Acoustic stratigraphy and hydrothermal activity within Epi Submarine Caldera,Vanuatu, New Hebrides Arc     

H. Gary Greene  Neville F. Exon 《Geo-Marine Letters》1988,8(3):121-129

Geological and geophysical surveys of active submarine volcanoes offshore and southeast of Epi Island, Vanuatu, New Hebrides Arc, have delineated details of the structure and acoustic stratigraphy of three volcanic cones. These submarine cones, named Epia, Epib, and Epic, are aligned east-west and spaced 3.5 km apart on the rim of a submerged caldera. At least three acoustic sequences, of presumed Quaternary age, can be identified on single-channel seismic-reflection profiles. Rocks dredged from these cones include basalt, dacite, and cognate gabbroic inclusions with magmatic affinities similar to those of the Karua (an active submarine volcano off the southeastern tip of Epi) lavas.  相似文献   

Regimes and the history of the major fisheries off Canada's west coast     

R. J. Beamish  A. J. Benson  R. M. Sweeting  C. M. Neville 《Progress in Oceanography》2004,60(2-4):355

The major fisheries on the Pacific coast of Canada can be grouped into 12 species that have consistently represented about 80–90% of the total catch from the past to the present. A review of population dynamics of these species indicates that climate and the ocean environment have a major impact on their productivity. We review the history of Canada's Pacific coast fishery to show that trends in catch were similar to trends in the climate and ocean environment. Decadal scale patterns in climate and the ocean are termed regimes and we show that it is the regime scale of climate variability that most influences the long-term trends in the catches in these major fisheries. Ignoring the impacts of regime shifts on the abundance trends in the future could result in collapses of major fisheries. The difficulty of knowing when a regime shift will occur may be overcome as we discover more about the mechanisms that affect the decadal-scale trends in the rotational velocity of the solid earth which is measured as the length of day (LOD).  相似文献   

Absolute spectrophotomery of comets 1973XII and 1975IX: II. Profiles of the Swan bands     

Lucy L. Danylewych  Ralph W. Nicholls  John S. Neff  Jeremy B. Tatum 《Icarus》1978,35(1):112-120

Absolute spectrophotometric measurements of the Swan bands of two comets have been compared with computed synthetic spectra using modern Franck-Condon and Hönl-London factors, and varying rotational, vibrational, and electronic excitation temperatures. Rotational and vibrational temperatures were obtained for the comets. Although the electronic excitation temperature and the molecular column density cannot be separated, a relationship is found between these two quantities. A review is made of recent determinations of column densities for CN in comets.  相似文献   

CONFERENCE AND ANNUAL MEETING OF THE NEW ZEALAND DEMOGRAPHIC SOCIETY, Wellington, July 1975     

Warwick  Neville 《New Zealand geographer》1976,32(1):92-92

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Multi‐year water balance assessment of a newly constructed wetland,Fort McMurray,Alberta          下载免费PDF全文

Erin M. Nicholls  Sean K. Carey  Elyn R. Humphreys  M. Graham Clark  Gordon B. Drewitt 《水文研究》2016,30(16):2739-2753

Oil sands mining in Alberta transforms the boreal landscape of forests and wetlands into open pits, tailings ponds and overburden piles. Whereas reclamation efforts have primarily focused on upland forests, rebuilding wetland systems has recently become a motivation for research. Wetland creation and sustainability in this region is complicated by the sub‐humid climate and salinity of underlying mining material. In 2012, Syncrude Canada Ltd. completed the construction of the Sandhill Fen Watershed (SFW), a 52‐ha upland‐wetland system to evaluate wetland reclamation strategies on soft tailings. SFW includes an active pumping system, upland hummocks, a fen wetland and underdrains. To evaluate the influence of management practices on the hydrology of the system, this study reports the water balance from January 2013 to December 2014, the first 2 years after commissioning. A semi‐distributed approach was taken to examine the fluxes and stores of water in uplands and lowlands. Natural and artificial inputs and outputs were measured using a series of precipitation gauges and pumps, and evapotranspiration was quantified using three eddy covariance towers. A series of near surface wells recorded water table position. Both 2013 and 2014 were normal rainfall years, with 2013 having more and 2014 less snow than normal. In 2013, inflow/outflow from pumping was the predominant hydrological fluxes, resulting in considerable variability in water table position and storage changes throughout the summer. In 2014, the artificial addition of water was negligible, yet the water table remained near the surface in lowland locations, suggesting that wetland conditions could be maintained under current conditions. Evapotranspiration rates between uplands and lowlands were similar between years and sites, ranging from 2.2 ± 1.8 to 2.5 ± 1.2 mm/day and were largely controlled by climate. These rates were less than nearby older upland systems, suggesting that water balance partitioning will change as vegetation develops. Comparison between years and with natural systems provides insight on how management practices influence hydrologic dynamics and the overall water balance of the SFW. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

A comparison of the main methods for estimating probabilities of extreme still water levels     

Ivan D. Haigh  Robert Nicholls  Neil Wells 《Coastal Engineering》2010

Sea-level return periods are estimated at 18 sites around the English Channel using: (i) the annual maxima method; (ii) the r-largest method; (iii) the joint probability method; and (iv) the revised joint probability method. Tests are undertaken to determine how sensitive these four methods are to three factors which may significantly influence the results; (a) the treatment of the long-term trends in extreme sea level; (b) the relative magnitudes of the tidal and non-tidal components of sea level; and (c) the frequency, length and completeness of the available data. Results show that unless sea-level records with lengths of at least 50 years are used, the way in which the long-term trends is handled in the different methods can lead to significant differences in the estimated return levels. The direct methods (i.e. methods i and ii) underestimate the long (> 20 years) period return levels when the astronomical tidal variations of sea level (relative to a mean of zero) are about twice that of the non-tidal variations. The performance of each of the four methods is assessed using prediction errors (the difference between the return periods of the observed maximum level at each site and the corresponding data range). Finally, return periods, estimated using the four methods, are compared with estimates from the spatial revised joint probability method along the UK south coast and are found to be significantly larger at most sites along this coast, due to the comparatively short records originally used to calibrate the model in this area. The revised joint probability method is found to have the lowest prediction errors at most sites analysed and this method is recommended for application wherever possible. However, no method can compensate for poor data.  相似文献   

Modelling the influences of climate change-associated sea-level rise and socioeconomic development on future storm surge mortality     

Simon J. Lloyd  R. Sari Kovats  Zaid Chalabi  Sally Brown  Robert J. Nicholls 《Climatic change》2016,134(3):441-455

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457 pp., hardcover, US $75.00Terry Engelder, Stress Regimes in the Lithosphere , Princeton University Press, Kandy, Sri Lanka (1992) ISBN 0-691-08555-2.     

Neville J. Price 《Engineering Geology》1994,36(3-4):311-312

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Plate and intraplate processes of Hercynian Europe during the late paleozoic     

Volker Lorenz  Ian A. Nicholls 《Tectonophysics》1984,107(1-2)

It is speculated that until Late Carboniferous time the region of Hercynian Europe was occupied by an elongated island arc system underlain by a segment of continental crust. In the Upper Carboniferous, two subduction zones are assumed to have extended from the north and south beneath Hercynian Europe. An extensive zone of hot, partially molten upper mantle lay above and between these, and diapiric uprise of portions of this material led to separation of mafic magmas, widespread partial melting in the lower and middle crust, high temperature-low pressure metamorphism in crustal rocks, and regional uplift and extension of the crust, as indicated by intermontane troughs and their associated volcanic rocks.In Visean to Westphalian time Hercynian Europe collided with both the large neighbouring plates North America-Europe and Africa. During these diachronous collisions and owing to reduced rigidity of the relatively hot island arc crust, the irregular continental margins of the larger and thicker continental plates induced oroclinal bending of Hercynian Europe. After the collision processes had been terminated, processes of upper mantle activity continued, causing further crustal uplift and even, enhanced crustal extension for several tens of million years into the Lower Permian. Decline of the upper mantle activity beneath Hercynian Europe is indicated by crustal subsidence and formation of a peneplain in Permian time followed by the Upper Permian transgression of both the Zechstein sea and the Tethys sea which mark the end of the Hercynian geodynamic cycle.  相似文献   

Electron beam analytical instruments and the determination of modes,spatial variations of minerals and textural features of rocks in polished section     

J. Nicholls  M. Z. Stout 《Contributions to Mineralogy and Petrology》1986,94(3):395-404

Point counts based on X-ray intensities collected with an automated electron beam analytical instrument can be used to estimate the accurate modes required by modern physical-chemical modelling of rock-forming processes. In addition, the spatial distributions of mineral species and mineral compositions can be extracted from the coordinates of the point counting grid. Statistical tests of whether the mineral and porosity distributions are uniform can be performed by comparing the results from subareas of the polished section. The separate and composite contributions of the mineral phases to the texture and structure of the rock can be visually represented with mineral distribution maps. Qualitative differences in grain size can be recognized because the nonzero, finite electron beam diameter can detect grain boundaries. Spots on the minerals are identified by comparing the ranking of X-ray intensities with the ranking of intensities on a set of standards. For example, this method identified more than 88% of the spots on the surface of a polished section of an alkali olivine basalt. A small additional number of spots, approximately 1%, were identified because their spectra were dominated by the X-ray intensities of two characteristic elements. This method was particularly efficient in identifying phases with a small grain size and simple chemistry, e.g. apatite. The modal amounts of an alkali olivine basalt obtained with a microprobe are within approximately one standard deviation of the results obtained by point counting the same areas of the polished section under reflected and transmitted light if the minerals are major constituents and occur only in the groundmass. Accessory and phenocryst phases agree to within approximately three standard deviations.  相似文献