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11.
Tomasz Janik Marek Grad Aleksander Guterch Ryszard Dadlez Jukka Yliniemi Timo Tiira G. Randy Keller Edward Gaczy&#x;ski CELEBRATION Working Group 《Tectonophysics》2005,411(1-4):129-156
The large-scale CELEBRATION 2000 seismic experiment investigated the velocity structure of the crust and upper mantle between western portion of the East European Craton (EEC) and the eastern Alps. This area comprises: the Trans-European Suture Zone, the Carpathian Mountains, the Pannonian Basin and the Bohemian Massif. This experiment included 147 chemical shots recorded by 1230 seismic stations during two deployments. Good quality data along 16 main and a few additional profiles were recorded. One of them, profile CEL03, was located in southeastern Poland and was laid out as a prolongation of the TTZ profile performed in 1993. This paper focuses on the joint interpretation of seismic data along the NW–SE trending TTZ–CEL03 transect, located in the central portion of the Trans-European Suture Zone. First arrivals and later phases of waves reflected/refracted in the crust and upper mantle were interpreted using two-dimensional tomographic inversion and ray-tracing techniques. This modelling established a 2-D (quasi 3-D) P-wave velocity lithospheric model. Four crustal units were identified along the transect. From northwest to southeast, thickness of the crust varies from 35 km in the Pomeranian Unit (NW) to 40 km in the Kuiavian Unit, to 50 km in the Radom–Łysogóry Unit and again to 43 km in the Narol Unit (SE). The first two units are thought to be proximal terranes detached from the EEC farther to the southeast and re-accreted to the edge of the EEC during the Early Palaeozoic. The origin of the remaining two units is a matter of dispute: they are either portions of the EEC or other proximal terranes. In the area of the Polish Basin (first two units), the P-wave velocity is very low (Vp < 6.1 km/s) down to depths of 15–20 km indicating that a very thick sedimentary and possibly volcanic rock sequence, whose lower portion may be metamorphosed, is present. The velocity beneath the Moho was found to be rather high, being 8.25 km/s in the northwestern portion of the transect, 8.4 km/s in the central sector, and 8.1 km/s in the southeastern sector. 相似文献
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Jouni I. Peltoniemi Jukka Piironen Jyri Nrnen Juha Suomalainen Risto Kuittinen Lauri Markelin Eija Honkavaara 《ISPRS Journal of Photogrammetry and Remote Sensing》2007,62(6):434-446
The Sjökulla test site is used for testing and calibrating aerial images. The permanent test field is made of four types of gravel (dark gabbro, grey granite, red granite, white limestone) in two sizes (diameters 8–16 mm and 4–8 mm) set in various patterns. The bidirectional reflection properties of the targets together with their temporal changes must be known in order to carry out radiometric and spectral evaluation and calibration.The bidirectional reflectance distribution functions (BRF) of the gravel have been measured several times in the test fields using portable field goniospectrometers belonging Finnish Geodetic Institute (FGI), and once using the European Goniometic Facility (EGO) of the Joint Research Centre (JRC) at Ispra, Italy. Detailed BRFs have been obtained, showing features typical to particulate media, e.g. a small bowl shape, strong backscattering, and smooth wavelength dependence. Temporal range measurements over several years show that the black gabbro and red granite are fairly stable, while the grey granite has changed somewhat over the years and the white limestone has experienced dramatic darkening effects, requiring action to be taken.The measured BRF data have increased the usability of the test field considerably. The results are also useful in the development and validation of scattering models for particulate media. The site has proved to be a good test bench for goniospectrometric instruments, too. 相似文献
13.
Spiral garnet porphyroblasts are known to record lengthy periods of deformation and metamorphism by preserving single or multiple FIAs (Foliation Intersection Axis) formed normal to tectonic shortening directions. Thanks to technological advances in X-ray computed micro-tomography (XCMT), FIAs can now be readily determined in relatively large samples in contrast to previous methods that require the preparation of a set of radial vertical and horizontal thin sections of samples. XCMT scanning not only alleviates tedious thin section based procedures but also illuminates the complete internal architecture of a rock sample allowing three-dimensional (3D) quantitative shape analysis of an individual porphyroblast as well as precise measurement of FIAs. We applied the technique to a sample from the Hunza Valley in the Karakoram metamorphic complex (KMC), NW Himalayas, containing numerous garnet porphyroblasts with spiral-shaped inclusion trails. The XCMT imaging reveals an E–W trending FIA within the sample, which is consistent with orthogonal N–S collision of the India-Kohistan Island Arc with Asia. Garnet long axes (XGT) have variable plunges that define a broad sub-vertical maximum and a small sub-horizontal maximum. The XGT principle maxima lie at N-090 and N-120. Smaller maxima lie at N-020 and N-340. Geometric relationships between XGT axes and FIA orientation in the sample suggest that porphyroblast shapes are controlled by the geometry of the lens-shaped microlithons in which they tend to nucleate and grow. The orientation of inclusion trails and matrix foliations in the sample are correlated with three discrete tectono-metamorphic events that respectively produced andalusite, sillimanite and kyanite in the KMC. Late staurolite growth in the sample reveals how the rocks extruded to the surface via a significant role of roll-on tectonics, which can be correlated with the Central Himalayas. 相似文献
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Sandra Siljeström Tomas Hode Jukka Lausmaa Peter Sjövall Jan Toporski Volker Thiel 《Organic Geochemistry》2009,40(1):135-143
In this study, we show that time of flight-secondary ion mass spectrometry (ToF-SIMS) can be used to detect organic biomarkers, such as hopanes and steranes, in non-fractionated crude oils, without extraction and chemical preparation. Hopanes and steranes may provide valuable information on the history of life on early Earth, particularly if they are present in fluid inclusions in ancient rocks. Due to the presence of different generations of inclusions in even very small rock samples, it would be advantageous to find a method capable of detecting biomarkers in single oil rich fluid inclusions. The capability of ToF-SIMS for detailed chemical analysis of very small sample amounts makes it a potential technique for such analysis, and in this work this possibility is explored. The presence of hopanes and steranes in four different crude oils of different ages and stages of biodegradation was investigated using ToF-SIMS and GC–MS. By combining analyses of biomarker standards, crude oils and chromatographic oil fractions, specific peaks for the different biomarkers were identified in the ToF-SIMS spectra. The presence of these peaks in the spectra from the crude oil samples could be attributed to the biomarkers based on exact mass determination and by comparison with the spectra from the biomarker containing and biomarker lacking fractions, respectively. In addition, the results show that a significant biomarker signal may be obtained from a 10 μm2 oil sample, demonstrating the potential of ToF-SIMS for analysis of single oil bearing fluid inclusions, which in turn may contribute to a better understanding of the early history of life on Earth. 相似文献
16.
Future fluvial erosion and sedimentation potential of cohesive sediments in a coastal river reach of SW Finland 
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下载免费PDF全文 Eliisa Lotsari Juha Aaltonen Noora Veijalainen Petteri Alho Jukka Käyhkö 《水文研究》2014,28(25):6016-6037
This study aims to analyse the combined impacts of future discharges and sea levels on erosion–sedimentation potential, and its seasonal changes, in a ~43‐km‐long coastal river reach of South‐west Finland. To our knowledge, this kind of combined study has not been performed before. In addition to surveying the present erosion–sedimentation conditions, the daily erosion–sedimentation potential is simulated with a one‐dimensional hydrodynamic model for the 1971–2000 and 2070–2099 periods by applying four discharge scenarios. Different sea level stages are also employed in the simulations. All scenarios forecast increasing autumn and winter discharges, but diminishing summer discharges. This indicates increasing river channel erosion, particularly during winters and autumns. Although discharge changes have altogether a greater influence on erosion–sedimentation potential, the importance of sea level changes on sedimentation is noticeable in the estuary. The rising sea level scenarios increase the sedimentation potential. In total, by 2070–2099, the erosion potential may increase in most parts of the study area. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
17.
Spatial information on climatic characteristics is beneficial in e.g. regional planning, building construction and urban ecology. The possibility to spatially predict urban?Crural temperatures with statistical techniques and small sample sizes was investigated in Turku, SW Finland. Temperature observations from 36 stationary weather stations over a period of 6?years were used in the analyses. Geographical information system (GIS) data on urban land use, hydrology and topography served as explanatory variables. The utilized statistical techniques were generalized linear model and boosted regression tree method. The results demonstrate that temperature variables can be robustly predicted with relatively small sample sizes (n????20?C40). The variability in the temperature data was explained satisfactorily with few accessible GIS variables. Statistically based spatial modelling provides a cost-efficient approach to predict temperature variables on a regional scale. Spatial modelling may aid also in gaining novel insights into the causes and impacts of temperature variability in extensive urbanized areas. 相似文献
18.
AbstractDetecting and describing movement of vehicles in established transportation infrastructures is an important task. It helps to predict periodical traffic patterns for optimizing traffic regulations and extending the functions of established transportation infrastructures. The detection of traffic patterns consists not only of analyses of arrangement patterns of multiple vehicle trajectories, but also of the inspection of the embedded geographical context. In this paper, we introduce a method for intersecting vehicle trajectories and extracting their intersection points for selected rush hours in urban environments. Those vehicle trajectory intersection points (TIP) are frequently visited locations within urban road networks and are subsequently formed into density-connected clusters, which are then represented as polygons. For representing temporal variations of the created polygons, we enrich these with vehicle trajectories of other times of the day and additional road network information. In a case study, we test our approach on massive taxi Floating Car Data (FCD) from Shanghai and road network data from the OpenStreetMap (OSM) project. The first test results show strong correlations with periodical traffic events in Shanghai. Based on these results, we reason out the usefulness of polygons representing frequently visited locations for analyses in urban planning and traffic engineering. 相似文献
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Jökulhlaups are the consequence of a sudden and significant release of meltwater from the edge of a glacier. Such floods are sourced commonly from ice-dammed lakes, but occasional volcanic eruptions beneath ice can produce intense jökulhlaups due to prodigious rates of meltwater release. Globally, volcanogenic jökulhlaups have caused fatalities and damage to infrastructure within effected catchments. Here, we present the results of one-dimensional hydraulic modelling of the inundation area of a massive, hypothetical jökulhlaup on the Jökulsá á Fjöllum River in northeast Iceland; the floodwater source for this simulation is an eruption within the ice-filled caldera of Bárðarbunga: an active volcano beneath the Vatnajökull ice cap. Remotely sensed data were used to derive a digital elevation model and to assign surface-roughness parameters. We used a HEC-RAS/HEC-GeoRAS system to host the hydraulic model; to calculate the steady water-surface elevation; to visualise the flooded area; and to assess flood hazards. Maximum discharge was set notionally at 180,000 m3 s?1 and the duration and volume of the jökulhlaup were placed at 39 h and 14 km3, respectively. During the simulated rise to maximum discharge, the mean velocity of the jökulhlaup was 2.8 m s?1 over a distance of 120 km. At the height of the jökulhlaup an area of 460 km2 was inundated. Modelling results showed that, along short reaches, stream-power values exceeded 11,000 W m?2; such energy conditions would have allowed boulders up to 10-m in diameter to be mobilised by the jökulhlaup. Unsteady flow was simulated along a 22-km reach of the flood tract and it revealed strong spatial and temporal variations in flood power. Besides providing insight into the erosional and depositional effects of a volcanogenic jökulhlaup, the modelling results enable estimates of the relative timing and location of likely flooding hazards. 相似文献
20.
SVEKALAPKO Seismic Tomography Working Group Jukka Yliniemi Elena Kozlovskaya Sven-Erik Hjelt Kari Komminaho Anton Ushakov 《Tectonophysics》2004,394(1-2):41-67
In 1998–1999, a large-scale seismic array was deployed in Finland as a part of the EUROPROBE/SVEKALAPKO subproject, involving 14 European universities and research institutes. The objective of the project was to map the deep lithosphere structure and thickness beneath the Fennoscandian Shield by means of teleseismic events. In addition, about 580 local seismic events were registered during the data acquisition period. Among them, only eight local earthquakes were recorded, the rest being quarry blasts from mining sites in Russia, Finland, Estonia and Sweden. In this study, we present the analysis of the seismic wave field from the strongest local events registered by the majority of the stations of the SVEcofennian–KArelian–LAPland–KOla Transect (SVEKALAPKO) array with the aim of mapping the structure of the upper mantle beneath the array. For this purpose, we selected the events corresponding to a single source type and compared these recordings with those from wide-angle reflection and refraction experiments in the area to identify the regional phases. The record sections of selected events demonstrate strong reflections (PmP) from the Moho boundary. The refracted Pn phases can be seen as first arrivals at distances of about 200–400 km from the source. At offsets of about 400–800 km, phases reflected from inhomogeneities in the uppermost mantle (P1) and double reflections from the Moho boundary (PmPPmP) were recorded.Results from 2D forward ray trace modeling of reflected and refracted P-waves along four profile swathes from SVEKALAPKO stations demonstrate that the mantle reflections originate from two different groups of boundaries beneath the array: one group of phases arrive from subhorizontal and gently dipping reflectors below the Moho boundary at a depth of 70–90 km, while the other group are phases originating from a depth of 100 to 130 km. Based on the irregular character of the first group of reflections, their different spatial orientation and correlation with the Moho offsets, we interpret the boundaries of this group as relicts of ancient subduction and collision processes. The second group of reflections can be explained by a transition from mechanically strong to mechanically weak lithosphere. 相似文献