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61.
S. Helsen 《International Journal of Earth Sciences》1995,84(4):738-747
Thickness distributions of Devono-Carboniferous formations and their relationship to conodont colour alteration indices (CAIs) from over 500 sample locations in Belgium and northern France have been studied to reconstruct the thermal alteration and burial history of Palaeozoic rocks. The depositional centre during Eifelian through Visean times was located in the subsiding southern part of the Dinant Basin, forming a thick sedimentary pile of probably more than 3.5 km. In order to explain conodont CAIs chiefly resulting from Upper Carboniferous sedimentation, two different depositional centres are considered, giving rise to approximately 4.5 km of sediment in the central part of the Dinant and Namur Basins. As a consequence of the northward shifting Variscan fold belt, the Upper Carboniferous succession in the southern part of the Dinant Basin and in the Rocroi area was reduced or absent. Conodont CAIs together with other thermal alteration data from the Condroz Massif indicate that this area was a structural high for most of the Devonian. The Brabant Massif was probably covered with approximately 1.5–2.0 km of Upper Carboniferous sediments in the south and less than 1.0 km in the central and northern parts. In the central Campine Basin Viséan strata could have been buried by 3.5–4.5 km of Upper Carboniferous rocks. 相似文献
62.
63.
地图符号及其色彩是现代地图必不可少的基本要素。分析了地图符号的分类,色彩的类别,阐述了地图(地质)符号的色彩设计及其应用。 相似文献
64.
In the present paper, a method is proposed to improve the performance of Artificial Neural Network(ANN)based algorithms for the retrieval of oceanic constituents in Case Ⅱ waters. The ANN-based algorithms have been developed based on a constraint condition, which represents, to a certain degree, the correlation between suspended particulate matter(SPM)and pigment(CHL), coloured dissolved organic matter(CDOM)and CHL, as well as CDOM and SPM, found in Case Ⅱ waters. Compared with the ANN-based algorithm developed without a constraint condition, the performance of ANN-based algorithms developed with a constraint conditions is much better for the retrieval of CHL and CDOM, especially in the case of high noise levels; however, there is not significant improvement for the retrieval of SPM. 相似文献
65.
《The Cartographic journal》2013,50(2):130-140
Abstract<title/>The cartogram, or value-by-area map, is a popular technique for cartographically representing social data. Such maps visually equalize a basemap before mapping a social variable by adjusting the size of each enumeration unit by a second, related variable. However, to scale the basemap units according to an equalizing variable, cartograms must distort the shape and/or topology of the original geography. Such compromises reduce the effectiveness of the visualisation for elemental and general map-reading tasks. Here we describe a new kind of representation, termed a value-by-alpha map, which visually equalizes the basemap by adjusting the alpha channel, rather than the size, of each enumeration unit. Although not without its own limitations, the value-by-alpha map is able to circumvent the compromise inherent to the cartogram form, perfectly equalizing the basemap while preserving both shape and topology. 相似文献
66.
This article investigates the performance of MERIS reduced resolution data to monitor water quality parameters in the Berau estuary waters, Indonesia. Total suspended matter (TSM), Chlorophyll-a (Chl-a) concentration and diffuse attenuation coefficient (Kd ) were derived from MERIS data using three different algorithms for coastal waters: standard global processor (MERIS L2), C2R and FUB. The outcomes were compared to in situ measurements collected in 2007. MERIS data processed with C2R gave the best retrieval of Chl-a, while MERIS L2 performed the best for TSM retrieval, but large deviations from in situ data were observed, pointing at inversion problems over these tropical waters for all standard processors. Nevertheless, MERIS can be of use for monitoring equatorial coastal waters like the Berau estuary and reef system. Applying a Kd (490) local algorithm to the MERIS RR data over the study area showed a sufficient good correlation to the in situ measurements (R 2 = 0.77). 相似文献
67.
H. J. Cranfield 《新西兰海洋与淡水研究杂志》2013,47(1):63-69
The effect of experimental method on the settlement pattern of Ostrea Iutaria was tested. The intensity of settlement differed with the type of settlement surface and the angle of the surface. The method of arranging the plates, in series or singly, was critical in determining the variation of spatfall with surface angle; the type of plate had no effect on this. Possibly, a factor such as turbulence differences within the plate units affecting free‐swimming larvae about to settle could account for the different settlement patterns but whether these could be caused by a reversal of iesponses or to some passive concentraton mechanism is unknown. Similar variation in experimental techniques probably accounts for most of the conflict in previous reports on the pattern of oyster settlement related to surface angle. 相似文献
68.
Average values of inherent optical properties for the 400–700 nm waveband were estimated from quantum irradiance measurements on 27 New Zealand lakes of diverse optical character, using published nomograms. Secchi disc depths, turbidity, algal pigment, non‐volatile suspended solids, and absorption by membrane‐filtered samples at 440 nm (g 440 ) were also measured. Turbidity (NTU) correlated closely with the scattering coefficient (m‐1) and these quantities were almost numerically equal, as found in other studies. The data were found to conform to an expression in the oceanographic literature relating Secchi disc depth to the beam attenuation and diffuse attenuation coefficients. Specific beam attenuation, scattering, and absorption coefficients were estimated from the coefficients of linear multiple regressions of the measured total coefficients on the variables: total pigment (chlorophyll a + phaeopigment), non‐volatile suspended solids, and g 440. The estimated values were in reasonable agreement with similar specific coefficients reported in the oceanographic literature. The coefficients provide a basis for predicting clarity in new impoundments or for predicting the effects of loading changes (e.g., of nutrients) on the clarity of existing lakes. The coefficients can be used for classifying lake waters into different optical types. 相似文献
69.
This study examines the release of dissolved organic carbon (DOC) from upland peat during the period of the autumn flushing. Hydroclimatic conditions were monitored in conjunction with measurements of absorbance and the E4/E6 ratio of the stream draining an 11·4 km2 upland peat catchment in northern England. During two months of monitoring the effects of 67 separate rainfall events were examined showing that:
- The peat behaves hydrologically as if it were a two end‐member system consisting of old, interevent, and new, event, water. Runoff is initiated by percolation excess of new water at the acrotelm–catotelm interface.
- The discharge of dissolved organic matter behaves like a three end‐member system with the between‐event water being low in DOC and storm events being characterized by two types of water. Initial runoff being characterized by new water rich in DOC that gives way to new water depleted in DOC. This transition can be ascribed to the runoff progressing from throughflow within the acrotelm progressing to saturation‐excess overland flow.
- Depletion of DOC during storm events is accompanied by a change in the character of the DOC as the E4/E6 ratio changes. This suggests that the decrease in DOC during events is the result of exhaustion of reserves rather than changes in the flowpaths being utilized by runoff.
- The amount of carbon released in any event is critically dependent upon the time between events during which oxidation processes generate a reservoir of available carbon. Production of available carbon in the catchment is as high as 4·5 g C per day per m3 of peat, suggesting a turnover rate of peat of the order of 42 years. Copyright © 2002 John Wiley & Sons, Ltd.
70.
Peter Davies 《Continental Shelf Research》2004,24(19):2317-2341
This paper investigates the waters of the Gulf of Papua during three cruises of the TROPICS (Tropical River Ocean Processes In Coastal Settings) programme. Plume characteristics were investigated during Leg 1 (May 1997), and estuarine properties during Leg 5a (September 1997) and Leg 7 (January 1999). During Leg 1 the plume was apparent as a well mixed layer up to 30 m deep extending offshore to a distance of 150 km off the Fly River. Lowest salinities were found off the Taruma Delta. Highest chlorophyll concentrations were found at the inner plume close to the river mouth. Dissolved phosphate and nitrate are removed in this zone, whereas silicate behaves conservatively. Primary productivity within the plume appears to rely upon recycled nutrients, with organic fractions representing the majority of the nutrient pool. In the estuaries nutrients were found to behave differently during the monsoon than during the low flow of the extremely dry conditions associated with the 1997 El Niño event. Normally the Fly is characterised by remineralisation of organic nitrogen in the upper estuary, but during drought conditions DON production and NH4+ uptake suggest that bacterial activity is more prevalent. Ocean Colour and Temperature Scanner imagery shows a number of features of the plume, but generally overestimates chlorophyll concentrations due to the effects of high suspended sediment concentrations and, to a lesser extent, coloured dissolved organic matter. 相似文献