009 at various sites. Increasing reports in the past five years suggest lionfish has expanded its range of distribution and habitats. Nevertheless, this information is mostly anecdotal and extensive surveys aimed to determine its abundance, size structure and other ecological aspects encompassing wider spatial scales are necessary to understand the actual role of this species on sub-tidal marine communities in Venezuela. We determined its density and population size structure through visual census along the Venezuelan coast. Visual censuses were made following strip transects at a depth between 5 and 20m and in daylight time, at 19 sites in five localities. Average density ranged between 7 to 55 individuals per hectare among sites. Most individuals were adults and most were found in caves, coexisting with other lionfish or with different species, while others were actively preying. The fish Pterois volitans seems to be well-established along the Venezuelan coast in densities that in some sites appear to be higher than in their Pacific native range but lower than in some invaded localities of the Atlantic.
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[Nursing perspective on psychiatric care in Ivory Coast].
Lecocq, Dan
2017-05-01
Michaël Bilson is a nurse at the psychiatric hospital of Bingerville, in Ivory Coast. Here, he describes his mission supporting the National Health Worker Training Institute. It is the only nurse training school in Ivory Coast. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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33 CFR 125.11 - Form of Coast Guard Port Security Card.
2010-07-01
... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Form of Coast Guard Port Security... WATERFRONT FACILITIES OR VESSELS § 125.11 Form of Coast Guard Port Security Card. The Coast Guard Port... data. ...
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Virginia Coast Reserve 2007 Remote Sensing Experiment
2012-03-09
beaches, maritime forests , wetlands, tidal flats, and coastal lagoons ; - Natural lands and built up areas along Cape Charles, VA are...representative of barrier island coasts , worldwide; and - It is a major natural resource for the Mid Atlantic Region. Imagery-derived information for...support Joint Logistics Over the Shore. This experiment uses the VCR to study a barrier island coast with coastal lagoons , tidal inlets, and
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Seawater Circulation and Thermal Sink at OCEAN Ridges - FIELD Evidence in Oman Ophiolite
Nicolas, A. A.; Boudier, F. I.; Cathles, L. M.; Buck, W. R.; Celerier, B. P.
2014-12-01
Exceptionally, the lowermost gabbros in the Oman ophiolite are black and totally fresh, except for minute traces of impregnation by seawater fluids at very high temperature (~1000°C). These black gabbros sharply contrast with normal, whitish gabbros altered down to Low-T~500-350°C. These hydrous alterations are ascribed to an unconventional model of seawater circulation and cooling of the permanent magma chambers of fast spreading ocean ridges. In this model, gabbros issued from the magma chamber cross a ~100 m thick thermal boundary layer (TBL) before reaching a narrow, Low-T high permeability channel where the heated return seawater is flowing towards black smokers and the local gabbros are altered. Uprising mantle diapirs in Oman diverge at ~5 km on each side of the palaeo-ridge axis and feed an overlying magma chamber that closes at this distance from axis. Preservation of black gabbros along the Moho implies that the loop of seawater alteration locally does not reach Moho beyond this ~5km distance (otherwise black gabbros would be altered in whitish gabbros). This defines an internal "thermal sink" within ~5 km to the ridge axis. There, the sink is efficiently cooled by the active hydrothermal convection that is ridge transverse. This has been documented near the Galapagos ridge by marine geophysical data, within the same distance. Beyond this critical distance, the cooling system becomes dominantly conductive and ridge-parallel. The TBL and attached return flow channels must be rising into the overcooled, accreted crust. Beyond the thermal sink, the 500°C isotherm rebounds into the crust. It is only after ~ 1My of crustal drift that this isotherm penetrates into the uppermost mantle in a sustained fashion, developing serpentinites at the expense of peridotites.
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75 FR 59686 - Proposed Information Collection; Comment Request; Coast Pilot Report
2010-09-28
... Collection; Comment Request; Coast Pilot Report AGENCY: National Oceanic and Atmospheric Administration (NOAA.... 165, or coast.pilot@noaa.gov . SUPPLEMENTARY INFORMATION: I. Abstract NOAA publishes the United States (U.S.) Coast Pilot, a series of nine books which supplement the suite of nautical charts published by...
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Benthic fauna of southwest and southeast coasts of India
Digital Repository Service at National Institute of Oceanography (India)
Devi, K.S.; Sheba, P.; Balasubramanian; Venugopal, P.; Sankaranarayanan, V.N.
Benthos, sediments characteristics and organic matter content were studied along southwest and southeast coasts of India. Number of groups/species varied with the stations and also with the depths. Population density was very low in southeast coast...
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75 FR 53667 - Space Coast Regional Innovation Cluster Competition
2010-09-01
... Coast Regional Innovation Cluster Competition AGENCY: Economic Development Administration (EDA... upcoming availability of funding for the Space Coast Regional Innovation Cluster (RIC) Competition under... economic development initiatives aligned with regional cluster and competitiveness analyses to sustain the...
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Rock coasts and seabird breeding sites : a common optimization
Marie, Eveillard-Buchoux
2014-05-01
The North-West coasts of Europe support a lot of part of Northern hemisphere breeding seabirds. In that context, Scotland has a preponderant place and Brittany has southernmost limit of these species areas, for most of them. Outside the breeding season these species live mainly on the open sea and when they do visit the land to breed, they nest on a specific sites : almost all the time they breed on the rock coasts, often on seacliffs. This specific habitat are defines by geomorphological characteristics which offer special forms of the coast. The forms of rock coasts are originally and different because of several proprieties of geology, of lithology, of structures. Breeding seabird, occupying these sites, reveals, in a new light, the richness of these forms and the originals geographic location of the coastline : seabirds prefer nest in exposed coastline like rock caps, rocky points or islands. Seabirds and rock coasts are research topics in environmental geography since several years. However, these combination studies is a new approach in this field and enlargement in the heritage field allows supplement scientific approach. For example, it show that in most important touristic sites, environmental protection measures focused on landscape, habitat or bird, but much more rarely on rock coasts for these intrinsic values. Indeed, in Brittany or in Scotland, seabirds are often stars species in lot of coastal nature reserves, where they're considered like greater ecological heritage. We could see it in touristic promotion field : bird is everywhere, cliff is mostly kept in the dark, as well in leaflets as in speech visitor's guides - without, for example, as a part of this landscape. In all cases, combination of these two heritages is extremely rare. Yet, this current research illustrates the interest and the issue of development of this comparative approach seabirds / rock coasts for optimization of nature tourism and geotourism.
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Heavy mineral occurrence off Hazira, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Vora, K.H.; Mislankar, P.G.; Gujar, A.R.
The occurrence of heavy mineral placers on the west coast of India are well known from Konkan and Malabar Coast. However, a geological and geophysical investigation (including echosounding and side scan sonar profiles and 7 samples) off Hazira...
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Connectivity for underway Coast Guard patrol boats
Busch, Gregory C.
1997-01-01
Approved for public release; distribution is unlimited This thesis examines the US Coast Guard patrol boat's ability to effectively exchange operational data while underway. The patrol boat is currently unable to obtain tactical law enforcement information from the central Law Enforcement Information System 2 (LEIS 2) database while on patrol. LEIS 2 provides access to law enforcement information from Coast Guard, FBI, and state and local law enforcement agencies. Availability of this info...
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Teagle, D. A. H.; Harris, M.; Crispini, L.; Deans, J. R.; Cooper, M. J.; Kelemen, P. B.; Alt, J.; Banerjee, N.; Shanks, W. C., III
2017-12-01
Anhydrite is important in mid-ocean ridge hydrothermal systems because of the high concentrations of calcium and sulfate in modern seawater and anhydrite's retrograde solubility. Because anhydrite hosts many powerful tracers of fluid-rock interactions (87Sr/86Sr, δ18O, δ34S, trace elements, fluid inclusions) it is useful for tracing the chemical evolution of hydrothermal recharge fluids and estimating time-integrated fluid fluxes. Anhydrite can form from heated seawater (>100°C), through water-rock reaction, or by mixing of seawater and hydrothermal fluids. Although abundant in active hydrothermal mounds, and predicted to form from downwelling, warming fluids during convection, anhydrite is rare in drill core from seafloor lavas, sheeted dikes and upper gabbros, with only minor amounts in ODP Holes 504B and 1256D. Because anhydrite can dissolve during weathering, its occurrence in ophiolites is unexpected. Instead, gypsum is present in Macquarie Island lavas and Miocene gypsum fills cavities within the Cretaceous Troodos ore deposits. Thus, the occurrence of numerous anhydrite veins in cores from the gabbroic lower crust of the Samail ophiolite in Oman was unanticipated. To our knowledge, anhydrite in Oman gabbros has not been previously reported. Oman Drilling Project Holes GT1A and GT2A were drilled into the Wadi Gideah section of the Wadi Tayin massif. Both recovered 400 m of continuous core from sections of layered gabbros (GT1) and the foliated-layered gabbro transition (GT2). Anhydrite is present throughout both holes, some in vein networks but more commonly as isolated 1-110 mm veins (>60 mm ave). Anhydrite is mostly the sole vein filling but can occur with greenschist minerals such as epidote, quartz, chlorite and prehnite. Anhydrite commonly exhibits prismatic and bladed textures but can also be capriciously microcrystalline. Though definitive cross cutting relationships are elusive, anhydrite veins cut across some greenschist veins. Anhydrite is
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National Oceanic and Atmospheric Administration, Department of Commerce — CoastWatch is a nationwide National Oceanic and Atmospheric Administration (NOAA) program within which the Great Lakes Environmental Research Laboratory (GLERL)...
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Marine Hydrokinetic Resource Assessment for Domestic Army, Air Force, and Coast Guard Facilities
Energy Technology Data Exchange (ETDEWEB)
Robichaud, Robi J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ingram, Michael [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2018-04-24
NREL/DOE undertook a study for the US Army, Coast Guard and Air Force to investigate the potential for marine hydrokinetic (MHK) devices to meet the energy load at coastal bases in the future as MHK technology evolves. A wide range of data from tidal and wave, environmental, shipping, etc. databases were used to screen the DOD bases. A series of scoring algorithms were developed to facilitate site review to lead to eventual down select for more detailed, site specific bathymetric tidal resource evaluation. The Army's Camp Edwards, MA and the Coast Guard's Training Center Cape May, NJ (TRACEN Cape May) were selected and the Georgia Institute of Technology performed the analyses. An NREL/DOE MHK team visited the bases to further discuss with the base personnel MHK technology's potential for providing power to the bases in the future and frame the potential impact to existing power systems.
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Grobe, Arne; Virgo, Simon; von Hagke, Christoph; Ralf, Littke; Urai, Janos L.
2017-04-01
Ophiolite obduction is an integral part of mountain building in many orogens. However, because the obduction stage is usually overprinted by later tectonic events, obduction geodynamics and its influence on orogenesis are often elusive. The best-preserved ophiolite on Earth is the Semail Ophiolite, Oman Mountains. 350 km of ophiolite and the entire overthrusted margin sequence are exposed perpendicular to the direction of obduction along the northeastern coast of the Sultanate of Oman. Despite excellent exposure, it has been debated whether early stages of obduction included formation of a micro-plate, or if the Oman Mountains result from collision of two macro-plates (e.g. Breton et al., 2004). Furthermore, different tectonic models for the Oman Mountains exist, and it is unclear how structural and tectonic phases relate to geodynamic context. Here we present a multidisciplinary approach to constrain orogenesis of the Oman Mountains. To this end, we first restore the structural evolution of the carbonate platform in the footwall of the Semail ophiolite. Relative ages of nine structural generations can be distinguished, based on more than 1,500 vein and fault overprintings. Top-to-S overthrusting of the Semail ophiolite is witnessed by three different generations of bedding confined veins in an anticlockwise rotating stress field. Rapid burial induced the formation of overpressure cells, and generation and migration of hydrocarbons (Fink et al., 2015; Grobe et al., 2016). Subsequent tectonic thinning of the ophiolite took place above a top-to-NNE crustal scale, ductile shear zone, deforming existing veins and forming a cleavage in clay-rich layers. Ongoing extension formed normal- to oblique-slip faults and horst-graben structures. This was followed by NE-SW oriented ductile shortening, the formation of the Jebel Akhdar anticline, potentially controlled by the positions of the horst-graben structures. Exhumation in the Cenozoic was associated with low angle normal
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Biological Potential in Serpentinizing Systems
Hoehler, Tori M.
2016-01-01
Generation of the microbial substrate hydrogen during serpentinization, the aqueous alteration of ultramafic rocks, has focused interest on the potential of serpentinizing systems to support biological communities or even the origin of life. However the process also generates considerable alkalinity, a challenge to life, and both pH and hydrogen concentrations vary widely across natural systems as a result of different host rock and fluid composition and differing physical and hydrogeologic conditions. Biological potential is expected to vary in concert. We examined the impact of such variability on the bioenergetics of an example metabolism, methanogenesis, using a cell-scale reactive transport model to compare rates of metabolic energy generation as a function of physicochemical environment. Potential rates vary over more than 5 orders of magnitude, including bioenergetically non-viable conditions, across the range of naturally occurring conditions. In parallel, we assayed rates of hydrogen metabolism in wells associated with the actively serpentinizing Coast Range Ophiolite, which includes conditions more alkaline and considerably less reducing than is typical of serpentinizing systems. Hydrogen metabolism is observed at pH approaching 12 but, consistent with the model predictions, biological methanogenesis is not observed.
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7 CFR 319.8-12 - From the West Coast of Mexico.
2010-01-01
... 7 Agriculture 5 2010-01-01 2010-01-01 false From the West Coast of Mexico. 319.8-12 Section 319.8... Conditions for the Entry of Cotton and Covers from Mexico § 319.8-12 From the West Coast of Mexico. Contingent upon continued freedom of the West Coast of Mexico and of Northwest Mexico from infestations of...
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US Coast Guard Stations in Louisiana, Geographic NAD83, USCG [coast_guard_stations_USCG_1997
Louisiana Geographic Information Center — This is is a point dataset for the locations and attributes of eight US Coast Guard stations in Louisiana. The attributes include name, address, latitude (NAD27),...
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West Coast Regional Office Permits
National Oceanic and Atmospheric Administration, Department of Commerce — NOAA Fisheries implemented a license limitation program for the trawl and fixed gear sectors of Pacific Coast commercial groundfish fishery on January 1, 1993. The...
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Polybrominated diphenyl ethers in pinnipeds stranded along the southern California coast
Energy Technology Data Exchange (ETDEWEB)
Meng Xiangzhou [Southern California Coastal Water Research Project, 3535 Harbor Blvd, Suite 110, Costa Mesa, CA 92626 (United States); Blasius, Mary Ellen; Gossett, Richard W. [Institute for Integrated Research in Materials, Environments and Society (IIRMES), California State University, Long Beach, 1250 Bellflower Blvd, Long Beach, CA 90840 (United States); Maruya, Keith A., E-mail: keithm@sccwrp.or [Southern California Coastal Water Research Project, 3535 Harbor Blvd, Suite 110, Costa Mesa, CA 92626 (United States)
2009-10-15
Little to no information exists for polybrominated diphenyl ethers (PBDEs) in marine mammals frequenting the highly urbanized southern California (USA) coast. Fourteen PBDE congeners were determined by GC-ECNI-MS in blubber of pinnipeds stranded locally between 1994 and 2006. Total PBDE concentrations (SIGMAPBDE) in California sea lion (n = 63) ranged from 0.04 to 33.7 mug/g wet weight (mean: 5.24 mug/g). To our knowledge, these are the highest reported PBDE levels in marine mammals to date. By comparison, mean SIGMAPBDE in Pacific harbor seals (n = 9) and northern elephant seals (n = 16) were 0.96 and 0.09 mug/g, respectively. PBDEs in adult males were higher than for adult females, however, no age class differences or temporal trends were observed. As the first PBDE data reported for marine mammals in this region, the elevated levels underscore the need for additional studies on the sources, temporal trends, and potential effects of PBDEs in highly urbanized coastal zones. - Levels of PBDEs in pinnipeds found stranded along the southern California coast (USA) between 1994 and 2006 are the highest reported to date for marine mammals.
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Polybrominated diphenyl ethers in pinnipeds stranded along the southern California coast
International Nuclear Information System (INIS)
Meng Xiangzhou; Blasius, Mary Ellen; Gossett, Richard W.; Maruya, Keith A.
2009-01-01
Little to no information exists for polybrominated diphenyl ethers (PBDEs) in marine mammals frequenting the highly urbanized southern California (USA) coast. Fourteen PBDE congeners were determined by GC-ECNI-MS in blubber of pinnipeds stranded locally between 1994 and 2006. Total PBDE concentrations (ΣPBDE) in California sea lion (n = 63) ranged from 0.04 to 33.7 μg/g wet weight (mean: 5.24 μg/g). To our knowledge, these are the highest reported PBDE levels in marine mammals to date. By comparison, mean ΣPBDE in Pacific harbor seals (n = 9) and northern elephant seals (n = 16) were 0.96 and 0.09 μg/g, respectively. PBDEs in adult males were higher than for adult females, however, no age class differences or temporal trends were observed. As the first PBDE data reported for marine mammals in this region, the elevated levels underscore the need for additional studies on the sources, temporal trends, and potential effects of PBDEs in highly urbanized coastal zones. - Levels of PBDEs in pinnipeds found stranded along the southern California coast (USA) between 1994 and 2006 are the highest reported to date for marine mammals.
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Digital Repository Service at National Institute of Oceanography (India)
Joseph, A.; Desai, R.G.P.; VijayKumar, K.; Mehra, P.; Nagvekar, S.
on simultaneous observations of tidal and surface meteorological parameters in four temporal segments of 1-month duration each during a 1-year period in 1997-98. Sea level oscillations along the Tikkavanipalem segment of the central east coast of India contain...
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Morphological development of coasts at very oblique wave incidence
DEFF Research Database (Denmark)
Petersen, Dorthe Pia; Deigaard, Rolf; Fredsøe, Jørgen
2003-01-01
This study focuses on one distinct feature to be found on coasts exposed to a very oblique wave incidence, namely an accumulating spit. That is a spit where no retreat of the shoreline is going on along the spit. This requires a monotonically decreasing sediment transport capacity from the updrift...... that such a spit grows without changing its shape i.e. an equilibrium form emerge if the coast is exposed to a constant wave climate. During experiments conducted in a wave tank where a uniform stretch of coast was exposed to waves approaching at a very oblique angle an accumulating spit was formed at the down......-drift end of the coast. The spits approached equilibrium forms when constant wave climates were applied. The sediment transport around the spit has been investigated by two-dimensional models. The characteristic length scale for the equilibrium form depends linearly on the width of the surf zone...
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Alien species on the coasts of Turkey
Directory of Open Access Journals (Sweden)
M.E. CINAR
2005-12-01
Full Text Available The compilation of data on alien species reported from the Turkish coasts yielded a total of 263 species belonging to 11 systematic groups, of which Mollusca had the highest number of species (85 species, followed by Crustacea (51, fishes (43 and phytobenthos (39. The Black Sea is represented by a total of 20 alien species, the Sea of Marmara by 48 species, the Aegean Sea by 98 species and the Levantine Sea by 202 species. The majority of aliens found in the Black Sea and the Sea of Marmara were transported via shipping, whereas the Levantine coast is extensively subjected to Lessepsian migration. Benthic habitats (soft and hard substrata comprise 76% of the total alien species and the pelagic environment is inhabited by thirty-nine species. Almost 50% of aliens collected from the Turkish coasts were found only at 0-10 m depth. Eight species occur at depths deeper than 100 m. The impacts of aliens on the benthic and pelagic ecosystems are presented.
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Campos, M.; Mothes, B.; Eckert, R.; van Soest, R.W.M.
2005-01-01
This work deals with haplosclerid sponges off the coast of Maranhão State, northeastern coast of Brazilian shelf (southwestern Atlantic). A new species is described, Haliclona (Halichoclona) lernerae. Four species are recorded for the first time for the Brazilian coast: Amphimedon caribica
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On burst-and-coast swimming performance in fish-like locomotion
International Nuclear Information System (INIS)
Chung, M-H
2009-01-01
Burst-and-coast swimming performance in fish-like locomotion is studied via two-dimensional numerical simulation. The numerical method used is the collocated finite-volume adaptive Cartesian cut-cell method developed previously. The NACA00xx airfoil shape is used as an equilibrium fish-body form. Swimming in a burst-and-coast style is computed assuming that the burst phase is composed of a single tail-beat. Swimming efficiency is evaluated in terms of the mass-specific cost of transport instead of the Froude efficiency. The effects of the Reynolds number (based on the body length and burst time), duty cycle and fineness ratio (the body length over the largest thickness) on swimming performance (momentum capacity and the mass-specific cost of transport) are studied quantitatively. The results lead to a conclusion consistent with previous findings that a larval fish seldom swims in a burst-and-coast style. Given mass and swimming speed, a fish needs the least cost if it swims in a burst-and-coast style with a fineness ratio of 8.33. This energetically optimal fineness ratio is larger than that derived from the simple hydromechanical model proposed in literature. The calculated amount of energy saving in burst-and-coast swimming is comparable with the real-fish estimation in the literature. Finally, the predicted wake-vortex structures of both continuous and burst-and-coast swimming are biologically relevant.
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On burst-and-coast swimming performance in fish-like locomotion.
Chung, M-H
2009-09-01
Burst-and-coast swimming performance in fish-like locomotion is studied via two-dimensional numerical simulation. The numerical method used is the collocated finite-volume adaptive Cartesian cut-cell method developed previously. The NACA00xx airfoil shape is used as an equilibrium fish-body form. Swimming in a burst-and-coast style is computed assuming that the burst phase is composed of a single tail-beat. Swimming efficiency is evaluated in terms of the mass-specific cost of transport instead of the Froude efficiency. The effects of the Reynolds number (based on the body length and burst time), duty cycle and fineness ratio (the body length over the largest thickness) on swimming performance (momentum capacity and the mass-specific cost of transport) are studied quantitatively. The results lead to a conclusion consistent with previous findings that a larval fish seldom swims in a burst-and-coast style. Given mass and swimming speed, a fish needs the least cost if it swims in a burst-and-coast style with a fineness ratio of 8.33. This energetically optimal fineness ratio is larger than that derived from the simple hydromechanical model proposed in literature. The calculated amount of energy saving in burst-and-coast swimming is comparable with the real-fish estimation in the literature. Finally, the predicted wake-vortex structures of both continuous and burst-and-coast swimming are biologically relevant.
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Wolfe, Benjamin E; Pringle, Anne
2012-04-01
The inability to associate with local species may constrain the spread of mutualists arriving to new habitats, but the fates of introduced, microbial mutualists are largely unknown. The deadly poisonous ectomycorrhizal fungus Amanita phalloides (the death cap) is native to Europe and introduced to the East and West Coasts of North America. By cataloging host associations across the two continents, we record dramatic changes in specificity among the three ranges. On the East Coast, where the fungus is restricted in its distribution, it associates almost exclusively with pines, which are rarely hosts of A. phalloides in its native range. In California, where the fungus is widespread and locally abundant, it associates almost exclusively with oaks, mirroring the host associations observed in Europe. The most common host of the death cap in California is the endemic coast live oak (Quercus agrifolia), and the current distribution of A. phalloides appears constrained within the distribution of Q. agrifolia. In California, host shifts to native plants are also associated with a near doubling in the resources allocated to sexual reproduction and a prolonged fruiting period; mushrooms are twice as large as they are elsewhere and mushrooms are found throughout the year. Host and niche shifts are likely to shape the continuing range expansion of A. phalloides and other ectomycorrhizal fungi introduced across the world.
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Gulf Coast Clean Energy Application Center
Energy Technology Data Exchange (ETDEWEB)
Dillingham, Gavin [Houston Advanced Research Center, TX (United States)
2013-09-30
The Gulf Coast Clean Energy Application Center was initiated to significantly improve market and regulatory conditions for the implementation of combined heat and power technologies. The GC CEAC was responsible for the development of CHP in Texas, Louisiana and Oklahoma. Through this program we employed a variety of outreach and education techniques, developed and deployed assessment tools and conducted market assessments. These efforts resulted in the growth of the combined heat and power market in the Gulf Coast region with a realization of more efficient energy generation, reduced emissions and a more resilient infrastructure. Specific t research, we did not formally investigate any techniques with any formal research design or methodology.
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Site-Specific Bluff Recession Rates Measured on the Alaskan Beaufort Sea Coast
Richmond, B.; Gadd, P.; Crowell, W.
2017-12-01
OverviewThe effects of climate change are being studied globally with coastal erosion in Arctic regions of particular concern. In support of Hilcorp Alaska's Northstar Development, short- and long-term bluff recession rates have been documented at a pipeline shore crossing located in Gwydyr Bay on the Alaskan Beaufort Sea coast. These data are presented, along with the predominant forcing mechanisms, and compared to local and regional recession rates recently published by the U.S. Geological Survey (USGS). Arctic Bluff RecessionCoastal retreat along the northern coast of Alaska occurs at two different rates: infrequent, but rapid erosion induced by strong westerly storms, and seasonal retreat related to thawing and sediment removal under more moderate wave conditions. Variability in the rate of bluff retreat is related to a number of factors, including bluff composition (ice content and sediment type), existence of a fronting beach, and wave exposure. Measured Bluff Recession at the Northstar Pipeline Shore CrossingThe location of the Northstar Development pipeline shore crossing was chosen based on analysis of historical aerial photos acquired between 1949 and 1996. Over this 47-year period, the average annualized rate of bluff retreat in the study area ranged from 1.6 to 3.0 ft/yr. Beginning in 1996, ground-based shoreline monitoring surveys have been conducted along the bluff and ten shore-perpendicular transects at the site. The rates of bluff retreat derived from the survey data have been modest, ranging from no change to 5.8 ft/yr. The monitoring surveys indicate that waves and currents erode the bluffs by direct impact only during infrequent, but strong westerly storms that promote a short-term rise in sea level (storm surge). The more prevalent easterly storms can cause set-down, or reduction in the sea level which limits direct wave impact on the bluff, thereby decreasing the potential for wave induced erosion. Comparative StudiesRecent studies conducted
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75 FR 24482 - Fisheries Off West Coast States; West Coast Salmon Fisheries; 2010 Management Measures
2010-05-05
... West Coast Vancouver Island (WCVI) troll and sport fishery and 15 percent in Alaska's Southeast Alaska... Chinook recreational TAC for north of Cape Falcon (C.5). --Cape Alava to Queets River (La Push Subarea...
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Geomorphology of the Goa Coast
Digital Repository Service at National Institute of Oceanography (India)
Wagle, B.G.
This paper is based on the observations and interpretations of aerial photographs (1;25, 000 and 1:15, 000) of the Goa Coast. Aerial photocharacters like zonal differences, texture, shape, size, form, pattern, vegetation, soil characteristics...
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Directory of Open Access Journals (Sweden)
Stešević Danijela
2017-12-01
Full Text Available Cutandia maritima is a circum-Mediterranean species that inhabits sandy dunes along the coast line. It is fairly frequent on the western Adriatic coast but fairly rare and possibly even non-native in the east. In Croatia, it was discovered in 1990 in Crnika Bay on the island of Rab, which was considered until 2005 to be the only site on the eastern Adriatic coast from the Gulf of Trieste in the north to Corfu in the south. In 2009, the species was briefly reported for Velika plaža (Long Beach in Ulcinj (Montenegro but without details about the habitat type and synecology. The aim of this paper is thus to provide a deeper insight into the ecology and synecology of C. maritima in the eastern Adriatic part of the distribution area. On Velika plaža in Ulcinj, the species was found along the whole sea-inland gradient of sand dunes, in various types of vegetation: [1210] - annual vegetation of drift lines, [2110] - embryonic shifting dunes, [2120] - shifting dunes with Ammophila arenaria (white dunes, [2220] - dunes with Euphorbia terracina, [2130*] - fixed coastal dunes with herbaceous vegetation (grey dunes, and also [2190] - humid dune slacks.
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2016 USGS West Coast El-Nino Lidar (WA, OR, CA)
National Oceanic and Atmospheric Administration, Department of Commerce — Towill collected approximately 75 square miles of coast in Oregon, 486 square miles of coast in Washington and California, and an additional 44 square miles for...
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Directory of Open Access Journals (Sweden)
Md Ataur Rahman
2015-12-01
Full Text Available The present study was conducted during September 2014 to July 2015 to identify the pearl bearing bivalves in south-eastern coast of Bangladesh and culture potentialities of marine oyster in captivity based on field investigation. A total of 7 pearl bearing bivalve species were identified in the coast with a salinity of 18-34 ppt, pH 8.1-8.3 and water depth ranged 0.2-2.0 meter in their habitat. From the collected bivalves, most abundant oyster species windowpane oyster, Placuna placenta (Linnaeus, 1758 was reared in fiber glass tanks with seawater for a period of 6 months. During rearing highest survival rate of 88% was observed in T1 with sandy and gravel substratum and lowest survival rate of 78% was found in T2 with muddy substratum. Average temperature and salinity were varied between 24 °C-25 °C and 21-26 ppt respectively. From the reared oyster, highest 54 nos. small pearls in the month of April and lowest 7 pearls in December from a single P. placenta were obtained. The study proved that pearls can be obtained from the marine oysters in captivity in Bangladesh, and this offers large scale culture potentialities in our coast.
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Influence of sea ice on Arctic coasts
Barnhart, K. R.; Kay, J. E.; Overeem, I.; Anderson, R. S.
2017-12-01
Coasts form the dynamic interface between the terrestrial and oceanic systems. In the Arctic, and in much of the world, the coast is a focal point for population, infrastructure, biodiversity, and ecosystem services. A key difference between Arctic and temperate coasts is the presence of sea ice. Changes in sea ice cover can influence the coast because (1) the length of the sea ice-free season controls the time over which nearshore water can interact with the land, and (2) the location of the sea ice edge controls the fetch over which storm winds can interact with open ocean water, which in turn governs nearshore water level and wave field. We first focus on the interaction of sea ice and ice-rich coasts. We combine satellite records of sea ice with a model for wind-driven storm surge and waves to estimate how changes in the sea ice-free season have impacted the nearshore hydrodynamic environment along Alaska's Beaufort Sea Coast for the period 1979-2012. This region has experienced some of the greatest changes in both sea ice cover and coastal erosion rates in the Arctic: the median length of the open-water season has expanded by 90 percent, while coastal erosion rates have more than doubled from 8.7 to 19 m yr-1. At Drew Point, NW winds increase shoreline water levels that control the incision of a submarine notch, the rate-limiting step of coastal retreat. The maximum water-level setup at Drew Point has increased consistently with increasing fetch. We extend our analysis to the entire Arctic using both satellite-based observations and global coupled climate model output from the Community Earth System Model Large Ensemble (CESM-LE) project. This 30-member ensemble employs a 1-degree version of the CESM-CAM5 historical forcing for the period 1920-2005, and RCP 8.5 forcing from 2005-2100. A control model run with constant pre-industrial (1850) forcing characterizes internal variability in a constant climate. Finally, we compare observations and model results to
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Great Lakes Surface Ice Reports from U.S. Coast Guard
National Oceanic and Atmospheric Administration, Department of Commerce — Data consist of ice observations from U.S. Coast Guard vessels operating on the Great Lakes, and from Coast Guard shore stations reported via teletype messages and...
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Microplastics in sediments from the littoral zone of the north Tunisian coast (Mediterranean Sea)
Abidli, Sami; Antunes, Joana C.; Ferreira, Joana L.; Lahbib, Youssef; Sobral, Paula; Trigui El Menif, Najoua
2018-05-01
The distribution of microplastics (MPs) was investigated in the sediments of five sampling sites from the northern Tunisian coast during June 2017. MPs were categorized according to type, colour and size. Representative MPs from the five sites were isolated for polymer identification using Fourier Transformed Infrared Spectroscopy in attenuated total reflectance mode (FTIR-ATR). Results showed that MPs were recovered, from all sediment samples, indicating for the first time, their extensive distribution in Tunisian coast. Concentrations varied from 141.20 ± 25.98 to 461.25 ± 29.74 items kg-1 dry weight. Fibres, fragments, Styrofoam®, pellets and films were the types registered in this study. With the exception of Menzel Bourguiba (MB), fibres significantly outnumbered plastic particles followed by fragments, Styrofoam®, films and pellets. The predominant colours are as follows: black > clear > white > red > blue > green for fibres, blue > white > clear > red > green > yellow > black for fragments, blue > white > black > clear for films while only white pellets and Styrofoam® were found. MPs particles ranged from 0.1 to 5 mm in length. A total of three polymer types were identified, polyethylene (PE), polypropylene (PP) and polystyrene (PS). Except for industrial pellets, the presence of MPs is likely due to the degradation of marine plastic debris accumulating in each site. This work provides original data of the presence of MPs in coastal sediments from Northern Tunisian coast.
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Coast Guard Proceedings. Volume 70, Number 2, Summer 2013
2013-01-01
and well-being. Most Inuit are coastal people who rely heavily on resources from the ocean for nutritional and cultural survival. The Inuit are a...defend a soccer ball from a crewmember of the Russian vessel Vorovsky at the Coast Guard gym at Base Kodiak, Alaska. U.S. Coast Guard photo by
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Short- and long-term thermo-erosion of ice-rich permafrost coasts in the Laptev Sea region
Günther, F.; Overduin, P. P.; Sandakov, A. V.; Grosse, G.; Grigoriev, M. N.
2013-06-01
Permafrost coasts in the Arctic are susceptible to a variety of changing environmental factors all of which currently point to increasing coastal erosion rates and mass fluxes of sediment and carbon to the shallow arctic shelf seas. Rapid erosion along high yedoma coasts composed of Ice Complex permafrost deposits creates impressive coastal ice cliffs and inspired research for designing and implementing change detection studies for a long time, but continuous quantitative monitoring and a qualitative inventory of coastal thermo-erosion for large coastline segments is still lacking. Our goal is to use observations of thermo-erosion along the mainland coast of the Laptev Sea, in eastern Siberia, to understand how it depends on coastal geomorphology and the relative contributions of water level and atmospheric drivers. We compared multi-temporal sets of orthorectified satellite imagery from 1965 to 2011 for three segments of coastline ranging in length from 73 to 95 km and analyzed thermo-denudation (TD) along the cliff top and thermo-abrasion (TA) along the cliff bottom for two nested time periods: long-term rates (the past 39-43 yr) and short-term rates (the past 1-4 yr). The Normalized Difference Thermo-erosion Index (NDTI) was used as a proxy to qualitatively describe the relative proportions of TD and TA. Mean annual erosion rates at all three sites were higher in recent years (-5.3 ± 1.3 m a-1) than over the long-term mean (-2.2 ± 0.1 m a-1). The Mamontov Klyk coast exhibits primarily spatial variations of thermo-erosion, while intrasite-specific variations caused by local relief were strongest at the Buor Khaya coast, where the slowest long-term rates of around -0.5 ± 0.1 m a-1 were observed. The Oyogos Yar coast showed continuously rapid erosion up to -6.5 ± 0.2 m a-1. In general, variable characteristics of coastal thermo-erosion were observed not only between study sites and over time, but also within single coastal transects along the cliff profile
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Occurrence of Porphyra vietnamensis (Bangiales, Rhodophyta) along the Goa coast
Digital Repository Service at National Institute of Oceanography (India)
Dhargalkar, V.K.; Agadi, V.V.; Untawale, A.G.
The occurrence of a red alga, Porphyra vietnamensis has been studied along the Goa Coast (west coast of India). The growth period was observed during the monsoon (July-October) and optimum growth was recorded during August, when temperature...
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Transformation of model data to information - experiences with coastDat
Meyer, E.; Weisse, R.
2016-02-01
The idea of coastDat is to improve the data base in sparse observational marine regions and to increase data homogeneity and consistency. In doing so long-term historical model data of e.g. wind (e.g. storms), wind wave and tide surge hindcasts are developed and proofed for regions like North Sea and Baltic Sea. These data-sets are available in hourly resolution and highly spatial resolution to simulate the marine environment from 1948/1958 up to now. Scenarios of potential future developments in a changing climate are also available. The coastDat data sets are used for applications e.g. offshore wind industry (design & logistics), risk analysis and analysis of pathways of energy transition. More than 80 stakeholders have used coastDat data sets. They are composed of science networks (31%), economic actors (45 %) and administrating policy actors (14%). The idea of coastDat is compatible in other coastal regions. Also coastDat is suitable as an information base in order to develop possible future adaptation measures. Here the data set and the history are briefly described, validation is reviewed, and an overview about recent uses of the data is provided.
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Coastal erosion: Coast problem of the Colombian Caribbean
International Nuclear Information System (INIS)
Martinez, Jaime Orlando
1986-11-01
The erosion promoted by the sea, affects different sectors of the coast of the Colombian Caribbean. The erosion is particularly clear in the central and western sector of the coast. The coastal problem of Punta Sabanilla - Puerto Salgar - Puerto Colombia; Pueblo Nuevo - Lomarena; Manzanillo del Mar; La Boquilla; sector Tolu - Covenas and Arboletes areas are described. This discussion is presented comform to the data obtained in field and of the revision of maps, pictures and other documents related with the coast design. The coastal erosion is not only affecting to low areas conformed by beaches, but rather this phenomenon impacts on rocky cliffs of different elevation; it is the case of El Castillo and Punta Sabanilla to Barranquilla (west Part) sectors . The causes of the setback that it experiences the coast of the Colombian Caribbean are not known in clear form; however they can be contributing such factors as: the elevation of the sea level, phenomenon that has been checked in different costs of the world; equally it can be due to a decrease in the volume of silts contributed by the Magdalena River, inside the coastal area. A third factor would be related with the diapirism of mud, that possibly would be altering the conformation of the Caribbean littoral
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78 FR 23135 - Safety Zone; Blue Water Resort & Casino West Coast Nationals; Parker, AZ
2013-04-18
...-AA00 Safety Zone; Blue Water Resort & Casino West Coast Nationals; Parker, AZ AGENCY: Coast Guard, DHS... Water Resort & Casino West Coast Nationals. This temporary safety zone is necessary to provide for the....). RPM Racing Enterprises is sponsoring the Blue Water Resort & Casino West Coast Nationals, which is...
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2013-01-17
... Rationalization Program; Emergency Rule Extension AGENCY: National Marine Fisheries Service (NMFS), National... Coast Groundfish Fishery Trawl Rationalization Program (program) regulations. This emergency rule... trawl rationalization program. Background on this rule was provided in the proposed rule, published on...
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Digital Repository Service at National Institute of Oceanography (India)
Setty, M.G.A.P.; Wagle, B.G.
constituents of beach rock found along Goa coast is dealt with in detail. While discussing the various views on its origin, it is emphasized that the process of cementation is chiefly controlled by ground water evaporation, inorganic precipitation and optimum...
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Submarine canyons off Madras Coast
Digital Repository Service at National Institute of Oceanography (India)
Setty, M.G.A.P.
Submarine canyons off the coast of Madras, Tamil Nadu, India were studied during cruise of @iINS Kistna@@ as part of the IIOE programme They consist of hill-like projections and V-shaped valleys Their other features are also reported...
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Coasting, embryo development and outcomes of blastocyst transfer: a case-control study.
Talebi Chahvar, Solmas; Zosmer, Ariel; Caragia, Alina; Balestrini, Simona; Sabatini, Luca; Tranquilli, Andrea Luigi; Al-Shawaf, Talha
2014-08-01
This study compared the effect on blastocyst development and clinical outcome of coasting in women at increased risk of moderate-severe ovarian hyperstimulation syndrome (OHSS; n=389) with a control group matched for age and basal FSH that did not undergo coasting (n=386) in IVF/intracytoplasmic sperm injection (ICSI) cycles. The main outcome measures were rate of blastocyst development and live birth. More cycles progressed to the blastocyst stage in the coasted group (n=169) compared with the control group (n=83; 43.4% versus 21.5%; P<0.001). The biochemical pregnancy, clinical pregnancy and live birth rates were similar (46.5% versus 42.0%; 40.6% versus 37.8%; 31.6% versus 30.1%). The duration of coasting up to 4 days did not affect progression to blastocyst stage. The multivariate model showed that coasting (OR 1.73, P=0.004) and the number of oocytes retrieved (OR 1.17, P=0.001) were positively correlated with blastocyst formation. Coasting, a measure to reduce the risk of OHSS, does not impair blastocyst development or clinical outcome. Coasting should remain an effective measure to prevent OHSS. Copyright © 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.
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Longshore-transport model for South Indian and Sri Lankan Coasts
Digital Repository Service at National Institute of Oceanography (India)
Chandramohan, P.; Nayak, B.U.; RamaRaju, V.S.
stream_size 17 stream_content_type text/plain stream_name J_Waterway_Port_Coast_Ocean_Eng_116_408.pdf.txt stream_source_info J_Waterway_Port_Coast_Ocean_Eng_116_408.pdf.txt Content-Encoding ISO-8859-1 Content-Type text...
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Zanethia D. Choice; Thomas K. Frazer; Charles A. Jacoby
2014-01-01
Seagrasses around the world are threatened by human activities that degrade water quality and reduce light availability. In this study, light requirements were determined for four common and abundant seagrasses along the Gulf coast of peninsular Florida using a threshold detecting algorithm. Light requirements ranged from 8% to 10% of surface irradiance for Halophila...
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Energy Technology Data Exchange (ETDEWEB)
Avery, Richard
2000-01-28
The Maine Coast Winds Project was proposed for four possible turbine locations. Significant progress has been made at the prime location, with a lease-power purchase contract for ten years for the installation of turbine equipment having been obtained. Most of the site planning and permitting have been completed. It is expect that the turbine will be installed in early May. The other three locations are less suitable for the project, and new locations are being considered.
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Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA.
Calder, Dale R
2013-01-01
This paper gives a systematic account of 67 species, referable to 22 families and 40 genera, identified in a small collection of hydroids from the central Atlantic coast of Florida between Melbourne and Palm Beach. The fauna mostly comprises an assemblage of tropical western Atlantic species ranging northwards along the southeastern coast of the United States. One new species, Lafoea intorta, is described. Applying Reversal of Precedence provisions in zoological nomenclature, the widely-used generic name Halopteris Allman, 1877 is designated as valid and as a nomen protectum, while its virtually unused senior synonym Halicornaria Hincks, 1865 (not Halicornaria Allman, 1874) is reduced to a nomen oblitum. The genus Pasya Stechow, 1922 is resurrected for the hydroid generally known as Dynamena quadridentata (Ellis & Solander, 1786). Laomedea tottoni Leloup, 1935 is shown to be a junior objective synonym of Clytia fragilis Congdon, 1907, which in turn is a junior subjective synonym of Clytia linearis (Thornely, 1900). Obelia oxydentata Stechow, 1914 is recognized as distinct from O. bidentata Clark, 1875. Hincksella brevitheca Galea, 2009, first described from Cuba, is reported for only the second time; records of the species are added here from Grand Cayman Island and the Caribbean coast of Panama as well as from the Atlantic coast of Florida. Also reported for the second time is Antennella incerta Galea, 2010, previ-ously known only from Guadeloupe in the Caribbean Sea. The true Halopteris diaphana (Heller, 1868), known from the Mediterranean Sea and from Brazil, is reported for the first time from the western North Atlantic. Earlier records of the species in the region are based on misidentifications of H. alternata (Nutting, 1900). Male gonothecae of Halecium calderi Galea, 2010 are reported and illustrated for the first time.
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International Nuclear Information System (INIS)
Wang, Yujue; Liu, Dongyan; Richard, Pierre; Di, Baoping
2016-01-01
To determine the dominant nitrogen sources and select effective macroalgal species for monitoring eutrophication along the Yantai coast, the total carbon (TOC), total nitrogen (TN) and nitrogen stable isotope ratio (δ 15 N) in macroalgal tissue were analyzed in conjunction with environmental variables in seawater along the Yantai coastline. The ranges of macroalgal tissue δ 15 N values together with dissolved inorganic nitrogen (DIN) composition indicated that except for the atmospheric deposition, there were three dominant types of nitrogen sources along the Yantai coast, with the agricultural fertilizer usage and factorial wastewater input at the S1 (Zhifu Island coast), the sewage discharge at S2 (the Moon Bay coast), the sewage discharge together with aquaculture impacts at S3 (Fisherman Wharf coast) and S4 (the Horse Island coast). Macroalgal growth were not limited by DIN but limited by P at S2, S3 and S4. Macroalgal species suitable or not for DIN source tracing along the Yantai coast were discussed. For sites with low DIN concentration, many species of three phyla could be used for DIN sources tracing with Laurencia okamurai, Gloiopeltis furcata and Ulva pertusa being ideal species. For site with high DIN concentration, however, species of Rhodophyta were not suitable and only Scytosiphon lomentaria and Monostroma nitidium were chosen. - Highlights: • Yantai coast was affected by three types of DIN sources. • Macroalgal species suitable or not for DIN source tracing were suggested; • TN and δ 15 N were affected by nutrient concentrations and the metabolic factors. • P instead of N limited the tissue N uptake in low nutrient concentration sites.
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Diagnosing indicators of large-scale forcing of east-coast cyclogenesis
International Nuclear Information System (INIS)
Dowdy, Andrew J; Mills, Graham A; Timbal, Bertrand
2010-01-01
Extra-tropical cyclones that develop near the east coast of Australia often have severe consequences such as flash flooding and damaging winds and seas, as well as beneficial consequences such as being responsible for heavy rainfall events that contribute significantly to total rainfall and runoff. There is subjective evidence that the development of most major events, commonly known as East Coast Lows, is associated with the movement of a high amplitude upper-tropospheric trough system over eastern Australia. This paper examines a number of upper-tropospheric diagnostic quantities that might provide a basis for preparing a climatology of the large-scale drivers of east-coast cyclogenesis. A preliminary climatology of these diagnostic quantities, based on ECMWF interim reanalyses, is compared with a database of observed East Coast Low events. The potential application of these diagnostics to global climate model simulations of past and future climates is also discussed.
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A Holistic Evaluation of a Typical Coast Nourishment on the Danish West Coast
DEFF Research Database (Denmark)
Margheritini, Lucia; Frigaard, Peter; Wahl, Niels Arne
2007-01-01
The case described in this article regards 4.7 km of beach in Ferring, situated approx. 5 km south to the mouth of the Limfjord strait on the west coast of Denmark. In 2005, this section of the beach was nourished with 721,000 m3 of material in order to protect backshore properties, natural herit...
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A Holistic Evaluation of a Typical Coast Nourishment on the Danish West Coast
DEFF Research Database (Denmark)
Margheritini, Lucia; Frigaard, Peter; Wahl, Niels Arne
2008-01-01
The case described in this article regards 4.7 km of beach in Ferring, situated approx. 5 km south to the mouth of the Limfjord strait on the west coast of Denmark. In 2005, this section of the beach was nourished with 721,000 m3 of material in order to protect backshore properties, natural...
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49 CFR 1520.15 - SSI disclosed by TSA or the Coast Guard.
2010-10-01
... 49 Transportation 9 2010-10-01 2010-10-01 false SSI disclosed by TSA or the Coast Guard. 1520.15... PROTECTION OF SENSITIVE SECURITY INFORMATION § 1520.15 SSI disclosed by TSA or the Coast Guard. (a) In... available for public inspection or copying, nor does TSA or the Coast Guard release such records to persons...
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U.S. Coast Guard (USCG) Districts
Department of Homeland Security — This layer is a polygonal dataset that represents land and maritime boundaries for each representative United States Coast Guard district, which includes district 1,...
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National Oceanic and Atmospheric Administration, Department of Commerce — Sablefish (Anoplopoma fimbria) have a wide distribution along the Pacific coast, extending from Baja California to Alaska, the Bering Sea and through to the eastern...
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National Oceanic and Atmospheric Administration, Department of Commerce — Sablefish (Anoplopoma fimbria) have a wide distribution along the Pacific coast, extending from Baja California to Alaska, the Bering Sea and through to the eastern...
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Safety Analysis of the ComCoast concept, Comcoast WP 3
Verhagen, H.J.; Ter Horst, W.L.A.
2005-01-01
ComCoast COMbined functions in COASTal defence zones is a European project which develops and presents innovative solutions for flood protection in coastal areas. The ComCoast concept is designed to develop alternative defence systems and new sustainable flood management strategies to cope with
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Paleomagnetism of the Oman Ophiolite: New Results from Oman Drilling Project Cores
Horst, A. J.; Till, J. L.; Koornneef, L.; Usui, Y.; Kim, H.; Morris, A.
2017-12-01
The Oman Drilling Project drilled holes at four sites in a transect through the southern massifs of the Samail ophiolite, and recovered 1500 m of igneous and metamorphic rocks. We focus on three sites from the oceanic crustal section including lower layered gabbros (GT1A), the mid-crustal layered to foliated gabbro transition (GT2A), and the shallower transition from sheeted dikes to varitextured gabbros (GT3A). Detailed core descriptions, analyses, and paleomagnetic measurements, were made on D/V Chikyu from July to September 2017 to utilize the core laboratory facilities similar to IODP expeditions. Shipboard measurements included anisotropy of magnetic susceptibility (AMS) and alternating field and thermal demagnetization of 597 discrete samples. Sample demagnetization behavior is varied from each of the cores, with some revealing multiple components of magnetization, and others yielding nearly univectorial data. The interpretation of results from the lower crustal cores is complicated by the pervasive presence of secondary magnetite. In almost all samples, a stable component was resolved (interpreted as a characteristic remanent magnetization) after removal of a lower-coercivity or lower unblocking-temperature component. The inclinations of the stable components in the core reference frame are very consistent in Hole GT1A. However, a transition from negative to positive inclinations in GT2A suggests some structural complexity, possibly as a result of intense late faulting activity. Both abrupt and gradual transitions between multiple zones of negative and positive inclinations occur in Hole GT3A. Interpretation and direct comparison of remanence between drill sites is difficult as recovered core pieces currently remain azimuthally unoriented, and GT2A was drilled at a plunge of 60°, whereas GT1A and GT3A were both drilled vertically. Work is ongoing to use borehole imagery to reorient the core pieces and paleomagnetic data into a geographic in situ reference
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2013-12-11
... Rationalization Program; Cost Recovery AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and... recovery program for the Pacific coast groundfish trawl rationalization program, as required by the...). Allocations to the limited entry trawl fleet for certain species were developed through a parallel process...
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Physicochemical parameters and seasonal variation of coastal water from Balochistan coast, Pakistan
Directory of Open Access Journals (Sweden)
Naeema Elahi
2015-03-01
Full Text Available Objective: To determine common physico-chemical parameters of coastal water. Methods: Physicochemical properties of water were determined according to the standards of the American Public Health Association. Generally, all those parameters were recorded a small variation between stations. The variation in physico-chemical parameters like salinity, temperature, dissolved oxygen and pH at Gwadar (Coastal water of Balochistan were recorded. Results: The range of air temperature of coastal water of Balochistan during 2004 and 2006 varies from 25 ºC to 37 ºC, water temperature ranged from 15.00 ºC to 33.00 ºC, pH ranged from 7.08 to 8.95, salinity ranged from 37.4‰ to 41.3‰ and dissolved oxygen ranged from 5.32 to 8.67 mg/L. Conclusions: Results showed that these parameters of Balochistan coast of Pakistan is not dangerous for marine habitat and the use of these parameters in monitoring programs to assess ecosystem health has the potential to inform the general public and decision-makers about the state of the coastal ecosystems. To save this vital important habitat, the government agencies and scientists should work with proper attention.
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NOAA/WEST COAST AND ALASKA TSUNAMI WARNING CENTER PACIFIC OCEAN RESPONSE CRITERIA
Directory of Open Access Journals (Sweden)
Garry Rogers
2008-01-01
Full Text Available New West Coast/Alaska Tsunami Warning Center (WCATWC response criteria for earthquakes occurring in the Pacific basin are presented. Initial warning decisions are based on earthquake location, magnitude, depth, and - dependent on magnitude - either distance from source or pre- computed threat estimates generated from tsunami models. The new criteria will help limit the geographical extent of warnings and advisories to threatened regions, and complement the new operational tsunami product suite.Changes to the previous criteria include: adding hypocentral depth dependence, reducing geographical warning extent for the lower magnitude ranges, setting special criteria for areas not well-connected to the open ocean, basing warning extent on pre-computed threat levels versus tsunami travel time for very large events, including the new advisory product, using the advisory product for far-offshore events in the lower magnitude ranges, and specifying distances from the coast for on-shore events which may be tsunamigenic.This report sets a baseline for response criteria used by the WCATWC considering its processing and observational data capabilities as well as its organizational requirements. Criteria are set for tsunamis generated by earthquakes, which are by far the main cause of tsunami generation (either directly through sea floor displacement or indirectly by triggering of slumps. As further research and development provides better tsunami source definition, observational data streams, and improved analysis tools, the criteria will continue to adjust. Future lines of research and development capable of providing operational tsunami warning centers with better tools are discussed.
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Yang, Byong Cheon; Chang, Tae Soo
2018-04-01
Generalized coastal facies models invariably assume that tidal flats and intertidally exposed shorefaces along macrotidal coasts are tide-dominated. Recent advances in coastal sedimentology, however, have revealed that wave-dominated macrotidal flats also occur in a wide range of coastal settings, in particular where tidal modulation forces the lateral translation of the wave-affected zone across the tidally exposed shoreface with the rising tide. Despite tidal modulation, the depositional character in the latter case (abundant storm deposits) exhibits a high degree of similarity with conventional subtidal shorefaces, implying that it is inherently difficult to distinguish between the two coastal systems in the rock record. In the present study, integrated sedimentological and ichnological data from the Dongho coast, which is located along the southwest coast of Korea, provide valuable information for the establishment of facies criteria that can assist in the recognition of such coastal deposits. In fact, the sedimentary character of the study area, which is dominated by an abundance of wave-formed structures, resembles that generally associated with subtidal shorefaces. In addition, the depositional processes responsible for sediment accumulation are, in the present case, also strongly influenced by pronounced seasonal variations in wave energy. In this context, the study has revealed a number of major features that appear to be characteristic of wave-dominated intertidal flats and shorefaces: (1) firmground muds may be encountered on the beach face, where intense swash-backwash motions are dominant; (2) the thickness of storm deposits decreases landward, reflecting the progressive decrease in wave energy; (3) ichnologically, there is an offshore shift in the dominance of trace fossils from the Skolithos ichnofacies, including Ophiomorpha, Thalassinoides and Psilonichnus, to a proximal expression of the Cruziana ichnofacies, which includes Siphonichnus and
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76 FR 17782 - Protection for Whistleblowers in the Coast Guard
2011-03-31
... ``Keyword'' box, and then clicking ``Search.'' FOR FURTHER INFORMATION CONTACT: If you have questions on..., telephone 202-372-3777, e-mail [email protected] . If you have questions on viewing or submitting... Protection for Whistleblowers in the Coast Guard AGENCY: Coast Guard, DHS. ACTION: Direct final rule...
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Probabilistic estimation of dune retreat on the Gold Coast, Australia
Palmsten, Margaret L.; Splinter, Kristen D.; Plant, Nathaniel G.; Stockdon, Hilary F.
2014-01-01
Sand dunes are an important natural buffer between storm impacts and development backing the beach on the Gold Coast of Queensland, Australia. The ability to forecast dune erosion at a prediction horizon of days to a week would allow efficient and timely response to dune erosion in this highly populated area. Towards this goal, we modified an existing probabilistic dune erosion model for use on the Gold Coast. The original model was trained using observations of dune response from Hurricane Ivan on Santa Rosa Island, Florida, USA (Plant and Stockdon 2012. Probabilistic prediction of barrier-island response to hurricanes, Journal of Geophysical Research, 117(F3), F03015). The model relates dune position change to pre-storm dune elevations, dune widths, and beach widths, along with storm surge and run-up using a Bayesian network. The Bayesian approach captures the uncertainty of inputs and predictions through the conditional probabilities between variables. Three versions of the barrier island response Bayesian network were tested for use on the Gold Coast. One network has the same structure as the original and was trained with the Santa Rosa Island data. The second network has a modified design and was trained using only pre- and post-storm data from 1988-2009 for the Gold Coast. The third version of the network has the same design as the second version of the network and was trained with the combined data from the Gold Coast and Santa Rosa Island. The two networks modified for use on the Gold Coast hindcast dune retreat with equal accuracy. Both networks explained 60% of the observed dune retreat variance, which is comparable to the skill observed by Plant and Stockdon (2012) in the initial Bayesian network application at Santa Rosa Island. The new networks improved predictions relative to application of the original network on the Gold Coast. Dune width was the most important morphologic variable in hindcasting dune retreat, while hydrodynamic variables, surge and
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Hydroelectric resources. Inventory of the hydroelectric resources of the Atlantic Coast
International Nuclear Information System (INIS)
Arrieta, R.M.; Insignares R, G.
1987-01-01
Basically this report gives a clear vision of the possibilities of energy development in the Colombian Atlantic Coast, projects that contemplate a wide range as soon as it refers that is to say to generation ranges, they have been identified at level macro in the Sierra Nevada region and the Peasant with a profitable hydroelectric potential of 631 MW; in the Sinu region, 3 projects were identified with a profitable potential of 1186 MW and in the Magdalena region, was also identified 3 projects whose profitable potential is of 475 MW. At level micro, the carried out studies defined in the same previous regions a series of projects that they necessarily reach the megawatt. The report contains a description of each one of the identified projects and its current situation. It also presents a review of the makers of turbines that exist at the moment in the country
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Bosch-Orea, Cristina; Sanchís, Josep; Farré, Marinella; Barceló, Damià
2017-09-01
Marine biotoxins regularly occur along the coast, with several consequences for the environment as well as the food industry. Monitoring of these compounds in seawater is required to assure the safety of marine resources for human consumption, providing a means for forecasting shellfish contamination events. In this study, an analytical method was developed for the detection of ten lipophilic marine biotoxins in seawater: azaspiracids 1, 2, 3, 4 and 5, classified as azaspiracid shellfish poisoning toxins, and pectenotoxin 2, okadaic acid and the related dinophysistoxin 1, yessotoxin and homoyessotoxin, classified as diarrheic shellfish poisoning toxins. The method is based on the application of solid-liquid ultrasound-assisted extraction and solid-phase extraction, followed by high-performance liquid chromatography coupled with high-resolution mass spectrometry. The limits of detection of this method are in the range of nanograms per litre and picograms per litre for most of the compounds, and recoveries range from 20.5% to 97.2%. To validate the effectiveness of this method, 36 samples of surface water from open coastal areas and marinas located along the Catalan coast on the Mediterranean Sea were collected and analysed. Eighty-eight per cent of these samples exhibited okadaic acid in particulate and aqueous phases in concentrations ranging from 0.11 to 560 μg/g and from 2.1 to 1780 ng/L respectively. Samples from open coastal areas exhibited higher concentrations of okadaic acid in particulate material, whereas in samples collected in sportive ports, the particulate material exhibited lower levels than the aqueous phase. Graphical Abstract Biotoxins investigated in seawater of the Catalan coast.
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Speaker Profiles and Abstracts
Indian Academy of Sciences (India)
2017-11-03
Nov 3, 2017 ... Origin of Manipur Ophiolite Complex, Indo-Myanmar Range, .... remote sensing to coastal and marine environments and has developed products for coastal management and .... industry giants at the cost of old businesses.
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77 FR 16929 - Safety Zones; Fireworks Displays within the Fifth Coast Guard District
2012-03-23
...-AA00 Safety Zones; Fireworks Displays within the Fifth Coast Guard District AGENCY: Coast Guard, DHS... for fireworks displays at various locations within the geographic boundary of the Fifth Coast Guard... by fireworks displays. Entry into or movement within these zones during the enforcement periods is...
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2013-02-01
... Rationalization Program; Cost Recovery AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and... Office rule goes final before the cost recovery program rule and if it would affect the appeals process... would implement a cost recovery program for the Pacific coast groundfish trawl rationalization program...
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2010-11-03
... economic benefits, create individual economic stability, provide full utilization of the trawl sector... taken in the U.S. exclusive economic zone (EEZ) off the coasts of Washington, Oregon, and California... holistic alternatives relative to the biological and socio-economic environment and consistent with the...
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Wave-power potential along the coast of the province of Buenos Aires, Argentina
Energy Technology Data Exchange (ETDEWEB)
Lanfredi, N.W. (Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC), La Plata (Argentina) Facultad de Ciencias Naturales y Museo, UNLP, La Plata (Argentina)); Pousa, J.L. (Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina) Facultad de Ciencias Naturales y Museo, UNLP, La Plata (Argentina)); Mazio, C.A.; Dragani, W.C. (Servicio de Hidrografia Naval, Buenos Aires (Argentina). Dept. Oceanografia)
1992-11-01
The coast of the Province of Buenos Aires, Argentina, has been studied to determine the wave-power potential. Using wave data (4 yr) from accelerometers, pressure sensors (1 yr) and a visual observation program (10 yr), the wave-power density was calculated at five locations. The annual average increases southwards, ranging between 2.3 kW/m at Mar de Ajo and 7.5 kW/m at Puerto Quequen. Annual averages of maximum wave power give 69 and 61.3 kW/m for Punta Medanos and Puerto Quequen, respectively. (Author).
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United States Coast Guard: Officer Corps Military Professional Development Program
2011-06-10
captain relieved of command after viewing porn on computer,‖ 10 July 2010, http://www.thenewstribune.com/2010/07/ 10/1259108/portland-coast-guard...Coast Guard captain relieved of command after viewing porn on computer,‖ 10 July 2010. http://www.thenewstribune.com/2010/07/ 10/1259108/portland
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Energy Technology Data Exchange (ETDEWEB)
Wang, Yujue [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China); Liu, Dongyan, E-mail: dyliu@yic.ac.cn [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China); Richard, Pierre [Littoral, Environnement et Sociétés, UMR 7266 CNRS-Université de La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle (France); Di, Baoping [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China)
2016-01-15
To determine the dominant nitrogen sources and select effective macroalgal species for monitoring eutrophication along the Yantai coast, the total carbon (TOC), total nitrogen (TN) and nitrogen stable isotope ratio (δ{sup 15}N) in macroalgal tissue were analyzed in conjunction with environmental variables in seawater along the Yantai coastline. The ranges of macroalgal tissue δ{sup 15}N values together with dissolved inorganic nitrogen (DIN) composition indicated that except for the atmospheric deposition, there were three dominant types of nitrogen sources along the Yantai coast, with the agricultural fertilizer usage and factorial wastewater input at the S1 (Zhifu Island coast), the sewage discharge at S2 (the Moon Bay coast), the sewage discharge together with aquaculture impacts at S3 (Fisherman Wharf coast) and S4 (the Horse Island coast). Macroalgal growth were not limited by DIN but limited by P at S2, S3 and S4. Macroalgal species suitable or not for DIN source tracing along the Yantai coast were discussed. For sites with low DIN concentration, many species of three phyla could be used for DIN sources tracing with Laurencia okamurai, Gloiopeltis furcata and Ulva pertusa being ideal species. For site with high DIN concentration, however, species of Rhodophyta were not suitable and only Scytosiphon lomentaria and Monostroma nitidium were chosen. - Highlights: • Yantai coast was affected by three types of DIN sources. • Macroalgal species suitable or not for DIN source tracing were suggested; • TN and δ{sup 15}N were affected by nutrient concentrations and the metabolic factors. • P instead of N limited the tissue N uptake in low nutrient concentration sites.
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2010-07-01
... Subpart B, for Determination of Coast Guard Authorized Persons B Appendix B to Subpart B of Part 1915... Enclosed Spaces and Other Dangerous Atmospheres in Shipyard Employment Pt. 1915, Subpt. B, App. B Appendix B to Subpart B of Part 1915—Reprint of U.S. Coast Guard Regulations Referenced in Subpart B, for...
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NWFSC Observer Trawl Data, off West Coast of US, 2002-2006
National Oceanic and Atmospheric Administration, Department of Commerce — Observer Trawl Data collected during 2002-2006 off West Coast of US. This data product originates from data collected by fishery observers in the West Coast...
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2016 USGS West Coast El-Nino Lidar DEM (WA, OR, CA)
National Oceanic and Atmospheric Administration, Department of Commerce — Towill collected approximately 75 square miles of coast in Oregon, 486 square miles of coast in Washington and California, and an additional 44 square miles for...
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75 FR 71187 - Atlantic Coast Financial Corporation, Waycross, GA; Approval of Conversion Application
2010-11-22
... DEPARTMENT OF THE TREASURY Office of Thrift Supervision [AC-56 OTS No. H-4438] Atlantic Coast... November 12, 2010, the Office of Thrift Supervision approved the application of Atlantic Coast Federal, MHC and Atlantic Coast Bank, Waycross, Georgia, to convert to the stock form of organization. Copies of...
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33 CFR 173.85 - Fees levied by the Coast Guard.
2010-07-01
.... 173.85 Section 173.85 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY VESSEL NUMBERING AND CASUALTY AND ACCIDENT REPORTING Issue of Certificate of.... (b) Fees are payable by check or money-order made payable to the “U.S. Coast Guard”; by major credit...
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2011-06-30
... are available, preventing additional harvest in fisheries that are important to coastal communities... document and undergo proposed and final rulemaking before these actions need to be in effect. For the... delay could impair achievement of one of the Pacific Coast Groundfish FMP goals to prevent overfishing...
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Project Coast: eugenics in apartheid South Africa.
Singh, Jerome Amir
2008-03-01
It is a decade since the exposure of Project Coast, apartheid South Africa's covert chemical and biological warfare program. In that time, attention has been focused on several aspects of the program, particularly the production of narcotics and poisons for use against anti-apartheid activists and the proliferation of both chemical and biological weapons. The eugenic dimension of Project Coast has, by contrast, received scant attention. It is time to revisit the testimony that brought the suggestion of eugenic motives to light, reflect on some of the Truth and Reconciliation Commission's findings and search for lessons that can be taken from this troubled chapter in South Africa's history.
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Study of mangrove environment of Maharashtra coast using remote sensing data
Digital Repository Service at National Institute of Oceanography (India)
Jagtap, T.G.; Untawale, A.G.; Inamdar, S.N.
Analysis of remote sensing data indicate approximately 210 km super(2) of the mangrove area along the Maharashtra coast in India. The dominant species along the coast are Rhizophora mucronata, Avicennia officinalis, A. marina, Sonneratia alba, S...
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Directory of Open Access Journals (Sweden)
Laurie A. Mauger
2012-12-01
Full Text Available The American crocodile, Crocodylus acutus, is widely distributed in the American neotropics. It is endangered throughout most of its range and is listed as vulnerable by the International Union for the Conservation of Natural Fauna and Flora (IUCN and on Appendix I of the Convention for the International Trade in Endangered Species of Wild Flora and Fauna (CITES. Despite this listing, there are few published reports on population status throughout most of its range. We investigated the status of the C. acutus, at several locations along the Pacific coast of Costa Rica. We carried out spotlight and nesting surveys from 2007-2009 along the Costa Rican Pacific coast in four distinct areas, coastal areas of Las Baulas (N=40 and Santa Rosa (N=9 National Parks and the Osa Conservation Area (N=13, and upriver in Palo Verde National Park (N=11. We recorded crocodile locations and standard environmental data at each observation. Encounter rates, population structure, distribution within each area and data on successful nesting (presence of hatchlings, nests, etc were determined. We attempted to capture all crocodiles to record standard morphometrics. A total of 586 crocodiles were observed along 185.8km of survey route. The majority of animals encountered (54.9% were either hatchlings (<0.5m or juveniles (0.5-1.25m. The average non-hatchling encounter rate per survey for the Pacific coast was 3.1 crocodiles/km, with individual encounter rates ranging from 1.2 crocodiles/km to 4.3 crocodiles/ km in Las Baulas National Park and the Osa Conservation Area respectively. Distribution of size classes within the individual locations did not differ with the exception of Santa Rosa and Las Baulas National Parks, where hatchlings were found in water with lower salinities. These were the first systematic surveys in several of the areas studied and additional work is needed to further characterize the American crocodile population in Costa Rica.
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National Oceanic and Atmospheric Administration, Department of Commerce — Members of the Fishery Resource Analysis and Monitoring Division Survey Team conduct an annual West Coast Groundfish Bottom Trawl Survey from May - October each...
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Nassar, Mohamed Z; El-Din, Nihal G Shams; Gharib, Samiha M
2015-10-01
Water samples were seasonally collected from 12 stations of the eastern coast of Suez Gulf during autumn of 2012 and winter, spring, and summer of 2013 in order to investigate phytoplankton community structure in relation to some physicochemical parameters. The study area harbored a diversified phytoplankton community (138 species), belonging to 67 genera. Four algal groups were represented and classified as Bacillariophyceae (90 species), Dinophyceae (28 species), Cyanophyceae (16 species), and Chlorophyceae (4 species). The results indicated a relative high occurrence of some species namely.; Pleurotaenium trabecula of green algae; Chaetoceros lorenzianus, Proboscia alata var. gracillima, Pseudosolenia calcar-avis, and Pseudo-nitzschia pungens of diatoms; Trichodesmium erythraeum and Pseudoanabaena limnetica of cyanophytes. Most of other algal species were fairly distributed at the selected stations of the study area. The total abundance of phytoplankton was relatively low (average of 2989 unit/L) in the eastern coast of Suez Gulf, as compared its western coast and the northern part of the Red Sea. The diversity of phytoplankton species was relatively high (2.35-3.82 nats) with an annual average of 3.22 nats in the present study. The results concluded that most of eastern coast of Suez Gulf is still healthy, relatively unpolluted, and oligotrophic area, which is clearly achieved by the low values of dissolved phosphate (0.025-0.3 μM), nitrate (0.18-1.26 μM), and dissolved ammonium (0.81-5.36 μM). Even if the occurrence of potentially harmful algae species was low, the study area should be monitored continuously. The dissolved oxygen ranged between 1.77 and 8.41 mg/L and pH values between 7.6 and 8.41. The multiple regression analysis showed that the dissolved nitrate and pH values were the most effective factors that controlled the seasonal fluctuations of phytoplankton along the eastern coast of Suez Gulf during 2012-2013.
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Prediction of ovarian hyperstimulation syndrome in coasted patients in an IVF/ICSI program
Directory of Open Access Journals (Sweden)
Fatimah Y Aljawoan
2012-01-01
Full Text Available Aim: To determine why a subgroup of coasted patients developed moderate/severe ovarian hyperstimulation syndrome (OHSS in an assisted reproduction setting. Materials and Methods: Retrospective study of 2948 in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI treatment cycles with 327 patients requiring coasting. Long protocol gonadotrophin releasing hormone analogue (GnRH-a regimen was used and serum estradiol (E 2 checked when ≥20 follicles were noted on follicular tracking. Coasting was initiated when leading three follicles were ≥15mm with E 2 ≥1635pg/ml. Results: The incidence of moderate/severe OHSS was 10.4% in coasted patients (equivalent 1.15% of the total IVF/ICSI cycles in the Center. Coasted patients who subsequently developed OHSS showed a significantly higher number of retrieved oocytes, higher serum E 2 level on the day of human chorionic gonadotrophin (hCG administration, and multiple pregnancies. No significant differences were noted with female age, BMI, cause of infertility, gonadotrophin dosage, coasting duration, and % of E 2 drop. Conclusion: Moderate/severe OHSS might be predicted in coasted patients by a combination of total oocyte numbers and E 2 level on the day of hCG. Multiple pregnancies also significantly increased the risk.
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Is Coasting Valuable in All Patients with Any Cause of Infertility?
Directory of Open Access Journals (Sweden)
Tahereh Madani
2016-11-01
Full Text Available Objectives: This study aimed to assess the influence of coasting duration on the number and quality of oocytes and fertilization rate in male factor infertile women and those with polycystic ovary syndrome (PCOS. Methods: In this prospective observational follow-up study, 114 patients undergoing coasting (53 women with male factor infertility and 61 women with PCOS were evaluated at the Royan Institute Research Center, Iran, between 2010 and 2012. Results: The results were analyzed according to the coasting periods of 1–4 days. In normal females, the number of oocytes retrieved was significantly reduced after the second day (p = 0.004. In addition, a statistically significant drop was observed in the number of metaphase II oocytes and fertilization rate after the third day (p = 0.006 and p = 0.006, respectively. No significant differences were observed in the number and quality of oocytes retrieved and fertilization rate with regard to coasting days in PCOS patients. Conclusion: Coasting with duration of more than three days should be performed with caution in normal females who are at risk of developing ovarian hyperstimulation syndrome.
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Acorn Yield During 1988 and 1989 on California's Central Coast
Sergio L. Garcia; Wayne A. Jensen; William H. Weitkamp; William D. Tietje
1991-01-01
In 1988, a study was began to evaluate acorn yield of valley oak (Quercus lobata), coast live oak (Q. agrifolia), and blue oak (Q. douglasii) in three of California's central coast counties: Santa Barbara, San Luis Obispo, and San Benito. The purpose of the study was to examine the degree and variability of...
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Louisiana's 2017 Master Plan for a Sustainable Coast
Haase, B.
2017-12-01
The Coastal Protection and Restoration Authority is charged with coordinating restoration and protection investments through the development and implementation of Louisiana's Comprehensive Master Plan for a Sustainable Coast. The first master plan was submitted to the Louisiana Legislature in 2007 and is mandated to be updated every five years. The plan's objectives are to reduce economic losses from flooding, promote sustainability by harnessing natural processes, provide habitats for commercial and recreational activities, sustain cultural heritage and promote a viable working coast. Two goals drive decision making about the appropriate suite of restoration and protection projects to include in the Plan: restore and maintain Louisiana's wetlands and provide flood protection for coastal Louisiana's citizens. As part of the decision making process, a wide range of additional metrics are used to evaluate the complex, competing needs of communities, industries, navigation and fisheries. The master plan decision making process includes the identification of individual protection and restoration projects that are evaluated with landscape, storm surge, and risk assessment models and then ranked by how well they perform over time across the set of decision drivers and metrics. High performing projects are assembled into alternatives constrained by available funding and river resources. The planning process is grounded not only on extensive scientific analysis but also on interdisciplinary collaboration between scientists, engineers, planners, community advocates, and coastal stakeholders which creates the long-term dialogue needed for complex environmental planning decisions. It is through this collaboration that recommended alternatives are reviewed and modified to develop the final Plan. Keywords:alternative formulation, comprehensive planning, ecosystem restoration, flood risk reduction and stakeholder engagement
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Rickettsia parkeri in Gulf Coast Ticks, Southeastern Virginia, USA
2011-05-01
Rickettsia parkeri in Gulf Coast Ticks, Southeastern Virginia, USA Chelsea L. Wright, Robyn M. Nadolny, Ju Jiang, Allen L. Richards, Daniel E...Virginia. We found that 43.1% of the adult Gulf Coast ticks collected in the summer of 2010 carried Rickettsia parkeri, suggesting that persons living in...or visiting southeastern Virginia are at risk for infection with this pathogen. Rickettsia parkeri is an obligate intracellular bacterium belonging
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Occurrence of green alga Ernodesmisverticillata (Kuetzing) Boergesen at Malvan (Maharashtra coast)
Digital Repository Service at National Institute of Oceanography (India)
Untawale, A.G.; Agadi, V.V.
of marine algal resources of the Maharashtra Coast, a green marine algal species was collected and identified as E. verticillata. From the literature it was observed that E. verticillata has not so far been reported from the Indian coast...
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Using MicroFTIR to Map Mineral Distributions in Serpentinizing Systems
Johnson, A.; Kubo, M. D.; Cardace, D.
2016-12-01
derived from drilling at the Coast Range Ophiolite Microbial Observatory (CROMO, Cardace et al., 2013). Preservation and well resolved description of organic compounds in secondary minerals in ultramafic rocks may allow assessment of changing habitability of past microenvironments fueled by serpentinization.
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Distribution of lithium in the Cordilleran Mantle wedge
Shervais, J. W.; Jean, M. M.; Seitz, H. M.
2015-12-01
Enriched fluid-mobile element (i.e., B, Li, Be) concentrations in peridotites from the Coast Range ophiolite are compelling evidence that this ophiolite originated in a subduction environment. A new method presented in Shervais and Jean (2012) for modeling the fluid enrichment process, represents the total addition of material to the mantle wedge source region and can be applied to any refractory mantle peridotite that has been modified by melt extraction and/or metasomatism. Although the end-result is attributed to an added flux of aqueous fluid or fluid-rich melt phase derived from the subducting slab, in the range of tens of parts per million - the nature and composition of this fluid could not be constrained. To address fluid(s) origins, we have analyzed Li isotopes in bulk rock peridotite and eclogite, and garnet separates, to identify possible sources, and fluid flow mechanisms and pathways. Bulk rock Li abundances of CRO peridotites (δ7Li = -14.3 to 5.5‰; 1.9-7.5 ppm) are indicative of Li addition and δ7Li-values are lighter than normal upper mantle values. However, Li abundances of clino- and orthopyroxene appear to record different processes operating during the CRO-mantle evolution. Low Li abundances in orthopyroxene (2 ppm) record subsequent interaction with Li-enriched fluids (or melts). The preferential partitioning of lithium in clinopyroxene could be indicative of a particular metasomatic agent, e.g., fluids from a dehydrating slab. Future in-situ peridotite isotope studies via laser ablation will further elucidate the fractionation of lithium between orthopyroxene, clinopyroxene, and serpentine. To obtain a more complete picture of the slab to arc transfer processes, we also measured eclogites and garnet separates to δ7Li= -18 to 3.5‰ (11.5-32.5 ppm) and δ7Li= 1.9 to 11.7‰ (0.7-3.9 ppm), respectively. In connection with previous studies focused on high-grade metamorphic assemblages within the Franciscan complex, an overall framework exists
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Paperno, R.; Ruiz-Carus, R.; Krebs, J.M.; McIvor, C.C.
2008-01-01
Introduced exotic species are a well-recognized problem in Florida's subtropical ecosystems. The presence of the exotic Mayan cichlid (Cichlasoma urophthalmus) was first confirmed in Florida in 1983, when numerous individuals were found in the northeastern Florida Bay. Since then, this species has continued to expand its range northward. The capture, beginning in October 2004 to present, of large numbers of Mayan cichlids from central Florida's east- and west-coast mangrove systems north of 28°N latitude is documented here. Mayan cichlids in a wide range of sizes (estimated ages 0-7 years) at both east- and west-coast sites were collected. In addition, macroscopic examination of gonads showed the presence of developing eggs. The occurrence of multiple age-classes, maturing individuals, cichlid nests, and juveniles, plus repeated collections over a four-year period, indicates that the Mayan cichlid is successfully reproducing and surviving the average winter temperatures in some estuarine waters in central Florida.
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CoastWatch Regions in HDF Format
National Oceanic and Atmospheric Administration, Department of Commerce — The mapped data derived from AVHRR is divided into files for CoastWatch regions of interest. Each file contains multiple data variables stored using the HDF-4...
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West Coast Rockfish Conservation Areas, 2015
National Oceanic and Atmospheric Administration, Department of Commerce — These data delineate Rockfish Conservation Areas (RCA) off the West Coast of the United States for 2015. There are three types of areas closures depicted in this...
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Modern Sedimentation along the SE Bangladesh Coast Reveal Surprisingly Low Accumulation Rates
McHugh, C.; Mustaque, S.; Mondal, D. R.; Akhter, S. H.; Iqbal, M.
2016-12-01
Recent sediments recovered along the SE coast of Bangladesh, from Teknaf to Cox's Bazar and drainage basin analyses reveal sediment sources and very low sedimentation rates of 1mm/year. These low rates are surprisingly low given that this coast is adjacent to the Ganges-Brahmaputra Delta with a yearly discharge of 1GT. The Teknaf anticline (elevation 200 m), part of the western Burma fold-thrust belt dominates the topography extending across and along the Teknaf peninsula. It is thought to have begun evolving since the Miocene (Alam et al. 2003 & Allen et al. 2008). Presently the anticline foothills on the west are flanked by uplifted terraces, the youngest linked to coseismic displacement during the 1762 earthquake (Mondal et al. 2015), and a narrow beach 60-200 m in width. Petrography, semi-quantitative bulk mineralogy and SEM/EDX analyses were conducted on sediments recovered along the west coast from 1-4 m deep trenches and three 4-8 m deep drill holes. GIS mapping of drainage basins and quartz-feldspar-lithic (QFL) ternary plots based on grain counting show mixing of sediments from multiple sources: Himalayan provenance of metamorphic and igneous origin (garnet-mostly almandine, tourmaline, rutile, kyanite, zircon, sillimanite and clinopyroxene) similar to Uddin et al. (2007); Brahmaputra provenance of igneous and metamorphic origin (amphibole, epidote, plagioclase 40% Na and 60% Ca, apatite, ilmenite, magnetite, Cr-spinel and garnet-mostly grossular,) as indicated by Garzanti et al. (2010) & Rahman et al. (2016) and Burmese sources (cassiterite and wolframite) (Zaw 1990 & Searle et al. 2007). Low sedimentation rates are the result of two main factors: 1. Strong longshore currents from the south-east that interact with high tidal ranges as evidenced by the morphology of sand waves and ridge and runnel landforms along the beach. 2. Streams draining the Teknaf anticline are dry during the winter and during summer monsoon rains, the sediments bypass the narrow
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Sedimentological parameters of beach sediments on the East Coast of India
Digital Repository Service at National Institute of Oceanography (India)
Chauhan, O.S.
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On some aspects of Barrier Islands of the west coast, India
Digital Repository Service at National Institute of Oceanography (India)
Kunte, P.D
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Hagedorn, B.; Ruane, M.; Clark, N.
2017-12-01
In California, the overuse of synthetic fertilizers and manure in agriculture have caused nitrate (NO3) to be one of the state's most widespread groundwater pollutants. Given that nitrogen fertilizer applications have steadily increased since the 1950s and given that soil percolation and recharge transit times in California can exceed timescales of decades, the nitrate impact on groundwater resources is likely a legacy for years and even decades to come. This study presents a methodology for groundwater vulnerability assessment that operates independently of difficult-to-constrain soil and aquifer property data (i.e., saturated thickness, texture, porosity, conductivity, etc.), but rather utilizes groundwater age and, more importantly, groundwater mixing information to illustrate actual vulnerability at the water table. To accomplish this, the modern (i.e., less than 60-year old) water proportion (MWP) in groundwater mixtures is computed via lumped parameter modeling of chemical tracer (i.e., 3H, 14C and 3Hetrit) data. These MWPs are then linked to groundwater dissolved oxygen (DO) values to describe the risk for soil zone-derived nitrate to accumulate in the saturated zone. Preliminary studies carried out for 71 wells in California's South Coast Range-Coastal (SCRC) study unit reveal MWP values derived from binary dispersion models of 3.24% to 21.8%. The fact that high MWPs generally coincide with oxic (DO ≥1.5 mg/L) groundwater conditions underscores the risk towards increased groundwater NO3 pollution for many of the tested wells. These results support the conclusion that best agricultural management and policy objectives should incorporate groundwater vulnerability models that are developed at the same spatial scale as the decision making.
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Directory of Open Access Journals (Sweden)
Shawn Larson
2015-06-01
Full Text Available A total of 77 giant Pacific octopus, Enteroctopus dofleini, tissue samples were collected from the Oregon Coast (OR, Neah Bay Washington (NB, Puget Sound Washington (PS and the southeast coast of Vancouver Island, British Columbia, Canada (BC for genetic analyses. A suite of eight variable microsatellite markers developed from giant Pacific octopuses were amplified in these samples to determine population diversity, structure, relatedness and paternity. The majority of loci met Hardy-Weinberg equilibrium expectations within each population. We found moderate genetic diversity (average observed heterozygosity = 0.445, range = 0.307–0.515 and average expected heterozygosity = 0.567, range = 0.506–0.696 and moderate population structuring with distinct separation of groups (FST values ranged from 0.101 between BC and PS to 0.237 between BC and NB. Several egg strings from the BC population were collected from three female octopus dens for relatedness and paternity analyses. Results suggest strong support for multiple paternity within one egg clutch with progeny sired by between two to four males.
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Implementing Strategy in a Budget: A Model of the Coast Guard Reserve
Bromund, Carl Douglas
1990-01-01
Approved for public release; distribution is unlimited. This thesis discusses the managment strategy of the Coast Guard Reserve; it examines the formulation and implmentation of strateqy. A model to develop and implement strategy is proposed, which defines the role of the budget in this strategic management process. The recent strategy of the Coast Guard Reserve is analyzed using this model.. This analysis seems to indicate that the Coast Guard Reserve had no explicit strate...
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A traditional boats and navigational history of Odisha, East coast of India
Digital Repository Service at National Institute of Oceanography (India)
Tripati, S.
Environ., vol.40(2); 2015; 80-93 A study of Traditional Boats and Navigational History of Odisha, East coast of India Sila Tripati Marine Archaeology Centre CSIR- National Institute of Oceanography Dona Paula, Goa 403 004... parts of the east coast of India and navigational technology. Keywords: Traditional boats, Navigation, Maritime trade, Odisha, East coast of India 2 Introduction The history of boatbuilding is as old as the relationship between man...
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SPECIES COMPOSITION OF PSAMMOPHILIC CILIATES OF SUMGAIT CASPIAN COAST
Directory of Open Access Journals (Sweden)
I. Kh. Alekperov
2014-01-01
Full Text Available Abstract. Comparative data on the species composition and species saprobic indicators of the psammon ciliates from Sumgait coast of the Caspian Sea are given.Methods. “Alive” samples were collected using a small clean plastic wide mouth bottles. Further processing was carried out under laboratory conditions. Small quantities of soil were examined under a binocular microscope MBS-9 . Ciliates detected microvessel caught and fixed castors for further impregnation kinetoma silver nitrate (Chatton et Lwoff, 1930 or silver proteinate. To determine the keys for ciliates used Foyssner’s major publications (Foissner et al., 1991, 1992, 1999 and “Free-living ciliates Atlas” (Alekperov, 2005.Results. We observed 75 species of ciliates during the studies, which species composition and distribution of the collection points are shown in table 1. Diagrams with average data were made relations groups psammophilous ciliates indicators saprobity different zones for each of the sites investigated Sumgait coast.Main conclusions. Environmental analysis using benthic ciliates indicators saprobity different zones showed that as expected, the industrial zone of Sumgayit coast coast, despite the decline in recent years, the total amount of pollution that is still highly contaminated portion of the coastal zone of the Caspian Sea.
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Recent marine archaeological investigations along the Saurashtra coast, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Gaur, A.S.; Sundaresh; Tripati, S.
., 2004), Bet Dwarka (Gaur et a]., 2005) and Somnath (Rao et al., 1992) have been focal points during the two decades of marine archaeological re- search on the Saurashtra coast. A large amount of data have been collected on seafaring activities... November 2003 for locating the re- mains of some ancient maritime activities such as an- chors, ancient port installation and submerged habitational site, etc. similar to those found at Dwarka, Bet Dwarka and Somnath. Porbandar is mentioned...
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Wave statistics around the Indian coast based on ship observed data
Digital Repository Service at National Institute of Oceanography (India)
Chandramohan, P.; SanilKumar, V.; Nayak, B.U.
the rest of the year. Waves are higher during the southwest monsoon (June-September) all around the Indian Coasts, with highest intensity of wave activity occurring off northern part of the West Coast and off southern most part of the peninsular India. Wave...
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Coast Guard Proceedings. Volume 71, Number 1, Spring 2014
2014-01-01
Canada. Rescue aircrew from Coast Guard Air Station Traverse City, Mich., conduct helicopter hoist training with the crew of the Canadian Coast...barge about 70-feet forward of the towing vessel — causing the barge to split nearly in half and dump thousands of gallons of oil into the...on the impeller B. double the liquid velocity through the pump when compared to a single volute C. reduce the hydraulic end thrust D. provide the
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Regionalization and Evaluation of Impacts of Climate Change on Mexican Coasts
Nava-Sanchez, E. H.; Murillo-Jimenez, J. M.; Godinez-Orta, L.; Morales-Perez, R. A.
2009-04-01
Mexican coasts exhibit a high variety of geoforms and processes, and consequently, are exposed to a variability of types and impact levels of geological hazards. Tropical cyclones are the most devastating hazards for the Mexican coast, although, impact levels are higher on the southern coast of both Atlantic and Pacific oceans. The second dangerous geo-hazards are earthquakes and tsunamis, which affect all Pacific coast, causing more damage the earthquakes generated in the Cocos Trench. For seismic hazards, there is a regionalization of the Mexican territory, however, even though the high levels of damages caused by other natural hazards, there is a lack of initiatives for performing atlas of natural hazards or coastal management plans. Exceptions are the local scale atlas of natural hazards by the Mexican Geological Survey or some other local scale atlas made with several errors by non experience private consultant companies. Our work shows results of analyses of coastal geological hazards associated to global warming such as the sea level rise, and the increase in strength of some coastal processes. Initially, due to the high diversity in coastal environments for the Mexican coast, it was considered that, a regional characterization of the coastal zone, and the gathering of environmental data for determining levels of impact of the various coastal hazards, as an evaluation of coastal vulnerability. Thus, the basic criteria for defining Coastal Regions, in order of importance, were the following: geomorphology, climate, geology, tectonics, and oceanography. Also, some anthropogenic factors were taken in account for the coastal regionalization, such as civil construction along the coastline, land used and modification of the fluvial system. The analysis of such criteria, allows us to classify the Mexican coasts in 10 Coastal Regions. On the Pacific coast regions are: (I) Pacific Coast of Baja California, (II) Gulf Coast of Baja California, (III) Coastal Plain of
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Mathany, Timothy M.; Burton, Carmen A.; Land, Michael; Belitz, Kenneth
2010-01-01
Groundwater quality in the approximately 766-square-mile South Coast Range-Coastal (SCRC) study unit was investigated from May to December 2008, as part of the Priority Basins Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basins Project was developed in response to legislative mandates (Supplemental Report of the 1999 Budget Act 1999-00 Fiscal Year; and, the Groundwater Quality Monitoring Act of 2001 [Sections 10780-10782.3 of the California Water Code, Assembly Bill 599]) to assess and monitor the quality of groundwater in California, and is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The SCRC study unit was the 25th study unit to be sampled as part of the GAMA Priority Basins Project. The SCRC study unit was designed to provide a spatially unbiased assessment of untreated groundwater quality in the primary aquifer systems and to facilitate statistically consistent comparisons of untreated groundwater quality throughout California. The primary aquifer systems (hereinafter referred to as primary aquifers) were defined as that part of the aquifer corresponding to the perforation interval of wells listed in the California Department of Public Health (CDPH) database for the SCRC study unit. The quality of groundwater in shallow or deep water-bearing zones may differ from the quality of groundwater in the primary aquifers; shallow groundwater may be more vulnerable to surficial contamination. In the SCRC study unit, groundwater samples were collected from 70 wells in two study areas (Basins and Uplands) in Santa Barbara and San Luis Obispo Counties. Fifty-five of the wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study unit (grid wells), and 15 wells were selected to aid in evaluation of specific water-quality issues (understanding wells). In addition to
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Cryo-conditioned rocky coast systems: A case study from Wilczekodden, Svalbard.
Strzelecki, M C; Kasprzak, M; Lim, M; Swirad, Z M; Jaskólski, M; Pawłowski, Ł; Modzel, P
2017-12-31
This paper presents the results of an investigation into the processes controlling development of a cryo-conditioned rock coast system in Hornsund, Svalbard. A suite of nested geomorphological and geophysical methods have been applied to characterise the functioning of rock cliffs and shore platforms influenced by lithological control and geomorphic processes driven by polar coast environments. Electrical resistivity tomography (ERT) surveys have been used to investigate permafrost control on rock coast dynamics and reveal the strong interaction with marine processes in High Arctic coastal settings. Schmidt hammer rock tests, demonstrated strong spatial control on the degree of rock weathering (rock strength) along High Arctic rock coasts. Elevation controlled geomorphic zones are identified and linked to distinct processes and mechanisms, transitioning from peak hardness values at the ice foot through the wave and storm dominated scour zones to the lowest values on the cliff tops, where the effects of periglacial weathering dominate. Observations of rock surface change using a traversing micro-erosion meter (TMEM) indicate that significant changes in erosion rates occur at the junction between the shore platform and the cliff toe, where rock erosion is facilitated by frequent wetting and drying and operation of nivation and sea ice processes (formation and melting of snow patches and icefoot complexes). The results are synthesised to propose a new conceptual model of High Arctic rock coast systems, with the aim of contributing towards a unifying concept of cold region landscape evolution and providing direction for future research regarding the state of polar rock coasts. Copyright © 2017 Elsevier B.V. All rights reserved.
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Plant Uptake of Atmospheric Carbonyl Sulfide in Coast Redwood Forests
Campbell, J. E.; Whelan, M. E.; Berry, J. A.; Hilton, T. W.; Zumkehr, A.; Stinecipher, J.; Lu, Y.; Kornfeld, A.; Seibt, U.; Dawson, T. E.; Montzka, S. A.; Baker, I. T.; Kulkarni, S.; Wang, Y.; Herndon, S. C.; Zahniser, M. S.; Commane, R.; Loik, M. E.
2017-12-01
The future resilience of coast redwoods (Sequoia sempervirens) is now of critical concern due to the detection of a 33% decline in California coastal fog over the 20th century. However, ecosystem-scale measurements of photosynthesis and stomatal conductance are challenging in coast redwood forests, making it difficult to anticipate the impacts of future changes in fog. To address this methodological problem, we explore coastal variations in atmospheric carbonyl sulfide (COS or OCS), which could potentially be used as a tracer of these ecosystem processes. We conducted atmospheric flask campaigns in coast redwood sites, sampling at surface heights and in the canopy ( 70 m), at the University of California Landels-Hill Big Creek Reserve and Big Basin State Park. We simulated COS atmosphere-biosphere exchange with a high-resolution 3-D model to interpret these data. Flask measurements indicated a persistent daytime drawdown between the coast and the downwind forest (45 ± 6 ppt COS) that is consistent with the expected relationship between COS plant uptake, stomatal conductance, and gross primary production. Other sources and sinks of COS that could introduce noise to the COS tracer technique (soils, anthropogenic activity, nocturnal plant uptake, and surface hydrolysis on leaves) are likely to be small relative to daytime COS plant uptake. These results suggest that COS measurements may be useful for making ecosystem-scale estimates of carbon, water, and energy exchange in coast redwood forests.
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Bioactivity of marine organisms. Part 5. Screening of some marine fauna from the Indian coast
Digital Repository Service at National Institute of Oceanography (India)
Naik, C.G.; Kamat, S.Y.; Parameswaran, P.S.; Das, B.; Patel, J.; Ramani, P.; Bhakuni, D.S.; Goel, A.K.; Jain, S.; Srimal, R.C.
(December), 1990, pp. 153-157 BIOACTIVITY OF MARINE ORGANISMS PART V : SCREENING OF SOME MARINE FAUNA FROM THE INDIAN COAST , CG. NAIK, S.Y. KAMAT, P.S. PARAMESHWARAN, B. DAS, JIVEXA PATEL, PRITA RAMANI, D.S. BHAKUNI", A.K. GOEL", SUDHA JAIN" AND R.c. SRIMAL... of Oceanography, Goa, in collaboration with the Central Drug Research Institute, Lucknow for the screening of extracts ofmarine organisms for a wide range of biological activities. The programme consists of collection, identification and extraction of marine flora...
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Marine conservation strategies for Maharashtra Coast
Digital Repository Service at National Institute of Oceanography (India)
Untawale, A.G.; Dhargalkar, V.K.
, Wildlife Sanctuaries, Marine Parks and Protected Areas. Detailed studies of 37 sites along the Maharashtra Coast, for their marine biota and also the ecological conditions, were taken up. Out of these, seven most luxuriant areas in marine biodiversity have...
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Simulation of Trajectories of Tar Ball Transport to the Goa Coast
Digital Repository Service at National Institute of Oceanography (India)
Suneel, V.; Vethamony, P.; VinodKumar, K.; Babu, M.T.; Prasad, V.S.R.
Arrival of tar balls to the Goa coast during pre- and southwest monsoon seasons has been a regular phenomenon in the past few years. In one such event, we observed tar ball deposits along the Goa coast during August 2010, April 2011 and May 2011...
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Radionuclide uptake in red macroalgae from the Bulgarian Black Sea coast
International Nuclear Information System (INIS)
Nonova, Tz.; Strezov, A.
2005-01-01
Technogenic and natural radionuclide content in red macroalgae (Ceramium rubrum, Corallina officinalis and Callithamnion corymbosum) from the Bulgarian Black Sea coast, collected in the period 1992-2003, was studied by low-level gamma-spectrometry. The data show that the nuclide concentrations depend on macroalgae species and coast locations. The highest nuclide content was measured in Ceramium rubrum species. The 137 Cs mean value is 9.8 Bq/kg, 19.6 Bq/kg for 226 Ra and 17 Bq/kg for 210 Pb. The radionuclide pollution is considerably small due to the absence of nuclear facilities along the Bulgarian Black Sea coast. (author)
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Air-water CO2 evasion from US East Coast estuaries
Gildas Laruelle, Goulven; Goossens, Nicolas; Arndt, Sandra; Cai, Wei-Jun; Regnier, Pierre
2017-05-01
This study presents the first regional-scale assessment of estuarine CO2 evasion along the US East Coast (25-45° N). The focus is on 42 tidal estuaries, which together drain a catchment of 697 000 km2 or 76 % of the total area within this latitudinal band. The approach is based on the Carbon-Generic Estuary Model (C-GEM) that allows the simulation of hydrodynamics, transport, and biogeochemistry for a wide range of estuarine systems using readily available geometric parameters and global databases of seasonal climatic, hydraulic, and riverine biogeochemical information. Our simulations, performed using conditions representative of the year 2000, suggest that, together, US East Coast estuaries emit 1.9 Tg C yr-1 in the form of CO2, which corresponds to about 40 % of the carbon inputs from rivers, marshes, and mangroves. Carbon removal within estuaries results from a combination of physical (outgassing of supersaturated riverine waters) and biogeochemical processes (net heterotrophy and nitrification). The CO2 evasion and its underlying drivers show important variations across individual systems, but reveal a clear latitudinal pattern characterized by a decrease in the relative importance of physical over biogeochemical processes along a north-south gradient. Finally, the results reveal that the ratio of estuarine surface area to the river discharge, S/Q (which has a scale of per meter discharged water per year), could be used as a predictor of the estuarine carbon processing in future regional- and global-scale assessments.
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Application of the Coasting Trade Act to offshore oil and gas operations
International Nuclear Information System (INIS)
De Jonge, B.B.
2002-01-01
The main features of the 1992 Coasting Trade Act are summarized. The main purpose of the Act is to protect Canadian ship owners and to ensure they have an opportunity to recover their investments in having Canadian built and crewed vessels. The Coasting Trade Act replaces provisions of the Canada Shipping Act which prohibited non-British ships from entering into Canadian domestic trade. The intention for the Coasting Trade Act is to reserve the coasting trade of Canada to Canadian-registered ships. However, when a Canadian ship is not available, a suitable foreign ship may be temporarily permitted to engage in the Canadian coasting trade as long as Canadian safety standards are met and duties are paid. The Canada Customs and Revenue Agency deals with licence applications while the Canadian Transportation Agency deals with unfair practices and enforcement. The provisions relating to the Coasting Trade License applications are examined along with how they are administered with particular reference to offshore oil and gas operations. The paper also presents recent decisions regarding application licences for Tycom (US) Inc., the Norwegian Polar Ship Management, and the Cyprus-registered seismic vessel, the Northern Access. It is noted that in evaluating the suitability and availability of a Canadian vessel for an activity proposed to be performed by a foreign vessel, the Canadian Transportation Agency examines the technical, financial and commercial elements brought by the parties
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Submarine canyons off the Coromandel coast
Digital Repository Service at National Institute of Oceanography (India)
Varadachari, V.V.R.; Nair, R.R.; Murty, P.S.N.
During the 26th Cruise of I.N.S. `KISTNA', a bathymetric survey was carried out in some detail off the Pondicherry coast. This survey has revealed the existence of three sets of distinctly separate canyons between Cuddalore and Palar River...
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Renal Cell Toxicity of Water-Soluble Coal Extracts from the Gulf Coast
Ojeda, A. S.; Ford, S.; Ihnat, M.; Gallucci, R. M.; Philp, P. R.
2017-12-01
In the Gulf Coast, many rural residents rely on private well water for drinking, cooking, and other domestic needs. A large portion of this region contains lignite coal deposits within shallow aquifers that potentially leach organic matter into the water supply. It is proposed that the organic matter leached from low-rank coal deposits contributes to the development of kidney disease, however, little work has been done to investigate the toxicity of coal extracts. In this study, human kidney cells (HK-2) were exposed to water-soluble extracts of Gulf Coast Coals to assess toxicity. Cell viability was measured by direct counts of total and necrotic cells. A dose-response curve was used to generate IC50 values, and the extracts showed significant toxicity that ranged from 0.5% w/v to 3% w/v IC50. The most toxic extract was from Louisiana where coal-derived organic material has been previously linked to high incidents of renal pelvic cancer (RPC). Although the toxic threshold measured in this study is significantly higher than the concentration of organic matter in the groundwater, typically affected areas may consume contaminated water over a lifetime. It is possible that the cumulative toxic effects of coal-derived material contribute to the development of disease.
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A New U.S. West Coast Network of Atmospheric River Observatories
White, A. B.; Wilczak, J. M.; Ayers, T. E.; King, C. W.; Jordan, J. R.; Shaw, W. J.; Flaherty, J. E.; Morris, V. R.
2015-12-01
The West Coast of North America is the gateway to winter storms forming over the Pacific Ocean that deliver most of the precipitation and water supply to the region. Satellites are capable of detecting the concentrated water vapor in these storms (a.k.a. atmospheric rivers) over the oceans, but because of the complex emissivity of land surfaces, fail to do so over land. In addition, these storms often are accompanied by a baroclinically induced low-level jet that drives the moisture up the windward slopes of coastal and inland mountain ranges and produces orographically enhanced precipitation. To date, satellites cannot resolve this important feature. NOAA's Hydrometeorology Testbed (HMT; hmt.noaa.gov) has developed the concept of an atmospheric river observatory (ARO); a collection of ground-based instruments capable of detecting and monitoring the water vapor transport in the low-level jet region. With funding provided by the California Department of Water Resources and U.S. Department of Energy, HMT has installed a picket fence of AROs along the U.S. West Coast. In addition, HMT has developed an award-winning water vapor flux tool that takes advantage of the data collected by the AROs to provide situational awareness and decision support for end users. This tool recently has been updated to include operational weather prediction output. The ARO network and water vapor flux tool will be described in this presentation.
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Forecasting sea fog on the coast of southern China
Huang, H.; Huang, B.; Liu, C.; Tu, J.; Wen, G.; Mao, W.
2016-12-01
Forecast sea fog is still full of challenges. We have performed the numerical forecasting of sea fog on the coast of southern China by using the operational meso-scale regional model GRAPES (Global/Regional assimilation and prediction system). The GRAPES model horizontal resolution was 3km and with 66 vertical levels. A total of 72 hours forecasting of sea fog was conducted with hourly outputs over the sea fog event. The results show that the model system can predict reasonable characteristics of typical sea fog events on the coast of southern China. The scope of sea fog coincides with the observations of meteorological stations, the observations of the Marine Meteorological Science Experiment Base (MMSEB) at Bohe, Maoming and satellite products of sea fog. The goal of this study is to establish an operational numerical forecasting model system of sea fog on the coast of southern China.
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Seasonal growth dynamics of the seagrass Zostera caulescens on the eastern coast of Korea
Kim, Jong-Hyeob; Park, Sang Hoon; Kim, Young Kyun; Kim, Seung Hyeon; Park, Jung-Im; Lee, Kun-Seop
2014-12-01
Zostera caulescens is an endemic seagrass species in Northeastern Asia. Estimated distributional area of this species is approximately 1-5 km2 on the coasts of Korea. Because Z. caulescens has a very limited distribution, the growth dynamics of Z. caulescens is little known in the coastal waters of Korea. In the present study, we investigated the growth dynamics of Z. caulescens in relation to coincident measurements of environmental factors, such as underwater irradiance, water temperature, and nutrient availability. The study was conducted on a monotypic meadow of Z. caulescens in Uljin on the eastern coast of Korea from September 2011 to September 2012. Shoot density and biomass of Z. caulescens showed distinct seasonal variations, and exhibited strong correlations with water temperature suggesting that the seasonal growth of this species was regulated by water temperature. Shoot density and biomass rapidly decreased during the high water temperature period in summer, and thus Z. caulescens is considered a cold water adapted species like other temperate seagrass species on coasts of Korea. Biomass of photosynthetic leaf tissues on reproductive shoots was approximately 4 times higher than that on vegetative shoots. The height of reproductive shoots ranged from 1.2 m in February 2012 to 3.2 m in August 2012, whereas the height of vegetative shoots was usually less than 1.0 m. Leaf tissues on reproductive shoots probably received much more light for photosynthesis than those on vegetative shoots. Thus, reproductive shoots may play an important role in total production of Z. caulescens.
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2010-01-29
... Coast groundfish fishery. The trawl rationalization program is intended to increase net economic benefits, create individual economic stability, provide full utilization of the trawl sector allocation... one time reporting will have a significant economic impact on small entities, as the estimated...
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Directory of Open Access Journals (Sweden)
Anjaneyulu Yerramilli
2008-12-01
Full Text Available Coastal atmospheric conditions widely vary from those over inland due to the land-sea interface, temperature contrast and the consequent development of local circulations. In this study a field meteorological experiment was conducted to measure vertical structure of boundary layer during the period 25-29 June, 2007 at three locations Seabee base, Harrison and Wiggins sites in the Mississippi coast. A GPS Sonde along with slow ascent helium balloon and automated weather stations equipped with slow and fast response sensors were used in the experiment. GPS sonde were launched at three specific times (0700 LT, 1300 LT and 1800 LT during the experiment days. The observations indicate shallow boundary layer near the coast which gradually develops inland. The weather research and forecasting (WRF meso-scale atmospheric model and a Lagrangian particle dispersion model (HYSPLIT are used to simulate the lower atmospheric flow and dispersion in a range of 100 km from the coast for 28-30 June, 2007. The simulated meteorological parameters were compared with the experimental observations. The meso-scale model results show significant temporal and spatial variations in the meteorological fields as a result of development of sea breeze flow, its coupling with the large scale flow field and the ensuing alteration in the mixing depth across the coast. Simulated ground-level concentrations of SO2 from four elevated point sources located along the coast indicate diurnal variation and impact of the local sea-land breeze on the direction of the plume. Model concentration levels were highest during the stable morning condition and during the sea-breeze time in the afternoon. The highest concentrations were found up to 40 km inland during sea breeze time. The study illustrates the application of field meteorological observations for the validation of WRF which is coupled to HYSPLIT for dispersion assessment in the coastal region.
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Using RFID and PIT tags to Quantify Bedload Transport in the Oregon Coast Range
Sanfilippo, J.; Lancaster, S. T.
2017-12-01
Introducing the methods, issues, and data collection techniques and interpretation over one water year using RFID (radio frequency identification) and PIT (passive integrated transponder) tags in Oak Creek, near Corvallis Oregon. We constructed an RFID four-antenna array that runs off of a single radiofrequency reader via a multiplexer board. Using 4 grain sizes we tagged 990 individual rocks, roughly 250 in of each four size ranges (8-16mm, 16-32mm, 32-64mm, 64-128mm). Using 12 mm and 23 mm PIT tags during 1 water year the antennas logged 477 tracer passage events. To calculate bedload transport for each size range, at each antenna, interarrival times yield count rates when combined with grain size fractions of the bed and tracer concentrations, yield bedload transport for each size class. We calculated transport rates for five events of varying magnitude and found that PIT tag RFID method under predicts transport between 1 and 3 orders of magnitude.
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Tsunami hazard at the Western Mediterranean Spanish coast from seismic sources
Álvarez-Gómez, J. A.; Aniel-Quiroga, Í.; González, M.; Otero, L.
2011-01-01
Spain represents an important part of the tourism sector in the Western Mediterranean, which has been affected in the past by tsunamis. Although the tsunami risk at the Spanish coasts is not the highest of the Mediterranean, the necessity of tsunami risk mitigation measures should not be neglected. In the Mediterranean area, Spain is exposed to two different tectonic environments with contrasting characteristics. On one hand, the Alboran Basin characterised by transcurrent and transpressive tectonics and, on the other hand, the North Algerian fold and thrust belt, characterised by compressive tectonics. A set of 22 seismic tsunamigenic sources has been used to estimate the tsunami threat over the Spanish Mediterranean coast of the Iberian peninsula and the Balearic Islands. Maximum wave elevation maps and tsunami travel times have been computed by means of numerical modelling and we have obtained estimations of threat levels for each source over the Spanish coast. The sources on the Western edge of North Algeria are the most dangerous, due to their threat to the South-Eastern coast of the Iberian Peninsula and to the Western Balearic Islands. In general, the Northern Algerian sources pose a greater risk to the Spanish coast than the Alboran Sea sources, which only threaten the peninsular coast. In the Iberian Peninsula, the Spanish provinces of Almeria and Murcia are the most exposed, while all the Balearic Islands can be affected by the North Algerian sources with probable severe damage, specially the islands of Ibiza and Minorca. The results obtained in this work are useful to plan future regional and local warning systems, as well as to set the priority areas to conduct research on detailed tsunami risk.
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NWFSC Observer Fixed Gear Data, off West Coast of US, 2002-2006
National Oceanic and Atmospheric Administration, Department of Commerce — Observer Fixed Gear Data collected during 2002-2006 off West Coast of US. This data product originates from data collected by fishery observers in the West Coast...
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Seasonal and spatial variations of marine litter on the south-eastern Black Sea coast.
Terzi, Yahya; Seyhan, Kadir
2017-07-15
The south-eastern Black Sea coast in Turkey was evaluated for marine litter composition and density covering nine beaches during four seasons. The marine litter (>2cm in size), was collected from the coast and categorized into material and usage categories. The data analysis showed that plastic was the most abundant litter (≥61.65%) by count and weight followed by styrofoam and fabric. The marine litter density ranged from 0.03 to 0.58 with a mean (±SD) of 0.16±0.02 items/m 2 by count. Based on weight, it varied between 0.44 and 14.74g/m 2 with 3.35±1.63. The east side had a higher marine litter density than the west side with significant differences between beaches. The variations due to different seasons were not significant for any beach. The results of this study should provide baseline information about the coastal marine pollution and will assist the mitigation strategies. Copyright © 2017 Elsevier Ltd. All rights reserved.
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San Francisco-Pacifica Coast Landslide Susceptibility 2011
California Natural Resource Agency — The San Francisco-Pacifica Coast grid map was extracted from the California Geological Survey Map Sheet 58 that covers the entire state of California and originally...
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International Nuclear Information System (INIS)
Zal U'yun Wan Mahmood; Hidayah Shahar; Zaharudin Ahmad; Yii Mei Wo; Ahmad Sanadi Abu Bakar
2010-01-01
The present distributions of 239+240 Pu, 241 Am and activity ratio of 241 Am/ 239+240 Pu in surface seawater of the Peninsular Malaysia east coast were studied. The surface seawater samples were collected at 30 identified stations during the expedition conducted in 2008. 239+240 Pu activity concentrations in surface seawater of the studied area were in the range of 2.33 ± 0.20-7.95 ± 0.68 mBq/m 3 , meanwhile 241 Am activity concentrations ranged from MDA to 1.90 ± 0.23 mBq/m 3 . The calculated activity ratios of 241 Am/ 239+240 Pu were varied and disperse distributed with the ranged of 0.12-0.53. The relationships between anthropogenic radionuclide and oceanographic parameters such as turbidity and salinity were examined. The linearly relationships between 239+240 Pu and oceanographic parameters are important for better understanding of its transport processes and behavior in the east coast of Peninsular Malaysia marine environment. Thus, the differ of distribution of 239+240 Pu, 241 Am and 241 Am/ 239+240 Pu in the studied area mainly due to high affinity of 239+240 Pu to associate with sinking particles, mobility nature of 241 Am, degree of particle reactive of both anthropogenic radionuclides, scavenging and removal process; and others. (author)
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2010-02-05
... Collection; Comment Request; Pacific Coast Groundfish, Rationalization Sociocultural Study AGENCY: National... requiring equivalent information. Fisheries rationalization programs have an impact on those individuals... rationalization program for the Pacific Coast Groundfish limited entry trawl fishery in January 2011. This...
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Lucy Kerhoulas; Nicholas Kerhoulas; Wade Polda; John-Pascal Berrill
2017-01-01
Reforestation following timber harvests is an important topic throughout the coast redwood (Sequoia sempervirens (D. Don) Endl.) range. Furthermore, as drought-induced mortality spreads across many of Californiaâs forests, it is important to understand how physiology and stand structure influence reforestation success. Finally, as climate...
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Phytophthora ramorum in coast live oak: search for resistance and mechanisms.
B.A. McPherson; D.L. Wood; S.R. Mori; A. Conrad; P. Bonello
2013-01-01
Despite the presence of Phytophthora ramorum in northern and central California forests since at least 1994, asymptomatic coast live oaks (Quercus agrifolia Née) still remain in heavily infested stands. Coast live oak infection and mortality rates of 5 percent y-1 and 3 percent y-1, respectively, observed in long-term...
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2012-12-10
... Quality Implementation Plans; California; South Coast Air Quality Management District; Prevention of... Implementation Plan (SIP) revision for the South Coast Air Quality Management District (SCAQMD or District... in a August 15, 2012 letter from the South Coast Air Quality Management District regarding specific...
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Seaweeds from the Portuguese coast: A potential food resource?
Soares, C.; Machado, S.; Vieira, E. F.; Morais, S.; Teles, M. T.; Correia, M.; Carvalho, A.; Domingues, V. F.; Ramalhosa, M. J.; Delerue-Matos, C.; Antunes, F.
2017-09-01
The Portuguese coast presents a large amount of potentially edible seaweeds that are underexploited. The identification of different macroalgae species and their availability in the northern and central coast of the continental territory was assessed. The nutritional value of seaweeds is discussed based on a literature review (when available) focused on data for species collected in Portugal with the aim to define the most important nutritional parameters that should be characterized in the samples. Possible health concerns related with the presence of contaminants are also considered.
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Estuarine beaches of the Amazon coast: environmental and recreational characterization
de Sousa, Rosigleyse C.; Pereira, Luci Cajueiro Carneiro; Jiménez Quintana, José Antonio
2016-01-01
The Amazon coast is rich in natural resources, with highly valued natural landscapes and ecological systems. These environments include estuarine beaches, which are important areas for recreational activities. The present study provides an environmental and recreational diagnosis of three of these estuarine beaches on the Amazon coast (Colares, Maruda, and Murubira). The study was conducted in July, 2012, 2013 and 2015. An set of variables was assessed: (i) physical variables (hydrodynamics),...
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The Kenya Coast in national perspective
Meilink, H.A.; Hoorweg, J.; Foeken, D.W.J.; Obudho, R.A.
2000-01-01
This chapter provides a concise review of the process of regional development and the concomitant growing regional inequalities in Kenya. By focusing on Coast Province, it aims to verify statements which stress that the province has gradually moved to a marginal position in Kenyan society. Examining
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Tsunami hazard at the Western Mediterranean Spanish coast from seismic sources
Directory of Open Access Journals (Sweden)
J. A. Álvarez-Gómez
2011-01-01
Full Text Available Spain represents an important part of the tourism sector in the Western Mediterranean, which has been affected in the past by tsunamis. Although the tsunami risk at the Spanish coasts is not the highest of the Mediterranean, the necessity of tsunami risk mitigation measures should not be neglected. In the Mediterranean area, Spain is exposed to two different tectonic environments with contrasting characteristics. On one hand, the Alboran Basin characterised by transcurrent and transpressive tectonics and, on the other hand, the North Algerian fold and thrust belt, characterised by compressive tectonics. A set of 22 seismic tsunamigenic sources has been used to estimate the tsunami threat over the Spanish Mediterranean coast of the Iberian peninsula and the Balearic Islands. Maximum wave elevation maps and tsunami travel times have been computed by means of numerical modelling and we have obtained estimations of threat levels for each source over the Spanish coast. The sources on the Western edge of North Algeria are the most dangerous, due to their threat to the South-Eastern coast of the Iberian Peninsula and to the Western Balearic Islands. In general, the Northern Algerian sources pose a greater risk to the Spanish coast than the Alboran Sea sources, which only threaten the peninsular coast. In the Iberian Peninsula, the Spanish provinces of Almeria and Murcia are the most exposed, while all the Balearic Islands can be affected by the North Algerian sources with probable severe damage, specially the islands of Ibiza and Minorca. The results obtained in this work are useful to plan future regional and local warning systems, as well as to set the priority areas to conduct research on detailed tsunami risk.
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Directory of Open Access Journals (Sweden)
S. Georgieva
2016-06-01
Full Text Available Abstract. Polychlorinated biphenyls (PCBs are characterized by high lipophilicity and persistence in the environment and will therefore bioaccumulate and biomagnify in the food chain. PCBs were determined in muscle tissue of four fish species: goby (Neogobius melanostomus, horse mackerel (Trachurus Mediterraneus ponticus, shad (Alosa pontica pontica and turbot (Psetta maxima maeotica. Samples were collected from Bulgarian Black Sea coast during 2007 – 2011. The PCBs were analyzed in order to examine the time trends of PCB concentrations in fish from Black Sea. The six individual PCBs congeners were determined by capillary gas chromatography system with mass spectrometry detection. PCBs were found in all fish species at concentrations ranging between 2.32 ng/g ww (wet weight and 32.87 ng/g ww in goby and shad, respectively. PCB profiles have been found to be similar in all the fish species tested. The most abundant PCB congeners in fish species were hexa- and heptachlorinated PCBs 138, 153 and 180. PCB 153 was the dominant congener in all fish studied and were found in the range from 0.95 ng/g ww (horse mackerel 2011 to 11.67 ng/g ww (shad 2010. The sum of six indicator PCBs in all fish species did not exceed the European maximum limit of 75 ng/g ww. The levels of PCBs in fish from Bulgarian Black Sea coast were found lower than in fish species from other seas – the Aegean Sea and the Mediterranean Sea.
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Directory of Open Access Journals (Sweden)
S. Pasquet
2013-02-01
Full Text Available A systematic survey of high-frequency sea level oscillations (<6 h measured between 2006 and 2011 along the US East Coast is performed. Raw 1-min resolution sea level data is used. After performing a data quality check, the nine most intense events, with maximum recorded wave heights ranging from 40 to 100 cm, are identified. Focusing on three of these events enables us to recognize two different generation mechanisms: (i topographically-trapped edge waves which are found to be a significant contributor to the strongest observed oscillations, and (ii standing waves, which occur over enclosed shallow waters and may result in significant wave heights of up to 100 cm. A reproduction of the observed oscillations is a part of a future work, which will include an assessment of a generating force in the atmosphere, allowing for a better prevention of potential flooding along the US East Coast.
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Eighteenth annual West Coast theoretical chemistry conference
Energy Technology Data Exchange (ETDEWEB)
NONE
1997-05-01
Abstracts are presented from the eighteenth annual west coast theoretical chemistry conference. Topics include molecular simulations; quasiclassical simulations of reactions; photodissociation reactions; molecular dynamics;interface studies; electronic structure; and semiclassical methods of reactive systems.
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Pacific Coast Groundfish Individual Fishing Quota Database
National Oceanic and Atmospheric Administration, Department of Commerce — On January 11, 2011, NOAA Fisheries implemented a new fishery management system for the West Coast Groundfish Trawl Catch Share Program as specified in the...
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Morse, Michael S.; Lu, Ning; Godt, Jonathan W.; Revil, André; Coe, Jeffrey A.
2012-01-01
Accurate estimation of the soil thickness distribution in steepland drainage basins is essential for understanding ecosystem and subsurface response to infiltration. One important aspect of this characterization is assessing the heavy and antecedent rainfall conditions that lead to shallow landsliding. In this paper, we investigate the direct current (DC) resistivity method as a tool for quickly estimating soil thickness over a steep (33–40°) zero-order basin in the Oregon Coast Range, a landslide prone region. Point measurements throughout the basin showed bedrock depths between 0.55 and 3.2 m. Resistivity of soil and bedrock samples collected from the site was measured for degrees of saturation between 40 and 92%. Resistivity of the soil was typically higher than that of the bedrock for degrees of saturation lower than 70%. Results from the laboratory measurements and point-depth measurements were used in a numerical model to evaluate the resistivity contrast at the soil-bedrock interface. A decreasing-with-depth resistivity contrast was apparent at the interface in the modeling results. At the field site, three transects were surveyed where coincident ground truth measurements of bedrock depth were available, to test the accuracy of the method. The same decreasing-with-depth resistivity trend that was apparent in the model was also present in the survey data. The resistivity contour of between 1,000 and 2,000 Ωm that marked the top of the contrast was our interpreted bedrock depth in the survey data. Kriged depth-to-bedrock maps were created from both the field-measured ground truth obtained with a soil probe and interpreted depths from the resistivity tomography, and these were compared for accuracy graphically. Depths were interpolated as far as 16.5 m laterally from the resistivity survey lines with root mean squared error (RMSE) = 27 cm between the measured and interpreted depth at those locations. Using several transects and analysis of the subsurface
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Motivations of backpackers in the Cape Coast-Elmina Conurbation, Ghana
Frederick Dayour
2013-01-01
Research has shown that the backpacker market is one of the tourism markets that economically benefit local communities than the conventional market or mass tourists. The purpose of the study was to examine the motivations of backpackers in the Cape Coast-Elmina conurbation, Ghana. Questionnaire was used to collect data from 184 backpackers in Cape Coast and Elmina. Factor Analysis and some descriptive statistical analysis were employed in presenting the report. The st...
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Energy benchmarking for shopping centers in Gulf Coast region
International Nuclear Information System (INIS)
Juaidi, Adel; AlFaris, Fadi; Montoya, Francisco G.; Manzano-Agugliaro, Francisco
2016-01-01
Building sector consumes a significant amount of energy worldwide (up to 40% of the total global energy); moreover, by the year 2030 the consumption is expected to increase by 50%. One of the reasons is that the performance of buildings and its components degrade over the years. In recent years, energy benchmarking for government office buildings, large scale public buildings and large commercial buildings is one of the key energy saving projects for promoting the development of building energy efficiency and sustainable energy savings in Gulf Cooperation Council (GCC) countries. Benchmarking would increase the purchase of energy efficient equipment, reducing energy bills, CO_2 emissions and conventional air pollution. This paper focuses on energy benchmarking for shopping centers in Gulf Coast Region. In addition, this paper will analyze a sample of shopping centers data in Gulf Coast Region (Dubai, Ajman, Sharjah, Oman and Bahrain). It aims to develop a benchmark for these shopping centers by highlighting the status of energy consumption performance. This research will support the sustainability movement in Gulf area through classifying the shopping centers into: Poor, Usual and Best Practices in terms of energy efficiency. According to the benchmarking analysis in this paper, the shopping centers best energy management practices in the Gulf Coast Region are the buildings that consume less than 810 kW h/m"2/yr, whereas the poor building practices are the centers that consume greater than 1439 kW h/m"2/yr. The conclusions of this work can be used as a reference for shopping centres benchmarking with similar climate. - Highlights: •The energy consumption data of shopping centers in Gulf Coast Region were gathered. •A benchmarking of energy consumption for the public areas for the shopping centers in the Gulf Coast Region was developed. •The shopping centers have the usual practice in the region between 810 kW h/m"2/yr and 1439 kW h/m"2/yr.
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DeLorme, D.; Collini, R.; Stephens, S. H.
2017-12-01
As sea level rises, nuisance flooding along coasts is increasing. There is a need to understand how the public views flooding events in order to tailor communications to different audiences appropriately and help improve community resilience. This interdisciplinary presentation is intended to foster greater awareness about present-day nuisance flooding, ongoing conversation about best practices for accurately and effectively communicating about this "cumulative hazard" and its risks, and consideration about possible preparation and mitigation options for community resilience. The presentation will begin by defining and explaining nuisance flooding according to scientific experts and the scholarly literature. Next, we will share several specific examples of how nuisance flooding is increasingly impacting certain areas in the Northern U.S. Gulf Coast to demonstrate the importance of raising attention to and better understanding of this phenomenon across a range of audiences. We will particularly focus on the complex interrelated social, economic, and ecological issues associated with this hazard. Then, we will compare and contrast conceptualizations of nuisance flooding (characteristics, causes, consequences) and associated concerns from the viewpoints and experiences of various stakeholders in the Northern U.S. Gulf Coast (e.g., natural resource managers, community planners, extension specialists). These data are synthesized from multiple research methods and engagement mechanisms (e.g., focus groups, workshop mapping exercises) implemented during the first year of a multi-year NOAA-sponsored interdisciplinary project on Dynamic Sea Level Rise Assessments of the Ability of Natural and Nature-based Features to Mitigate Surge and Nuisance Flooding. To conclude, we will provide future research recommendations along with references and resources about nuisance flooding.
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Geological and geophysical surveys of Visakhapatnam coast
Digital Repository Service at National Institute of Oceanography (India)
Rao, T.C.S.; Rao, K.M.; Lakshminarayana, S.
Continuous records of the total earth's magnetic field and the surface sediment samples from the ocean bottom have been collected off Ramakrishna Beach and Lawsons Bay along the Visakhapatnam Coast. The magnetic data has recorded significant...
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Sieh, K.; Daly, P.; McKinnon, E. E.; Tai, Y. S.; Feener, R. M.; Ishmail, N.
2017-12-01
Our colleagues and we have reconstructed partial earthquake and tsunami histories along the coast of Aceh, Sumatra. Chlieh et al (2006) documented and modeled deformation of offshore islands associated with the 2004 rupture. Meltzner et al (2010) found coral evidence of uplifts in 1394±2 and 1450±3 CE. Sieh et al. (2015) documented associated tsunami that destroyed a structure built in 1366±3 CE, 40 km east of Banda Aceh at Lamreh. Since 2015, our landscape archaeology survey of 43 coastal villages over a 40-km reach of the coast has revealed 995 archaeological sites ranging from 10th century to present and containing over 5,000 carved gravestones and 50,000 ceramic sherds. The distribution of ceramic material suggests 7 discrete areas of cultural activity before the 1394 tsunami. Six of these appear to be villages that used imported ceramics and have been populated since the 10th century. However, detailed analysis indicates a clear reduction in activity between 1360 and 1450 CE. This suggests that one or both of the 1394 and 1450 tsunami disrupted the villages. The distribution of post-1500 CE ceramic material shows a gradual repopulation of pre-tsunami sites and a significant expansion of activity starting at the end of the 16th Century, for all areas except Lamreh. Only at on the elevated Lambaro highlands, above modern Lamreh, does material conclusively date between the 1394 and 1450 CE tsunamis. This historic trading site of "Lambri" contains large quantities of ceramics ranging from the early 11th century until the early 16th century, including precisely dated early-Ming (1403-1425 CE) material, some of which is distinctive imperial trade ceramics. We suspect that after the 1394 tsunami destroyed the other coastal settlements, the relatively safe highlands of Lambri were the only areas of the coast utilized for at least 50 years. After about 1450 CE, however, these highlands were abandoned, while the low-lying coastal communities began once again to
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Ustaszewski, Kamil; Schmid, Stefan M.; Lugović, Boško; Schuster, Ralf; Schaltegger, Urs; Bernoulli, Daniel; Hottinger, Lukas; Kounov, Alexandre; Fügenschuh, Bernhard; Schefer, Senecio
2009-03-01
The Kozara Mountains of northern Bosnia and Hercegovina form part of the internal Dinarides and host two tectonically juxtaposed ophiolitic successions of different age. The southern part of the Kozara Mountains exposes the Western Vardar Ophiolitic Unit, which was obducted onto the Adriatic margin in the Late Jurassic. The northern part exposes a bimodal igneous succession that was thrust onto the Western Vardar Ophiolitic Unit during the latest Cretaceous to Early Paleogene. This bimodal igneous succession comprises isotropic gabbros, doleritic dikes, basaltic pillow lavas and rhyolites. Pelagic limestones, intercalated with pillow lavas, yielded a Campanian globotruncanid association, consistent with concordant U-Pb ages on zircons from dolerites and rhyolites of 81.39 ± 0.11 and 81.6 ± 0.12 Ma, respectively. Chondrite-normalised rare earth element patterns of the bimodal igneous rocks show enrichment of LREE over HREE. Primitive mantle-normalised multi-element diagrams do not reveal significant depletion of HFSE. The ɛNd(T) and initial 87Sr/ 86Sr isotopic values range from + 4.4 to + 6.3 and from 0.70346 to 0.70507 respectively, suggesting an intraoceanic origin. The bimodal igneous succession is unconformably overlain by Maastrichtian to Paleocene siliciclastics that contain abundant ophiolitic detritus, suggesting reworking of the Campanian magmatics. An Eocene turbiditic sandstone succession unconformably covers both the Western Vardar Ophiolitic Unit and the Late Cretaceous bimodal igneous successions. These observations suggest that the Adriatic Plate and the Europe-derived Tisza and Dacia Mega-Units were still separated by a deep basin floored by oceanic lithosphere until the Campanian and that its closure did not occur before the Maastrichtian to earliest Paleogene. This Late Cretaceous oceanic domain probably represented a remnant of the Vardar Ocean, or alternatively, the Alpine Tethys; possibly the traces of both oceanic domains were connected in
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Circadian Rhythm of Ambient Noise Off the Southeast Coast of India
Kannan, R.; Latha, G.; Prashanthi Devi, M.
An ambient noise system consisting of a vertical linear hydrophone array was deployed in the shallow waters off Chennai, southeast coast of India from 1 August to 16 September 2013 to record ambient ocean noise of frequencies up to 10kHz. Biological sounds, which are broadband, short duration signals resulting from Terapon theraps, a native species, are a prominent feature of the ocean soundscape. Terapon activity peaks at 8pm and 11pm, and its presence is not observed after 12 midnight in both the months. In the other period, the ambient noise fluctuation is due to wind and vessel traffic. Hence, the present study focuses on the description of the ambient noise fluctuation over two 12h periods, i.e., 12 midnight-12 noon considered as period I, and 12 noon-12 midnight as period II in order to show the circadian rhythm of ambient noise. In this study area, Terapon vocalization reached 25dB above the ambient noise level and it dominates the short-term spectra records in the 0.4-4kHz range. All Terapon signals had daily patterns of sound production with highest levels of activity after dusk during the study period. The result shows that the circadian rhythm of ambient noise is mainly of biological sound generated by Terapon and it is reported first time in the shallow waters off the southeast coast of India.
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Latitudinal variation in nematode diversity and ecological roles along the Chinese coast.
Wu, Jihua; Chen, Huili; Zhang, Youzheng
2016-11-01
To test changes in the phylogenetic relatedness, niche breadth, and life-history strategies of nematodes along a latitudinal gradient. Sixteen wetland locations along the Pacific coast of China, from 20°N to 40°N. Linear regression was used to relate nematode phylogenetic relatedness (average taxonomic distinctness (AvTD) and average phylogenetic diversity [AvPD]), life-history group (based on " c - p " colonizer-persister group classification), and dietary specificity (based on guild classification of feeding selectivity) to latitude. Wetland nematode taxonomic diversity (richness and Shannon diversity indices) decreased with increasing latitude along the Chinese coast. Phylogenetic diversity indices (AvTD and AvPD) significantly increased with increasing latitude. This indicates that at lower latitudes, species within the nematode community were more closely related. With increasing latitude, the nematode relative richness and abundance decreased for selective deposit feeders but increased for nonselective deposit feeders. The proportion of general opportunists decreased with increasing latitude, but persisters showed the opposite trend. The annual temperature range and the pH of sediments were more important than vegetation type in structuring nematode communities. Nematode niche breadth was narrower at lower latitudes with respect to dietary specificity. Higher latitudes with a more variable climate favor r over K life-history strategists. Nematode communities at lower latitudes contained more closely related species.
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Synthetic tsunamis along the Israeli coast.
Tobias, Joshua; Stiassnie, Michael
2012-04-13
The new mathematical model for tsunami evolution by Tobias & Stiassnie (Tobias & Stiassnie 2011 J. Geophys. Res. Oceans 116, C06026) is used to derive a synthetic tsunami database for the southern part of the Eastern Mediterranean coast. Information about coastal tsunami amplitudes, half-periods, currents and inundation levels is presented.
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Karthikeyan, A.
2015-12-01
The 2004 Indian Tsunami has deposited a varied layer of sand sheets along the coast which depends upon on the coastal topography. Recognition Tsunami deposits were clearly observed as the sand sheets were laid over the soil which is distinctly different due to differences in the weathering and presence of organic material of vegetation. To understand the preservation potential of 2004 tsunami deposits we were studied a transect profile with seven pits sediments along Thiruvengadu coast , Nagapattinam. The study reveals that presence of sand sheets preserved a mínimum of 10 cm thickness to máximum of 22 cm and the distance is 300 from HTL. From the present study six sedimentary layers were identfied which are (a) Top sediments deposited after IOT, (b). Tsunami sand sheets (c) Silty sand (d). Erosional base and top (e) Silty sand (d) Lagoonal sediments. The 2013 Phailin cyclon with wind speed of 220 kmph which was remnant cyclonic circulation from south china; it had major impact on geomorphology and sedimentology of odisha coast. At rushikulya river mouth, Ganjam district, cyclone had produced washover sand sheets as described in eyewitness along the river mouth of both north and south bar. The study reveals that the washover sand sheets provides the inundation of the water level, and characteristics of sediments where storm deposit has a highly variable grain-size distribution with a marked coarsening at its landward extent, is better sorted, coarser, and has a sharp, non-erosional lower contact associated with buried vegetation and soil. Also, the thickness of cyclone deposits are about 5 cm with the distance from coast 80 m, heavy mineral percentage ranges between 9 % to 75% for entire pit and sandsheets lateral extent are about 45 m. The presence of the laminations and alternate layers of heavy minerals are indicative of the complexity of sedimentation on the coast. The recent marine event Phailin cylcone deposits and 2004 tsunami deposits characteristic and
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76 FR 7131 - Safety Zones; Eleventh Coast Guard District Annual Fireworks Events
2011-02-09
...-AA00 Safety Zones; Eleventh Coast Guard District Annual Fireworks Events AGENCY: Coast Guard, DHS... permanent safety zones to ensure public safety during annual firework displays at various locations in the... events, delete events that are no longer occurring, add new unlisted annual fireworks events to the...
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Human interreference along the coast of Goa
Digital Repository Service at National Institute of Oceanography (India)
Mascarenhas, A.
, the promotion of tourism, increase in population and construction activities have created a heavy demand for resources resulting in congestion on coasts, increase in density of constructions and pressures on infrastructure. Large scale conversions of dune belts...
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Distribution of seagrasses along the Indian coast
Digital Repository Service at National Institute of Oceanography (India)
Jagtap, T.G.
the Tamil Nadu Coast. Seagrasses were observed from intertidal to subtidal regions down to 8 m depth. Thalassia hemprichii (Ehrenberg) Aschers. and Cymodocea serrulata (R. Brown) Aschers. and Magnus were the dominant seagrasses in the subtidal zones...
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Assessment of wave energy potential along the south coast of Java Island
Song, Qingyang; Mayerle, Roberto
2018-04-01
The south coast of Java Island has a great potential for wave energy. A long-term analysis of a 10-year wave dataset obtained from the ERA-Interim database is performed for preliminary wave energy assessment in this area, and it was seen that the annual median power is expected to exceed 20kW/m along the coast. A coastal wave model with an unstructured grid was run to reveal the wave conditions and to assess the wave energy potential along the coast in detail. The effect of swells and local wind on the wave conditions is investigated. Annual median wave power, water depth and distance from the coast are selected as criteria for the identification of suitable locations for wave energy conversion. Two zones within the study area emerge to be suitable for wave energy extraction. Swells from the southwest turned out to be the major source of wave energy and highest monthly median wave power reached about 33kW/m.
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Seyler, L. M.; Rempfert, K. R.; Kraus, E. A.; Spear, J. R.; Templeton, A. S.; Schrenk, M. O.
2017-12-01
Environmental metabolomics is an emerging approach used to study ecosystem properties. Through bioinformatic comparisons to metagenomic data sets, metabolomics can be used to study microbial adaptations and responses to varying environmental conditions. Since the techniques are highly parallel to organic geochemistry approaches, metabolomics can also provide insight into biogeochemical processes. These analyses are a reflection of metabolic potential and intersection with other organisms and environmental components. Here, we used an untargeted metabolomics approach to characterize dissolved organic carbon and aqueous metabolites from groundwater obtained from an actively serpentinizing habitat. Serpentinites are known to support microbial communities that feed off of the products of serpentinization (such as methane and H2 gas), while adapted to harsh environmental conditions such as high pH and low DIC availability. However, the biochemistry of microbial populations that inhabit these environments are understudied and are complicated by overlapping biotic and abiotic processes. The aim of this study was to identify potential sources of carbon in an environment that is depleted of soluble inorganic carbon, and to characterize the flow of metabolites and describe overlapping biogenic and abiogenic processes impacting carbon cycling in serpentinizing rocks. We applied untargeted metabolomics techniques to groundwater taken from a series of wells drilled into the Semail Ophiolite in Oman.. Samples were analyzed via quadrupole time-of-flight liquid chromatography tandem mass spectrometry (QToF-LC/MS/MS). Metabolomes and metagenomic data were imported into Progenesis QI software for statistical analysis and correlation, and metabolic networks constructed using the Genome-Linked Application for Metabolic Maps (GLAMM), a web interface tool. Further multivariate statistical analyses and quality control was performed using EZinfo. Pools of dissolved organic carbon could
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75 FR 53195 - Security Zone; U.S. Coast Guard BSU Seattle, Pier 36, Seattle, WA
2010-08-31
... its effects on them and participate in the rulemaking process. Small businesses may send comments on... DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 165 [Docket No. USCG-2010-0021] RIN 1625-AA87 Security Zone; U.S. Coast Guard BSU Seattle, Pier 36, Seattle, WA AGENCY: Coast Guard, DHS. ACTION...
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Morphological variation in the hydromedusa genus Polyorchis on the west coast of North America
Energy Technology Data Exchange (ETDEWEB)
Rees, John T.; Larson, R. J.
1980-11-01
Morphological variation in the hydromedusan genus Polyorchis on the west coast of North American is analyzed in relation to gonad number, tentacle number, and radial canal diverticula number relative to the height of the bell. In specimens of Polyorchis examined, it is concluded that P. penicillatus (Eschscholtz, 1829) is highly variable morphologically over its known geographic range from Alaska to Baja California. P. montereyensis Skogsberg, 1948 is considered a synonym of P. penicillatus, while P. haplus Skogsberg. 1948, is retained as a valid species.
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The Coast Artillery Journal. Volume 59, Number 5, November 1923
1923-11-01
white blue, red, white, and that upon the restoration King Kamehameha III de- C) Coast Defense, of Pearl Harbor, Coast Defenses of Honolulu, 41st Artil...suspicion that more than one variety of the flag may have existed. All we know certainly of the early history of the flag is that Vancouv~r gave Kamehameha I... Kamehameha , all sorts of mechanical difficultie3 with the tractors and other motor transportation were developed. These organizations took approximately
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33 CFR 165.506 - Safety Zones; Fifth Coast Guard District Fireworks Displays.
2010-07-01
... District Fireworks Displays. 165.506 Section 165.506 Navigation and Navigable Waters COAST GUARD... § 165.506 Safety Zones; Fifth Coast Guard District Fireworks Displays. (a) Regulations. The following regulations apply to the fireworks safety zones listed in the Table to § 165.506. (1) The general regulations...
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2013-03-28
... California State Implementation Plan, South Coast Air Quality Management District AGENCY: Environmental... revision to the South Coast Air Quality Management District (SCAQMD) portion of the California State...) * * * (411) * * * (i) * * * (F) South Coast Air Quality Management District. (1) Rule 463, ``Organic Liquid...
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2011-05-27
... the California State Implementation Plan, South Coast Air Quality Management District AGENCY... the South Coast Air Quality Management District (SCAQMD) portion of the California State... overwhelmingly formed as a secondary pollutant. (South Coast 2007 Air Quality Management Plan, page ES-9...
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2011-07-15
... the California State Implementation Plan, South Coast Air Quality Management District AGENCY... approve revisions to the South Coast Air Quality Management District (SCAQMD) portion of the California... Governor's Designee. (i) Incorporation by reference. (A) South Coast Air Quality Management District. (1...
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2013-09-26
...] Revisions to the California State Implementation Plan, South Coast Air Quality Management District AGENCY... the South Coast Air Quality Management District (SCAQMD) portion of the California State...'s Designee. (i) Incorporation by Reference. (A) South Coast Air Quality Management District. (1...
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Zhao, Zhen; Xie, Zhiyong; Möller, Axel; Sturm, Renate; Tang, Jianhui; Zhang, Gan; Ebinghaus, Ralf
2012-11-01
The global distribution and long-range transport of polyfluoroalkyl substances (PFASs) were investigated using seawater samples collected from the Greenland Sea, East Atlantic Ocean and the Southern Ocean in 2009-2010. Elevated levels of ΣPFASs were detected in the North Atlantic Ocean with the concentrations ranging from 130 to 650 pg/L. In the Greenland Sea, the ΣPFASs concentrations ranged from 45 to 280 pg/L, and five most frequently detected compounds were perfluorooctanoic acid (PFOA), perfluorohexanesulfonate (PFHxS), perfluorohexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS). PFOA (15 pg/L) and PFOS (25-45 pg/L) were occasionally found in the Southern Ocean. In the Atlantic Ocean, the ΣPFASs concentration decreased from 2007 to 2010. The elevated PFOA level that resulted from melting snow and ice in Greenland Sea implies that the Arctic may have been driven by climate change and turned to be a source of PFASs for the marine ecosystem. Copyright © 2012 Elsevier Ltd. All rights reserved.
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33 CFR 23.15 - Coast Guard ensign.
2010-07-01
... distinctive emblem of the Coast Guard in blue and white is placed with its center on a line with the lower..., the emblem covering a horizontal space of three stripes. [CGFR 57-35, 22 FR 6765, Aug. 22, 1957] ...
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Sissmann, O.; Martinez, I.; Deville, E.; Beaumont, V.; Pillot, D.; Prinzhofer, A.; Vacquand, C.; Chaduteau, C.; Agrinier, P.; Guyot, F. J.
2014-12-01
The isotopic compositions (d13C, d18O) of natural carbonates produced by the alteration of basic and ultrabasic rocks on the Oman ophiolite have been measured in order to better understand their formation mechanisms. Fossil carbonates developed on altered peridotitic samples, mostly found in fractures, and contemporary carbonates were studied. The samples bear a large range of d13C. Those collected in veins are magnesian (magnesite, dolomite) and have a carbon signature reflecting mixing of processes and important fractionation (-11‰ to 8‰). Their association with talc and lizardite suggests they are by-products of a serpentinization process, that must have occurred as a carbon-rich fluid was circulating at depth. On the other hand, the carbonates are mostly calcic when formed in alkaline springs, most of which are located in the vicinity of lithological discontinuities such as the peridotite-gabbro contact (Moho). Aragonite forms a few meters below the surface of the ponds in Mg-poor water, and is systematically associated with brucite (Mg(OH)2). This suggests most of the Mg dissolved at depth has reprecipitated during the fluid's ascension through fractures or faults as carbonates and serpentine. Further up, on the surface waters of the ponds (depleted in Mg and D.I.C.), thin calcite films precipitate and reach extremely negative d13C values (-28‰), which could reflect either a biological carbon source, or kinetic fractionation from pumping atmospheric CO2. Their formation represent an efficient and natural process for carbon dioxide mineral sequestration. The d18O signature from all samples confirm the minerals crystallized from a low-temperature fluid. The hyperalkaline conditions (pH between 11 and 12) allowing for these fast precipitation kinetics are generated by the serpentinization process occurring at depth, as indicated by the measured associated H2-rich gas flows (over 50%) seeping out to the surface.
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An operational wave forecasting system for the east coast of India
Sandhya, K. G.; Murty, P. L. N.; Deshmukh, Aditya N.; Balakrishnan Nair, T. M.; Shenoi, S. S. C.
2018-03-01
Demand for operational ocean state forecasting is increasing, owing to the ever-increasing marine activities in the context of blue economy. In the present study, an operational wave forecasting system for the east coast of India is proposed using unstructured Simulating WAves Nearshore model (UNSWAN). This modelling system uses very high resolution mesh near the Indian east coast and coarse resolution offshore, and thus avoids the necessity of nesting with a global wave model. The model is forced with European Centre for Medium-Range Weather Forecasts (ECMWF) winds and simulates wave parameters and wave spectra for the next 3 days. The spatial pictures of satellite data overlaid on simulated wave height show that the model is capable of simulating the significant wave heights and their gradients realistically. Spectral validation has been done using the available data to prove the reliability of the model. To further evaluate the model performance, the wave forecast for the entire year 2014 is evaluated against buoy measurements over the region at 4 waverider buoy locations. Seasonal analysis of significant wave height (Hs) at the four locations showed that the correlation between the modelled and observed was the highest (in the range 0.78-0.96) during the post-monsoon season. The variability of Hs was also the highest during this season at all locations. The error statistics showed clear seasonal and geographical location dependence. The root mean square error at Visakhapatnam was the same (0.25) for all seasons, but it was the smallest for pre-monsoon season (0.12 m and 0.17 m) for Puducherry and Gopalpur. The wind sea component showed higher variability compared to the corresponding swell component in all locations and for all seasons. The variability was picked by the model to a reasonable level in most of the cases. The results of statistical analysis show that the modelling system is suitable for use in the operational scenario.
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2011-08-04
... the California State Implementation Plan; South Coast Air Quality Management District AGENCY... the South Coast Air Quality Management District portion of the California State Implementation Plan... following local rule: South Coast Air Quality Management District Rule 1175, Control of Emissions from the...
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2010-10-01
... and tests: Coast Guard action. 159.007-7 Section 159.007-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL APPROVAL....007-7 Application for acceptance for production inspections and tests: Coast Guard action. (a) From...
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Inshore small-mesh trawling survey of the Cape south coast. Part 5 ...
African Journals Online (AJOL)
Inshore small-mesh trawling survey of the Cape south coast. Part 5. Crustacea, Stomatopoda, Isopoda and. Decapoda. B. Kensley and C.D. Buxton. Port Elizabeth Museum, Port Elizabeth. Forty-six species of Crustacea from the shallow marine waters of the southern Cape coast are listed. Five new records for the area.
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78 FR 8027 - Safety Zone, Coast Guard Exercise Area, Hood Canal, Washington
2013-02-05
... 5, 2012. The Coast Guard received zero comments submitted via regulations.gov and received zero... zero comments from the Small Business Administration on this rule. The Coast Guard certifies under 5 U... more in any one year. Though this rule will not result in such an expenditure, we do discuss the...
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International Nuclear Information System (INIS)
Nurrul Assyikeen Mohd Jaffary; Zal Uyun Wan Mahmood; Zaharudin Ahmad; Yii, Mei Wo; Kamarozaman Ishak
2010-01-01
The present distributions of 226 Ra, 228 Ra and activity ratios of 228 Ra/ 226 Ra covering the east coast of Peninsular Malaysia were studied. Sediment core samples were collected at 10 identified stations with the thickness of water column between 14 - 72 m depth during the cruise conducted in 2008. Activity concentrations of 226 Ra and 228 Ra in sediment cores of the studied area were in the range of 18.95 ±4.25 Bq/ kg to 46.48 ± 6.41 Bq/ kg dry wt. and 35.50 ± 7.50 Bq/ kg to 77.10 ±11.37 Bq/ kg dry wt., respectively. Meanwhile, the calculated activity ratios of 228 Ra/ 226 Ra were varied mostly 1.48 to 2.24. The finding showed that there has relationships between 226 Ra, 228 Ra and oceanographic parameters which are can be attributed for better understanding of its transport processes and behavior in the east coast of Peninsular Malaysia marine environment. (author)
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The Commercial Profitability of Growing Hybrid Eucalyptus Clones in The Coast Province, Kenya
Directory of Open Access Journals (Sweden)
Balozi Bekuta Kirongo
2014-04-01
Full Text Available Due to the current high demand for timber, fuelwood, and building poles and the realization that tree growing may pay dividends in the short and long term, many farmers are planting trees on their farms. Farmers are increasingly planting eucalyptus partly due to the fast growth rates of the hybrid clones as well as the opportunity to earn money within a short time. In this paper we report on the profitability of growing eucalyptus hybrid clones in the coastal region, Kenya. Tree growth and cost data was sourced from farmers in Malindi, Kilifi, and Msambweni. Market information was sourced from hardwares in North and South Coast while tree growth models were used to provide average tree sizes at various ages. Results showed that a farmer could make a net income of upto Kshs.500,000.00 (USD6,250 in 5 years. Farmers in the South Coast (Kwale and Msambweni spent more on transport than their counterparts in the North Coast (near Gede-KEFRI. This, added to the fact that trees in the South Coast (Msambweni grew less compared to those in North Coast meant that farmers in the south made less profits.
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Natural radioactivity measurements in beach sand along the South East coast of Tamil Nadu, India
International Nuclear Information System (INIS)
Selvi, B.S.; Vijayakumar, B.; Ravi, P.M.
2017-01-01
Measurement of natural radioactivity in beach sand was carried out along the south east coast of Tamil Nadu, India, The activity concentrations of "2"3"8U, "2"3"2Th and "4"0K in beach sand ranged from 2 to 2,762 Bqkg"-"1 with a mean value of 236 Bq.kg"-"1, 7 to 30,872 Bqkg"-"1 with a mean value of 2,300 Bqkg"-"1 and 6.0 to 890 Bqkg"-"1 with a mean value of 85 Bqkg"-"1, respectively. The Radium Equivalent Activity, the external hazard index, the absorbed dose rate and the annual effective dose were assessed and compared with world average values. The results indicate that the absorbed dose rates range from 10 to 20506 nGyh"-"1 with mean value of 1545 nGy.h"-"1. The annual effective dose range between 0.01 and 25.15 mSvy"-"1, with the mean value of 1.90 mSvy"-"1. (author)
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Marine archaeological exploration on the western coast, Gulf of Khambhat
Digital Repository Service at National Institute of Oceanography (India)
Gaur, A.S.; Bhatt, B.K.
large number of stone anchors at Gogha, Hatab, and Gopnath. These are similar to those reported from the western coast of the Saurashtra, particularly at Dwarka (Gaur et al. 2001), Bet Dwarka (Sundaresh et al. 2004), Miyani, Visawada (Gaur et al. 2007.... Stone Anchors from Bet Dwarka Island, Gujarat Coast, Bulletin of Australian Institute of Maritime Archaeology 26: 43-50 Yang, Q.Z. 1990. South- Song Stone Anchors in China, Korea and Japan, International Journal of Nautical Archaeology 19 (2): 113-121. ...
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'Saurashtra stone anchors' (Ring-stones) from Dwarka and Somnath, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Gaur, A.S.; Sundaresh; Tripati, S.; Gudigar, P.; Bandodkar, S.N.
Last two decades of marine archaeological research along the Indian coast has brought to light a large number of stone anchors of different types and sizes, indicating that the Indian coast has witnessed brisk maritime activities in the past...
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2011-12-20
... the California State Implementation Plan, South Coast Air Quality Management District AGENCY... approve a revision to the South Coast Air Quality Management District (SCAQMD) portion of the California... Reference (A) South Coast Air Quality Management District (1) Rule 2005, ``New Source Review for RECLAIM...
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2012-12-14
... the California State Implementation Plan, South Coast Air Quality Management District AGENCY... of South Coast Air Quality Management District (SCAQMD) Rule 317, ``Clean Air Act Non- Attainment Fee... of Appeals for the District of Columbia Circuit. South Coast Air Quality Management District v. EPA...
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2011-08-04
... California State Implementation Plan; South Coast Air Quality Management District AGENCY: Environmental... revision to the South Coast Air Quality Management District portion of the California State Implementation... Submittal A. What rule did the State submit? We are approving South Coast Air Quality Management District...
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Oceanic Storm Characteristics off the Kennedy Space Center Coast
Wilson, J. G.; Simpson, A. A.; Cummins, K. L.; Kiriazes, J. J.; Brown, R. G.; Mata, C. T.
2014-01-01
Natural cloud-to-ground lightning may behave differently depending on the characteristics of the attachment mediums, including the peak current (inferred from radiation fields) and the number of ground strike locations per flash. Existing literature has raised questions over the years on these characteristics of lightning over oceans, and the behaviors are not yet well understood. To investigate this we will obtain identical electric field observations over adjacent land and ocean regions during both clear air and thunderstorm periods. Oceanic observations will be obtained using a 3-meter NOAA buoy that has been instrumented with a Campbell Scientific electric field mill and New Mexico Techs slow antenna, to measure the electric fields aloft. We are currently obtaining measurements from this system on-shore at the Florida coast, to calibrate and better understand the behavior of the system in elevated-field environments. Sometime during winter 2013, this system will be moored 20NM off the coast of the Kennedy Space Center. Measurements from this system will be compared to the existing on-shore electric field mill suite of 31 sensors and a coastal slow antenna. Supporting observations will be provided by New Mexico Techs Lightning Mapping Array, the Eastern Range Cloud to Ground Lightning Surveillance System, and the National Lightning Detection Network. An existing network of high-speed cameras will be used to capture cloud-to-ground lightning strikes over the terrain regions to identify a valid data set for analysis. This on-going project will demonstrate the value of off-shore electric field measurements for safety-related decision making at KSC, and may improve our understanding of relative lightning risk to objects on the ground vs. ocean. This presentation will provide an overview of this new instrumentation, and a summary of our progress to date.
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A review and re-assessment of sediment transport along the Goa Coast, India
Digital Repository Service at National Institute of Oceanography (India)
Kunte, P.D.; Wagle, B.G.; Yasuhiro Sugimori
Although, a variety of methods have been employed to determine sediment transport along Goa coast, India, the results differ in some sections. Fifteen studies have been reviewed, compared, re-assessed and a corrected shore drift map of the Goa coast...
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Rubal, Marcos; Veiga, Puri; Cacabelos, Eva; Moreira, Juan; Sousa-Pinto, Isabel
2013-03-01
There are well-documented changes in abundance and geographical range of intertidal invertebrates related to climate change at north Europe. However, the effect of sea surface warming on intertidal invertebrates has been poorly studied at lower latitudes. Here we analyze potential changes in the abundance patterns and distribution range of rocky intertidal gastropods related to climate change along the Iberian Peninsula. To achieve this aim, the spatial distribution and range of sub-tropical, warm- and cold-water species of intertidal gastropods was explored by a fully hierarchical sampling design considering four different spatial scales, i.e. from region (100 s of km apart) to quadrats (ms apart). Variability on their patterns of abundance was explored by analysis of variance, changes on their distribution ranges were detected by comparing with previous records and their relationship with sea water temperature was explored by rank correlation analyses. Mean values of sea surface temperature along the Iberian coast, between 1949 and 2010, were obtained from in situ data compiled for three different grid squares: south Portugal, north Portugal, and Galicia. Lusitanian species did not show significant correlation with sea water temperature or changes on their distributional range or abundance, along the temperature gradient considered. The sub-tropical species Siphonaria pectinata has, however, increased its distribution range while boreal cold-water species showed the opposite pattern. The latter was more evident for Littorina littorea that was almost absent from the studied rocky shores of the Iberian Peninsula. Sub-tropical and boreal species showed significant but opposite correlation with sea water temperature. We hypothesized that the energetic cost of frequent exposures to sub-lethal temperatures might be responsible for these shifts. Therefore, intertidal gastropods at the Atlantic Iberian Peninsula coast are responding to the effect of global warming as it
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Actinides detection in the Pacific Coast of Mexico
International Nuclear Information System (INIS)
Ordonez R, E.; Almazan T, M. G.; Cruz C, G. J.; Ramirez S, R.
2013-10-01
In this work is evaluated the activity of the alpha emitters, uranium and plutonium, in sand samples and seawater coming from diverse points of the Mexican Pacific Coast (Baja California, Jalisco, Colima and Guerrero). The used techniques were: radiochemistry separation and alpha spectrometry, with these techniques could be observed that the sand contains natural uranium and trace quantities of 239 Pu and 240 Pu combinations. The biggest activity in Pu was found in Finisterra, Baja California Sur (0.13 Bq/kg) and the minor (0 Bq/kg) in Miramar, Colima. The relationship between the geographical localization and the Pu activity suggests that while there is more interaction of the site with the oceanic currents, more is the content of Pu in the sands of the coast. (Author)
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Nayak, Ganapati; D'Souza, Joseph
2010-05-01
Coastal and estuarine environments, world over are facing immense impact due to both natural and anthropogenic processes. The natural processes include climatic changes, rise in sea level, cyclone, flood, tsunamis, coastal erosion, salinity ingress and siltation. Likewise, anthropogenic pressures include population expansion, ocean traffic, dredging, resource exploitation, pollution, unplanned urbanization and intensive industrialization. Due to these impacts the fragile coastal ecosystem and its entities, like sub ecosystems, resources, morphological units are undergoing unprecedented degradation, rendering these coastal regions vulnerable, impinging risk to human population, livestock, properties, as also, devastation of resourceful lands. This accelerates economic fatalities and irreversible obliteration to the ecosystems. Evidences on the global concern towards this issue have been well established. The countries world over, including India, pledged consensus towards the protection of the fragile coastal ecosystems through UNCED, Agenda-21. India, on 19th February 1991, has designated specified corridors along the landward side of the coastline as "Coastal Regulatory Zones" (CRZ), through appropriate policy and law. In context with the CRZ notification, scientific database at local and site-specific areas, developed. Synergy of ecosystems, landscape and resources with demographic, tourism data, vis-à-vis, economic corridors/sectors aided the paradigms and criterion for local and site specific prescriptions for Goa Coast. The Goa coast is a part of central west coast of India and is characterized by pocket beaches flanked by rocky cliffs, estuaries, bays, and at some places mangroves. Beaches in southern Goa are long and linear in nature with sand dunes. The Mandovi and Zuari estuarine system in Goa is the largest in this part of the coast. Mud flats, swampy marshes and wetlands are found mainly along estuaries and creeks. The beaches of Goa are stable beaches
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Regional gravity and magnetic studies over the continental margin of the Central West Coast of India
Digital Repository Service at National Institute of Oceanography (India)
SubbaRaju, L.V.; KameshRaju, K.A.; Subrahmanyam, V.; Rao, D.G.
Institute of Oceanography, Dona Paula, Goa 403 004, India Abstract Gravity studies over the continental margin of the central west coast of India show a sediment thickness of 2-3 km on the shelf associated with deeper hoest and graben structures, of 6 km... sequence ranges from Palaeocene to Recent. Stratigraphy as obtained from the explor atory wells BH-I, DCS-IA, HI2-1, and R6-110cated in the Bombay offshore basin is shown in Figure 2. Figure 3 depicts the seismogeological section of the Bombay offshore...
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Coast redwood live crown and sapwood
John-Pascal Berrill; Jesse L. Deffress; Jessica M. Engle
2012-01-01
Understanding crown rise and sapwood taper will help meet management objectives such as producing long branch-free boles for clear wood and old-growth restoration, or producing sawlogs with a high proportion of heartwood. Coast redwood (Sequoia sempervirens) tree crown ratio data were collected 20 years after partial harvesting in a 65-year-old second growth stand....
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U.S. Coast Guard Posture Statement With 2009 Budget in Brief
2008-02-01
projects, new Response Boat- Medium vessels, and improvements to our command, control, communications, and National Distress and Response System. It...to the Guardian Ethos cultivated over 217 years, the Coast Guard responded to over 27,000 Search and Rescue cases and saved over 5,000 lives in 2007...Transportation Security Administration ( TSA ) Visual Intermodal Protection and Response (VIPR) Teams, the Coast Guard’s newly- formed Deployable Operations Group
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Dinoflagellate cyst distribution in recent sediments along the south-east coast of India
Digital Repository Service at National Institute of Oceanography (India)
Narale, D.D.; Patil, J.S.; Anil, A
sediment) as compared to sub-tropical and temperate regions, but it is on a par with tropical regions, including the west coast of India Comparison of the cyst assemblage along the Indian coast revealed a smaller number of potentially harmful and red...
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Tide-surge interaction along the east coast of the Leizhou Peninsula, South China Sea
Zhang, Heng; Cheng, Weicong; Qiu, Xixi; Feng, Xiangbo; Gong, Wenping
2017-06-01
A triply-nested two-dimensional (2D) ocean circulation model along with observed sea level records are used to study tide-surge interaction along the east coast of the Leizhou Peninsula (LP) which is characterized by extensive mudflats, large tidal ranges and a complex coastline. The dependency of surge maxima on the water level and the phase of tide are respectively investigated using two statistical approaches. Results show that tide-surge interaction along the east coast of the LP is significant, where surges peak 3-6 h before or after the nearest high water. The triply-nested 2D ocean circulation model is used to quantify tide-surge interaction in this region and to investigate its physical cause. The largest amplitudes of tide-surge interaction are found in the shallow water region of the Leizhou Bay, with values up to 1 m during typhoon events. Numerical experiments reveal that nonlinear bottom friction is the main contributor to tide-surge interaction, while the contribution of the nonlinear advective effect can be neglected. The shallow water effect enhances the role of nonlinear bottom friction in determining tide-surge modulation, leaving the surge peaks usually occur on the rising or falling tide. It is also found that the relative contribution of local wind and remote wind is different depending on the storm track and storm intensity, which would finally affect the temporal and spatial distribution of tide-surge interaction during typhoon events. These findings confirm the importance of coupling storm surges and tides for the prediction of storm surge events in regions which are characterized by shallow water depths and large tidal ranges.
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Energy Technology Data Exchange (ETDEWEB)
Mellink, Eric, E-mail: emellink@cicese.m [Departamento de Biologia de la Conservacion, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, B.C. Carretera Tijuana-Ensenada Km. 107, 22860 Ensenada, B.C. (Mexico); Riojas-Lopez, Monica E., E-mail: meriojas@cucba.udg.m [Departamento de Ecologia, Centro Universitario de Ciencias Biologicas y Agropecuarias, Universidad de Guadalajara, Km. 15.5 Carretera a Nogales, 45100 Zapopan, Jalisco (Mexico); Luevano-Esparza, Jaime, E-mail: jluevano@cicese.m [Departamento de Biologia de la Conservacion, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, B.C. Carretera Tijuana-Ensenada Km. 107, 22860 Ensenada, B.C. (Mexico)
2009-07-15
We determined egg concentrations of organochlorines and thickness of eggshells from brown boobies at eight colonies ranging from the northern Gulf of California to southern Mexico. The only common residue was that of DDE, which was found in almost all eggs. DDE content apparently reflected pre-1990 DDT use in nearby agricultural areas and, at one site, intensive mosquito control for high-end tourism development. There were no inter-colony differences in eggshell thickness, and variation in this variable likely reflected individual bird characteristics and/or individual feeding source. This variable was not a good proxy to DDE exposure of brown boobies, under current DDE levels in the brown booby trophic chain. In the northern Gulf of California, eggshell thickness has recovered to pre-DDT conditions. Our data indicate that the Gulf of California and southwestern coast of Mexico have a healthy near-shore marine environment, as far as organochlorines are concerned. - Wide-range, current picture of organochlorine presence in the environment along the western coast of Mexico.
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International Nuclear Information System (INIS)
Mellink, Eric; Riojas-Lopez, Monica E.; Luevano-Esparza, Jaime
2009-01-01
We determined egg concentrations of organochlorines and thickness of eggshells from brown boobies at eight colonies ranging from the northern Gulf of California to southern Mexico. The only common residue was that of DDE, which was found in almost all eggs. DDE content apparently reflected pre-1990 DDT use in nearby agricultural areas and, at one site, intensive mosquito control for high-end tourism development. There were no inter-colony differences in eggshell thickness, and variation in this variable likely reflected individual bird characteristics and/or individual feeding source. This variable was not a good proxy to DDE exposure of brown boobies, under current DDE levels in the brown booby trophic chain. In the northern Gulf of California, eggshell thickness has recovered to pre-DDT conditions. Our data indicate that the Gulf of California and southwestern coast of Mexico have a healthy near-shore marine environment, as far as organochlorines are concerned. - Wide-range, current picture of organochlorine presence in the environment along the western coast of Mexico.
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Directory of Open Access Journals (Sweden)
D. E. Saveliev
2017-07-01
Full Text Available The article considers a chemical variation of accessory and ore-forming chrome spinels from the Kraka ultramafic massif at the different scales, from the deposit to the thin section. A correlation analysis of compositional and structural features of ultramafic rocks and ores was performed. The ultramafic rocks and chromitites in the studied massif show the distinct deformation structures and tectonite olivine fabric. A typical chemical gap (i.e. Cr#=Cr/(Cr+Al was observed between peridotite, on the one hand, and dunite and chromitite, on the other hand, on the scale of deposits and ore-bearing zones. The location and size of this gap depend on the type of deposit. The gap becomes wider from the disseminated tabular bodies to the typical podiform ones. It has been found that in the thin initial dunite veinlets in peridotite the chrome spinels chemistry changes gradually and there is no Cr# gap between peridotite and dunite. The dunite venlets show a strong olivine fabric, which is an evidence of their high-temperature plastic flow origin. It has been revealed that new chrome spinel grains previously formed as rods or needles and then coarsened. We explained this observation as the result of impurity segregation, coalescence and spheroidization induced by the plastic deformation of olivine. It is inferred that a solid crystal flow is the main requirement for the dunite and chromitite body formation in the Kraka ophiolite massif. In the solid stream, the mineral phase separation takes place. For example, olivine and orthopyroxene grains of parental peridotite separate from one another, and weaker (more mobile olivine grains form dunite bodies in which chromitite appears as a result of impurity segregation.
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Distribution and ecology of bees on the Polish Baltic coast (Hymenoptera, Apoidea, Apiformes
Directory of Open Access Journals (Sweden)
Banaszak Józef
2016-09-01
Full Text Available The present study provides data on the distribution of 128 bee species on the Polish Baltic coast. This brings the total number of species of Apiformes in this region to 164, including those that I reported earlier. The bee fauna of the Polish coast is characterized by a very high proportion of bumblebees and cuckoo bees (locally up to 70-80% of the total catch, and the dominant proportion of Megachilidae, especially Megachile species. The species diversity and dominance structure of the Apiformes differ between the western coast (a very high proportion of bumblebees and the eastern coast (a large number of dominant species. These results confirm my earlier hypothesis regarding the maritime-continental gradient of bumblebee abundance, indicating that the densities of these insects are higher in NW Poland. This study is the first to assess bee densities on coastal dunes in Poland.
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Plutonium isotopes in sediments from the Sudanese coast of the Red Sea
International Nuclear Information System (INIS)
Khatir Sam, A.; Ahamed, M.M.O.; El Khangi, F.; Roos, P.
2000-01-01
Activity concentrations of Pu isotopes in surface marine sediments collected from the Sudanese coast of the Red Sea is presented. The following concentration ranges were determined: 238 Pu, 4.7-28.6 mBq/kg; 239+240 Pu, 53-343 mBq/kg dry weight. The average activity ratios of 238 Pu/ 239+240 Pu (0.075 ± 0.045 mBqk/kg) and 239+240 Pu/ 137 Cs (0.026 ± 0.025 mBq/kg) are appropriately comparable to the literature values that are characteristic of the global fallout from the atmospheric nuclear weapon tests. However, 239/240 Pu/ 137 Cs ratio in sediments collected from the biologically rich fringing reef is an order of magnitude higher compared to other sampling locations. (author)
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Moore, Diane E.; Rymer, Michael J.
2012-05-01
Magnesium-rich clayey gouge similar to that comprising the two actively creeping strands of the San Andreas Fault in drill core from the San Andreas Fault Observatory at Depth (SAFOD) has been identified in a nearby outcrop of serpentinite within the fault zone at Nelson Creek. Each occurrence of the gouge consists of porphyroclasts of serpentinite and sedimentary rocks dispersed in a fine-grained, foliated matrix of Mg-rich smectitic clays. The clay minerals in all three gouges are interpreted to be the product of fluid-assisted, shear-enhanced reactions between quartzofeldspathic wall rocks and serpentinite that was tectonically entrained in the fault from a source in the Coast Range Ophiolite. We infer that the gouge at Nelson Creek connects to one or both of the gouge zones in the SAFOD core, and that similar gouge may occur at depths in between. The special significance of the outcrop is that it preserves the early stages of mineral reactions that are greatly advanced at depth, and it confirms the involvement of serpentinite and the Mg-rich phyllosilicate minerals that replace it in promoting creep along the central San Andreas Fault.
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Moore, Diane E.; Rymer, Michael J.
2012-01-01
Magnesium-rich clayey gouge similar to that comprising the two actively creeping strands of the San Andreas Fault in drill core from the San Andreas Fault Observatory at Depth (SAFOD) has been identified in a nearby outcrop of serpentinite within the fault zone at Nelson Creek. Each occurrence of the gouge consists of porphyroclasts of serpentinite and sedimentary rocks dispersed in a fine-grained, foliated matrix of Mg-rich smectitic clays. The clay minerals in all three gouges are interpreted to be the product of fluid-assisted, shear-enhanced reactions between quartzofeldspathic wall rocks and serpentinite that was tectonically entrained in the fault from a source in the Coast Range Ophiolite. We infer that the gouge at Nelson Creek connects to one or both of the gouge zones in the SAFOD core, and that similar gouge may occur at depths in between. The special significance of the outcrop is that it preserves the early stages of mineral reactions that are greatly advanced at depth, and it confirms the involvement of serpentinite and the Mg-rich phyllosilicate minerals that replace it in promoting creep along the central San Andreas Fault.
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Sporotrichosis (Sporothrix schenckii infection) in the New South Wales mid-north coast, 2000-2010.
Sivagnanam, Shobini; Bannan, Aiveen M; Chen, Sharon C-A; Ralph, Anna P
2012-05-21
To determine the geographical, epidemiological and clinical features of sporotrichosis (a cutaneous fungal infection caused by Sporothrix schenckii) in the New South Wales mid-north coast. We undertook a retrospective case review of S. schenckii infections that occurred during the period 2000-2010. Microbiology laboratory staff and medical practitioners in the NSW mid-north coast were contacted to identify cases through database searches and clinical data collection. Thirty-one cases of S. schenckii infection were identified. Twenty-one occurred in males, the mean age of patients was 59 years, and all cases with data available involved cutaneous disease affecting the limbs (multiple lesions in 18 of 20 cases). Despite an impression of temporal clustering (eight cases in 1 year), this was not statistically significant (P = 0.3). Most cases occurred in months with higher rainfall (13 of 14 cases with data available). Inoculating events included injuries in gardens, in bushland and on farms, and possible bites. Symptom duration before correct diagnosis ranged from 4 to 30 weeks (median, 8 weeks; data available for 15 cases), unnecessary antibacterial therapy was common (13 of 19 cases with data available), and morbidity occurred in the form of recurrence (three cases) and mild itraconazole-induced hepatotoxicity (two cases). In all cases with recorded treatment details, the patients received itraconazole, and the median duration of itraconazole treatment was 24 weeks. These data highlight that health providers on the NSW mid-north coast should consider sporotrichosis when patients present with characteristic lesions after an inoculating injury sustained from or contaminated by decaying vegetation. The risk may be higher in older people and in wetter months. Fungal culture to confirm the diagnosis needs to be specifically requested. In contrast to outbreaks reported from other states, the epidemiological pattern in NSW appears most consistent with sporadic occurrence
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Marine biodiversity in the Atlantic and Pacific coasts of South America: knowledge and gaps.
Miloslavich, Patricia; Klein, Eduardo; Díaz, Juan M; Hernández, Cristián E; Bigatti, Gregorio; Campos, Lucia; Artigas, Felipe; Castillo, Julio; Penchaszadeh, Pablo E; Neill, Paula E; Carranza, Alvar; Retana, María V; Díaz de Astarloa, Juan M; Lewis, Mirtha; Yorio, Pablo; Piriz, María L; Rodríguez, Diego; Yoneshigue-Valentin, Yocie; Gamboa, Luiz; Martín, Alberto
2011-01-31
The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three different oceanic domains--the Caribbean, the Pacific, and the Atlantic--ranging in latitude from 12∘N to 55∘S. The 10 countries that border these coasts have different research capabilities and taxonomic traditions that affect taxonomic knowledge. This paper analyzes the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America (SA): the Tropical East Pacific, the Humboldt Current,the Patagonian Shelf, the Brazilian Shelves, and the Tropical West Atlantic, and it provides a review of ecosystem threats and regional marine conservation strategies. South American marine biodiversity is least well known in the tropical subregions (with the exception of Costa Rica and Panama). Differences in total biodiversity were observed between the Atlantic and Pacific oceans at the same latitude. In the north of the continent, the Tropical East Pacific is richer in species than the Tropical West Atlantic, however, when standardized by coastal length, there is very little difference among them. In the south, the Humboldt Current system is much richer than the Patagonian Shelf. An analysis of endemism shows that 75% of the species are reported within only one of the SA regions, while about 22% of the species of SA are not reported elsewhere in the world. National and regional initiatives focusing on new exploration, especially to unknown areas and ecosystems, as well as collaboration among countries are fundamental to achieving the goal of completing inventories of species diversity and distribution.These inventories will allow accurate interpretation of the biogeography of its two oceanic coasts and latitudinal trends,and will also provide relevant information for science based policies.
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Stranding Events of Kogia Whales along the Brazilian Coast.
Directory of Open Access Journals (Sweden)
Jailson F Moura
Full Text Available The genus Kogia, which comprises only two extant species, Kogia sima and Kogia breviceps, represents one of the least known groups of cetaceans in the global ocean. In some coastal regions, however, stranding events of these species have been relatively common over the last decades. Stranding provides the opportunity to investigate the biology of these cetaceans and to explore the epidemiological aspects associated with the mortality of the organisms found on the beach. A number of disturbances (including pelagic fisheries, chemical pollution, boat strikes, and noise pollution have been confirmed to pose a particular threat to the Kogia species. However, no study has yet investigated potential relationships between environmental conditions and stranding events. Here we analyse how a collection of environmental, physical, and biological variables, such as wind, sea surface temperature (SST, water depth, and chlorophyll-a, correlate to Kogia stranding events along the Brazilian coast. The results of our statistical analyses suggest that K. sima is more likely found in warm tropical waters, which provide an explanation for the high frequency of stranding in northeastern Brazilian coast. In contrast, K. breviceps appears to have a preference for temperate and productive waters. Wind speed results to be also an important factor for predicting Kogia strandings in Brazilian coast. Additionally, literature information in combination with our own data and analyses of stomach contents confirms that oceanic cephalopods constitute the primary nutritional source of both Kogia species. By using the available information as a qualitative proxy for habitat preference and feeding ecology, our study provides a novel and comprehensive assessment of Kogia stranding data in relation to environmental conditions along the Brazilian coast.
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Self-stabilized Fractality of Sea-coasts Through Damped Erosion
Sapoval, B.; Baldassari, A.; Gabrielli, A.
2004-05-01
Coastline morphology is of current interest in geophysical research and coastline erosion has important economic consequences. At the same time, although the geometry of seacoasts is often used as an introductory archetype of fractal morphology in nature there has been no explanation about which physical mechanism could justify that empirical observation. The present work propose a minimal, but robust, model of evolution of rocky coasts towards fractality. The model describes how a stationary fractal geometry arises spontaneously from the mutual self-stabilization of a rocky coast morphology and sea eroding power. If, on one hand, erosion generally increases the geometrical irregularity of the coast, on the other hand this increase creates a stronger damping of the sea and a consequent diminution of its eroding power. The increased damping argument relies on the studies of fractal acoustical cavities, which have shown that viscous damping is augmented on a longer, irregular, surface. A minimal two-dimensional model of erosion is introduced which leads to the through a complex dynamics of the earth-sea interface, to the appearance of a stationary fractal seacoast with dimension close to 4/3. Fractal geometry plays here the role of a morphological attractor directly related to percolation geometry. The model reproduces at least qualitatively some of the features of real coasts using only simple ingredients: the randomness of the lithology and the decrease of the erosion power of the sea. B. Sapoval, Fractals (Aditech, Paris, 1989). B. Sapoval, O. Haeberlé, and S.Russ, J. Acoust. Soc. Am., 2014 (1997). B. Hébert B., B. Sapoval, and S.Russ, J. Acoust. Soc. Am., 1567 (1999).
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Office of Coast Survey Wrecks and Obstructions Database
National Oceanic and Atmospheric Administration, Department of Commerce — The Office of Coast Survey's Wrecks and Obstructions database contains information on the identified submerged wrecks and obstructions within the U.S. maritime...
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Avionics system design for requirements for the United States Coast Guard HH-65A Dolphin
Young, D. A.
1984-01-01
Aerospatiale Helicopter Corporation (AHC) was awarded a contract by the United States Coast Guard for a new Short Range Recovery (SRR) Helicopter on 14 June 1979. The award was based upon an overall evaluation of performance, cost, and technical suitability. In this last respect, the SRR helicopter was required to meet a wide variety of mission needs for which the integrated avionics system has a high importance. This paper illustrates the rationale for the avionics system requirements, the system architecture, its capabilities and reliability and its adaptability to a wide variety of military and commercial purposes.
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Tides in the Mandovi and Zuari estuaries, Goa, west coast of India
Indian Academy of Sciences (India)
Indian Ocean, including the Arabian Sea. As a result, the windward side of the Ghats receives high precipitation due to the topographic effect. The rainfall along the central west coast of India is about 250 cm during June–September. The Mandovi and the Zuari are two estuaries that are located along the west coast, in Goa.
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Bird Habitat Conservation at Various Scales in the Atlantic Coast Joint Venture
Andrew Milliken; Craig Watson; Chuck Hayes
2005-01-01
The Atlantic Coast Joint Venture is a partnership focused on the conservation of habitats for migratory birds within the Atlantic Flyway/Atlantic Coast Region from Maine south to Puerto Rico. In order to be effective in planning and implementing conservation in this large and diverse area, the joint venture must work at multiple spatial scales, from the largest ?...
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Dependence of frictional strength on compositional variations of Hayward fault rock gouges
Morrow, Carolyn A.; Moore, Diane E.; Lockner, David A.
2010-01-01
The northern termination of the locked portion of the Hayward Fault near Berkeley, California, is found to coincide with the transition from strong Franciscan metagraywacke to melange on the western side of the fault. Both of these units are juxtaposed with various serpentinite, gabbro and graywacke units to the east, suggesting that the gouges formed within the Hayward Fault zone may vary widely due to the mixing of adjacent rock units and that the mechanical behavior of the fault would be best modeled by determining the frictional properties of mixtures of the principal rock types. To this end, room temperature, water-saturated, triaxial shearing tests were conducted on binary and ternary mixtures of fine-grained gouges prepared from serpentinite and gabbro from the Coast Range Ophiolite, a Great Valley Sequence graywacke, and three different Franciscan Complex metasedimentary rocks. Friction coefficients ranged from 0.36 for the serpentinite to 0.84 for the gabbro, with four of the rock types having coefficients of friction ranging from 0.67-0.84. The friction coefficients of the mixtures can be predicted reliably by a simple weighted average of the end-member dry-weight percentages and strengths for all samples except those containing serpentinite. For the serpentinite mixtures, a linear trend between end-member values slightly overestimates the coefficients of friction in the midcomposition ranges. The range in strength for these rock admixtures suggests that both theoretical and numerical modeling of the fault should attempt to account for variations in rock and gouge properties.
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Tsunami hazard assessment along Diba-Oman and Diba-Al-Emirates coasts
Directory of Open Access Journals (Sweden)
El-Hussain Issa
2017-01-01
Full Text Available Tsunami is among the most devastating natural hazards phenomenon responsible for significant loss of life and property throughout history. The Sultanate of Oman and United Arab Emirates are among the Indian Ocean countries that were subjected to one confirmed tsunami in November 27, 1945 due to an Mw 8.1 earthquake in Makran Subduction Zone. In this study, we present preliminary deterministic tsunami hazard assessment for the coasts of Diba Oman and Diba Al-Emirates, which are located on the western coast of the Oman Sea. The tsunami vulnerability of these cities increases due to the construction of many critical infrastructures and urban concentration along their coasts. Therefore, tsunami hazard assessment is necessary to mitigate the risk on the socio-economic system and sustainable developments. The major known source of tsunamis able to impact both coasts of Oman and United Arab Emirates is the Makran Subduction Zone (MSZ which extends for approximately 900 km. The deterministic approach uses specific scenarios considering the maximum credible earthquakes occurring in the MSZ and computes the ensuing tsunami impact in the coasts of the study area. The maximum wave height graphs and inundation maps are obtained for tsunami scenarios caused by 8.8 earthquake magnitude in eastern MSZ and 8.2 magnitude from western MSZ. The Mw8.8 eastern MSZ causes a maximum inundation distance of 447 meters and a maximum flow depth of 1.37 meter. Maximum inundation distance larger than 420 meters occurs due to the Mw8.2 western MSZ scenario. For this scenario, numerical simulations show a maximum flow depth of about 2.34 meters.
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Significance of coast down time on safety and availability of a pool type fast breeder reactor
International Nuclear Information System (INIS)
Natesan, K.; Velusamy, K.; Selvaraj, P.; Chellapandi, P.
2015-01-01
Highlights: • Plant dynamics studies for quantifying the benefits of flow coast down time. • Establishment of minimum flow coast down time required for safety. • Assessment of influence of flow coast down on enhancing plant availability. • Synthesis of thermo mechanical benefits of flow coast down time on component design. - Abstract: Plant dynamic investigation towards establishing the influence of flow coast down time of primary and secondary sodium systems on safety and availability of plant has been carried out based on one dimensional analysis. From safety considerations, a minimum flow coast down time for primary sodium circuit is essential to be provided to limit the consequences of loss of flow event within allowable limits. Apart from safety benefits, large primary coast down time also improves plant availability by the elimination of reactor SCRAM during short term power failure events. Threshold values of SCRAM parameters also need optimization. By suitably selecting the threshold values for SCRAM parameters, significant reduction in the inertia of pumping systems can be derived to obtain desirable results on plant availability. With the optimization of threshold values and primary flow coast down behaviour equivalent to a halving time of 8 s, there is a possibility to eliminate reactor SCRAM during short term power failure events extending up to 0.75 s duration. Benefits of secondary flow halving on reducing transient thermal loading on components have also been investigated and mixed effects have been observed
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Stone sculptures of goddesses on the boats from Goa, west coast of India
Digital Repository Service at National Institute of Oceanography (India)
Gaur, A.S.; Kerkar, R.
Goa situated on the central west coast of India, has served as an overseas trading post since the early historic times. An onshore exploration along the river Mhadei in the north Goa on the west coast of India yielded 13 boat motifs of different...
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Thermal responses of marine animals with reference to Kalpakkam Coast (South East Coast of India)
International Nuclear Information System (INIS)
Shahul Hameed, P.; Syed Mohamed, H.E.; Krishnamoorthy, R.
2008-01-01
Kalpakkam has been chosen as model coastal site to study the impact of thermal discharges on water qualities, benthic animals and fishes. The results of this study are expected to be valid for any given open coastal location on the east and west coast of India. The present study investigates, the impact of the elevated temperature due to thermal discharge on two groups of marine animals viz. Benthos (non-swimming bottom dwellers) and fishes
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Saglam, Hacer; Ak, Orhan
2012-06-01
Specimens of Raja clavata were monthly collected at the coast of Havaalanı (Trabzon/Turkey) from January 2009 to December 2009 at depths between 20 and 40 m. A total of 230 individuals of thornback ray (131 females and 99 males) were collected by bottom trawls during research cruises. Using logistic regression, it was determined that TL at 50% maturity of males was 718 mm TL and of females 746 mm TL. The ovarian fecundity ranged from 27 to 60 yellow follicles in both ovaries. Females carrying egg cases were found in July and October. Variations in the gonadosomatic and hepatosomatic indices indicated a continuous reproductive cycle during the year.