The atlantic margin of Iberia and Morocco, a reinterpretation     

Willem J.M. Van Der Linden 《Tectonophysics》1979,59(1-4)

Morphology, magnetic and seismic properties, and the geology of the sea-floor and adjacent continent indicate that the area west of Iberia and Morocco is a deformed passive continental margin. Formation of this margin is envisaged as having proceeded through a doming and rifting phase, whereby thinned continental fragments became detached from the continent and each other to form a wide zone with geophysical characteristics intermediate between those of the continent and those of the ocean. A wedge-shaped basin opened between Iberia and some of the larger detached continental fragments, the Madeira—Tore Rise and Galicia Bank. The opening of this basin and of the Bay of Biscay in Late Jurassic—Early Cretaceous time is a direct consequence of the counter-clockwise rotation of Iberia between relatively stable Europe and eastward-moving Africa. During the Tertiary the continental margin became compressed in the north—south direction and pieces of the sea-floor were thrust up and over each other to form the predominantly northeast oriented Horseshoe Seamounts. At the same time left-lateral shears developed in the margin between then northward-moving Africa and Iberia and the eastward-spreading Atlantic. Massive outpourings of Late Tertiary to Recent lavas along some of these shears are responsible for the ultimate shape of the Atlantic margins of northwest Africa and Iberia.  相似文献   

The enlargement of local power in trans-scalar strategies of planning: recent tendencies in two European cases     

Stan J. H. Majoor  Willem G. M. Salet 《GeoJournal》2008,72(1-2):91-103

The increasing ‘trans-scalar’ conditions of urbanity imply unique opportunities and threats for urban policies. When drawing up strategic urban policies, cities are confronted with the dominance of higher level policy programmes and even more so with the hegemonic power of globalizing markets. Could urban policies also undergo a similar change and actively pursue the enlargement of local power and energies by becoming actively involved in the higher level scaled networks? By building on useful concepts of urban regime theory and more recent rescaling theories, the authors argue that this element of ‘foreign policy’ should be integrated in the core analysis of urban policy approaches. The case is explored and illustrated in two European examples of strategic urban planning, namely Barcelona and Copenhagen. The cases provide evidence of the enlargement of local power via active trans-scalar policies. For civic groups, however, this strategy still appears to be a bridge too far in both cases.  相似文献   

Spatiotemporal monthly rainfall forecasts for south-eastern and eastern Australia using climatic indices   总被引：1，自引：0，他引：1  

Maryam Montazerolghaem  Willem Vervoort  Budiman Minasny  Alex McBratney 《Theoretical and Applied Climatology》2016,124(3-4):1045-1063

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Interannual variability of seasonal rainfall over the Cape south coast of South Africa and synoptic type association     

Christien J. Engelbrecht  Willem A. Landman 《Climate Dynamics》2016,47(1-2):295-313

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Holocene vegetation development in the catchment of Sägistalsee ( 1935 m asl), a small lake in the Swiss Alps     

Lucia Wick  Jacqueline F.N. van Leeuwen  Willem O. van der Knaap  André F. Lotter 《Journal of Paleolimnology》2003,30(3):261-272

Pollen and plant macrofossils were analysed at Sägistalsee (1935 m asl), a small lake near timber-line in the Swiss Northern Alps. Open forests with Pinus cembra and Abies alba covered the catchment during the early Holocene (9000–6300 cal. BP), suggesting subcontinental climate conditions. After the expansion of Picea abies between 6300 and 6000 cal. BP the subalpine forest became denser and the tree-line reached its maximum elevation at around 2260 m asl. Charcoal fragments in the macrofossil record indicate the beginning of Late-Neolithic human impact at ca. 4400 cal. BP, followed by a extensive deforestation and lowering of the forest-limit in the catchment of Sägistalsee at 3700 cal. BP (Bronze Age). Continuous human activity, combined with a more oceanic climate during the later Holocene, led to the local extinction of Pinus cembra and Abies alba and favoured the mass expansion of Picea and Alnus viridis in the subalpine area of the Northern Alps. The periods before 6300 and after 3700 cal. BP are characterised by high erosion activity in the lake's catchment, whereas during the phase of dense Picea-Pinus cembra-Abies forests (6300–3700 cal. BP) soils were stable and sediment-accumulation rates in the lake were low. Due to decreasing land-use at higher altitudes during the Roman occupation and the Migration period, forests spread beween ca. 2000 and 1500 cal. BP, before human impact increased again in the early Middle Ages. Recent reforestation due to land-use changes in the 20th century is recorded in the top sediments. Pollen-inferred July temperature and annual precipitation suggest a trend to cooler and more oceanic climate starting at about 5500 cal. BP.  相似文献   

What caused the decline of the Lake IJsselmeer eel stock after 1960?   总被引：1，自引：0，他引：1  

Dekker  Willem 《ICES Journal of Marine Science》2004,61(3):394-404

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Beta diversity of tropical marine benthic assemblages in the Spermonde Archipelago, Indonesia     

Leontine E. Becking  Daniel F. R. Cleary  Nicole J. de  Voogd  Willem Renema  Manon de  Beer  Rob W. M. van  Soest & Bert W. Hoeksema 《Marine Ecology》2006,27(1):76-88

In order to preserve diversity it is essential to understand how assemblages change across space. Despite this fact, we still know very little about how marine diversity is spatially distributed, especially among lesser‐studied invertebrate taxa. In the present study beta‐diversity patterns of sea urchins, sponges, mushroom corals and larger foraminifera were assessed in the Spermonde Archipelago (Indonesia). Using ordinations we showed that the inshore zone (<5 km offshore), midshore zone (5 < x < 30 km offshore) and distance offshore zone (>30 km offshore) all contained distinct assemblages of sponges and corals, while only foraminifera assemblages from the inshore (<5 km offshore) zone were distinct. There was a significant spatial pattern of community similarity for all taxa surveyed, but this pattern proved to be wholly related to environmental variables for sponges and foraminifera, and primarily for mushroom corals and sea urchins. The lack of a pure spatial component suggests that these taxa may not be dispersal limited within the spatial scales of this study (c. 1600 km²). The analyses of the corals and foraminifera were additionally tested at two spatial scales of sampling. Both taxa were primarily associated with local‐scale environmental variables at the local scale and larger‐scale variables at the larger scale. Mean inter‐plot similarity was also higher and variation lower at the larger scale. The results suggest that substantial variation in similarity can be predicted using simple locally assessed environmental variables combined with remotely sensed parameters.  相似文献   

Quaternary Environmental Change in the Tropics,edited by Sarah E. Metcalfe and David J. Nash. Wiley‐Blackwell,Chichester, 2012. No of pages: xiv + 421. Price: UK£62.50 (hardback). ISBN: 978‐1‐118‐34325‐8.     

Willem Rnema 《Geological Journal》2016,51(3):501-501

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Solving the complex near‐surface problem using 3D data‐driven near‐surface layer replacement     

Yimin Sun  Eric Verschuur  Jan Willem Vrolijk 《Geophysical Prospecting》2014,62(3):491-506

In many land seismic situations, the complex seismic wave propagation effects in the near‐surface area, due to its unconsolidated character, deteriorate the image quality. Although several methods have been proposed to address this problem, the negative impact of 3D complex near‐surface structures is still unsolved to a large extent. This paper presents a complete 3D data‐driven solution for the near‐surface problem based on 3D one‐way traveltime operators, which extends our previous attempts that were limited to a 2D situation. Our solution is composed of four steps: 1) seismic wave propagation from the surface to a suitable datum reflector is described by parametrized one‐way propagation operators, with all the parameters estimated by a new genetic algorithm, the self‐adjustable input genetic algorithm, in an automatic and purely data‐driven way; 2) surface‐consistent residual static corrections are estimated to accommodate the fast variations in the near‐surface area; 3) a replacement velocity model based on the traveltime operators in the good data area (without the near‐surface problem) is estimated; 4) data interpolation and surface layer replacement based on the estimated traveltime operators and the replacement velocity model are carried out in an interweaved manner in order to both remove the near‐surface imprints in the original data and keep the valuable geological information above the datum. Our method is demonstrated on a subset of a 3D field data set from the Middle East yielding encouraging results.  相似文献   

The influence of underwater data transmission sounds on the displacement behaviour of captive harbour seals (Phoca vitulina)     

Kastelein RA  van der Heul S  Verboom WC  Triesscheijn RJ  Jennings NV 《Marine environmental research》2006,61(1):19-39

To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network (ACME) using underwater sounds to encode and transmit data is currently under development. Marine mammals might be affected by ACME sounds since they may use sound of a similar frequency (around 12 kHz) for communication, orientation, and prey location. If marine mammals tend to avoid the vicinity of the acoustic transmitters, they may be kept away from ecologically important areas by ACME sounds. One marine mammal species that may be affected in the North Sea is the harbour seal (Phoca vitulina). No information is available on the effects of ACME-like sounds on harbour seals, so this study was carried out as part of an environmental impact assessment program. Nine captive harbour seals were subjected to four sound types, three of which may be used in the underwater acoustic data communication network. The effect of each sound was judged by comparing the animals' location in a pool during test periods to that during baseline periods, during which no sound was produced. Each of the four sounds could be made into a deterrent by increasing its amplitude. The seals reacted by swimming away from the sound source. The sound pressure level (SPL) at the acoustic discomfort threshold was established for each of the four sounds. The acoustic discomfort threshold is defined as the boundary between the areas that the animals generally occupied during the transmission of the sounds and the areas that they generally did not enter during transmission. The SPLs at the acoustic discomfort thresholds were similar for each of the sounds (107 dB re 1 microPa). Based on this discomfort threshold SPL, discomfort zones at sea for several source levels (130-180 dB re 1 microPa) of the sounds were calculated, using a guideline sound propagation model for shallow water. The discomfort zone is defined as the area around a sound source that harbour seals are expected to avoid. The definition of the discomfort zone is based on behavioural discomfort, and does not necessarily coincide with the physical discomfort zone. Based on these results, source levels can be selected that have an acceptable effect on harbour seals in particular areas. The discomfort zone of a communication sound depends on the sound, the source level, and the propagation characteristics of the area in which the sound system is operational. The source level of the communication system should be adapted to each area (taking into account the width of a sea arm, the local sound propagation, and the importance of an area to the affected species). The discomfort zone should not coincide with ecologically important areas (for instance resting, breeding, suckling, and feeding areas), or routes between these areas.  相似文献