Tertiær landhævning og erosion

Intet resum

Конкурентоспроможність машинобудівних підприємств на ринку залізничного рухомого складу

Охарактеризовано распределение производственных мощностей и потребителей вагоно-строительной продукции на экономических рынках СНГ. Дана оценка конкурентной среды в подотрасли машиностроения железнодорожного подвижного состава на макро и микроуровне, выявлены факторы риска и обоснованы мероприятия, ориентированные на укрепление конкурентоспособности исследуемых предприятий. Ключевые слова: машиностроительное предприятие, конкурентоспособность, рынок, железнодорожный подвижной состав.Охарактеризовано розподіл виробничих потужностей і споживачів вагонобудівної продукції на економічних ринках СНД. Наведено оцінку конкурентного середовища в підгалузі маши-нобудування залізничного рухомого складу на макро і мікрорівні, виявлено фактори ризику й обґрунтовано заходи, орієнтовані на зміцнення конкурентоспроможності досліджуваних підприємств. Ключові слова: машинобудівне підприємство, конкурентоспроможність, ринок, залізничний рухомий склад.The paper characterizes production capacities and consumers of wagon products on the economic markets of CIS countries. The competition environment in the sector of railway rolling stock building on macro and micro-level was assessed, the factors of risk were identified, and measures oriented to streng-thening the competitiveness of the enterprises under investigation are well-grounded. Keywords: machine-building enterprise, competitiveness, market, railway rolling stock

Identification of hydrocarbons in chalk reservoirs from surface seismic data: South Arne field, North Sea

Seismic data are mainly used to map out structures in the subsurface, but are also increasingly used to detect differences in porosity and in the fluids that occupy the pore space in sedimentary rocks. Hydrocarbons are generally lighter than brine, and the bulk density and sonic velocity (speed of pressure waves or P-wave velocity) of hydrocarbon-bearing sedimentary rocks are therefore reduced compared to non-reservoir rocks. However, sound is transmitted in different wave forms through the rock, and the shear velocity (speed of shear waves or S-wave velocity) is hardly affected by the density of the pore fluid. In order to detect the presence of hydrocarbons from seismic data, it is thus necessary to investigate how porosity and pore fluids affect the acoustic properties of a sedimentary rock. Much previous research has focused on describing such effects in sandstone (see Mavko et al. 1998), and only in recent years have corresponding studies on the rock physics of chalk appeared (e.g. Walls et al. 1998; Røgen 2002; Fabricius 2003; Gommesen 2003; Japsen et al. 2004). In the North Sea, chalk of the Danian Ekofisk Formation and the Maastrichtian Tor Formation are important reservoir rocks. More information could no doubt be extracted from seismic data if the fundamental physical properties of chalk were better understood. The presence of gas in chalk is known to cause a phase reversal in the seismic signal (Megson 1992), but the presence of oil in chalk has only recently been demonstrated to have an effect on surface seismic data (Japsen et al. 2004). The need for a better link between chalk reservoir parameters and geophysical observations has, however, strongly increased since the discovery of the Halfdan field proved major reserves outside four-way dip closures (Jacobsen et al. 1999; Vejbæk & Kristensen 2000)

De norske fjelde - rodløse realiteter

I GeologiskNyt 5/2007 opsummerede vi et væld af oplysninger, der viser, at de norske fjelde har været udsat for vertikale bevægelser i kilometer-skala i Kænozoikum, og at fjeldene først har nået deres nuværende højder i Neogen. Søren B. Nielsen (SBN) kommenterer i GeologiskNyt 1/2008 vores indlæg, men kommer desværre ikke med yderligere argumenter for sin hypotese om, at de norske fjelde er resterne af den bjergkæde, der blev dannet under den kaledonske kollision mellem Baltica og Grønland for mere end 400 millioner år siden. Derimod skaber SBN usikkerhed om simple kendsgerninger, der er af afgørende betydning for vurderingen af de norske fjeldes alder og struktur

Miocene uplift of the NE Greenland margin linked to plate tectonics: Seismic evidence from the Greenland Fracture Zone, NE Atlantic:Margin Uplift and Plate Tectonics

Tectonic models predict that following breakup, rift margins undergo only decaying thermal subsidence during their postrift evolution. However, postbreakup stratigraphy beneath the NE Atlantic shelves shows evidence of regional-scale unconformities, commonly cited as outer margin responses to inner margin episodic uplift, including the formation of coastal mountains. The origin of these events remains enigmatic. We present a seismic reflection study from the Greenland Fracture Zone-East Greenland Ridge (GFZ-EGR) and the NE Greenland shelf. We document a regional intra-Miocene seismic unconformity (IMU), which marks the termination of synrift deposition in the deep-sea basins and onset of (i) thermomechanical coupling across the GFZ, (ii) basin compression, and (iii) contourite deposition, north of the EGR. The onset of coupling across the GFZ is constrained by results of 2-D flexural backstripping. We explain the thermomechanical coupling and the deposition of contourites by the formation of a continuous plate boundary along the Mohns and Knipovich ridges, leading to an accelerated widening of the Fram Strait. We demonstrate that the IMU event is linked to onset of uplift and massive shelf progradation on the NE Greenland margin. Given an estimated middle to late Miocene (~15–10Ma) age of the IMU, we speculate that the event is synchronous with uplift of the east and west Greenland margins. The correlation between margin uplift and plate motion changes further indicates that the uplift was triggered by plate tectonic forces, induced perhaps by a change in the Iceland plume (a hot pulse) and/or by changes in intraplate stresses related to global tectonics

Norges fjelde - og de geologiske kendsgerninger

Hvorfor der er bjerge i Norge? For at kunne besvare dette tilsyneladende simple spørgsmål, må man først fi nde ud af, hvornår bjergene blev til bjerge. Er de gamle og skabt af kolliderende kontinenter, eller er de unge og dannet af aktive (men måske dårligt forståede) kræfter i Jordens indre

Seismic and petrophysical properties of Faroe Islands basalts: the SeiFaBa project

Flood basalt-covered basins exist worldwide along continental margins and are now in focus as targets for future hydrocarbon exploration. It is generally difficult to image through the basalt cover by conventional seismic reflection methods, and this is a major challenge to future petroleum exploration offshore the Faroe Islands. Long-offset profiling has proven very successful (White et al. 2003). Surprisingly, however, it is possible to image through kilometre-thick basalt sequences on some conventional profiles. Details of basalt stratigraphy are revealed on old, reprocessed seismic profiles as well as on recently acquired profiles, even though the imaging may be unsuccessful on nearby profiles (e.g. Boldreel & Andersen 1993). This stresses the need for a better understanding of the acoustic and other physical properties of basalt as well as of the degree of three-dimensional heterogeneity. The SeiFaBa project (Seismic and petrophysical properties of Faroes Basalt, 2002–2005) is funded by the Sindri Group as part of the programmes for licensees within the Faroese offshore area, and addresses these issues with special focus on the subaerially extruded flood basalts of the Faroe Islands (cf. Japsen et al. in press)

ULTRASONIC VELOCITIES OF CHALK SAMPLES: INFLUENCE OF POROSITY, FLUID CONTENT AND TEXTURE

ABSTRACT The acoustic properties of the pure chalk of the Upper Cretaceous Tor Formation have been studied on core material from the Dan and South Arne fields, Danish North Sea. Detailed investigations were carried out on 56 vertical plug samples with porosities ranging from 14% to 45%, i.e. measurement of P-and S-wave velocities of dry and water-wet samples and microtextural image analysis on backscatter micrographs. Porosity is the primary control on sonic velocities and elastic moduli of chalk with identical pore fluids. For chalk samples dominated by fine carbonate particles (mud) we obtain a well-defined relation between elastic moduli and porosity, which can be modeled using a modified upper Hashin-Shtrikman bound. The trend is defined by a bulk and shear modulus at zero porosity of 54 and 22 GPa, and by a high-porosity end-member at 47%. We find that compaction, grain size distribution, and possibly mineralogy, rather than pore-filling cementation, control the variation of porosity for the samples. Variations in chalk particle size distribution and the content of non-carbonates influence the relation between elastic properties and porosity for the samples investigated even though the carbonate content is >95%. South Arne samples are found to be stiffer than Dan/Gorm samples for identical porosities e.g. a porosity of 30% corresponds on average to a bulk modulus of 17 GPa and 14 GPa, respectively, for the saturated samples. Conversely, a bulk modulus of 15 GP

Upper Jurassic – Lower Cretaceous of the Danish Central Graben: structural framework and nomenclature

The Danish Central Graben is part of the mainly Late Jurassic complex of grabens in the central and southern North Sea which form the Central Graben. The tectonic elements of the Danish Central Graben in the Late Jurassic are outlined and compared to those in the Early Cretaceous based on reduced versions of published maps (1:200 000), compiled on the basis of all 1994 public domain seismic and well data. The Tail End Graben, a half-graben which stretches for about 90 km along the East North Sea High, is the dominant Late Jurassic structural feature. The Rosa Basin (new name) is a narrow, north–south-trending basin extending from the south-western part of the Tail End Graben. The Tail End Graben ceased to exist as a coherent structural element during the Early Cretaceous and developed into three separate depocentres: the Iris and Gulnare Basins to the north and the Roar Basin to the south (new names). The Early Cretaceous saw a shift from subsidence focused along the East North Sea High during the Late Jurassic to a more even distribution of minor basins within the Danish Central Graben. The depth to the top of the Upper Jurassic – lowermost Cretaceous Farsund Formation reaches a maximum of 4800 m in the northern part of the study area, while the depth to the base of the Upper Jurassic reaches 7500 m in the Tail End Graben, where the Upper Jurassic attains a maximum thickness of 3600 m. The Lower Cretaceous Cromer Knoll Group attains a maximum thickness of 1100 m in the Outer Rough Basin