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Selected AbstractsAccounting for uncertainty in DEMs from repeat topographic surveys: improved sediment budgetsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2010Joseph M. Wheaton Abstract Repeat topographic surveys are increasingly becoming more affordable, and possible at higher spatial resolutions and over greater spatial extents. Digital elevation models (DEMs) built from such surveys can be used to produce DEM of Difference (DoD) maps and estimate the net change in storage terms for morphological sediment budgets. While these products are extremely useful for monitoring and geomorphic interpretation, data and model uncertainties render them prone to misinterpretation. Two new methods are presented, which allow for more robust and spatially variable estimation of DEM uncertainties and propagate these forward to evaluate the consequences for estimates of geomorphic change. The first relies on a fuzzy inference system to estimate the spatial variability of elevation uncertainty in individual DEMs while the second approach modifies this estimate on the basis of the spatial coherence of erosion and deposition units. Both techniques allow for probabilistic representation of uncertainty on a cell-by-cell basis and thresholding of the sediment budget at a user-specified confidence interval. The application of these new techniques is illustrated with 5 years of high resolution survey data from a 1,km long braided reach of the River Feshie in the Highlands of Scotland. The reach was found to be consistently degradational, with between 570 and 1970,m3 of net erosion per annum, despite the fact that spatially, deposition covered more surface area than erosion. In the two wetter periods with extensive braid-plain inundation, the uncertainty analysis thresholded at a 95% confidence interval resulted in a larger percentage (57% for 2004,2005 and 59% for 2006,2007) of volumetric change being excluded from the budget than the drier years (24% for 2003,2004 and 31% for 2005,2006). For these data, the new uncertainty analysis is generally more conservative volumetrically than a standard spatially-uniform minimum level of detection analysis, but also produces more plausible and physically meaningful results. The tools are packaged in a wizard-driven Matlab software application available for download with this paper, and can be calibrated and extended for application to any topographic point cloud (x,y,z). Copyright © 2009 John Wiley & Sons, Ltd. [source] Wood storage in a wide mountain river: case study of the Czarny Dunajec, Polish CarpathiansEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2005omiej Wy Abstract Storage of large woody debris in the wide, mountain, Czarny Dunajec River, southern Poland, was investigated following two floods of June and July 2001 with a seven-year frequency. Within a reach, to which wood was delivered only by bank erosion and transport from upstream, wood quantities were estimated for eighty-nine, 100 m long, channel segments grouped into nine sections of similar morphology. Results from regression analysis indicated the quantity of stored wood to be directly related to the length of eroded, wooded banks and river width, and inversely related to unit stream power at the flood peak. The largest quantities of wood (up to 33 t ha,1) were stored in wide, multi-thread river sections. Here, the relatively low transporting ability of the river facilitated deposition of transported wood while a considerable length of eroded channel and island banks resulted in a large number of trees delivered from the local riparian forest. In these sections, a few morphological and ecological situations led to the accumulation of especially large quantities of wood within a small river area. Very low amounts of wood were stored in narrow, single-thread sections of regulated or bedrock channel. High stream power facilitated transport of wood through these sections while the high strength of the banks and low channel sinuosity prevented bank retreat and delivery of trees to the channel. Considerable differences in the character of deposited wood existed between wide, multi-thread channel sections located at different distances below a narrow, 7 km long, channellized reach of the river. Wood deposited close to the downstream end of the channellized reach was highly disintegrated and structured into jams, whereas further downstream well preserved shrubs and trees prevailed. This apparently reflects differences in the distance of wood transport and shows that in a mountain river wider than the height of trees growing on its banks, wood can be transported long distances along relatively narrow, single-thread reaches but is preferentially deposited in wide, multi-thread reaches. Copyright © 2005 John Wiley & Sons, Ltd. [source] Estimation of erosion and deposition volumes in a large, gravel-bed, braided river using synoptic remote sensingEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2003Stuart N. Lane Abstract System-scale detection of erosion and deposition is crucial in order to assess the transferability of findings from scaled laboratory and small field studies to larger spatial scales. Increasingly, synoptic remote sensing has the potential to provide the necessary data. In this paper, we develop a methodology for channel change detection, coupled to the use of synoptic remote sensing, for erosion and deposition estimation, and apply it to a wide, braided, gravel-bed river. This is based upon construction of digital elevation models (DEMs) using digital photogrammetry, laser altimetry and image processing. DEMs of difference were constructed by subtracting DEM pairs, and a method for propagating error into the DEMs of difference was used under the assumption that each elevation in each surface contains error that is random, independent and Gaussian. Data were acquired for the braided Waimakariri River, South Island, New Zealand. The DEMs had a 1·0 m pixel resolution and covered an area of riverbed that is more than 1 km wide and 3·3 km long. Application of the method showed the need to use survey-specific estimates of point precision, as project design and manufacturer estimates of precision overestimate a priori point quality. This finding aside, the analysis showed that even after propagation of error it was possible to obtain high quality DEMs of difference for process estimation, over a spatial scale that has not previously been achieved. In particular, there was no difference in the ability to detect erosion and deposition. The estimates of volumes of change, despite being downgraded as compared with traditional cross-section survey in terms of point precision, produced more reliable erosion and deposition estimates as a result of the large improvement in spatial density that synoptic methods provide. Copyright © 2003 John Wiley & Sons, Ltd. [source] Mitigation of the produced voltages in AC overhead power-lines/pipelines parallelism during power frequency and lightning conditionsEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2005I. A. Metwally Abstract This paper presents a theoretical simulation for a pipeline running in parallel to AC overhead power lines using the ,CONCEPT II' package. This package is based on the method of moment combined with a transmission-line model. A 1,km long, 132,kV, three-phase, double-circuit transmission line, and a 2,km long, 40,cm diameter, 1,m high above-ground pipeline are modelled. Extra shielding wires (ESW) under the phase conductors are investigated. Produced voltages in the pipeline are computed under steady-state power frequency (50,Hz) as well as under direct and indirect lightning strikes to the power line. Different current waveforms are simulated to cover the whole range of those of the anticipated lightning. Under lightning strikes, the voltages across line insulators are computed, too. The results reveal that the ESW give many advantages; namely, (1) reducing the power-frequency electric and magnetic fields at the ground level to meet the regularity limits, (2) improving the shielding effectiveness during lightning strikes by reducing the insulator voltages, (3) mitigating the induced voltages in any metallic structure near the power lines, e.g., pipelines, and (4) using them as optical ground wires for telecommunication purposes, where the probability of lightning strikes to such ESW is much lower than that for the normally used grounding wire(s) at the tower top. Copyright © 2005 John Wiley & Sons, Ltd. [source] The North American P group of Heterobasidion annosum s.l. is widely distributed in Pinus pinea forests of the western coast of central ItalyFOREST PATHOLOGY, Issue 5 2007L. D'Amico Summary The distribution of the North American P group of Heterobasidion annosum s.l., recently reported from a Pinus pinea forest in the surroundings of Rome, was studied using mating tests and DNA fingerprinting (mitochondrial DNA, random amplified microsatellite technique and two group-specific markers). This fungus is present in several forests and small plantations along the Tyrrhenian coast of the Italian peninsula, within an area approximately 100 km long, extending from Fregene in the north to the National Park of Circeo in the south, and 27 km wide including the city of Rome. In pine forests of Castelporziano, Castel Fusano and Anzio, where US troops resided during the Second World War, the North American P group is more frequent than the European P group. The low number of mating alleles in the Italian population of the North American P group supports the hypothesis of its origin from a small number of introductions. The near 100% sexual compatibility between the North American and European P groups, together with inconsistencies in results obtained with different identification methods of these groups, suggests that hybridization between the North American and European P populations occurs occasionally. [source] Maintenance of a small anadromous subpopulation of brown trout (Salmo trutta L.) by strayingFRESHWATER BIOLOGY, Issue 2 2006F. AYLLON Summary 1. Microsatellite and isozyme loci variation were used to study structure and dynamics of a brown trout (Salmo trutta) population heavily affected by damming. The downstream area accessible for spawning was drastically reduced to a stream 1 km long influenced by regulated discharge. 2. Stocking of hatchery-reared juveniles failed and the population is entirely supported by anadromous adults from neighbouring populations. 3. Temporal genetic stability is reported here. Some punctual between-river genetic differences are likely because of different contribution from each neighbouring river through years. 4. High anadromy-mediated gene flow produces a lack of genetic substructure in the region. The role of anadromous brown trout on maintenance of endangered small populations is emphasised. [source] The Next Generation Road Weather Information System: A New Paradigm for Road and Rail Severe Weather Prediction in the UKGEOGRAPHY COMPASS (ELECTRONIC), Issue 4 2008John Thornes The use of road weather information systems for the winter maintenance of roads is now widespread around the world. However, road weather forecasts are normally only made available for a limited number of road sensor sites in a region. For example, in Birmingham, UK, there is one forecast site for 26 salting routes. XRWIS is the next generation road weather information system that forecasts for every 20 m along each salting route (typically 50 km long) using a geographical information system, sky-view factor analysis and mesoscale weather forecasts. Treatment requirements for each salting route are then visualised in simple ,traffic-light' style colours. In a recent winter-long trial in Devon, UK, up to 78 salting runs on six salting routes could have been prevented saving up to £80,000 in labour and materials. Other potential applications of XRWIS include the prediction of low rail adhesion in winter, due to ice, frost and snow, and track buckling in summer. [source] Permo-Triassic development from Ireland to Norway: basin architecture and regional controlsGEOLOGICAL JOURNAL, Issue 6 2009tolfová Abstract Extensive occurrences of Permo-Triassic strata are preserved along the Northwest European Atlantic margin. Seismic reflection and well data are used to describe large-scale Permo-Triassic basin geometries along a swath of the continental shelf more than 2000,km long extending from the Irish to the mid-Norwegian sectors. Successions in the Celtic Sea, the flanks of the Irish Rockall Basin, basins west and north of Scotland, and the Trøndelag and Horda platforms west of Norway are described. The large-scale Permo-Triassic depositional geometries commonly represent erosional remnants of larger basins modified by later rifting episodes, uplift, inversion and continental breakup. However, the interpreted geometries reveal spatial and temporal differences in rifting style. The basins developed above a complex mosaic of petrologically heterogeneous crustal terranes with inherited crustal fabrics, which had a significant impact on the depositional basin geometries. Small Permian basins with growth faulting developed in the southern Celtic Sea region. Extensive, uniformly thick Triassic strata are characteristic of the wide rift basins in the southeastern Rockall Basin and northwest of the Solan Bank High. Thick, fault-controlled basins developed in the Horda and Trøndelag platform regions. The main controls on Permo-Triassic basin architecture are (a) crustal thickness and composition, which determined the development of narrow or wide rift basin geometries, (b) inherited Variscan, Caledonian and Precambrian basement structures and (c) pre-rift palaeotopography. Copyright © 2009 John Wiley & Sons, Ltd. [source] Insights into biaxial extensional tectonics: an examplefrom the Sand,kl, Graben, West Anatolia, TurkeyGEOLOGICAL JOURNAL, Issue 1 2003Mustafa Cihan Abstract West Anatolia, together with the Aegean Sea and the easternmost part of Europe, is one of the best examples of continental extensional tectonics. It is a complex area bounded by the Aegean,Cyprus Arc to the south and the North Anatolian Fault Zone (NAFZ) to the north. Within this complex and enigmatic framework, the Sand,kl, Graben (10,km wide, 30,km long) has formed at the eastern continuation of the Western Anatolian extensional province at the north-northwestward edge of the Isparta Angle. Recent studies have suggested that the horst,graben structures in West Anatolia formed in two distinct extensional phases. According to this model the first phase of extension commenced in the Early,Middle Miocene and the last, which is accepted as the onset of neotectonic regime, in Early Pliocene. However, it is controversial whether two-phase extension was separated by a short period of erosion or compression during Late Miocene,Early Pliocene. Both field observations and kinematic analysis imply that the Sand,kl, Graben has existed since the Late Pliocene, with biaxial extension on its margins which does not necessarily indicate rotation of regional stress distribution in time. Although the graben formed later in the neotectonic period, the commencement of extension in the area could be Early Pliocene (c. 5,Ma) following a severe but short time of erosion at the end of Late Miocene. The onset of the extensional regime might be due to the initiation of westward motion of Anatolian Platelet along the NAFZ that could be triggered by the higher rate of subduction at the east Aegean,Cyprus Arc in the south of the Aegean Sea. Copyright © 2003 John Wiley & Sons, Ltd. [source] Earthquake effects on the Anatolian Motorway, TurkeyGEOLOGY TODAY, Issue 2 2009Hayrettin Koral On 12 November 1999, the Anatolian earthquake in Turkey damaged a partially completed motorway viaduct. The viaduct, which is some 2.3 km long, passes over the Düzce Fault as the route starts its ascent into the Turkish plateau. The Düzce Fault is a northern offshoot of the main North Anatolian Fault (NAF) Zone, and cuts the viaduct at an acute angle of 15 degrees. Movements along the NAF have been identified as the prime cause of the earthquake. Alternatives to a viaduct crossing had been considered in the feasibility stage, but were ruled out because of the rugged landslide-influenced terrain and requirements for an even motorway ascent grade. The relative displacement of around 120 equally spaced piers identified the nature of the ground displacements and gave an indication as to the likely areas of foundation damage. This article examines the damage caused to the viaduct during the earthquake. [source] Calculations in the Field of GeotechnicsGEOMECHANICS AND TUNNELLING, Issue 4 2009Article first published online: 5 AUG 200 The cover picture shows the Terfens portal of the main contract H5 of the Vomp-Terfens tunnel. The tunnel is 8,480 km long and was built between August 2003 and January 2009. Das Titelbild zeigt das Portal Terfens des Hauptbauloses H5 Tunnel Vomp-Terfens im Unterintal. Der Tunnel ist 8.480 m lang und wurde zwischen August 2003 und Januar 2009 errichtet. [source] Austria's Koralm tunnel: one of the world's largest tunnel projectsGEOMECHANICS AND TUNNELLING, Issue 4 2008Article first published online: 19 AUG 200 The Koralm railway line is currently one of the most prestigious construction projects of ÖBB-Infrastruktur Bau AG. In 2018 the new 130 km long two-track electrified route is supposed to raise the capacities and reduce travel times along this important northsouth railway axis. The 33 km long, ambitious Koralm tunnel forms the core piece of this line. Forcing the track development in Austria, ÖBB-Infrastruktur Bau AG focuses on the development of the main connections to high performance routes such as the Koralm railway line, the four-track development of the Danube line and of the Lower Inn Valley route. Furthermore, ÖBB invests in the modernisation of its largest stations, many suburban service projects, enhanced tunnel safety, noise protection measures as well as park & ride facilities and extensive reinvestments in the existing rail network. [source] Gravity evidence for a larger Limpopo Belt in southern Africa and geodynamic implicationsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2002R. T. Ranganai Summary The Limpopo Belt of southern Africa is a Neoarchean orogenic belt located between two older Archean provinces, the Zimbabwe craton to the north and the Kaapvaal craton to the south. Previous studies considered the Limpopo Belt to be a linearly trending east-northeast belt with a width of ,250 km and ,600 km long. We provide evidence from gravity data constrained by seismic and geochronologic data suggesting that the Limpopo Belt is much larger than previously assumed and includes the Shashe Belt in Botswana, thus defining a southward convex orogenic arc sandwiched between the two cratons. The 2 Ga Magondi orogenic belt truncates the Limpopo,Shahse Belt to the west. The northern marginal, central and southern marginal tectonic zones define a single gravity anomaly on upward continued maps, indicating that they had the same exhumation history. This interpretation requires a tectonic model involving convergence between the Kaapvaal and Zimbabwe cratons during a Neoarchean orogeny that preserved the thick cratonic keel that has been imaged in tomographic models. [source] Simulation of groundwater dynamics in the North China Plain by coupled hydrology and agricultural modelsHYDROLOGICAL PROCESSES, Issue 16 2006Tadanobu Nakayama Abstract We simulated the effects of irrigation on groundwater flow dynamics in the North China Plain by coupling the NIES Integrated Catchment-based Ecohydrology (NICE) model with DSSAT-wheat and DSSAT-maize, two agricultural models. This combined model (NICE-AGR) was applied to the Hai River catchment and the lower reach of the Yellow River (530 km wide by 840 km long) at a resolution of 5 km. It reproduced excellently the soil moisture, evapotranspiration and crop production of summer maize and winter wheat, correctly estimating crop water use. So, the spatial distribution of crop water use was reasonably estimated at daily steps in the simulation area. In particular, NICE-AGR reproduced groundwater levels better than the use of statistical water use data. This indicates that NICE-AGR does not need detailed statistical data on water use, making it very powerful for evaluating and estimating the water dynamics of catchments with little statistical data on seasonal water use. Furthermore, the simulation reproduced the spatial distribution of groundwater level in 1987 and 1988 in the Hebei Plain, showing a major reduction of groundwater level due mainly to overpumping for irrigation. Copyright © 2006 John Wiley & Sons, Ltd. [source] The use of breeding sites of Tilapia congica (Thys & van Audenaerde 1960) to delineate conservation sites in the Lake Tumba, Democratic Republic of Congo: toward the conservation of the lake ecosystemAFRICAN JOURNAL OF ECOLOGY, Issue 3 2010Bila-Isia Inogwabini Abstract To guide the zoning process in Lake Tumba, Democratic Republic of Congo, breeding sites of Tilapia congica were studied. Physical metrics measured were: nest depths, exposure to sun rays, distance from the edges, site spreads, and habitat types. Mean nest depth = 0.23 m ± 0.08 (SD), range = 0.04,2.2 m (n = 553 nests); 100% (n = 70 sites) sites were exposed to the sun and the polynomial regression analysis showed 90% sites were within the range 51,250 m from the lake shores (y = ,1.7143x2 + 10.371x, 1.8; R2 = 0.597, n = 70 sites), with 60% clumped within the range of 51,150 m, indicating a relationship between nesting sites and the distance from edges. The largest group spread group was 300 m, and among the four breeding sites identified, one was ,10 km long, meaning a zonal spatial spread , = 300 ha and a core reproduction zone ,, = 100 ha. T. congica built 87.30% of their nest in habitats where Hippo grass Vossia cuspidata (48.20%) and Water lily Nympheae stellata (39.10%) dominated. T. congica shared 41.81% of its nesting sites with other fish species, leading to the conclusion that protecting the species habitats would provide the umbrella for the conservation of other species. Résumé Pour orienter le processus de zonage au lac Tumba, en République Démocratique du Congo, nous avons étudié les sites de reproduction de Tilapia congica. Les paramètres physiques mesurés étaient : la profondeur des nids, l'exposition aux rayons du soleil, la distance par rapport à la berge, l'étendue des sites et les types d'habitat. La profondeur moyenne des nids = 0,23 m ± 0,08 (DS), le domaine vital du nid = 0,04,2,2 m (n = 553 nids); 100% des sites (n = 70) étaient exposés au soleil, et l'analyse de la régression polynomiale a montré que 90% des sites se trouvaient entre 51 et 250 m des berges du lac (y = ,1,7143x2 + 10,371x , 1,8; R2 = 0,597; n = 70 sites) et 60% d'entre eux étaient rassemblés à une distance comprise entre 51 et 150 m des berges, ce qui indique une relation entre les sites de nidification et la distance par rapport aux berges. Le groupe le plus étendu avait 300 m et, parmi les quatre sites de reproduction identifiés, un avait , 10 km de long, ce qui signifie une dispersion spatiale zonale , = 300 ha et une zone de reproduction centrale ,' = 100 ha. Les T.congica construisent 87,30% de leurs nids dans des habitats où dominent l'herbe à hippos Vossia cuspidata (48,20%) et les nénuphars Nymphea stellata (39,10%). Les T. congica partagent 41,81% de leurs sites de nidification avec d'autres espèces de poissons, d'où la conclusion que la protection des habitats de cette espèce fournirait aussi une protection à d'autres espèces. [source] The ranging patterns of elephants in Marsabit protected area, Kenya: the use of satellite-linked GPS collarsAFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Shadrack M. Ngene Abstract We investigated the ranging patterns of elephants in the Marsabit protected area, north eastern Kenya, to ascertain the range of bachelor and female family herds in different seasons, and to identify corridor and noncorridor areas. Data were acquired for five bachelor and four female family herds equipped with satellite-linked geographical positioning system collars, and monitored from December 2005 to December 2007. Distinct dry (about 260 km2) and wet seasons (about 910 km2) ranges were observed, with connecting corridors (north-eastern corridor: about 90 km long, about 2-7 km wide; southern corridors: about 10-20 km long, about 2-3 km wide). The dry season range corresponded with Marsabit evergreen forest, while the wet season range matched with dry deciduous lowland shrubs. The ranging elephants moved at speed of about 0.2-20 kmh,1. Bachelor herds moved faster than female family herds. Elephants moved fast during the intermediate and wet seasons than during the dry season. The speed of ranging elephants was over 1 kmh,1 in the corridor areas and about 0.2 to less than 1 kmh,1 in the non-corridor areas. Expansion of settlements towards corridor areas needs to be controlled to avoid future blocking of connectivity between wet and dry season elephant ranges. Résumé Nous avons étudié les schémas spatiaux des éléphants dans l'aire protégée de Marsabit, au nord-est du Kenya, pour évaluer le domaine vital des hardes de mâles et des hardes matriarcales à différentes saisons, et pour identifier les zones qui sont, ou pas, des corridors. Nous avons récolté des données pour cinq hardes de mâles et quatre hardes matriarcales équipées de colliers émetteurs reliés par satellite à un système de positionnement mondial, et nous les avons suivies de novembre 2005 à décembre 2007. Nous avons observé des domaines distincts de saison sèche (environ 260 km²) et de saison des pluies (environ 910 km²) ainsi que les corridors qui les relient (corridor du nord-est : près de 90 km de long, entre 2 et 7 km de large environ ; corridors du sud : entre 10 et 20 km de long, de 2 à 3 km de large). Le domaine vital de saison sèche correspondait à la forêt sempervirente de Marsabit, tandis que celui de saison des pluies correspondait à des arbustes décidus secs de plaine. Les éléphants se déplaçaient à une vitesse comprise entre 0,2 et 20 km/h. Les hardes de mâles allaient plus vite que les familles de femelles. Les éléphants se déplaçaient plus vite à l'entre-saison et en saison des pluies qu'en saison sèche. La vitesse des éléphants en mouvement était de plus d'un km/h dans l'étendue des corridors et elle variait de 0,2 à moins d'un km/h dans les zones qui ne faisaient pas partie des corridors. Il faut contrôler les extensions vers les aires qui servent de corridors pour éviter tout futur blocage de la connectivité entre les espaces vitaux de saison sèche et de saison des pluies. [source] Late Cretaceous blueschist facies metamorphism in southern Thrace (Turkey) and its geodynamic implicationsJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2008G. TOPUZ Abstract A blueschist facies tectonic sliver, 9 km long and 1 km wide, crops out within the Miocene clastic rocks bounded by the strands of the North Anatolian Fault zone in southern Thrace, NW Turkey. Two types of blueschist facies rock assemblages occur in the sliver: (i) A serpentinite body with numerous dykes of incipient blueschist facies metadiabase (ii) a well-foliated and thoroughly recrystallized rock assemblage consisting of blueschist, marble and metachert. Both are partially enveloped by an Upper Eocene wildflysch, which includes olistoliths of serpentinite,metadiabase, Upper Cretaceous and Palaeogene pelagic limestone, Upper Eocene reefal limestone, radiolarian chert, quartzite and minor greenschist. Field relations in combination with the bore core data suggest that the tectonic sliver forms a positive flower structure within the Miocene clastic rocks in a transpressional strike,slip setting, and represents an uplifted part of the pre-Eocene basement. The blueschists are represented by lawsonite,glaucophane-bearing assemblages equilibrated at 270,310 °C and ,0.8 GPa. The metadiabase dykes in the serpentinite, on the other hand, are represented by pumpellyite,glaucophane,lawsonite-assemblages that most probably equilibrated below 290 °C and at 0.75 GPa. One metadiabase olistolith in the Upper Eocene flysch sequence contains the mineral assemblage epidote + pumpellyite + glaucophane, recording P,T conditions of 290,350 °C and 0.65,0.78 GPa, indicative of slightly lower depths and different thermal setting. Timing of the blueschist facies metamorphism is constrained to c. 86 Ma (Coniacian/Santonian) by Rb,Sr phengite,whole rock and incremental 40Ar,39Ar phengite dating on blueschists. The activity of the strike,slip fault post-dates the blueschist facies metamorphism and exhumation, and is only responsible for the present outcrop pattern and post-Miocene exhumation (,2 km). The high- P/T metamorphic rocks of southern Thrace and the Biga Peninsula are located to the southeast of the Circum Rhodope Belt and indicate Late Cretaceous subduction and accretion under the northern continent, i.e. the Rhodope Massif, enveloped by the Circum Rhodope Belt. The Late Cretaceous is therefore a time of continued accretionary growth of this continental domain. [source] Formation and reorientation of structure in the surge-type glacier Kongsvegen, SvalbardJOURNAL OF QUATERNARY SCIENCE, Issue 3 2002John Woodward Abstract Kongsvegen, a surge-type glacier in Spitsbergen, Svalbard, shares a tide-water margin with the glacier Kronebreen. The complex has been in retreat since a surge advance of Kongsvegen around 1948. The surface of Kongsvegen displays suites of deformational structures highlighted by debris-rich folia. These structures are melting out to form a network of sediment ridges in the grounded terminal area. The structures are also visible in a marginal, 1 km long, 5,20 m high cliff-face at the terminus. Current models for the evolution of deformational structures at Kongsvegen divide the structures into suites based on their orientation and dip, before assigning a mechanism for genesis based on structure geometry. Interpretation of aerial photographs and field mapping of surface structures suggest that many structures were reorientated or advected during the surge. We suggest that many of the deformational structures highlighted by debris-rich folia represent reorientated, sediment-filled crevasses. Some evidence of thrusting is apparent but the process is not as ubiquitous as previously suggested. Many deformational structures also appear to have been offset by more recent structures. Mechanisms of structural development must, therefore, be considered within the context of distinct stages of glacier flow dynamics and multiple surge episodes. Furthermore, evidence for thrusting and folding within the glacier systems of Svalbard has been used as the basis for interpreting Quaternary glacial landforms in the UK. The findings of this paper, therefore, have implications for interpretations of the Quaternary record. Copyright © 2002 John Wiley & Sons, Ltd. [source] Mineralogy and petrology of melt rocks from the Popigai impact structure, SiberiaMETEORITICS & PLANETARY SCIENCE, Issue 5 2002J. Whitehead The fine-grained to cryptocrystalline texture of the more melt-rich rocks, despite their occurrence in bodies locally in excess of 800 m thick and 28 km long, suggests that the melt crystallized in response to (1) cooling by the clast load, and/or; (2) rapid nucleation on finely brecciated clasts, which have since been assimilated and/or; (3) crystallization enhanced by the relatively low water contents of the melts. Rapid crystallisation of the melt is indicated by the lack of zoning in minerals, the presence of glass, the lack of strain recovery features in clasts and the lack of evidence for fractionation in the major and trace elements, including the rare earth elements. Optical and analytical electron microscopy reveal that the previously reported division of the melt rocks into high- and low-temperature variants based on hand sample appearance, or glass content, is not warranted. Clasts within the melt-rich rocks exhibit a wide range of shock metamorphic features, though they are not distributed in the impact melts in a systematic manner. This indicates that the melt-rich rocks were well mixed during their formation, thus juxtaposing unshocked with shocked material. Injection of mesostasis melt into partially melted checkerboard plagioclase and orthopyroxene clasts also occurred during this mixing stage. [source] On the accuracy of retrieved wind information from Doppler lidar observationsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 587 2003F. Davies Abstract A single pulsed Doppler lidar was successfully deployed to measure air flow and turbulence over the Malvern hills, Worcester, UK. The DERA Malvern lidar used was a pulsed Doppler lidar. The lidar pulse repetition rate was 120 Hz and had a pulse duration of . The system was set up to have 41 range gates with range resolution of 112 m. This gave a theoretical maximum range of approximately 4.6 km. The lidar site was 2 km east of the Malvern hill ridge which runs in a north,south direction and is approximately 6 km long. The maximum height of the ridge is 430 m. Two elevation scans (Range,Height Indicators) were carried out parallel and perpendicular to the mean surface flow. Since the surface wind was primarily westerly the scans were carried out perpendicular and parallel to the ridge of the Malvern hills. The data were analysed and horizontal winds, vertical winds and turbulent fluxes were calculated for profiles throughout the boundary layer. As an aid to evaluating the errors associated with the derivation of velocity and turbulence profiles, data from a simple idealized profile was also analysed using the same method. The error analysis shows that wind velocity profiles can be derived to an accuracy of 0.24 m s,1 in the horizontal and 0.3 m s,1 in the vertical up to a height of 2500 m. The potential for lidars to make turbulence measurements, over a wide area, through the whole depth of the planetary boundary layer and over durations from seconds to hours is discussed. Copyright © 2003 Royal Meteorological Society [source] Does alpine grazing reduce blazing?AUSTRAL ECOLOGY, Issue 8 2006A landscape test of a widely-held hypothesis Abstract ,Alpine grazing reduces blazing' is a widely and strongly held view concerning the effects of livestock grazing on fuels, and therefore fire behaviour and impact, in Australia's high country landscapes. As a test of this hypothesis, we examined the patterns of burning across the alpine (treeless) landscapes of the Bogong High Plains in Victoria, following the extensive fires of January 2003. Data were collected from multiple transects, each 3,5 km long, with survey points located randomly at either 50, 200 or 500 m intervals. The transects traversed the major regions of the Bogong High Plains, both grazed and ungrazed. At each point, we recorded whether the point was burnt or unburnt, the vegetation type (closed-heath, open-heath, grassland or herbfield), the estimated prefire shrub cover, slope, aspect, and a GPS location. At burnt heathland sites, we recorded the minimum twig diameter (an a posteriori measure of fire severity) in a sample of common shrubs. In total, there were 108 km of transect lines, 419 survey points and 4050 twig measurements, with sample points equally distributed across grazed and ungrazed country. The occurrence of fire (i.e. burnt or unburnt) in grazed and ungrazed areas was analysed by logistic regression; the variation in twig diameters by anova. Approximately half of all points were burnt. There was no statistically significant difference between grazed and ungrazed areas in the proportion of points burnt. Fire occurrence was determined primarily by vegetation type, with the proportion burnt being 0.87 for closed-heath, 0.59 for open-heath, and 0.13 for grassland and all snow-patch herbfield points unburnt. In both closed-heath and open-heath, grazing did not significantly lower the severity of fire, as measured by the diameter of burnt twigs. We interpret the lack of a grazing effect in terms of shrub dynamics (little or no grazing effect on long-term cover of taller shrubs), diet and behaviour of cattle (herbs and dwarf shrubs eaten; tall shrubs not eaten and closed-heath vegetation generally avoided), and fuel flammability (shrubs more flammable than grass). Whatever effects livestock grazing may have on vegetation cover, and therefore fuels in alpine landscapes, they are likely to be highly localized, with such effects unlikely to translate into landscape-scale reduction of fire occurrence or severity. The use of livestock grazing in Australian alpine environments as a fire abatement practice is not justified on scientific grounds. [source] Fault architecture, basin structure and evolution of the Gulf of Corinth Rift, central GreeceBASIN RESEARCH, Issue 6 2009R. E. Bell ABSTRACT The style of extension and strain distribution during the early stages of intra-continental rifting is important for understanding rift-margin development and can provide constraints for lithospheric deformation mechanisms. The Corinth rift in central Greece is one of the few rifts to have experienced a short extensional history without subsequent overprinting. We synthesise existing seismic reflection data throughout the active offshore Gulf of Corinth Basin to investigate fault activity history and the spatio-temporal evolution of the basin, producing for the first time basement depth and syn-rift sediment isopachs throughout the offshore rift. A major basin-wide unconformity surface with an age estimated from sea-level cycles at ca. 0.4 Ma separates distinct seismic stratigraphic units. Assuming that sedimentation rates are on average consistent, the present rift formed at 1,2 Ma, with no clear evidence for along-strike propagation of the rift axis. The rift has undergone major changes in relative fault activity and basin geometry during its short history. The basement depth is greatest in the central rift (maximum ,3 km) and decreases to the east and west. In detail however, two separated depocentres 20,50 km long were created controlled by N- and S-dipping faults before 0.4 Ma, while since ca. 0.4 Ma a single depocentre (80 km long) has been controlled by several connected N-dipping faults, with maximum subsidence focused between the two older depocentres. Thus isolated but nearby faults can persist for timescales ca. 1 Ma and form major basins before becoming linked. There is a general evolution towards a dominance of N-dipping faults; however, in the western Gulf strain is distributed across several active N- and S-dipping faults throughout rift history, producing a more complex basin geometry. [source] 3D seismic analysis of slope-confined canyons from the Plio,Pleistocene of the Ebro Continental Margin (Western Mediterranean)BASIN RESEARCH, Issue 1 2005Claudia Bertoni This paper documents the importance of three-dimensional (3D) seismic data for integrated stratigraphic,morphological analysis of slope systems. Furthermore, it contributes to the general understanding of the evolutionary mechanisms of slope-confined submarine canyons on continental margins and their significance in a sequence stratigraphic framework. Recently acquired 3D seismic data from the Ebro Continental Margin (Western Mediterranean) have been used to study a series of remarkably well-imaged submarine canyons in the Plio-Pleistocene succession. Detailed mapping shows that these canyons are restricted to the slope, and thus can be compared with slope-confined canyons observed on the present day seabed of many continental margins. The slope-confined canyons are typically 0.5,2 km wide, 10,15 km long, and incise more than 50 m into the slope units. Their most striking characteristic is an upslope branching geometry in the head region involving up to three orders of bifurcation, with downslope development of a single incisional axis. The submarine canyons are characterized by a nested stacking pattern, undergoing alternating phases of cutting and filling. Limited parts of the upper and middle slope remain outside the canyon system, confined in sharp depositional ridges. The canyons are observed on closely spaced surfaces and exhibit a geometry that allowed the construction and discussion of a local sequence stratigraphic model for their evolution. In general, active incision of the canyons is observed at times throughout almost the entire cycle of base-level change. However, erosional activity is more significant during the later stages of the relative sea level rise and the entire falling stage, with the timing of maximum erosion observed at the end of the cycle. The minimum erosional activity of the canyons is linked instead to the earliest part of the relative sea level rise. [source] Brazilian Tapir Density in the Pantanal: A Comparison of Systematic Camera-Trapping and Line-Transect SurveysBIOTROPICA, Issue 2 2008Mogens Trolle ABSTRACT The density of Brazilian tapirs (Tapirus terrestris) was studied in the northeastern part of the Pantanal wetlands of Brazil using two simultaneous and independent methods: (1) systematic camera trapping combined with capture,recapture analysis, with camera traps spaced 1 km apart and distributed over 54 km2; and (2) line-transect sampling using an array of 12 linear transects, from 3.8 to 7.2 km long, covering the principal open and forest habitat types across the entire 1063 km2 SESC Pantanal Reserve. The two methods yielded conservative density estimates of 0.58 ± 0.11 tapirs/km2 (camera trapping) and 0.55 (95% CI 0.30,1.01) tapirs/km2 (line transects). The study suggests that certain Pantanal habitats and sites can sustain relatively high population densities of tapirs when these animals are protected from hunting. Further testing of the camera-trapping methodology as applied to tapirs is required, particularly focusing on extending the survey period. As it represents a relatively rapid method for estimating population density, in comparison to line-transect surveys, and as it generates information simultaneously on multiple species that are conservation priorities, we recommend that camera-trapping surveys be applied more widely across a variety of Pantanal habitats and land-use categories in order to confirm the value of the vast 140,000 km2 wilderness region for this vulnerable species. RESUMO A densidade de Tapirus terrestris foi avaliada na região Nordeste do Pantanal do Mato Grosso usando dois métodos simultâneos e independentes: 1) método sistemático com armadilhas fotográficas, combinado com análises de captura e recaptura, com câmaras fotográficas espaçadas 1 km entre si e distribuídas sobre uma área de 54 km2, dispostas em 4 grades contínuas, com 14 câmaras ativas por 9 dias consecutivos em cada grade; e 2) 12 transecções lineares variando em dimensões de 3,8,7,2 km de extensão, cobrindo os principais habitats abertos e fechados, sobre uma região de 1063 km2 da Reserva Particular do Patrimônio Natural SESC Pantanal. Os dois métodos resultaram em estimativas de densidade de 0.58 ± 0.11 antas/km2 (câmaras fotográficas) e 0.55 (95% intervalo de confiança 0.30,1.01) antas/km2 (transecções lineares). Os resultados sugerem que certos hábitats e áreas do Pantanal podem sustentar densidades relativamente elevadas de antas, quando protegidas da caça. A metodologia utilizando câmaras fotográficas em estudos sobre antas deve ser testada incrementando períodos de avaliação. Como o método representa uma forma rápida de avaliação das densidades populacionais, em comparação com transecções lineares, e gera informações simultâneas sobre múltiplas espécies que podem ser prioritárias para conservação, recomendamos que avaliações com armadilhas fotográficas sejam amplamente aplicadas para a espécie na variedade de hábitats do Pantanal, visando afirmar o valor dessa vasta e selvagem região de 140.000 km2. [source] Rapid tunnel-valley formation beneath the receding Late Weichselian ice sheet in Vendsyssel, DenmarkBOREAS, Issue 4 2009PETER B. E. SANDERSEN Interpretation of Transient ElectroMagnetic (TEM) data and wire-line logs has led to the delineation of an intricate pattern of buried tunnel valleys, along with new evidence of glaciotectonically dislocated layers in recessional moraines in the central part of Vendsyssel, Denmark. The TEM data have been compared with recent results of stratigraphical investigations based on lithological and biostratigraphical analyses of borehole samples and dating with Optically Stimulated Luminescence (OSL) and radiocarbon. This has provided an overview of the spatial distribution of the late Quaternary lithostratigraphical formations, and the age of the tunnel valleys has been estimated. The tunnel valleys are typically 5,10 km long, 1 km wide and are locally eroded to depths of more than 180 m b.s.l. The valleys are interpreted to have been formed by subglacial meltwater erosion beneath the outermost part of the ice sheet during temporary standstills and minor re-advances during the overall Late Weichselian recession of the Scandinavian Ice Sheet. The formation of the tunnel valleys occurred after the retreat of the Main ice advance c. 20 kyr BP and before the Lateglacial marine inundation c. 18 kyr BP. Based on the occurrence of the tunnel valleys and the topography, four ice-marginal positions related to the recession of the northeastern Main advance and seven ice-marginal positions related to the recession from the following eastern re-advance across Vendsyssel are delineated. All the tunnel valleys were formed within a time interval of a few thousand years, giving only a few hundred years or less for the formation of the tunnel valleys at each ice-marginal position. [source] | |||||||||||||||||||