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81.
Lateglacial and Holocene relative sea‐level changes and first evidence for the Storegga tsunami in Sutherland,Scotland 下载免费PDF全文
Antony J. Long Natasha L. M. Barlow Sue Dawson Jon Hill James B. Innes Catherine Kelham Fraser D. Milne Alastair Dawson 《第四纪科学杂志》2016,31(3):239-255
82.
Jane Hunter Charles Brooking Lucy Reading Sue Vink 《International Journal of Digital Earth》2016,9(2):197-214
The 3D Water Chemistry Atlas is an intuitive, open source, Web-based system that enables the three-dimensional (3D) sub-surface visualization of ground water monitoring data, overlaid on the local geological model (formation and aquifer strata). This paper firstly describes the results of evaluating existing virtual globe technologies, which led to the decision to use the Cesium open source WebGL Virtual Globe and Map Engine as the underlying platform. Next it describes the backend database and search, filtering, browse and analysis tools that were developed to enable users to interactively explore the groundwater monitoring data and interpret it spatially and temporally relative to the local geological formations and aquifers via the Cesium interface. The result is an integrated 3D visualization system that enables environmental managers and regulators to assess groundwater conditions, identify inconsistencies in the data, manage impacts and risks and make more informed decisions about coal seam gas extraction, waste water extraction, and water reuse. 相似文献
83.
The first use of Fulton's K for assessing and comparing the conditions of inter‐tidal fish populations 下载免费PDF全文
Fulton's K condition factor was applied, for the first time, to inter‐tidal specimens of the shanny (Lipophrys pholis) and long‐spined scorpion fish (Taurulus bubalis) from two English rocky shore and two Welsh rocky shore sites during summer 2010 and winter 2011. As both species contribute to the diet of commercial species such as cod (Gadus morhua) and near‐threatened species such as the European otter (Lutra lutra), their condition may affect that of these predators. Fulton's K found that inter‐tidal Welsh fish maintained a ‘good’ condition between seasons, whereas the inter‐tidal English fish were in a poorer condition during winter. Although condition also changed amongst the sites on each coast, further studies are needed into fish morphologies, environmental parameters, prey availabilities and abundances, and fish specimen sex and maturities. 相似文献
84.
Identifying granite sources by SHRIMP U-Pb zircon geochronology: an application to the Lachlan foldbelt 总被引:24,自引:1,他引:23
Sue Keay David Steele William Compston 《Contributions to Mineralogy and Petrology》1999,137(4):323-341
The potential genetic link between granites and their host sediments can be assessed using zircon age inheritance patterns.
In the Lachlan fold belt, southeastern Australia, granites and associated high-grade metasedimentary rocks intrude low-grade
Ordovician country rock. This relationship is well-exposed in the Tallangatta region, northeast Victoria (part of the Wagga-Omeo
Metamorphic Complex). In this region granites (two I-types and two S-types) have intruded during the mid-late Silurian between
approximately 410–430 Ma based on the ages of magmatic zircons. The age spectra for inherited zircons from the granites have
been compared with those of detrital zircons from the enclosing low- and high-grade metasediments. In broad terms, both for
detrital zircons in all four sediments and for inherited zircons in three of the four granites, the dominant ages are early
Paleozoic and Late Precambrian, with sporadic older Precambrian ages extending up to 3.5 Ga. The ages of the youngest detrital
zircons from the low-grade Lockhart and Talgarno terranes limit the time of sedimentation to ca. 466 Ma or younger. The youngest
detrital zircons from two samples of the high-grade Gundowring terrane are 473 Ma, making these sediments Ordovician or younger,
not Cambrian as originally suggested. However, the individual age spectra for the four selected metasediments are not well
matched when closely examined. The age spectra of the inherited zircons in the granites also do not adequately match those
in any of the metasediments. Thus, the metasediments might not be representative of the actual source rocks of the granites.
While the exact source of the granites cannot be identified from the analysed samples, the existence of a large population
of ca. 495 Ma inherited zircon grains in the S-type granites requires that the granite source contains a significant proportion
of Cambrian or younger material. This does not preclude the existence of a Precambrian basement to the Lachlan fold belt but
indicates that at the level of S-type magma generation, a Cambrian and/or younger protolith is required.
Received: 28 August 1998 / Accepted: 7 July 1999 相似文献
85.
86.
Mass loss caused by glacier calving is one of the direct contributors to global sea level rise. Reliable calving laws are required for accurate modelling of ice sheet mass balance. Both continuous and discontinuous methods have been used for glacial calving simulations. In this study, the discrete element method(DEM) based on dilated polyhedral elements is introduced to simulate the calving process of a tidewater glacier. Dilated polyhedrons can be obtained from the Minkowski sum of a sphere and a core polyhedron. These elements can be utilized to generate a continuum ice material, where the interaction force between adjacent elements is modeled by constructing bonds at the joints of the common faces. A hybrid fracture model considering fracture energy is introduced. The viscous creep behavior of glaciers on long-term scales is not considered. By applying buoyancy and gravity to the modelled glacier, DEM results show that the calving process is caused by cracks which are initialized at the top of the glacier and spread to the bottom. The results demonstrate the feasibility of using the dilated polyhedral DEM method in glacier simulations, additionally allowing the fragment size of the breaking fragments to be counted. The relationship between crack propagation and internal stress in the glacier is analyzed during calving process. Through the analysis of the Mises stress and the normal stress between the elements, it is found that geometric changes caused by the glacier calving lead to the redistribution of the stress. The tensile stress between the elements is the main influencing factor of glacier ice failure. In addition, the element shape,glacier base friction and buoyancy are studied, the results show that the glacier model based on the dilated polyhedral DEM is sensitive to the above conditions. 相似文献
87.
Y. Kuramitsu Y. Sakawa T. Morita S. Dono H. Aoki H. Tanji C. D. Gregory J. N. Waugh B. Loupias M. Koenig N. Woolsey T. Ide T. Sano H. Takabe 《Astrophysics and Space Science》2011,336(1):269-272
Density inhomogeneities for a test bed of magnetic field amplification in supernova remnants (SNRs) were created in laser produced plasmas. The density inhomogeneity is considered to be essential to the large magnetic field amplification to account for the very fast cosmic ray acceleration. In order to model the density variations about an order of magnitude in an interstellar medium, we performed three types of experiments using a high-power laser system: (1) irradiating a plastic (CH) plane with a single focal spot beams, (2) the same target with spatial separation of laser focal spots, and (3) irradiating a striped target of thin and thick CH plane. By irradiating a CH plane target with a single focal spot laser beams, a plasma plume was produced with the large density range. On the other hand, when the several laser beams with displacements of the focal spots, bumpy structures of electron density were produced. Making thin stripes on a CH plane target, density and velocity inhomogeneities were produced by irradiating the striped target with the laser beams. In the all methods the density variations were very large, which can be used for a model experiment of the magnetic field amplification. 相似文献
88.
The New Zealand snapper Chrysophrys auratus is the object of a major fishery and contributes approximately 30% of the annual landed weight of fin‐fish. Samples of 65 fish from 7 localities on the New Zealand coast were analysed for mercury. Though there is an increase in mercury concentration with size of fish, the larger, older individuals with relatively high mercury levels contribute only a small proportion to the landed catch. Therefore, in establishing the average concentration of mercury in fish, due weight should be accorded to the differences in size composition of the catch. On this basis the average levels of mercury in snapper offered for human consumption are of the order of 0.25 ppm. As this is only half the “permissible safe level” of most other countries where fish consumption is much higher, the risk to the New Zealand consumer is negligible. 相似文献
89.
Dietary samples collected at Campbell Island in summer 1997 indicate that southern blue whiting (Micromesistius australis) formed the bulk of the food of black‐browed albatrosses (Diomedea melanophrys impavida) during the chick‐rearing period. Birds preyed upon a single size class of fish with a mode at 80–90 mm standard length; fish were 4–5 months old and belonged to the 0+ age group. Satellite tracking showed that, when performing trips of short duration, adult albatrosses foraged within the 1000 m depth contour in the subantarctic zone north of Campbell Island. The feeding ecology of albatrosses thus suggests that juvenile (0+) southern blue whiting are pelagic and occur in dense schools in the top 5 m of the water column over the Campbell Plateau during the summer months. The high reliance of birds on juvenile southern blue whiting during the chick‐rearing period has implications for the management of the southern blue whiting fishery and the conservation of black‐browed albatrosses and other marine predators occurring in the New Zealand subantarctic area. 相似文献
90.
For ages, links between environment, climate and their impacts on human health have been observed and studied. Research to improve our understanding of environmental key determinants of infectious diseases can provide innovative information for adaptation strategies and lead to new tools optimizing surveillance, vector control measures, and disease prevention. As earth observation satellites can measure meteorological and environmental parameters, NASA and CNES have separately engaged in an innovative use of their earth observation infrastructure development programs: space tools addressing public health. As NASA and CNES have fruitful cooperation for satellite development missions for years, both health programs have proposed to explore a new area of collaboration: satellites addressing health issues. As members of international organizations, NASA and CNES could promote their common views towards the Group on Earth Observations (GEO) Community of Practice for Health & Environment and the Committee on Earth Observation Satellites (CEOS) Societal Benefit Area on Health. 相似文献